STABLE HIGH TEMPERATURE CABLES AND DEVICES MADE THEREFROM

CABLES DE CHAUFFAGE STABLES A TEMPERATURE ELEVEE, ET DISPOSITIFS QUI EN SONT FAITS

English Abstract

ABSTRACT


Compacted mineral insulated integrally sheathed
electrically conductive cables, thermocouple sensors, heat
detectors and heating elements utilizing nickel-base alloys
are disclosed, characterized in that the cable includes at
least one thermoelement composed of a type N alloy, and the
sheath is composed of an alloy having similar characteristics
to the alloy of which the or at least one thermoelement is
composed.

Claims

WHAT IS CLAIMED IS:

1. A compacted mineral-insulated integrally sheathed cable,
characterized in that the cable includes at least one
thermoelement composed of a type N alloy, and the sheath is
composed of an alloy chosen from the group consisting of (a) and
(b), wherein (a) consists essentially of from 13.0 weight percent
to 15.0 weight percent of chromium, from 1.0 weight percent to
2.0 weight percent of silicon, from 0.03 weight percent to 0.25
weight percent of magnesium and the balance nickel, and (b)
consists essentially of from 3.0 weight percent to 5.0 weight
percent of silicon, from 0.03 weight percent to 0.25 weight
percent of magnesium and the balance nickel.
2. A cable according to Claim 1, characterized in that the
sheath is composed of an alloy (a1) consisting essentially of
from 13.9 weight percent to 14.5 weight percent of chromium, from
1.3 weight percent to 1.5 weight percent of silicon, from 0.05
weight percent to 0.20 weight percent of magnesium, and the
balance nickel.
3. A cable according to Claim 1, characterized in that the
sheath is composed of an alloy (a2) consisting essentially of
from 14.05 weight percent to 14.35 weight percent of chromium,
from 1.35 weight percent to 1.45 weight percent of silicon, from
0.10 weight percent to 0.20 weight percent of magnesium, 0.15
weight percent maximum of iron, 0.05 weight percent maximum of
carbon, and the balance nickel.
4. A cable according to Claim 1, characterized in that the
sheath is composed of an alloy (a3) consisting essentially of
14.2 weight percent chromium, 1.4 weight percent silicon, 0.1



- 22 -

weight percent iron, 0.03 weight percent magnesium and the
balance nickel.
5. A cable according to Claim 1, characterized in that the
sheath is composed of an alloy (b1) consisting essentially of
from 4.0 weight percent to 4.8 weight percent of silicon, from
0.05 weight percent to 0.20 weight percent of magnesium, and the
balance nickel.
6. A cable according to Claim 1, characterized in that the
sheath is composed of an alloy (b2) consisting essentially of
from 4.2 weight percent to 4.6 weight percent silicon, from 0.10
weight percent to 0.20 weight percent magnesium, 0.05 weight
percent maximum chromium, 0.15 weight percent maximum iron, 0.05
weight percent maximum of carbon, and the balance nickel.
7. A cable according to Claim 1, characterized in that the
sheath is composed of an alloy (b3) consisting essentially of 4.4
weight percent silicon, 0.1 weight percent iron, 0.1 weight
percent magnesium and the balance nickel.
8. A cable according to Claim 1, characterized in that the
cable includes a thermoelement composed of a positive type N
alloy and a thermoelement composed of a negative type N alloy and
the sheath is composed of a positive type N alloy.
9. A cable according to Claim 1, characterized in that the
cable includes a thermoelement composed of a positive type N
alloy and a thermoelement composed of a negative type N alloy and
the sheath is composed of a negative type N alloy.
10. A cable according to Claim 1, characterized in that the
cable includes one only thermoelement, said thermoelement is
composed of a positive type N alloy and the sheath is composed of
a negative type N alloy.



- 23 -

11. A cable according to Claim 1, characterized in that the
cable contains one only thermoelement, said thermoelement is
composed of a negative type N alloy and the sheath is composed of
a positive type N alloy.
12. A cable according to Claim 1, characterized in that the
cable includes a thermoelement composed of a positive type N
alloy and a thermoelement composed of a negative type N alloy.
13. A cable according to Claim 2, characterized in that the
cable includes a thermoelement composed of a positive type N
alloy and a thermoelement composed of a negative type N alloy.
14. A cable according to Claim 3, characterized in that the
cable includes a thermoelement composed of a positive type N
alloy and a thermoelement composed of a negative type N alloy.
15. A cable according to Claim 4, characterized in that the
cable includes a thermoelement composed of a positive type N
alloy and a thermoelement composed of a negative type N alloy.
16. A cable according to Claim 5, characterized in that the
cable includes a thermoelement composed of a positive type N
alloy and a thermoelement composed of a negative type N alloy.
17. A cable according to Claim 6, characterized in that the
cable includes a thermoelement composed of a positive type N
alloy and a thermoelement composed of a negative type N alloy.
18. A cable according to Claim 7, characterized in that the
cable includes a thermoelement composed of a positive type N
alloy and a thermoelement composed of a negative type N alloy.
19. A cable according to Claim 1, characterized in that the
cable includes one only thermoelement, said thermoelement is
composed of a positive type N alloy and the sheath is composed of



