WO2021171747A1 - 多孔質金属体の製造方法及び、多孔質金属体 - Google Patents
多孔質金属体の製造方法及び、多孔質金属体 Download PDFInfo
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- WO2021171747A1 WO2021171747A1 PCT/JP2020/046805 JP2020046805W WO2021171747A1 WO 2021171747 A1 WO2021171747 A1 WO 2021171747A1 JP 2020046805 W JP2020046805 W JP 2020046805W WO 2021171747 A1 WO2021171747 A1 WO 2021171747A1
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- 229910052751 metal Inorganic materials 0.000 title claims abstract description 115
- 239000002184 metal Substances 0.000 title claims abstract description 115
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 20
- 238000000034 method Methods 0.000 title abstract description 17
- 239000000843 powder Substances 0.000 claims abstract description 116
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 109
- 239000010936 titanium Substances 0.000 claims abstract description 80
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 79
- 239000001301 oxygen Substances 0.000 claims abstract description 56
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 56
- 238000005245 sintering Methods 0.000 claims abstract description 56
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 55
- 238000010438 heat treatment Methods 0.000 claims abstract description 17
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 35
- 239000002245 particle Substances 0.000 claims description 27
- 238000010301 surface-oxidation reaction Methods 0.000 claims description 26
- 229910052742 iron Inorganic materials 0.000 claims description 18
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 16
- 229910052799 carbon Inorganic materials 0.000 claims description 16
- 238000000151 deposition Methods 0.000 claims description 7
- 230000008021 deposition Effects 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims 1
- 238000007254 oxidation reaction Methods 0.000 abstract description 2
- 230000035699 permeability Effects 0.000 description 50
- 239000007788 liquid Substances 0.000 description 22
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 15
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 13
- 229910001069 Ti alloy Inorganic materials 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- 239000006104 solid solution Substances 0.000 description 11
- 229910052757 nitrogen Inorganic materials 0.000 description 7
- 238000012360 testing method Methods 0.000 description 7
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 7
- 238000005452 bending Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 238000013001 point bending Methods 0.000 description 4
- 239000004020 conductor Substances 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 239000004408 titanium dioxide Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical group [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000004438 BET method Methods 0.000 description 2
- 229910000883 Ti6Al4V Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910002065 alloy metal Inorganic materials 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- MKYBYDHXWVHEJW-UHFFFAOYSA-N N-[1-oxo-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propan-2-yl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(C(C)NC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 MKYBYDHXWVHEJW-UHFFFAOYSA-N 0.000 description 1
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000007561 laser diffraction method Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000000790 scattering method Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- -1 titanium hydride Chemical compound 0.000 description 1
- 229910000048 titanium hydride Inorganic materials 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/16—Metallic particles coated with a non-metal
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- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/05—Metallic powder characterised by the size or surface area of the particles
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- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
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- B22F3/10—Sintering only
- B22F3/1003—Use of special medium during sintering, e.g. sintering aid
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- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
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- C22C1/04—Making non-ferrous alloys by powder metallurgy
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- B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
Definitions
- the present invention relates to a method for producing a porous metal body containing titanium and a porous metal body.
- Titanium and titanium alloys are known to be materials with excellent corrosion resistance due to the formation of a passivation film on the surface. Utilizing such high corrosion resistance, it is expected that titanium or a titanium alloy is used, for example, as a porous conductive material that is used in an environment where it can be corroded and requires required air permeability or liquid permeability. ..
- Patent Document 1 discloses a method for producing a porous metal body by a wet method.
- the titanium-containing powder is heated and the titanium-containing powders are sintered together, so that the porous metal body can be obtained as the sintered body.
- Patent Document 1 a wet method is adopted in producing a porous metal body.
- the powders contained in the dried body are bonded to each other as they are to form a porous metal body, so that the above-mentioned reciprocal relationship is unavoidable, and both strength and air permeability or liquid permeability are compatible. I can't let you.
