Note: Descriptions are shown in the official language in which they were submitted.
ii57~
METHOD OF MAKING AND USING A TITANIUM
DEBARRED COMPRISING BODY
This invention relates Jo the art of making heat
fused titanium bride bodies useful as cutting tussle,
particularly for aluminum bawd Muriel.
Considerable interest, as a potential tool
material, has been aroused in the use of abrasion
resistant materials which consist of or contain boron,
usually in the form of a bride of titanium. The material
is usually fabricated by cementing together the titanium
bride material with a metallic binder which may include
iron, nickel, or cobalt however, utilizing such metal
binders has not met with success because of (a)
unsatisfactory strength and hardness at high temperatures,
and (b) the processing temperature required for formation
of the bond between the particles is too high (see Uo5.
patent 3,256,072).
To create a higher density sistered body with
higher Messianic strength, the art has attempted to
replace such metal binders with a combination of two
separate components, the first of which includes a nickel
phosphide or nickel phosphorus alloy, and the second
consists of a metal selected from the group comprising
chromium, molybdenum, rhenium, and the like, or a metal
debarred, chromium debarred, or zirconium debarred (Lee
U.S. patent 4,246,027). However, this particular
replacement and chemistry has not proved entirely
successful because the resulting combination of hardness
and strength still remains below desired levels and still
requires expensive hot pressing to achieve deification
But, more importantly, the presence of phosphorus in this
prior art material can make the material unsuitable for
machining aluminum based materials due to embrittlement.
,,,
- 2 ~2355~9
The invention herein disclosed includes both a method
of making and a method of using a high density, high
strength titanium debarred comprising material as well as
a titanium debarred based material itself. The method of
making comprises the steps of: (a) compacting a powder
mixture milled to a maximum particle size of 5 microns and
consisting essentially of 5 to 20% by weight of a metal
binder with the elements thereof selected from the group
consisting of cobalt, nickel and iron, and the remainder
being essentially titanium debarred except for up to 1.0%
oxygen, and up to 2% graphite, the mixture being compacted
into a body of less than required density; and by stinter-
in the compact by heating to a temperature sufficient to
density the compact to at least 97% of full theoretical
density. Preferably, the metal binder consists of an
alloy of iron and nickel with the nickel occupying 20 to
50% of the alloy. Alternatively, the binder may consist
of an alloy comprising iron, nickel, and cobalt with
nickel occupying 5 to 10% of the alloy and cobalt keenest-
tuning 2.5 to 5% of the alloy.
AdYantag~ously, the titanium debarred may replaced by up to 10% titanium carbide to further improve
the strength and hardness combination. Graphite becomes a
preferable addition, particularly up to 2% by weight of
25 the mixture, when the oxygen kitten of the titanium
debarred starting powder is in the range of 0.2-l.0~ by
wright of the mixture
The titanium debarred based material which forms one
aspect of the invention consists essentially of 5 to 20%
by weight of an iron metal binder, the binder being select
ted from the group consisting of cobalt, nickel, and iron,
or alloys thereof, and the remainder being essentially
titanium debarred except for up to 1.0% oxygen and up to
2% graphite, the material being the heat fused product of
the compacted mixture and exhibiting a hardness of at
least 90 Rockwell A and a transverse rupture strength of
at least 100,000 psi, the heat fused product having a
titanium debarred grain size equal to or less than 5
microns.
~23~ 9
-- 3
The invention further includes the method of
using such titanium debarred comprising body. The method
of use essentially comprises relatively moving a titanium
debarred based cutting tool against an aluminum based
material to machine cut the material, preferably at a
relative surface speed of at least 400 surface feet per
minute and depth of cut of from 0.010 to 0.250 inch, the
titanium debarred based cutting tool being the heat fused
product of a compacted powder mixture of 5 to 20% by
weight of a metal binder selected from the group consist
tying of cobalt, nickel and iron, and the remainder of the
mixture being essentially titanium debarred except for up
to 1.0% oxygen and up to 2% graphite.
