Note: Descriptions are shown in the official language in which they were submitted.
3547
The present invention relates to a process for coating
inorganic subs~rates with carbides, nitrides or carbonitrides or
mixtures thereof.
It has been found that inorganic substrates can be coated
in a simple manner with carbides, nitrides or carbonitrides or mix-
tures thereof, of iron, boron or silicon or of the transition metals
of sub-groups 4 - 6 of the periodic table by direct thermal reaction
of iron, boron, silicon or transition metals of sub-groups 4 - 6 of
the periodic table or derivatives thereof with substances which act
as sources of carbon and nitrogen, by using, as sources of carbon
and nitrogen, at least one compound of the formula I
, .
Xl ~ N ~ x3
Y ~N (I)
X2
wherein Y represents =N-, =CH- or =C-halogen, one of Xl, X2
and X3 represents hydrogen, halogen, alkyl, phenyl, -CN,
_~ ~ 1 or -~ -N ~ 3 and the other two independently of one another
represent halogen, -CN, -NH2, -N ~ 1 or -~ -N ~ 3 , Rl, R3 and R4
independently of one another denote hydrogen, alkyl, halogeno-
alkyl, cyanoalkyl, aminoalkyl, alkylaminoalkyl or alkenyl, R2
denotes alkyl, halogenoalkyl, cyanoalkyl, aminoalkyl, alkylamino-
- 2 -
~: - -: :
- ~ : ~ :
::: . . .
,: : : ,: :
la~3s47
alkyl or alkellyl and ~5 denotes hydrogen or alkyl, and alkyl
groups contain 1-4 carbon atoms, the alkyl parts in substituted
alkyl groups contain 2-4 carbon atorns each and alkenyl groups
contain 3 or 4 carbon atoms each.
Compared to known methods, the process according to
the invention is distinguished, above all, by its simplicity
and economy, in that the elements car~on and nitrogen required
to form the carbides, nitrides and/or carbonitrides, and
optionally other elements which influence the course of the
reaction, such as hydrogen and/or halogen, can be fed to the
reaction zone in a simple manner and in the desired ratios.
Furthermore high deposition rates and smooth coatings
of goo~ to very good adhesion can be achieved in accordance
with the process of the invention, regardless of the type ~f
substrate and even at reaction temperatures below approx.
900C. A further advantage is that the process can in
general be carried out at normal pressure or slightly
reauced or slightly elevated pressure (approx. 700-800 mm Hg)
-which in many cases permits simplification of the apparatuses
required to carry out the reaction.
The compounds of the formula I provide carbon and
nitrogen, and where rele~ant hydrogen and/or halogen, in a
reactive state, under the reaction conditions.
Alkyl or alkenyl groups represented by Xl, X2 or X~
or Rl, R2, R3, R4 or R5, can be straight-chain or branched.
Halogen denotes fluorine, bromine or iodine, but especially
chlorine.
Examples of alkyl groups Xl, X2 or X3 according to the
- - 3 -
.
, . ~- . . ,: :.
-.-. . . . . . . ...
1053S47
definition are the methyl, ethyl, n-propyl, isopropyl, n butyl,
sec,-bu~yl and -tert.-butyl group, The following are examples of
/ Rl 15 / R~
radicals -N \ or -N -N \ represented by Xl, X2 or X3:
R2 R4
. /C~3
CH3, ~ CT.2''H3, -~7l~CH , ~H2Cl?c~l3'
. C~
CH3
-N~l CH2C~12CH2CH3, In~;l -CH3, N\ ~ N(C~12v~l3j2,
CH3 ~H3 . 3
~ 3 /~H : .
N~ . , ~ 3 , ~ ~CH2C~2Br,--~C~2C~I2C~I2c~r,
. C~12C}I:~i,
C~
'H
CH3
', ' ' ' 1'~2CH2C~`r , ~CH3
~N~l-cH2cH2cH2h~H2~ -lY~ ' ~2~ 2
CN CH3
C~I2(~13, , : '
`.. --N~C:H2CH2N~ , , --N~C~I2CH=CH2,
I2CH3
H3
2 2~ ~I2~ -N~ -~CH~, -NH--NI~CH CH CH
~: - 4 -
.. . ~ : , .. . . . . .