- 24 -

an alloy selected from the group consisting of (b), (b1), (b2)
and (b3) wherein
(b) consists essentially of from 3.0 weight percent to
5.0 weight percent of silicon, from 0.03 weight percent
to 0.25 weight percent of magnesium and the balance
nickel;
(b1) consists essentially of from 4.0 weight percent to
4.8 weight percent of silicon, from 0.05 weight percent
to 0.20 weight percent of magnesium, and the balance
nickel;
(b2) consists essentially of from 4.2 weight percent to
4.6 weight percent silicon, from 0.10 weight percent to
0.20 weight percent magnesium, 0.05 weight percent
maximum chromium, 0.15 weight percent maximum iron, 0.05
weight percent maximum of carbon, and the balance
nickel;
(b3) consists essentially of 4.4 weight percent silicon,
0.1 weight percent iron, 0.1 weight percent magnesium
and the balance nickel.
20. A cable according to Claim 1, characterized in that the
cable contains only one thermoelement, said thermoelement is
composed of a negative type N alloy and the sheath is composed of
an alloy selected from the group consisting of (a), (a1), (a2)
and (a3) wherein
(a) consists essentially of from 13.0 weight percent to
15.0 weight percent of chromium, from 1.0 weight percent
to 2.0 weight percent of silicon, from 0.03 weight
percent to 0.25 weight percent of magnesium, and the
balance nickel;



- 25

(a1) consists essentially of from 13.9 weight percent to
14.5 weight percent of chromium, from 1.3 weight percent
to 1.5 weight percent of silicon, from 0.05 weight
percent to 0.20 weight percent of magnesium, and the
balance nickel;
(a2) consists essentially of from 14.05 weight percent
to 14.35 weight percent of chromium, from 1.35 weight
percent to 1.45 weight percent of silicon, from 0.10
weight percent to 0.20 weight percent of magnesium, 0.15
weight percent maximum of iron, 0.05 weight percent
maximum of carbon, and the balance nickel;
(a3) consists essentially of from 14.2 weight percent
chromium, 1.4 weight percent silicon, 0.03 weight
percent magnesium and the balance nickel.
21. A resistive heating element particularly useful for
operation at high temperatures comprising a cable according to
Claim 1, containing one or more thermoelements and a sheath,
characterized in that the thermoelements and the sheath are
composed of alloys which may be the same or different, and said
alloys are chosen from the group consisting of positive type N
alloys, negative type N alloys, and alloys (a), (a1), (a2), (a3),
(b), (b1), (b2) and (b3) as defined in Claim 19.
22. A resistive heating element particularly useful for
operation at high temperatures comprising a cable according to
Claim 1, containing one or more thermoelements and a sheath,
characterized in that the thermoelements and the sheath are
composed of alloys which may be the same or different, and said
alloys are chosen from the group consisting of positive type N




- 26 -

alloys, negative type N alloys, and alloys (a), (a1), (a2), (a3),
(b), (b1), (b2) and (b3) as defined in Claim 20.
23. A compacted mineral-insulated integrally sheathed
thermocoupled cable, characterized in that the cable includes at
least one thermoelement composed of a type N alloy, and the
sheath is composed of a type N alloy, further characterized in
that the alloy of which the sheath is composed is
thermoelectrically opposite to the alloy of which the or at least
one thermoelement is composed.
24. A heat detector operable at temperatures above about
1100°C comprising an elongated compacted mineral insulated
integrally sheathed cable as defined in Claim 23, disposed in an
environment where local rises in temperature may occur, causing
local increase in the conductivity of the insulating material,
said detector including means for determining the location of the
said local increase in conductivity and hence the location of the
said rise in temperature.
25. A stagnation temperature probe incorporating a type N
thermocouple as the temperature sensor, said thermocouple being
made from a cable as defined in Claim 1.
26. A stagnation temperature probe incorporating a type N
thermocouple as the temperature sensor, said thermocouple being
made from a cable as defined in Claim 2.
27. A stagnation temperature probe incorporating a type N
thermocouple as the temperature sensor, said thermocouple being
made from a cable as defined in Claim 3.
28. A stagnation temperature probe incorporating a type N
thermocouple as the temperature sensor, said thermocouple being
made from a cable as defined in Claim 4.



- 27 -

29. A stagnation temperature probe incorporating a type N
thermocouple as the temperature sensor, said thermocouple being
made from a cable as defined in Claim 5.
30. A stagnation temperature probe incorporating a type N
thermocouple as the temperature sensor, said thermocouple being
made from a cable as defined in Claim 6.
31. A stagnation temperature probe incorporating a type N
thermocouple as the temperature sensor, said thermocouple being
made from a cable as defined in Claim 7.
32. A cable according to Claim 1, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
33. A cable according to Claim 2, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
34. A cable according to Claim 3, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
35. A cable according to Claim 4, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
36. A cable according to Claim 5, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.

28

37. A cable according to Claim 6, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
38. A cable according to Claim 7, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
39. A cable according to Claim 8, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
40. A cable according to Claim 9, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
41. A cable according to Claim 10, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
42. A cable according to Claim 11, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
43. A cable according to Claim 12, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.

- 29 -

44. A cable according to Claim 13, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
45. A cable according to Claim 14, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
46. A cable according to Claim 15, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
47. A cable according to Claim 16, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
48. A cable according to Claim 17, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
49. A cable according to Claim 18, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
50. A cable according to Claim 19, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.


