U.S. patent application number 11/820107 was filed with the patent office on 2008-02-07 for attrited titanium powder.
This patent application is currently assigned to International Titanium Powder, LLC. Invention is credited to Donn Armstrong, William Ernst, Lance Jacobsen, Dariusz Kogut.
Application Number | 20080031766 11/820107 |
Document ID | / |
Family ID | 39029353 |
Filed Date | 2008-02-07 |
United States Patent
Application |
20080031766 |
Kind Code |
A1 |
Kogut; Dariusz ; et
al. |
February 7, 2008 |
Attrited titanium powder
Abstract
A method of increasing the apparent density of agglomerated
ligmental titanium or titanium alloy powder produced by the
subsurface reduction of titanium tetrachloride vapor or a mixture
of titanium tetrachloride and other halide vapors in a flowing
stream of alkali or alkaline earth metal or mixtures thereof having
a first apparent density after distillation is disclosed. The
agglomerated ligmental titanium or titanium alloy powder is
introduced into an attriting system wherein the agglomerated
ligmental titanium or titanium alloy powder is attrited until the
powder becomes more spherical than ligmental and the first apparent
density is increased by a factor of from about 3 to about 8. Inert
atmosphere may be used to prevent unwanted oxygen
contamination.
Inventors: |
Kogut; Dariusz; (Tinley
Park, IL) ; Jacobsen; Lance; (Minooka, IL) ;
Ernst; William; (Frankfurt, IL) ; Armstrong;
Donn; (Waukesha, IL) |
Correspondence
Address: |
Harry M. Levy;Olson & Hierl, Ltd.
36th Floor
20 North Wacker Drive
Chicago
IL
60606
US
|
Assignee: |
International Titanium Powder,
LLC
Lockport
IL
|
Family ID: |
39029353 |
Appl. No.: |
11/820107 |
Filed: |
June 18, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60814362 |
Jun 16, 2006 |
|
|
|
Current U.S.
Class: |
420/420 ; 75/245;
75/748 |
Current CPC
Class: |
B22F 2009/043 20130101;
B22F 2998/10 20130101; C22C 14/00 20130101; B22F 2998/10 20130101;
C22B 34/1272 20130101; B22F 9/04 20130101; B22F 2009/044 20130101;
B22F 9/28 20130101; B22F 9/04 20130101 |
Class at
Publication: |
420/420 ;
075/245; 075/748 |
International
Class: |
C22C 14/00 20060101
C22C014/00; B22F 9/16 20060101 B22F009/16; C22B 1/00 20060101
C22B001/00 |
Claims
1. A method of increasing the apparent density of agglomerated
ligmental titanium or titanium alloy powder produced by the
subsurface reduction of titanium tetrachloride vapor or a mixture
of titanium tetrachloride and other halide vapors in a flowing
stream of alkali or alkaline earth metal or mixtures thereof having
a first apparent density after distillation, comprising introducing
the agglomerated ligmental titanium or titanium alloy powder into
an attriting system, attriting the agglomerated ligmental titanium
or titanium alloy powder until the powder becomes more spherical
than ligmental and the first apparent density is increased by a
factor of from about 3 to about 8.
2. The method of claim 1, wherein the attriting is performed in an
inert atmosphere.
3. The method of claim 2, wherein the inert atmosphere includes
argon.
4. The method of claim 2, wherein the inert atmosphere includes
nitrogen.
5. The method of claim 1, wherein the attriting system includes at
least one of a ball mill, a jet mill, a high pressure water mill, a
mechanco-fusion mill or a hammer mill.
6. The method of claim 1, wherein the titanium or titanium alloy
powder having a first apparent density has a first packing fraction
in the range of from about 4% to about 11% and after attrition has
a packing fraction in the range of from about 20% to about 45%.
7. The method of claim 6, wherein the packing fraction after
attrition is in the range of from about 20% to about 30%.
8. A titanium or titanium alloy powder made according to the method
of claim 1.
9. A titanium or titanium alloy powder made according to the method
of claim 7.
10. A method of increasing the apparent density of agglomerated
ligmental titanium or titanium alloy powder produced by the
subsurface reduction of titanium tetrachloride vapor or a mixture
of titanium tetrachloride and other halide vapors in a flowing
stream of sodium or alkaline earth metal or mixtures thereof having
a first apparent density after distillation, comprising introducing
the agglomerated ligmental titanium or titanium alloy powder into
an attriting system, attriting the agglomerated ligmental titanium
or titanium alloy powder in an inert atmosphere until the powder
becomes more spherical than ligmental and the first apparent
density is increased by a factor of from about 3 to about 8.