.. . . . .. .
. . ,
i .. . . . . .
14~5;~547
3~ 2~ I; C~ 3
N ~ n~ N - N}~2 ~ . . NE~H--C~2C~'52C'~J,
Cil3 ' C~ C
C~21~2C~
f-~Cr~2~}12ilH2 ~ --~r~I~ ~C~I2CEI2~12NE~CH3 and
CH~
C~ H2.
Preferred compounds of the formula I are those wherein
~: Y represents =N- or =C-halogen, one of Xl, X2 and X3 represents
2 < R or -N - N / and the other t~o
independently of one another represent halogen, -N < or
R5 R3 . 2
-N-N ~ R ' wherein Rl, R3, R4 and R5 lndependently of one another
. denote hydrogen or alkyl with 1-4 carbon atoms and R2 denotes
alkyl with 1-4 carbon atoms or alkenyl with 3 or 4 carbon atoms.
'J.' Particularly preferred compounds are those of the form-
:- ula I wherein Y represents =N-, one of Xl, X2 and X3 represents
-N'" Rl or -N - N ~ R3 and the other two independently of one
another represent chlorine, -N or -N - N~~~ 3, and those
of the formula I ~herein Y represents -N- and Xl, X2 and X3
independently of one another repr.esent -N or -N-NH2, and
: - 5 -
.~ , .
~ , . , ~ ~ - . . ., -
.. - .. : : ~ . ... . . . . - - -
1(~53547
Rl and R5 denote hydrogen or alkyl ~ith 1-4 carbon atoms, R2
denotes alkyl with 1-4 carbon atoms or alkenyl with 3 or 4
carbon atoms and R3 and R4 denote alkyl with 1-4 carbon atoms.
The compounds of the formula I are known or can be
manufactured in a kno~ manner. The following may be
mentioned as specific compounds of -the formula I: 2,4J5,6-tetra-
chloropyrimidine, 2,4,6-tribromopyrimidine or 2,4,6-trichloro-
pyrimidine, 2,4-dichloropyrimidine, 2,4-dichloro-6-methyl-
pyrimidine, 2,4-dichloro-6-isopropyl-pyrimidine or 2,4-d-ch'oro-
6-phenylpyrimidine, 2,4-dib~omo-6-cyano~yrimidlne, 2-chloro-4-n-
butyl-6-methylam-ino-pyrimidine, 2-chloro-4,6-diethylamino-
pyrimidine,~2-chloro-4,6-b s-(dimethylamino)-pyrimidine, 2,4,6
tris-methylamino-pyrimidine, 2,6-bis-(dimethylamino)-5-cyano-
pyrimidine, 2-propyl-4,6-di-isopropylamino-pyrimidine, 2-chloro-
4,6-bis-(~-cyanoethylarnino)-pyrimidine, 2-chloro-4,6-bis-(~-
bromoethylamino)-pyrimidine, 2,4-dichloro-6-(~-dimethylamino-
ethylamino)-pyrimidine, 2-chloro-4,6-diallylamino-pyrimidine,
2-chloro-4,6-dihydrazino-pyrimidine, 2-bromo-4-ethyl-6-ethyl-
hydrazino-pyrimidine, 2,4,6-trichloro-s-triazine or 2,4,6-tri-
bromo-s-triazine, 2,4-dichloro-6-n-butyl-s-triazine, 2,4-
, .
dichloro-6-phenyl-s-triazine, 2-chloro-4,6-diethylamino-s-
triazine, 2,4-dichloro-6-methylamino-s-triazine, 2~4-dichloro-6-
diethylamlno-s-triazine and 2,4-dichloro-6-diisopropylamino-s-
; triazine, 2-chloro-4,6-dimethylamino-s-triazine, 2-chloro-4,6-
. di-n-butylamino-s-triazine, 2-chloro-4,6-bis-(diethylamino)-s-
triazine and 2-chloro-4,6-bis-(diisopropylarnino)-s-triazine,
~^ 2,6-dichloro-4-(~-cyanoethylamino)-s triazine, 2-chloro-4-iso-
- - 6 -
., , . . :
-
; . .