The invention further resides in creation of a
unique, hard, and dense sintPred compact composition, the
composition consisting of the heat fused product of a
powder mixture of 5-20% by weight of a metal binder
selected from the group consisting of cobalt, nickel t and
iron, and the remainder being essentially titanium
debarred except for up to 1.0% oxygen and up to 2%
graphite, the particles of said powder, prior to heat
fusion, having a maximum particle size equal to or less
than 5 microns The opposition is characterized by a
hardness equal to or greater than 90 Rockwell A, and a
transverse rupture strength equal to or greater than
100,000 psi.
It will be shown that Capote materials
produced from titanium debarred powder combined with
either iron, nickel, cobalt, or alloys of such metals, and
when prepared in a manner that the titanium debarred
particle size in the final sistered product is less than 5
microns will produce a combination of physical
characteristics of hardness, strength, and density
superior to titanium debarred based articles prepared by
prior art techniques.
A preferred method for fabricating the material
of this invention is as follows
Jo
--4--
1. I, .
Jo A powder mixture of 5-20% by weight of a metal
binder, the metal elements being selected from the iron
group (here defined to be the group consisting of cobalt,
5 nickel and iron), and the remainder of said mixture being
essentially titanium debarred, except for up to 1.0%
oxygen and up to 2% graphite. The titanium debarred
power has a purity of 99% or greater, and has typical
contaminants which comprise 2' No and Fe. The metal
10 binder powder has a purity of 99.5% or greater, and a
starting particle size usually below 325 mesh. For
purposes of the preferred embodiment, 90 parts by weight
of a titanium diehard powder, having less than 325 mesh
in particle size, was mixed with lo parts by weight of
15 electrolytic iron powder. Four parts by weight of
Carbowax aye polyethylene glycol) was stirred into the
mixture to form a powder slurry.
A 2Q0 gram batch of these constituents was. ball
milled under acetone for 72 hours in a stainless steel
2Q mill having a chamber approximately 12 centimeters in
diameter and 12 centimeters long. Milling media in the
form of 1300 grams of Tic based media, approximately 1
centimeter in diameter and l centimeter long, was employed.
The acetone was then evaporated and the dried powder mix
25 was screened through a 30 mesh sieve.
2. Compact
Specimen bodies of the powder mixture were
compacted at a pressure of ~9-207 Ma (5-15 tons per
square inch), preferably 138 Ma lo tons per square
pa inch), and then heated to a temperature of about 673C for
one hour in a dry hydrogen atmosphere to Dixie or remove
the Carbowax 600 from the mixture.
3. Heating to Full Densification
The compacted bodies then were sistered by
35 heating each in a furnace which was evacuated to a
* - Trademark
--5--
pressure of 0.3 microns of mercury and heated to
temperature of about 1540C. The bodies were held at the
sistering temperature for a period of about 15 minutes.
Titanium carbide crystalline grains were used as the inert
substrate material. The resulting sistered product
possessed a hardness of 94 Rockwell A, an average
transverse rupture strength of 115,000 psi, and a density
over 97% of the theoretical apparent density.
It was found during experimentation with this
10 process that the presence of a certain amount of oxygen,
either as an oxide or as a elemental amount in the
mixture, caused the hardness and transverse rupture
strength to be less than desired. It was found that the
addition of up to 2% graphite (free carbon) to the
15 mixture, prior to milling, removed the influence of the
high oxygen content and restored the physical parameters
to that of specimens which did not have such oxygen
content.
Iron, cobalt, and nickel, as well as their
20 alloys, have proved to be successful binders for titanium
debarred. As long as the titanium debarred grain size in
the final sistered compact is maintained equal to or below
5 microns, good properties have been obtained using any of
the iron group metals or their alloys as a binding agent
25 Examples
Several samples were prepared according to the
preferred mode wherein a specific powder mixture was
prepared with titanium debarred as the base material and a
metal binder in varying amounts of the selected elements.