11. The method of claim 10, wherein the inert atmosphere includes a
noble gas and/or nitrogen.
12. The method of claim 10, wherein the inert atmosphere is
nitrogen.
13. The method of claim 10, wherein the titanium alloy is
substantially 6% Al and 4% V by weight with the balance
titanium.
14. The method of claim 10, wherein the attriting system includes
at least one of a ball mill, a jet mill, a high pressure water
mill, a mechanco-fusion mill or a hammer mill.
15. A titanium or titanium alloy powder made according to the
method of claim 10.
16. A titanium or titanium alloy powder made according to the
method of claim 14.
17. A titanium alloy made according to the method of claim 13.
18. A method of increasing the apparent density of agglomerated
ligmental titanium or titanium alloy powder produced by the
subsurface reduction of titanium tetrachloride vapor or a mixture
of titanium tetrachloride and other chloride vapors in a flowing
stream of sodium or alkaline earth metal or mixtures thereof having
a first apparent density after distillation, comprising introducing
the agglomerated ligmental titanium or titanium alloy powder into
an attriting system including a jet mill, attriting the
agglomerated ligmental titanium or titanium alloy powder in an
inert atmosphere in the jet mill until the powder becomes more
spherical than ligmental and the first apparent density is
increased by a factor of from about 3 to about 8.
19. The method of claim 18, wherein the jet mill is operated at a
pressure of at least 70 psi.
20. The method of claim 18, wherein the jet mill is operated at a
pressure of at least 90 psi.
21. The method of claim 19, wherein the titanium or titanium alloy
powder having a first apparent density has a first packing fraction
in the range of from about 4% to about 11% and after attrition has
a packing fraction in the range of from about 20% to about 45%.
22. The method of claim 21, wherein the jet mill is at least a 12
inch mill and the powder is fed into the mill at a rate of at least
100 lbs/hr.
23. The method of claim 22, wherein the jet mill is operated at a
pressure greater than 90psi during substantially all of the
attriting.
Description
RELATED APPLICATIONS
[0001] This application, pursuant to 37 C.F.R. 1.78(c), claims
priority based on provisional application U.S. Provisional
Application Ser. No. 60/814,362 filed Jun. 16, 2006.
FIELD OF THE INVENTION
[0002] This invention relates to a process whereby titanium and
titanium alloy powders produced by the Armstrong process are
inertly attrited to increase the apparent density, tap density and
packing fraction while maintaining the powder chemistry for further
processing to obtain high quality consolidated material.
BACKGROUND OF THE INVENTION
[0003] The powder of the invention is produced by the Armstrong
Process as previously disclosed in U.S. Pat. Nos. 5,779,761,
5,958,106 and 6,409,797, the entire disclosures of which are herein
incorporated by reference.
[0004] Production of titanium powder by the Armstrong Process
inherently produces agglomerated ligmental powder in which the
average diameter of individual particles is less than five microns
with a packing fraction in the range of from about 4% to about 11%.
Tap density is defined as the mass of a material that, upon packing
in a precisely specified manner, fills a container to a specified
volume, divided by the container volume. Apparent density is
defined as the weight per unit volume of a metal powder, in
contrast to the weight per unit volume of the individual particles.
Packing fraction percentage is the tap density divided by the
theoretical density and multiplied by 100.
[0005] Many projected powder metallurgy uses of titanium and
titanium alloy powders require a apparent density or packing
fraction higher than the powder typically produced by the Armstrong
Process. Increasing the apparent density or packing fraction of the
powders produced by the Armstrong Process without significantly
increasing oxygen concentration is important to future commercial
success in the powder metallurgy field. Powder metallurgy processes
include consolidation, molding and also several direct powder to
mill shape processes such as powder extrusion and powder roll
compaction.
SUMMARY OF THE INVENTION
[0006] Accordingly, a principal object of the present invention is
to provide a titanium or titanium alloy powder having apparent
densities and packing fractions greater than powder produced by the
subsurface reduction of titanium tetrachloride vapor or mixtures of
halide vapors in a flowing stream of alkali or alkaline earth metal
or mixtures thereof.