~053547
propylamino-6-allylamino-s-triazine, 2,4-diamino-6-methallyl-
amlno-s-triazine, 2,4~diamino-6-cyano-s-triazine, 2-chloro-4,6
bis-(~-bromoethylamino)-s-triazine, 2,4-dichloro-6-ethylamino-
methylamino-s-triazine, 2-dipropylamino-4,6-dihydrazino-s-
triazine, 2,4-diisopropylamino-6-methylhydrazino-s-triazine,
2,4-bis-(dimethylaJnino)-6-[N,N-bis-(aminoethyl)]-hydrazino-s-
triazine, 2,4,6-tris-(diethylamino)-s-triazlne, 2,4-bis-(di-
e~hylamino)-6-dimethylamino-s-triazine, 2,4-bis-(diethylamino)-
6-isopropylamino-s-triazine, 2,4-bis-(dimethylamino)-6-n-butyl-
amino-s-*riazine and 2,4-bis-(dimethylamino)-6-(1-methylhydraz-
ino)-s-triazine.
Examples of transition metals of sub-groups 4-6 o~ the
periodic table which can be used in the process according to
the lnvention are titanium, zirconium; hafnium, vanadium,
niobium, tantalum, chromium, molybdenum, tungsten and uranium.
Preferred elements are iron, uranium, tantalum, vanadium and
tungsten, but especially boron, silicon and titanium.
The iron, boron and silicon ar,d the transition metals
of sub-groups 4-6 of the periodic table can be employed in
any desired form, for example in the ~orm of the elements.
Ho~lever, they are conveniently used in the form of deriva~ives,
especially in the case of the transition metals according to -
the definition. Examples of suitable derivatives are
hydrides, carbonyls, carbonyl-hydrides, organometallic com-
pounds and halides, such as silicon hydride (SiH4), titanium
hydride (TiH2), zirconium hydride (ZrH2), boranes, chromium
hexacarbonyl, molybdenum hexacarbonyl and tungsten hexa-
carbonyl, iron pentacarbonyl [Fe(CO)5~, FeH2(CO)4, tetra-
,
.. ,, ~ . ................... . .
, . . , . . -,
1053547
ethylti~anium, tetrame-thyl~i.l.me and tetraethylsilane, methyl-
dic~orosilane, trichlorosilane, methyl-trichlorosilane, ethyl-
trichlorosllane, trime-thylchlorosilane, boron trichloride,
silicon te-trachloride, titanium dibromide, titanium trichloride,
titanium tetrachloride and-titanium tetrabromide, zirconium
tetrachloride, vanadium trichloride and vanadium tetrachloride,
niobium pen-tachlori.de, tantalum pentachloride, chromium tri~
chloride, tungsten hexachloride and tungsten hexafluoride,
iron-II chloride and iron-III chloride, uranium tetrachloride
an~ uranium hexafluoride.
The halides, especially the chlorides, above all those
o~ boron, silicon and the transition metals, are preferred.
Boron trichloride, silicon tetrachloride and titanium tetra-
chloride are very particularly preferred.
Depending on the end use and/or the type of compound
of the formula I it can be desirable to carry out the
reaction in the presence of further additives, such as hydro-
gen, hydrogen chloride, atomic or molecular nitrogen or other
compounds which act as sources of nitrogen and/or carbon under
the reaction conditions. These substances or compounds can
contribute to the formation of the carbides, nitrides or
: carbonitrides or shift the equilibrium of the formation
reactio~ more towards the nitrides or the carbides. Examples
of such additional compounds which ac-t as sources of nitrogen
and/or carb~n under the reaction conditions are methane,
ethane, n-butane, N-methylamine, N,N-diethylamine, ethylene
diamine, benzene and ammonia,
The coating, according to the inven-tion, of inorganic
-- 8 --
-, , ~, ~ . ~ .