51. A cable according to Claim 20, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
52. A cable according to Claim 21, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
53. A cable according to Claim 22, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
54. A cable according to Claim 23, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
55. A cable according to Claim 24, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
56. A cable according to Claim 25, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
57. A cable according to Claim 26, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.

31

58. A cable according to Claim 27, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
59. A cable according to Claim 28, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
60. A cable according to Claim 29, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
61. A cable according to Claim 30, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
62. A cable according to Claim 31, in which the sheath alloy
is strengthened by addition of one or more components known for
the purpose of increasing mechanical strength of said alloys at
high temperature.
63. A cable according to Claim 32, 33 or 34, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions.
64. A cable according to Claim 35, 36 or 37, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions.

- 32 -

65. A cable according to Claim 38, 39 or 40, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions.
66. A cable according to Claim 41, 42 or 43, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide particle
dispersions.
67. A cable according to Claim 44, 45 or 46, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions.
68. A cable according to Claim 47, 48 or 49, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions.
69. A cable according to Claim 50, 51 or 52, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions.
70. A cable according to Claim 53, 54 or 55, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions.
71. A cable according to Claim 56, 57 or 58, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions.

33

72. A cable according to Claim 59, 60 or 61, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions.
73. A cable according to Claim 62, in which the said
components are chosen from the group consisting of manganese,
iron, molybdenum cobalt, tungsten and oxide-particle
dispersions.
74. A cable according to Claim 1, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
75. A cable according to Claim 2, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
76. A cable according to Claim 3, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
77. A cable according to Claim 4, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
78. A cable according to Claim 5, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.


34

79. A cable according to Claim 6, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
80. A cable according to Claim 7, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
81. A cable according to Claim 8, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
82. A cable according to Claim 9, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
83. A cable according to Claim 10, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
84. A cable according to Claim 11, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
85. A cable according to Claim 12, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.



86. A cable according to Claim 13, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
87. A cable according to Claim 14, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
88. A cable according to Claim 15, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
89. A cable according to Claim 16, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
90. A cable according to Claim 17, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
91. A cable according to Claim 18, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
92. A cable according to Claim 19, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.

36

93. A cable according to Claim 20, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
94. A cable according to Claim 21, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
95. A cable according to Claim 22, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
96. A cable according to Claim 23, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
97. A cable according to Claim 24, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
98. A cable according to Claim 25, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
99. A cable according to Claim 26, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.

37

100. A cable according to Claim 27, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
101. A cable according to Claim 28, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
102. A cable according to Claim 29, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
103. A cable according to Claim 30, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
104. A cable according to Claim 31, in which the sheath alloy
contains in addition one or more elements known for the purpose
of inhibiting metallurgical grain growth occurring at high
temperature.
105. A cable according to Claim 74, 75 or 76, in which the
said elements are chosen from the group consisting of niobium and
titanium.
106. A cable according to Claim 77, 78 or 79, in which the
said elements are chosen from the group consisting of niobium and
titanium.
107. A cable according to Claim 80, 81 or 82, in which the
said elements are chosen from the group consisting of niobium and
titanium.

38


108. A cable according to Claim 83, 84 or 85, in which the
said elements are chosen from the group consisting of niobium and
titanium.
109. A cable according to Claim 86, 87 or 88, in which the
said elements are chosen from the group consisting of niobium and
titanium.
110. A cable according to Claim 89, 90 or 91, in which the
said elements are chosen from the group consisting of niobium and
titanium.
111. A cable according to Claim 92, 93 or 94, in which the
said elements are chosen from the group consisting of niobium and
titanium.
112. A cable according to Claim 95, 96 or 97, in which the
said elements are chosen from the group consisting of niobium and
titanium.
113. A cable according to Claim 98, 99 or 100, in which the
said elements are chosen from the group consisting of niobium and
titanium.
114. A cable according to Claim 101, 102 or 103, in which the
said elements are chosen from the group consisting of niobium and
titanium.
115. A cable according to Claim 104, in which the said
elements are chosen from the group consisting of niobium and
titanium.
116. A cable according to Claim 1, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of


39

inhibiting metallurgical grain growth occurring at high
temperature.
117. A cable according to Claim 2, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
118. A cable according to Claim 3, in which the sheath alloy
contains in addition one or more components known for the purpose
increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
119. A cable according to Claim 4, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
120. A cable according to Claim 5, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
121. A cable according to Claim 6, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high



temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
122. A cable according to Claim 7, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
123. A cable according to Claim 8, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
124. A cable according to Claim 9, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
125. A cable according to Claim 10, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
126. A cable according to Claim 11, in which the sheath alloy
contains in addition one or more components known for the purpose


41

of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
127. A cable according to Claim 12, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
128. A cable according to Claim 13, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
129. A cable according to Claim 14, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
130. A cable according to Claim 15, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.