30 Some samples employed titanium carbide as a replacement
for titanium dlboride,and others contained an addition of
graphite. The results from processing such mixtures
according to the preferred method are illustrated in Table
I, which sets forth the specific hardness, transverse
35 rupture strength, and density for each of the specimens as
processed. A hardness of no less than 90 Rockwell A and a
transverse rupture strength of no less than 100,000 psi is
considered satisfactory.
The latter samples 16 and 17 in Table I draw a
comparison between equal mixtures of titanium debarred,
titanium carbide, and nickel, one sample producing a lower
hardness and strength than the other sample; the
difference between the two mixtures is the oxygen content
(sample 16 having 0.19% 2 and sample 17 having 0-95% 2~
When up to 2% by weight of the composition consisted of
graphite, the hardness and strength of sample 17 were
restored to the level of that of a mixture having a lower
level of oxygen (see sample 18). The beneficial effect of
graphite additions to compositions having a higher oxygen
content it important. Chemical analysis for carbon
content of sistered specimens with various carbon
additions up to 4% by weight indicates losses of carbon
during sistering up to a maximum loss of about I by
weight. It would appear then that the beneficial effect
of carbon additions to compositions prepared is due to the
reduction of oxygen that is present as an oxide or oxides
in the titanium debarred powder.
Titanium debarred compacts produced in the manner
described above have been found particularly suitable for
use in an unobvious manner for the machining of aluminum
and aluminum alloys. It has been found that titanium
debarred is nonreactive in the presence of molten
aluminum; and when used as a cutting tool against aluminum
based materials, the titanium debarred based cutting tool
exhibits a low affinity for aluminum based work pieces,
provided the strength and hardness of the cutting material
exceeds 100,000 psi and 90 Rockwell A respectively. The
machining test results displayed in Table II demonstrate
the unobvious utility of the use of this material for
35 machining aluminum based materials. Cutting tests were
run both with and without coolants to compare the titanium
I
debarred based cutting tool material with commercial grade
C-3 tungsten carbide based cutting tools. The machining
workups was continuously cast aluminum alloy AA 333
(8.5% silicon, 3.6~ copper, and .4% magnesium). The
5 work pieces were used both in the unmodified and sodium
modified conditions. The tool was comprised of a material
processed according to the preferred mode and having Jo%
Tub and 10% Nix The tool configuration was SPY 422. The
conditions of machine cutting were ~011 inches per
10 revolution and depth of cut .06Q inch. The cutting fluid
was 5% soluble oil in water.
The average tool it e is given in the Table in
minutes; the life is measured up to a condition when the
tool experiences .010 inch of flank wear. The average
15 tool life for the titanium debarred based tool was 2.36
times greater than that of the commercial tungsten carbide
based tool for the unmodified aluminum. similar
improvement in tool life occurred with respect to the use
of the titanium debarred tool on sodium modified aluminum;
pa the improvement in tool life was 2.52 times the life of
the tungsten carbide tool. It is worth noting that, at
2000 surface feet per minute, this improvement took place
when machining dry as well as when coolant was present.
Composition
The resulting material from the practice of the
preferred mode is unique because it consists essentially
of a titanium debarred based material consisting
essentially of 5-20% by weight of an iron metal binder,
said binder being selected from the group consisting of
3Q cobalt, nickel and iron, or alloys thereof, and the
remainder being essentially titanium debarred except for
up to 1.0% oxygen and up to 2% graphite, said material
being the heat fused product of said compacted mixture and
exhibiting a hardness of at least 90 Rockwell A and a
35 transverse rupture strength of at least 100,000 psi, said
heat fused product having a titanium debarred grain size
equal to or less than 5 microns.
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TABLE II
Tool Life of TiB2/Ni (Lowe) Material
When Machining Aluminum Work pieces
(Tool Life in Minutes, 0.010 Inch Flank Wear)
Lowe sum 2000 sum
Cutting Fluid Dry Cutting Fluid
Tub 99 290 86 59
C-3 WE 91 72 34 29
A. 333 Na-Modified
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Tub - . 175 ll9 134
C-3 WE - 90 43 37