,. .: , ~ , . :
3547
sub~trates l~i.`t~! carbides, nitrid~, and/or carbonitrides can be
carrie~ out, ~ithin the scope of the definitio~, in accordance
with any desire~ methods which are in themselves known.
One of the most important processes is the chemical
deposition from the gas phase, also referred to as the CVD
process (chemical vapour deposition), The reaction in the
gas phase can be carried out with application o~ heat or
radiant energy In this process, the iron, boron and sili-
con or the transition metals, and the compound of the formula
I are usually employed in the form of gaseous compounds.
The reaction tempera-tures are in general between about 500
and 1,800C, preferably between 800 and 1,500C.
Hydrogen is preferably used as -the reducing agent.
In certain cases it can also be advantageous to use a carrier
gas, such as argon, to transport the starting materials into
the reaction z~ne.
According to another method7 the substrates to be
coated can also be covered with mixtures of materials, for
example powder mixtures, or be mixed, and optionally
compacted with materials which contain all or - preferably -
some of the starting materials required to form the carbides,
nitrides or carbonitridesO Thereafter, the whole is heated,
preferably to temperatures of between 500 and 1,200~C, the
heating being carried out, in accordance with the
composition OI the mixture of materials, in the presence
of the starting materials which are as yet lacking in the
,, _ 9
. . ~ .
' .
,... . . . - : ,
., ., ~ . ,,
- : . . .
1053S47
mixtur~ ol mateIials, that is to say in the presence of a
gaseous compoulld of the forrnula I or i.n the presence of
suitabln de~i~ratives, in the gaseous state, of i~on, boron or
silicon or of a transition metal
- The coating of -the subs-trates with carbides, nitrides
and/or carbonitrides can also be carried out by reaction of
the starting materials in a plasma, for example by so-called
; plasma spraying. The plasma can be produced in ~ny desired
manner, for ex~mple by means of an electric arc, glow dis-
charge or corona discharge The plasma gases used are pre-
ferably argon or hydrogen. Coa-tings according to the defi-
nition can furthermore be produced in accordance with the
~lame spraying process 5 wherein hydrogen/oxygen or ace-tylene/
oxygen flames are generally used.
A further method is to impregnate the substrate ~hich
is to be coated ~ith a solution or suspension o~ a suitable
derivative o~ iron, boron or silicon or of a transition metal
and subsequently to react the impregnated material, at
elevated temperatures, with a compound of the formula I .
The process according to the invention is preferably
carried out in accordance with the CVD technique.
Inorganic substrates which can be coated with the aid
of the process according to the invention are above all
metallic and metalloid substrates, sintered metal carbides
and carbon materials of any desired type, which can also con-
tain incompletely pyrolysed constituents, such as glassy
(amorphous) carbon, partially graphitised carbon and graphite.
The process according to the invention is also suitable for
coating ceramic substrates, glasses, oxides, nitrides and
- 10 ~
:.;
Y
~- - . .
- ~ . . ~ -
1 0 ~ 3 5 4 7
carbides.
E~amples of metallic subs-trates are ferrous metals,
such as steel and cast iron, -titani~lmS and high-melting
metals, such as tungsten, molybdenum, niobium, vanadi.um and
tantalum. Examples of sui-table metalloids are boron and
silicon, whilst suitable sintered metal carbides, that is to
say sintered materials consisting of carbides of the transi-
tion metals of sub-groups 4-6 of the periodic table and
cobalt as the binder,are above all alloys of tungsten car-
bide/cobalt, tungsten carbide/tantalu~ carbide/cobalt,
tungsten carbide/titaniurn carbide/cobalt, tungsten carbide/
vanadium carbide/cobalt, tungsten carbid~/titanium carbide/
tantalum carbide/cobalt, tungsten carbide/tantalum carbide/
niobium carbide/cobalt and tungsten carbide/titanium carbide/
tantalum carbide/niobium carbide/cobalt, Examples of suit-
able ceramic substrates and oxides are porcelain, chamotte
and clay materials, or aluminiurn oxide, SiO2 and zirconium
dioxide; Examples of nitrides and carbides are Si3N4, SiC
and chromium carbides~ ;
If carbon materials are used as substrates, a con-
siderable improvement in the oxidation resistance and
corrosion resistance of the carbon materials can in some cases
be achieved by coating the materials in accordance with the
invention.