42

131. A cable according to Claim 16, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
132. A cable according to Claim 17, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
133. A cable according to Claim 18, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
134. A cable according to Claim 19, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
135. A cable according to Claim 20, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of

43

inhibiting metallurgical grain growth occurring at high
temperature.
136. A cable according to Claim 21, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
137. A cable according to Claim 22, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
138. A cable according to Claim 23, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
139. A cable according to Claim 24, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
140. A cable according to Claim 25, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high

44

temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
141. A cable according to Claim 26, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
142. A cable according to Claim 27, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
143. A cable according to Claim 28, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
144. A cable according to Claim 29, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
145. A cable according to Claim 30, in which the sheath alloy
contains in addition one or more components known for the purpose



of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
146. A cable according to Claim 31, in which the sheath alloy
contains in addition one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, and one or more elements known for the purpose of
inhibiting metallurgical grain growth occurring at high
temperature.
147. A cable according to Claim 116, 117 or 118, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.
148. A cable according to Claim 119, 120 or 121, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.
149. A cable according to Claim 122, 123 or 124, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.
150. A cable according to Claim 125, 126 or 127, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle

46

dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.
151. A cable according to Claim 128, 129 or 130, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.
152. A cable according to Claim 131, 132 or 133, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.
153. A cable according to Claim 134, 135 or 136, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.
154. A cable according to Claim 137, 138 or 139, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.
155. A cable according to Claim 140, 141 or 142, in which the
said components are chosen from the group consisting of
manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.
156. A cable according to Claim 143, 144 or 145, in which the
said components are chosen from the group consisting of



- 47


manganese, iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.
157. A cable according to Claim 146, in which the said
components are chosen from the group consisting of manganese,
iron, molybdenum, cobalt, tungsten and oxide-particle
dispersions, and the said elements are chosen from the group
consisting of niobium and titanium.


48

Description

-- 2 --




STABLE HIGH TEMPERATURE CABLES AND
DEVICES MADE THEREFROM
This invention relates to electrically
conductive cables, including thermocouple cables, and
also includes thermocouple sensors made from the said
thermocouple cables. The electrically conductive cables
10 of the invention also include heat detectors and heating
elements that are particularly useful at high
temperatures.
The invention utilizes nickel-base alloys,
including those alloys which are used in -the thermocouple
15 system designated "type N" by such standards bodies as




the Instrument Society of America, the American Society
for Testing and Materials, the International
Electrotechnical Commission and the British Standards
Institution.
In one aspect the invention provides nickel-
base thermocouple cables, and nickel-base thermocouple
sensor systems made therefrom, having superior oxidation
resistance, greater longevity and greater thermoelectric
stability under longer time periods and over a range of
10 higher temperatures up to 1300C, than existing base-
metal cables and sensor systems of the same general kind.
The invention also provides electrically
conductive cables including such cables suitable for use
as heat detectors and heating elements.
Nickel-base alloys have been used as
thermocouples since the early part of this century. One
of the commonly used thermocouples is the type K
thermocouple (so designated by the Instrument Society of
America). The positive type K thermoelement is a
20 nickel-base alloy containing 9.25 percent by weight of
chromium and 0.4 percent by weight of silicon, balance
essentially nickel. The negative type K thermoelement is
a nickel-base alloy containing 3 percent by weight of
manganese, 2 percent by weight of aluminum, 1 percent by
25 weight of silicon, with small amounts of iron and cobalt,
and the balance essentially nickel.
The type K thermocouple is recommended to be
used in an air atmosphere. At the higher temperatures
the type K thermocouple fails because of its relatively
30 poor oxidation resistance. One way in which attempts
have been made to overcome this problem is to incorporate
the type K thermocouple in a compacted ceramic-insulated
thermocouple sensor assembly.



OR

~23~

-- 4 --

As is well known in the art a first step in the
manufacture of such thermocouple sensors is to produce
the so-called "MI" (mineral insulated) cable which
comprises a sheath containing one or more thermoelement
5 conductor wires electrically insulated from the sheath
(and from each other when two or more conductor wires are
used) by compacted mineral insulation material.
In the accompanying drawings:-
Fig. 1 illustrates a typical MI cable
10 containing two conductor wires (thermoelements);
Fig. 2 illustrates two basic designs for stagnation temperature probes as more fully discussed
below; and
Fig. 3 illustrates the large negative
15 temperature coefficient of resistance of the densely
compacted insulation in heat sensors according to the
invention as more fully discussed below.
The MI cable illustrated in Fig. 1 is of a
conventional type comprising a sheath 1, compacted
20 insulation 2 and conductor wires (thermoelements) 3.
Further details of the manufacture of MI cable
as illustrated in Fig. 1 are given in Example 1 below.
To make an actual sensor from this cable, the
cable is cut and the ends of the conductors are exposed
25 by removing some of the insulation therefrom. The
exposed ends of the conductors are then joined to form a
thermojunction, which may be accomplished for example by
crimping and/or welding.
The thermojunction may simply be left exposed
30 for use in appropriate environments or may be protected
by capping -the sheath over the thermojunction with or
without insolent.
The latter type of thermocouple sensor has come
into common use because it isolates the thermocouple
35 wires from environments that may cause rapid