[0007] Another object of the present invention is to provide powder
with increased apparent density or packing fraction without
significantly increasing the oxygen concentration or other
contamination above as-produced powder.
[0008] Yet another objection of the present invention is to provide
a method of increasing the apparent density of agglomerated
ligmental titanium or titanium alloy powder produced by the
subsurface reduction of titanium tetrachloride vapor or a mixture
of titanium tetrachloride and other halide vapors in a flowing
stream of alkali or alkaline earth metal or mixtures thereof having
a first apparent density after distillation, comprising introducing
the agglomerated ligmental titanium or titanium alloy powder into
an attriting system, attriting the agglomerated ligmental titanium
or titanium alloy powder until the powder becomes more spherical
than ligmental and the first apparent density is increased by a
factor of from about 3 to about 8.
[0009] Still another object of the present invention is to provide
a method of increasing the apparent density of agglomerated
ligmental titanium or titanium alloy powder produced by the
subsurface reduction of titanium tetrachloride vapor or a mixture
of titanium tetrachloride and other halide vapors in a flowing
stream of sodium or alkaline earth metal or mixtures thereof having
a first apparent density after distillation, comprising introducing
the agglomerated ligmental titanium or titanium alloy powder into
an attriting system, attriting the agglomerated ligmental titanium
or titanium alloy powder in an inert atmosphere until the powder
becomes more spherical than ligmental and the first apparent
density is increased by a factor of from about 3 to about 8.
[0010] A final object of the present invention is to provide a
method of increasing the apparent density of agglomerated ligmental
titanium or titanium alloy powder produced by the subsurface
reduction of titanium tetrachloride vapor or a mixture of titanium
tetrachloride and other chloride vapors in a flowing stream of
sodium or alkaline earth metal or mixtures thereof having a first
apparent density after distillation, comprising introducing the
agglomerated ligmental titanium or titanium alloy powder into an
attriting system including a jet mill, attriting the agglomerated
ligmental titanium or titanium alloy powder in an inert atmosphere
in the jet mill until the powder becomes more spherical than
ligmental and the first apparent density is increased by a factor
of from about 3 to about 8.
[0011] The invention consists of certain novel features and a
combination of parts hereinafter fully described, illustrated in
the accompanying drawings, and particularly pointed out in the
appended claims, it being understood that various changes in the
details may be made without departing from the spirit, or
sacrificing any of the advantages of the present invention.
BRIEF DESCRIPTION OF THE DRAWING
[0012] For the purpose of facilitating an understanding of the
invention, there is illustrated in the accompanying drawing a
preferred embodiment thereof, from an inspection of which, when
considered in connection with the following description, the
invention, its construction and operation, and many of its
advantages should be readily understood and appreciated.
[0013] FIG. 1 is a schematic of an attriting system for inertly
attriting titanium and/or titanium alloy powder in a jet mill for
subsequent consolidation and processing;
[0014] FIG. 2 is another schematic of an attriting system utilizing
a jet mill;
[0015] FIG. 3 is an SEM of agglomerated ligmental titanium powder
with an as produced apparent density of 0.27 g/cc;
[0016] FIGS. 4(a) and 4(b) are SEMs of agglomerated ligmental
titanium powder after milling with an apparent density of 1.13
g/cc;
[0017] FIGS. 5(a) and 5(b) are SEMs of agglomerated ligmental
titanium powder after milling with an apparent density of 0.82
g/cc;
[0018] FIG. 6 is an SEM of agglomerated ligmental titanium powder
with an as produced apparent density of 0.26 g/cc;
[0019] FIGS. 7(a)-(b) are SEMs of agglomerated ligmental titanium
powder after milling with an apparent density of 1.12 g/cc; and
[0020] FIG. 8(a)-(b) are SEMs of agglomerated ligmental titanium
powder after milling with an apparent density of 0.68 g/cc.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Referring to FIGS. 1 and 2, an attriting system for titanium
or titanium alloy powder is disclosed with powder being placed in
an inert feeder containing an inert gas atmosphere. The powder is
fed into a jet mill that uses an inert gas to provide the milling
action where it is attrited by impact between powder particles.
Attrited powder is carried out of the mill to a classifier by an
inert gas stream. The classifier removes the desired, densified
powder from the gas stream, and possibly, recycles the entrained
fines to the jet mill. The densified powder may then pass directly
to another process or container without ever making contact with
oxygen that could increase the oxygen content of the powder. For
example, the powder could be placed into an inerted container that
could either be used directly in another process such as extrusion
or roll compaction or be used to transport the powder to another
process.