The substrates can consist wholly or partially of one
or more of the materials mentioned and can be in any desired
form, for example in the form of powders, foils, fibres,
filaments, shaped articles or components of very diverse
. .
-- 11 --
, ,
- , . . .. . . ..
- . ,
.; .. - . ~ ~ . -
~ , ,.. , ,, ~. .. .. ....
.
19353547
ty~cs .
Dependillg on the choice of the s-tarting materials and
addi-tives, the reaction temperatures and/or the substrates,
carbides, nitrides, carboni-trides or mix-tures thereof are
formed in accordance with the process of the inven-tion;
The principal fields in which the process according
to the invention is applied are: the surface irnprovement or
surface hardening of metals and sintered metal carbides to
increase the wear resis-tance and corrosion resistance, for
example in the case of tool steel, cast iron, titanium,
metal subs-trates containing titanium, shee-t tantalum, sheet
vanadium and sheet iron and sintered metal carbides of the
abovementioned type, such as WC-Co alloys, for example for
use in lathe tools, press tools, punches, cutting tools and
drawing dies, engine components, precision components for
watches and textile machinery, rocket jets, corrosion-
resistant apparatuses for the chemical industry, and the like;
the coating of carbon electrodes and graphite electrodes, of
carbon fibres, including so-called "chopped fibres", to pro-
t~ct the fibres, to improve the adhesion and wettability by
the metal matrix and to prevent undesired reactions between
the carbon fibres and the metal matrix, of carbon-carbon
composites, above all for turbine construction; of graphite
seals and the like; the coating of ceramic materials or
glasses, for example ceramic supports for catalysts and
filter glasses, and, finally, the coating OI` boron, silicon
and tungsten fibres or filaments to achieve better wettability
by the me-tal matrix, and to protect the fibres.
. .,
- 12 -
~, - - . - .
- -.
.,
.. ,,................... - ::. .. . ..
.. . . . . .
- . :
.. . , . -
- ~05~S47
Example 1
The ex~)eLilnen~s are c~rried out in a vertical CVD
reactor of ~yrex glass (Pyrex" is a trade mark) which is closed
at the top and bo~tom by means of a flan~e lid. The reaction
gases are passed i~ltO the reactor through a sprayhead, to
~Leve a unifonll stream of gas. The temperature on the sub-
strate i~ measured by means of a pyrometer. The compounds of
the formula I are v~porised ln a vaporiser device inside or
out~ide the reactor
Th~ sub~trate can be heated by res1stance heating,
inductive heating or high frequency heating or in a reactor
externally hea-ted by mean~ of a ~urnace.
A wire of carbon-rich ~teel (piano wire) of diameter
0.6 mm i8 heated to 950C by resistance heating in an argon
atmo~phere ln an apparatus o~ e type described above. At ~-
this temperature, a.gas mix-ture consi8ting of 97% by volume of
hydrogen, 1% by ~olume o~ titanium tetrachloride and 2% by
volume of cyanuric chlor~de is passed over the substrate for
2 hour8~ the total ga8 flow being 0.202 li~re/minute [1/min,3
and th~ internal pressure in the reactor being 720 mm Hg.
A$ter thl~ perlod~ a grey, hard layer has ~ormed on the ~ub-
strate~ The layer thicknes8 i8 120-140 ~m; Vickers micro-
hardnes~ HVo 05 = 3,700 kg/mm2.
Examples 2-6
Wire9 of steel (analy9is: 1% by weight C, 0.1% by
weight Sil 0.25% b~ weight Mn, 0.1% by weight V), molybdenum,
tung8ten and niobium are coated analogously to the procedure
de~cribed in Example 1. The reaction conditions and results
are 8ummari~ed in Table I which follows.
. . .
~ ~ - 13-
~., .. , , .. , . ~ , . . . . .