OR

LOWE

deterioration and it provides excellent high-temperature
insulation for the thermocouple conductor wires. The
sheath can be made of a material which, hopefully, is
compatible with the environments and processes in which
5 it is being used and which provides a measure of
mechanical protection. There are numerous commercial
suppliers of type K thermocouples in compacted ceramic-
insulated integrally-sheathed forms.
At temperatures above about 1050C known types
10 of compacted ceramic-insulated integrally-sheathed cables
and thermocouples fail prematurely because of factors
such as-
(i) the materials of which their sheaths are made such as inconel and stainless steel, fail by
15 deterioration due to oxidation or other accelerated
interaction with their gaseous environment;
(ii) the individual alloys of the type K
thermocouple fail as a result of accelerated oxidation by
low-pressure air residual in the compacted ceramic
20 insulation;
(iii) the thermoelement conductor wires fail
mechanically because of substantial alternating strains
imposed during thermal cycling. These strains are caused
primarily by longitudinal stresses which arise because of
25 substantially different temperature coefficients of
linear expansion of the sheath and thermoelement
materials. Some typical average values of these
coefficients of expansion are -




OR

isle
-- 6 --

Component Material 10-6 o -1 ( 11
sheath stainless steel 20
thermals type K 17

(iv) the thermoelement conductor alloys are
5 contaminated by dissolution of extraneous elements
received from a different sheath alloy by thermal
diffusion through the compacted insulating material.
These elements, ego My, Fe, Mow Cut cause substantial
changes in the thermoelectromotive force of the
10 thermocouple.
(v) the composition of the thermoelement conductor
wires is altered by exposure of the thermocouple to
prolonged nuclear irradiation, which results in the
transmutation of one or more elements in the alloy.
As a result, there is a need for a new integral
compacted ceramic-insulated cable suitable as a heating
element or for production of thermocouple sensors which
is substantially free of the degradative influences
described above and which demonstrates enhanced
20 environmental and thermoelectric stability at
temperatures significantly in excess of 1050C.
It is believed, therefore, that a new compacted
ceramic-insulated integrally-sheathed cable,
substantially free of degradative influences such as
25 accelerated oxidation, differential thermal stresses
cross-contamination by diffusion, and transmutations and
demonstrating enhanced resistance to environmental
interactions and to drifts in thermal em and
resistivity at temperatures up to 1300C in a variety of
30 different atmospheres, is an advancement in the art.
It is also an advancement of the art that
certain causes of thermoelectric instability which plague
conventional base-metal thermocouple transducers, namely
accelerated oxidation, in homogeneous short-range


OR

lo
-- 7 --

structural ordering, nuclear transmutations, and magnetic
transformations, are virtually eliminated in the new
thermocouple sensor of this invention. This is because
the compositions of the type N thermoelement conductor
5 wires incorporated in the new integral compacted
ceramic-insulated thermocouple sensor are such as to
virtually eliminate thermal-emf shifts due to oxidation,
in particular internal oxidation, and short-range order,
contain no strongly transmuting component elements, and
10 have magnetic transformations below room temperatures.

OBJECTS AND SUMMARY OF INVENTION
It is one of the objects of this invention to
provide an integral compacted base-metal thermocouple
cable and sensor which are thermoelectrically stable up
15 to 1300C. It is a further object of this invention to
provide an integral compacted base-metal thermocouple
cable and sensor which are highly oxidation resistant up
to 1300C~
It is another object of the invention to
20 provide electrically conductive cables and heating
elements which have similar advantages at high
temperatures.
It is a further object of this invention to
provide electrically conductive cables and heat detectors
25 which have similar advantages at high temperatures.
These and other objects of this invention are
achieved, in one aspect of the invention, by the use of
two specific alloys, and certain compositional variants
of these alloys, as sheath materials. The said alloys
30 are similar to those which are suitable for use as the
positive and negative thermoelements of the thermocouple.
The chemical compositional tolerances (percentages by



OR

3~1~6
-- 8 --

weight) for the alloying constituents of the alloys for
the positive and negative thermoelements of the
thermocouple conductors are -

Positive Alloy Element Negative Alloy
. _
14.2 + 0.15 -I ----- Or ------------- 0.02 max.
1.4 + 0.05 ----------- So ------------- 4.4 0.2
0.1 _ 0.03 ----------- Fe ------------- 0.1 + 0.03
0.03 max. ----------- C -------------- 0.03 lax.
My ------------- 0.1 + 0.05
Balance ----------- No ------------- Balance

Thermocouples of these alloys are designated
'type N' by the Instrument Society of America and other
such bodies.
The first sheath alloy of this invention
15 consists essentially of:-
(a) from about 13.0 weight percent to about 15.0
weight percent of chromium, from about 1.0 weight percent
to about 2.0 weight percent of silicon, from about 0.03
weight percent to about 0.25 weight percent of magnesium,
20 and the balance nickel.
The second sheath alloy of this invention
consists essentially of:-
(b) from about 3.0 weight percent to about 5.0
weight percent of silicon, from about 0.03 weight percent
25 to about 0.25 weight percent of magnesium and the balance
nickel.
The refractory insulating materials for the
integral compacted base-metal thermocouple sensor include
magnesium oxide, beryllium oxide, aluminum oxide,
30 zirconium oxide and other suitable refractory oxides.
This invention also includes several
applications of the novel device. One of these
applications relates to the measurement of the