[0022] A variety of different mechanisms may be used to attritte
powder such as but not limited to a ball mill, a jet mill, a high
pressure water mill, a mechanco-fusion mill or a hammer mill all of
which are included in the invention. A jet mill is illustrated in
FIGS. 1 and 2 is preferred and should be inerted to prevent
undesirable oxygen pick-up. Any noble gas or nitrogen may be used,
with nitrogen being preferred. Although various ASTM grades of Ti
or its alloys may be used in this invention, CP (grade 2) Ti and
(grade 5) 6:4 alloy are the most commonly used.
[0023] The milling of the titanium powder was done on two different
Micron-Master jet mills, which are manufactured by the Jet
Pulverizer Company. The powder was fed into the mill through a
rotating screw conveyor. From that conveyor, the powder flowed into
the mill. The compressed nitrogen entered the mill through two
nuzzles and the two streams met together in the main chamber of the
mill, where the actual milling takes place, as seen in FIGS. 1 and
2.
[0024] Three different batches of titanium powder were used to
perform the attrition study. Batch R20.13, R20.14, and R20.15 was
milled on an 8 inch mill to develop the appropriate jet milling
parameters for the desired apparent density. Those parameters were
subsequently used to scale up to an 12'' but a 24'' jet mill or
larger could be employed. Table 1 summarizes the results from an
8'' mill test. Pre-sieving of the titanium powder was necessary in
order to feed the powder into an 8'' mill, which can be eliminated
by using a larger mill. TABLE-US-00001 TABLE 1 Parameters for an
8'' mill 8'' mill Sample Size Feed rate Pressure Sample ID lb lb/hr
psi R20.13 5.1 50 93 R20.14 5.2 50 70 R20.15 4.0 50 40
[0025] The feed rates and pressures determined from jet milling the
powder on an 8'' mill were used to directly feed batch R19.28,
R19.29, R22.23, and R22.24 into a 12'' mill. The parameters used
for a 12'' mill are shown in Table 2. TABLE-US-00002 TABLE 2
Parameters for a 12'' mill 12'' mill Sample Size Feed rate Pressure
Sample ID lb lb/hr psi R19.28 7.1 110 93 R19.29 12.5 110 30 R22.23
11.0 110 93 R22.24 10.8 110 30
[0026] The attrition study concentrated on improving the apparent
density of the Armstrong Process powder while minimizing the
subsequent oxygen pick up resulting from the jet milling process.
The purpose for improving the powder density was to make Armstrong
powder more amenable to standard powder metallurgy practices.
Typically, densities greater than 20% are desired. Based on
previous small scale milling experience with Armstrong powder, ITP
selected an opposed jet mill as the means to accomplish the
attrition. Summary of results for the attrition study is shown in
Table 3. TABLE-US-00003 TABLE 3 Results of the attrition study
Density Particle Size Analysis Chemical Analysis Sample Apparent
Tap Mean d50 d90 O2 N2 H2 ID g/cc % g/cc % um um um % % % R20.12
0.26 5.73 0.29 6.39 Raw powder (not milled) 0.234 0.021 0.0032
R20.13 1.05 23.13 1.39 30.53 133.5 63.43 327.1 0.297 0.039 0.0025
R20.14 0.95 20.93 1.25 27.62 139.1 60.88 383.9 0.361 0.05 0.0029
R20.15 0.68 14.98 0.90 19.77 222.4 162.5 525.2 0.295 0.057 0.003
R19.27 0.27 5.95 0.29 6.39 Raw powder (not milled) 0.175 0.003
0.0032 R19.28 1.13 24.89 1.49 32.85 91.26 46.06 176.6 0.275 0.009
0.0038 R19.29 0.82 18.06 1.08 23.84 187.8 102 386.2 0.238 0.01
0.0032 R22.21 0.26 5.73 0.30 6.61 Raw powder (not milled) 0.143
0.009 0.0018 R22.23 1.12 24.67 1.48 32.56 113.5 50.58 259 0.331
0.021 0.0045 R22.24 0.68 14.98 0.90 19.77 240.5 200.4 473.1 0.256
0.009 0.0038
[0027] Scotts biometric density meter was used to determine the
attrited batch sample's apparent densities and all samples showed
considerable improvement. The apparent densities ranged from
approximately 6% for raw powder to 25% for milled powder. The
particle size analysis was preformed using Coulter LS 230 and
showed as expected a decrease in particle size as the apparent
density increased across all samples. Inert gas fusion method was
used to conduct the chemical analysis for oxygen, nitrogen, and
hydrogen. The results showed an increase in oxygen level with
dissimilar amounts for different samples. The large increase in
oxygen could have resulted from not having a closed system during
the milling process. Therefore, to optimize the milling process an
inert feeding chamber and completing closed mill might minimize the
oxygen increase. The hydrogen level was virtually unchanged during
the milling process. Nitrogen level for the powder samples after
attrition did increase to some extent, but not enough to cause any
problems in further processing of the powder. Scanning Electron
Microscope (SEM) was used to evaluate the influence of jet milling
on titanium powder particles. SEM's of batch samples R19 and R22
are shown in FIGS. 3,4(a)(b), 5(a)-(b), 6, 7 (a)-(b) and 8(a)-(b).