. :, ~ . .-,
:; ~ . ..... :' - ~ - : -
: : ' ., , :
as3s47
- - o -- o - o -
;~ ;~
u~ l l
u~ o o o o o
I a, c~l u~ o ~ ~-- u~ c~ Lr~ o Lr~ c~
h ~ ~O C~ O O O O~ O O O O
O hO C~J O ~ O C\J O t~ O
~ ~ ~ ~ ~ ~Ij ~j ~;
h,~ .~ _ __
+~ ~ O ~ O 0 ~D
~ ~ J J ~ L~ _ J
O
P~ h
a,a) ~ .,
h ~ ~ h
h h ~ ~.0 .- ~ ~-- +' ~
~) ~ r~~1~ ~ ~ ~n ~D ~LO
u~ O a) ~ a) h~ a~ ~ ~ a) ~ r` , ~,
.Q rl a) O h ~ O a)r I h Oa) ~ h O a~ O O o
~ c~ ~ ~a ~ ~ ~-~ ~ ~ &
_ .
~I h 0
O J ~ `J ;~
E~ C
__
O - ~ ~.
~ ~\J t) C) r-l
O ~ ~ h ~ ~ C` ~J t~l ~I C~l
O O J ~ h C~ - - - -
r~ O ~ ~ C~ 1~ 1
U ~5 ~1 ~1 t~ cn o~ o~
. rl ~ O
h
0,~
o a) ~ o o o o o
0 ~ ~ ~OC`J C~l C`JC~
P~
~' ~ .
~bO
~o~ O O O O O
~q C~l C\J ~I ~ C~l
:, a)~ C~
. _ _ ___
q1 ~ o o o o o
~ ~ C~ U~ In LO ~ ~
~ E-l~ _ __ cr~ a~ ~
H _ ____ _
~ ~ -
X ~ ~ ~ ~ U~
~i ~ ~ Q~ æ ~ ~_ .
;~
- 14 -
.. :
,
: ~. .. .. .` : ~ .
.. . . .,. . -
lV53S47
Exa
A steel wire of diameter 0.78 mm (analysis: 1% by
weight C, 0.1% by weight Si, 0.25% by weight Mn, 0.1% by weight
V) is coated analogously to Example l at 95~C/72~ mm Hg and a
gas flow of 1.03 l/min. The gas mixture used contains 97%
by volur.le of hydrogen, 1% by volume of titanlum tetrachloride
and 2% by volume o~ 2-chloro-4,6-bis-(diethylamino)-s_triazine.
After 120 minutes, a layer 20 ~m thick is obtained; Vickers
micro-hardness HVo 05 = 2,270 kg/mm ~
~ Further steel wires are coated analogously -to the
description in Example 7. The reaction conditions and
results are summarlsed ir Table II wAich follows:
~'
.
. .
,
.
., .
_ 15 --
~f
~,
.. . .
,, ~ ... . .. .
: ~ - - , . ,
-: , . . .
lC~53547
_ o
CO o
u~ N ZiO
I a) N lf~ LS~ N 11~ 1
0 5~ ~ 00 00 O 00 U'~
5 . ~ ~i . o . o . . ~)
~-) h ~ O Lr~ O C`J O O ~N O
_ ~ _ ~ l
. _ _ a~
C
h.~ ~ rl
~ 1~ O O
~1 1~ ~
_ ~n ~
O Q~ ~ C) ~ Q) ,~ _~
h ~ h f:~ ~ ~ S~ ,_
P~ ~ . ~ ~: ~ h
h h 01:) ~ 00 ,n 0~ ,n ,~
- I ~ I ~ I ~ X
u~ o a) ~ a) . ~ a) . ~ sd
,Q ~1 a) O a~ a) O a~ ~) O ~ ~1
~ O +~ h ~ h ~ h P~
. u~ o ~ o u~ ~o u~ _ ~ a
~ ~ ~ .