OR

do
g _

temperature of moving gases such as are encountered in
gas-turbines, flues, pipes, chimneys and other confined
spaces intended for the conveyance of gases.
If an attempt is made to use a solid sensor
5 element or probe to measure temperatures in a body of gas
moving relative to the element or probe, a heating effect
due to adiabatic compression of the gaseous layer
contiguous to the surface of the sensitive probe results
in an elevated temperature measurement error. This
10 problem is conventionally combated by the use of a
'stagnation-temperature probe'. Basic designs of such a
probe are exemplified in Figure 2, wherein the components
are:-
a, h thermoelement conductor wires
b, i, n stagnation tube components
c plastic
d hold screw
e, m measurement thermojunction
f, 1 vent holes
g tight fit
j silica tube
k cement
The construction usually consists of a stem
protruding into the gas stream with a thermoelectric
25 junction in some sort of cup at its end. The thermoelectric junction is located in the 'stagnation
zone' of the gas-flow disturbance produced by this cup
and its associated orifices. These devices, in general,
are characterized by flow restrictions suited to nearly
30 stopping the gas-flow at the location of the measuring
thermoelectric junction. The idea is to obtain the
temperature reading that would occur were there no
relative velocity between the gas and the sensor probe,
that is, the temperature that would prevail in the
35 absence of the thermoelectric stagnation probe.


OR

-
81~6

-- 10 --

Stagnation probe thermocouples, particularly
those employed to measure gas temperatures in high-
performance gas-turbine engines, suffer from several
inherent error sources additional to that attributed
5 above to adiabatic compression. Examples of these
additional error sources include thermal em drift in
base-metal thermocouple alloys due to high-temperature
corrosion, catalysis of incompletely combusted air/fuel
mixtures by conventional rare-metal thermocouples, and
10 heat radiation to and from thermocouple measuring
thermojunctions from and to the internal surfaces of the
gas containment vessel.
These errors in temperature measurement
additional to the adiabatic compression error will be
15 largely eliminated by the use of type N thermocouples as
the temperature sensor incorporated in the stagnation
probe, more particularly the type N thermocouples in the
form of the integral compacted thermocouple sensor of
this invention.
Such a stagnation temperature probe
incorporating a type N thermocouple, either as a bare-
wire thermocouple or as an integral compacted
thermocouple sensor of this invention, is a significant
advancement in the art. A further advancement still is
25 to utilize one or any of the alloys specified (a), (at),
(a), (a), (b), (by), (by), (by) below as the stagnation
tube of the stagnation probe in lieu of any of the
stainless steels or any of the other alloys
conventionally used.
Another application of the novel device relates
to the detection, location and monitoring of expected or
unexpected sources of heat such as may be encountered in
machinery, storage spaces such as bins, kilns, silos,
etc.; pipelines, buildings, instruments, ships, aircraft,
35 nuclear reactors, and in many other locations. Such


OR
,,


devices, which are in most respects similar in
construction to the conventional MI cable described
above, are well known in the art. One essential
difference is that the densely compacted insulation has
5 insulating properties including a large negative
temperature coefficient of resistance, as is illustrated
in principle in Fig. 3.
Incipient local sources of heat are detected by
this device because the conductivity of the compacted
10 insulation in the vicinity of such sources increases,
over the temperature range up to about 900C, causing
local short-circuiting of the thermoelectric conductors
to form a local measuring thermojunction. This
reversible effect allows the location, intensity and
15 duration of a temporal heat source to be determined and
monitored.
Unfortunately, conventional heat sensors of
this kind show the same tendency to premature failure, by
the same causes shown by MI cables of the conventional
20 kind, when exposed to high temperatures for prolonged
periods of time. Novel heat sensors made from type N
alloys, in the manner provided by this invention, are a
significant advancement in the art in that they are
virtually free of the degradative influences described
25 above for conventional MI cable. The virtual freedom
shown by the novel heat detectors from nuclear
transmutations is of singular importance, as they are
thus suitable for use inside nuclear reactors for
substantial periods of time. Conventional heat sensors
30 of MI cable form are not free of transmutational effects.
Conventional heat detectors will fail
electrically when heated for periods of time at
temperatures above about 1100C. The novel heat detector



OR

~.Z3~
- 12 -

will withstand temperatures up to 1300C, such as might
be caused by the direct impingement of flame, for
prolonged periods of time.
A further application of the novel device
5 relates to resistive heating elements such as are used
for raising the temperature of heated enclosures such as
furnaces, ovens, baths, etc., and other spaces. Such
heating devices, which are in most respects similar in
construction to conventional MI cable described above,
10 are well known in the art. One essential difference is
that the conductor elements are made of a conventional
resistor alloy such as 'nichrome' (nichrome is a trade
mark of the Driver-Harris Company of U.K.~Italy, France,
Australia and U.S.A.) which provides resistive heating on
15 the passage of electric current.
Unfortunately conventional heater elements of
this kind show the same tendency to premature failure
from the same causes as shown by MI cables of the
conventional kind. Novel heater elements made from type
20 N alloys in the manner provided by this invention are a
significant advancement in the art in that they are
virtually free of the degradative influences described
above for conventional MI cable.
It is fortuitous that the resistivity and the
25 temperature coefficient of resistance of the positive
type N alloys are comparable with those of nichrome.
Such type N alloys can thus most efficaciously be used as
the resistive heating element in the novel invention at
high temperatures.




OR


.. . . .. . . ..