The SEM's showed agglomerated ligmental that as the apparent
density increased, the particles became more spherical in shape,
which improved the apparent and tap densities. TABLE-US-00004 TABLE
4 JET PULVERIZER ATTRITION RESULTS 4 inch Feed rate Prssure
d50/d100 PF tap density apparent density mill (PPH) (psi) (MICRON)
(%) O2 (g/cc) (g/cc) R7U3.10A 25 65 223/2000 20 0.329 0.908 0.69008
R7U3.10B 8 120 25/1143 37 0.516 1.6798 1.276648 R7U3.10C 5 120
18.5/282 45 0.666 2.043 1.55268 R7U3.10E 20 110 45/2000 0.384
R7U3.10D STARTING 5 0.296 0.227 0.19976 POWDER 4 inch Feed rate
Prssure d50/d90 PF tap density apparent density mill (PPH) (psi)
(MICRON) (%) O2 (g/cc) (g/cc) R6U2.15B STARTING 0.2 POWDER R6U2.15B
20 110 39/92 25 0.37 1.135 0.8626 R12U3.3 STARTING 0.266 POWDER
R12U3.3 20 110 48/155 27 0.39 1.2258 0.931608 R7U3.10D STARTING 0.3
POWDER R7U3.10D 5 130 21/75 40 0.6 1.816 1.38016 8 inch Feed rate
Prssure d50/d90 PF tap density apparent density mill (PPH) (psi)
(MICRON) (%) O2 (g/cc) (g/cc) R15U2.06, STARTING 0.22 R15U2.07
POWDER R15U2.06, 8 100 17.52/28.71 42 0.487 1.9068 1.449168
R15U2.07 R15U3.10, STARTING 0.11 R15U3.11 POWDER R15U3.10, 7 110
20.65/33.08 41 0.395 1.8614 1.414664 R15U3.11 R15U3.13 STARTING
0.19 POWDER R15U3.13 8 110 17/27 45 0.496 2.043 1.55268
[0028] Table 4 shows additional results using 4 and 8 inch mills
such as illustrated in FIGS. 1 and 2. Here, the results showed that
apparent densities increased from about 3 to about 8 times without
significantly increasing the oxygen content of the agglomerated
ligmental titanium powder produced by the Armstrong Process set
forth in the incorporated patents and illustrated in the SEMs of
FIGS. 3 and 6. FIGS. 4(a)-(b), 5(a)-(b), 7(a)-(b) and 8(a)-(b) are
SEMs of powder milled and reported in Tables 1-3. Table 4 reports
results of powders like FIGS. 3 and 6 milled as previously
described herein.
[0029] For certain powder metallurgy, tap densities between about
20% to about 30% are preferred, but as illustrated in Tables 1-4,
packing fractions of as produced powders (inherently in the range
of from about 4% to about 11%) may be increased to at least 45%,
see particularly Table 4. The jet mills were operated at various
feed rates in pounds per hour (lb./hr) and at various pressures in
pounds per square inch (psi). Pressure as low as 30 psi (Table 1)
or up to 130 psi (Table 4) have been used and feed rates from 5 to
110 lbs/hr. have been used (Tables 1 and 4). Pressures and feed
rates affect the increase in apparent density, tap density and
packing fraction.
[0030] While there has been disclosed what is considered to be the
preferred embodiment of the present invention, it is understood
that various changes in the details may be made without departing
from the spirit, or sacrificing any of the advantages of the
present invention.
* * * * *