+O ~ i O C~ O
E~ ~CH ~ ~ ~ ~ .~ U
_ _
4~ ~ ~
~ ~ tU ~
. o o ~ o ~1 ;- - - o a
~ ~ C~ C~ ~
U~ Q ~ C~ ~ ~ rl
1 0 ~ ~ .. .- . .. t~
u~ H ~3R r-l H r-l t~l
~ _ I O
.~ .,1.~ ~ H ~::
~ O~ C~OJ C~~l C~Ol t~
t~ ~1 ~_1 ~1 ~ ~0
,, ~ ~ u
h ~ 'H ~:;
. ~ ~ ~ O ~ ~ ~
C-- L-- O O
~' _
I nl t~
V $ g O :1 o
O ~ O ~
~1 ~ .
, ~ ~ O ~ ~
.
- 16 -
- .~ .~ . . . - , .
-. . ~ ~ ~ . ,
1(3S3~7
Exa~ple 11
A sintered metal carbide rod (containing 92% by weight -~
of tungsten carbide, 2% by weight of titanium carbide and 6% by
weight of cobalt) of 1 mm diameter is coated, in the manner de-
scribed in the preceding examples, for 120 minutes at 950C and
720 mm Hg. The gas mixture used contains 97% by volume of
hydrogen, 1% by volume of titanium tetrachloride and 2% by volume
of 2-chloro-4,6-bis-(diethylamino)-s-triazine. The total gas flow
is 1.03 l/min. A grey-yellow, very well-adhering layer, which
shows no cracks or pores, is obtained. Layer thickness approx.
22 ~m; Vickers micro-hardness HVo 05 = 2>600 - 3,000 kg/mm2, as
compared to a micro-hardness of the uncoated substrate of
HVo 05 = 1,800 - 2,000 kg/mm .
Example 12
- A tungsten wire of diameter 0.5 mm is coated, analogo-
usly to the procedure described in Example 1, at 950C and 720
, mm Hg. The gas mixture used contains 1% by volume of titanium
tetrachloride, 2% by volume of 2,4,5,6-tetrachloropyrimidine
and 97% by volume of hydrogen. The total gas flow is 1.03 l/min.
2Q After a reaction time of two hours, a layer which is approx.
70 ~m thick and has a Vickers micro-hardness of HVo 05 = 2,150
kg/mm is obtained.
Example 13
:
Nioblum wire coated with Al?O3 in accordance with
the CyD process ~diameter 0.7 mm; thickness of the layer of
ceramic coating 3 ~m) is coated, in the manner described in
the preceding examples, for 120 minutes at 950C and 720 mm Hg.
- 17 -
~' .
.~ - - .
.
. .
.
- ,.
105~5~7
The ~as rni.xiure u-.e(l contains 97~0 by volume o~ hydrogen, 1% by
volume o~ titani~ tetrachloride, 20,' by volume of 2,4-dichloro-
6-diethylamino-s-triazi.ne; total gas 10w 1.03 l/min. A well-
adhering grey layer is obtai.ned; laycr thickness 20 ~m;.
Vi.ckers micro-hardness HVo 015 = 2,720 kg/mm2; composition of
the layer, as determined by X-ray methods: TiCo 55No ~5.
Example 14
A steel wirc coated with chromium carbide (diameter
0.78 mm; thickness of the layer of ceramic coating 6 ~m) is
coated,analogously to Exam~le 13,with a gas mixture consisting
of 97% by volume of hydrogen, 1~' by volume of titanium tetra-
chloride and 2/~ by volume of 2,4,6-tris--(diethylamino)--s~
triazine. A well-adhering grey-brown layer which is 30 ~m
thick and has a Vickers micro-hardness HVo o5 = 2,580 kg/mm2
is obtained.
Examples 15 32
Table III which follows describes further substrates
which were Goated in a CVD reactor in the manner indicated
above:
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1053S47
~,xamPl e ~
A graphite rod of diameter 2 n~ is heated to 950C by
resistance heating in an argon atmosphere in an apparatus of
the type clescribed in Example 1. At this temperature, a gas
mixture corsisting o~ 97% by volume of hydrogen, 1% by volume
of titanium tetrachloride and 2% by volume of cyanuric chloride
is passed over the graphite rod for 2 hours, the total gas flow
being 1.03 l/min. and the in-ternal pressure in the reactor
being 720 mm Hg; After this period, a matt grey, uniform,
crack-free and non-porous layer has formed on the graphite
rod. The layer, ~hich adheres very firmly, is 190 ~m thick
and has a Vickers micro-hardness HVo 05 = 4,330-4,5~0 kg/mm2.