1;~3lS~1~6
- 13 -

AlloyResistivity at Temperature Coefficient
-
20C of Resistance
(~Q.cm) - (Q Q -1 ouzel)
nichrome110 - 0.00004 ) *
+ 0.00~07
positive N 95 + 0.00011
*different reports
The net effects of these properties are to make
the resistivity of a positive N alloy comparable with
10 that of nichrome at elevated temperatures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
For a better understanding of the present
invention together with other and further objects,
advantages, and capabilities thereof, reference is made
15 to the following disclosure.
The integral base-metal thermocouple sensor of
the present invention has excellent oxidation resistance
and thermoelectric stability at temperatures up to
1300C. It has been found that the alloys of this
20 invention change very little both in thermal em
output and degree of oxidation even after about 1000
hours of exposure at 1250C. When compared with the
conventional thermals of type K and sheath alloys of
inconel and stainless steel, which materials are
25 conventionally used in existing integral compacted
thermocouple sensors; the integral compacted thermocouple
sensor of this invention incorporating the type N
specified thermoelements and sheaths of alloys (a) and
(b) described above show markedly better thermoelectric
30 and environmental stability to a degree hitherto
unattainable with conventionally used base-metal alloys.


OR
,

I
- 14 -

The thermoelectric conductor alloys to be
incorporated in this invention consist essentially of the
type N alloys specified above. The sheath alloys to be
incorporated in this invention consist essentially of the
5 elemental compositions (a) and (b) described above.
Preferred compositions of type (a) consist
essentially of:-
(at) from about 13.9 weight percent to about 14.5
weight percent of chromium, from about 1.3 weight percent
10 to about 1.5 weight percent of silicon, from about 0.05
weight percent to about 0.20 weight percent of magnesium,
and the balance nickel, or more preferably -
(a) from about 14.05 percent weight to about 14.35
percent weight of chromium, from about 1.35 percent
15 weight to about 1.45 percent weight of silicon, from
about 0.10 weight percent to about 0.20 weight percent of
magnesium, about 0.15 percent weight maximum of iron,
about 0.05 percent weight maximum of carbon, and the
balance nickel.
A specific preferred composition of type (a)
consists essentially, within the usual limits of
manufacturing tolerance of:-
(a) 14.2 weight percent chromium,
1.4 weight percent silicon,
0.1 weight percent iron,
0.03 weight percent magnesium
and the balance nickel.
Preferred compositions of type (b) consist
essentially of:-
30 (by) from about 4.0 weight percent to about 4.8
weight percent of silicon, from about 0.05 weight percent
to about 0.20 weight percent of magnesium, and the
balance nickel, or more preferably -




OR
.

~;238~
- 15 -

(by) from about 4.2 percent weight to about 4.6
percent weight silicon, from about 0.10 weight percent to
about 0.20 weight percent magnesium, about 0.05 weight
percent maximum chromium, about 0.15 weight percent
5 maximum iron, about 0.05 percent weight maximum of
carbon, and the balance nickel.
A specific preferred composition of type (b)
consists essentially, within the usual limits of
manufacturing tolerance of:-
10 (by) 4.4 weight percent silicon,
0.1 weight percent iron,
0.1 weight percent magnesium
and the balance nickel
It will be clearly understood that when the
15 cable contains a single thermoelement, the most preferred sheath material is the thermoelectrically opposite alloy
to the said single thermoelement. In this case a sensor
is formed by joining the thermoelement to the sheath.
When more than one thermoelement is employed and the
20 thermoelements are made of dissimilar alloys, the sheath
material is most preferably made of the same alloy as any
one of the thermoelements.
In a further modification of the invention, of
particular value in hostile environments such as are
25 encountered in the chemical and petroleum industries, the
sheath may be fabricated of appropriate corrosion
resistant material.
The invention will be further illustrated by
the following non-limiting examples.

EXAMPLE 1
The integral compacted thermocouple cable of
this Example is fabricated using existing manufacturing
procedures. They begin with thermoelectrically matched
thermoelement wires surrounded by non-compacted ceramic


OR

- 16 -

insulating material held within a metal tube. By
rolling, drawing, swaying, or other mechanical reduction
processes the tube is reduced in diameter and the
insulation is compacted around the wires. The
5 manufacturing process parameters are adjusted so that the
ratios of sheath diameter to wire-size and sheath wall-
thickness offer a balance between maximum wall-thickness
and suitable insulation spacing for effective insulation
resistance at elevated temperatures.
An important feature of the fabrication process
is that considerable attention is given to the initial
cleanliness and chemical purity of the components and
retention of a high degree of cleanliness and dryness
throughout fabrication. As already noted above, to make
15 an actual sensor from this cable, the cable is cut and
the ends of the conductors are exposed by removing some
of the insulation therefrom. The exposed ends of the
conductors are then joined to form a thermojunction,
which may be accomplished for example by crimping and/or
20 welding.
The thermojunction may simply be left exposed
for use in appropriate environments, or may be protected
by capping the sheath over the thermojunction with or
without insolent. The measuring thermojunction of the
25 thermocouple is usually, but not always, electrically
isolated from the end of the sheath.
In this example, the alloys for the
thermocouple conductor wires are those specified above as
type N and the alloy for the sheath is that specified in
30 (a) above.
An important feature of the finished product of
this example is that the essential similarity between the
properties of the sheath alloy and the thermocouple
conductor alloys virtually eliminates the destructive
35 influences of -thermocouple contamination by cross-