Example 34
A graphite rod of 2 mm diameter is coated analogously
to Example 33, under the following reaction conditions:
temperature 950C; pressure 720 mm Hg; reaction time 2
hours; gas mixture: 97% by volume of hydrogen, 1% by volume
of titanium tetrachloride, 2% by volume of 2-chloro-4,6-bis-
(diethylamino)-s-triazine; total gas flow: 1 03 l/min.
A graphite rod coated with a grey, hard layer is
obtained; layer thickness45 ~m; layer micro-hardness H~o 05 =
3,000-3,430 kg/mm2
Example 35
Example 34 is repeated, but at a temperature of 1,100C/
720 mm Hg and with a reaction time of 110 minutes A grey
layer, 200-250 ~m thick, having a micro-hardness HVo-05 =
2,580-3,180 kg~mm2 is obtained on the graphite rod.
- 23 _
. ~ . . .: - . ,
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Examples ~ 4-4
Table lV which follows describes further carbon
materials which were coated in the abovementioned manner in
a CVD reactor~ The coatings obtained in accordance ~ith these
examples have good adhesion and are free from pores and cracks.
. . .
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- 24 _
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10'~35~7
Exam~le 45
The cxperirnent is carried out in a plasma reactor using
a plasma torch of conven-tional construction rModel PJ 139 II of
Messrs Arcos, Brussels; torch ra-t.i.ng: 7.8 kw (30 V, 260 A)~,
The reactor is locat~d in a water-cooled reaction chamber of
stainless steel, sealed from the outside atmosphere. The
plasma is produced by a ~C ~ec-bic arc formed between the tung- -
sten cathode and -the copper anode of the plasma torch. The
cathode and anode are also water-cooled. Argon or hydrogen
can be used as plasma gases. The recction gases are intrc~ced
into the plasMa beam with the aid of a carrier gas, through
lateral bores in the outlet jet of the copper anode. The con
centration of the reac-tion gases in the stream of carrier gas
is ad~usted by means of the~nostatically controllable vaporiser
devices and flow regulators. The substrate, which ~der
certain circumstances can be water-cooled, is at a distance of
1-5 cm in front of the outlet orifice of the plasma beam in
the copper anode.
At the beginning of the experiment, ~he reaction chamber
is evacuated, flushed ar.d filled with argon. The plasma gas
(argon, 90 mols/hour) is then introduced and the plasma fl~ne
is lit. A graphite substrate is located at a aist~nce of 2 cm
from the outlet orifice of the plasma bearn and the reaction
gases and the carrier gas are introduced into the plasma beam
as follows: titaniwn tetrachloride: 0.02 mol/hour; carrier
gas (hydrogen) for TiCl4: l mol/hour; 2,4,6--tris-(diethyl-
amino)-s-triazine: 0.001 mol/hour. The temperature of the
plasma flame is above 3,000C; -the temperature of the substrate
- 27 -
... .- .. . - -
- ,.... . . .
: - . . .
, . . . .
1053547
surface i.s ap~rox. 2,500C. After a reaction time of 6
rninutes the plasma torch is switched off and the coated sub-
stra-te is cooled in the gas-filled reaction chamber. A
homogeneous, light grey layer having a metallic gloss is
obtained; thickness 4 ~I.m; composition as determined by
X-ray diffraction: TiC (lattice constant a = 4.33
Example 46
An aluminium oxide subs-trate is treated analogously
to the method described in ~xample 45. The temperature o~
the substrate surface during coating is approx. 1,900C.
A hard, relatively porous layer is obtained, which is built
up of several zones of different colour. The outermost,
grey layer has a lattice constan-t a = 4.25 ~.
- 28 -
....... .