OR

I 6
- 17 -

diffusion, mechanical failure due to differential thermal
stresses, and accelerated oxidation above about 1050C.
The strains caused by longitudinal stresses arising during
thermal cycling are small because of the very small dip-
furnaces in the temperature coefficients of lineal expansion
between the materials of the sheath and of the thermoelement
conductors. Some typical average values of these coefficients
of expansion are -
Component Material lo OKAY 1 (1200C)
sheath alloy (a) above 17.5
thermals type N 17.0 (average of positive
and negative)

EXAMPLE 2.
- The integral compacted thermocouple cable and sensor
of this Example is the same as described in Example 1, except
that the alloy for the sheath is that specified (at) above
used in lieu of that alloy specified (a) above.

EXAMPLE 3.
The integral compacted thermocouple cable and sensor
of this Example is the same as described in Example 1, except
that the alloy for the sheath is that specified (a) above
used in lieu of that alloy specified (a) above.

- EXAMPLE 4.
An integral compacted thermocouple cable is made as
in Example 1, the composition of the components being:-

positive thermoelement - alloy (a)
negative thermoelement - alloy (by)
sheath - alloy (a)


23/4F

ISLE

18

EXAMPLES 5 to 8
The thermocouple cables of these Examples are the
same, respectively, as those described in Examples 1 to 4
except that the sheath alloys are strengthened by addition
of one or more components known for the purpose of increase
in mechanical strength of said alloys at high temperature
for example one or more of manganese, iron, molybdenum,
cobalt, tungsten, and oxide-particle dispersions.

EXAMPLES 9 to 16
The integral compacted thermocouple cables and
sensors of these Examples are the same, respectively, as
those described in Examples 1 to 8, except that the sheath
alloys are coated to further inhibit chemical high-temperature
corrosive degradation. Such coatings include those deposited
by a wide variety of conventional protective coating processes
such as electrolytic deposition from aqueous solution or
fused salts or other electrolytic liquids, such as metallic
diffusion processes including aluminizing, chromizing,
valorizing and similar processes, such as overlay coatings,
and other protective coating processes.




23/4F

a
LOWE
- 19 -
.




EXAMPLE 17
The integral compacted thermocouple cable and
sensor of this Example is the same as described in Example
1, except that the alloy for the sheath is that specified
(b) above used in lieu of that alloy specified (a) above.

_ AMPLE 18
The integral compacted thermocouple cable and
sensor of this Example is the same as described in Example
1, except that the alloy for the sheath is that specified
(blue above used in lieu of that alloy specified (a) above.

EXAMPLE 19
The integral compacted thermocouple cable and
sensor of this Example is the same as described in Example
1, except that the alloy for the sheath is that specified
It (by) above used in lieu of that alloy specified (a) above.

EXAMPLE 20
The integral compacted thermocouple cable of this
example is the same as Example 4 except that the sheath
is composed of alloy by instead of alloy (a).




23/4F

I lo
Jo
EXAMPLES 21 to 24
The integral compacted thermocouple cables and
sensors of these Examples are the same, respectively, as
those described in Examples 17 to 20 except that the sheath
alloys contain in addition up to 1.0 weight percent of one
or more elements known for the purpose of inhibiting metal-
surgical grain growth, occurring at high temperature, for
example niobium or titanium.
EXAMPLES 25 to 28
The integral compacted thermocouple cables and
sensors of these Examples are the same, respectively, as
those described in Examples 17 to 20, except that the
sheath alloys contain in addition an appropriate amount
of one or more components known for the purpose of increase
in mechanical strength of said alloys at high temperature,
for example manganese, iron, molybdenum, cobalt, tungsten,
and oxide-particle dispersions.
EXAMPLES 29 to 32
.
The integral compacted thermocouple cables and
sensors of these Examples are the same as those described,
respectively, in Examples 17 to 20, except that the sheath
alloys contain in addition up to 1.0 weight percent of one
or more elements known for the purpose of inhibiting metal-
surgical grain growth occurring at hick temperature, for
example niobium or titanium; and also an appropriate
amount of one or more components known for the purpose
of increasing mechanical strength of said alloys at high
temperature, for example manganese, iron, molybdenum, cobalt,
tungsten, and oxide-particle dispersions.




23/4F

~L23~16
_ 21 _

EXAMPLES 33 to 48
.
The integral compacted thermocouple cables and
sensors of these Examples are the same, respectively, as
those described in Examples 17 through 32, except that the
sheath alloys are coated my any of the processes and for
the purposes describe din Example 9 through Example 16.
EXAMPLES 49 to 96
Heat detectors in accordance with the invention
are produced in the same manner as the integral compacted
cables of examples 1 through 48 except that the refractory
compacted insolent incorporates insulating properties with
a high negative temperature coefficient of resistance.

EXAMPLES 97 to 576
Heating elements in accordance with the invention
are produced in the same manner as the integral compacted
cables of examples 1 through 96, except that a single
resistive heating conductor is used in each case and the
said conductor is composed of an alloy which is respect-
lively: positive type N, (a), (at), (a) or (a).


It will be clearly understood that the invention
in its general aspects is not limited to the specific
details referred to hereinabove.

.




23/4F