- An object of the present invention is to provide a method for producing a porous metal body capable of achieving both strength and air permeability or liquid permeability at a relatively high level, and to provide a porous metal body.
- the inventor devised to separately heat-treat the titanium-containing powder in an oxygen-containing atmosphere to form an oxide layer on the surface thereof before sintering. After that, it was found that when such a surface oxide powder having an oxide layer on the surface is heated at a predetermined temperature and sintered, the strength of the porous metal body obtained as a sintered body is improved. It is considered that this is because oxygen in the oxide layer on the surface of the surface oxidized powder is solid-solved and diffused inside the powder to be strengthened at the time of sintering.
- the present invention is not limited to such a theory.
- a porous metal body having a relatively high strength can be obtained without sintering the powder more densely than necessary, so that the required air permeability or liquid permeability of the porous metal body can be ensured.
- the strength can be improved.
- the method for producing a porous metal body of the present invention is a method for producing a porous metal body containing titanium, in which a titanium-containing powder is heated to a temperature of 250 ° C. or higher for 30 minutes or longer in an oxygen-containing atmosphere.
- the average particle size of the titanium-containing powder used in the surface oxidation step is preferably 15 ⁇ m to 90 ⁇ m.
- the surface oxidized powder can be deposited and sintered without applying pressure at least in the deposition direction.
- the titanium content of the titanium-containing powder is 75% by mass or more, the iron content is 0.08% by mass or less, the oxygen content is 0.40% by mass or less, and the carbon content is 0.02% by mass. % Or less is preferable.
- the porous metal body of the present invention has a titanium content of 75% by mass or more, an iron content of 0.08% by mass or less, an oxygen content of 0.40% by mass to 0.80% by mass, and a carbon content of 0.
- the amount of dissolved oxygen is 0.35% by mass to 0.70% by mass, and the amount of dissolved oxygen is 0.35% by mass to 0.70% by mass.
- the above-mentioned porous metal body may be in the form of a sheet having a thickness of 5.0 mm or less.
- the porosity of the above-mentioned porous metal body is preferably 30% to 70%.
- the method for producing a porous metal body according to an embodiment of the present invention is a method for producing a porous metal body containing titanium, wherein the titanium-containing powder is heated at 250 ° C. or higher in an oxygen-containing atmosphere.
- titanium-containing powder First, a titanium-containing powder is prepared.
- various powders can be used as long as they contain titanium.
- pure titanium powder or titanium alloy powder can be used.
- the pure titanium powder referred to here may be a powder substantially composed of only titanium, and the titanium alloy powder is a powder containing titanium and alloying elements.
- the titanium alloy is an alloy of titanium and a metal (alloy element) such as Fe, Sn, Cr, Al, V, Mn, Zr, Mo, and as a specific example, Ti-6-4 (Ti-6Al).
- Ti-5Al-2.5Sn Ti-8-1-1 (Ti-8Al-1Mo-1V), Ti-6-2-4-2 (Ti-6Al-2Sn-4Zr-2Mo-0) .1Si)
- Ti-6-6-2 Ti-6Al-6V-2Sn-0.7Fe-0.7Cu
- Ti-6-2-4-6 Ti-6Al-2Sn-4Zr-6Mo
- SP700 Ti-4.5Al-3V-2Fe-2Mo
- Ti-17 Ti-5Al-2Sn-2Zr-4Mo-4Cr
- ⁇ -CEZ Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe
- TIMETAL555 Ti-553 (Ti-5Al-5Mo-5V-3Cr-0.5Fe)
- TIMETAL21S Ti-15Mo-2.7Nb-3Al-0.2Si
- TIMETAL LCB Ti-4.5Fe-6.
- Ti-6Al-4V refers to a titanium alloy containing 6% by mass of Al and 4% by mass of V as an alloy metal.
- the pure titanium powder described above means a powder having a titanium content of 95% by mass or more.
- the titanium-containing powders specifically, as pure titanium powder, for example, hydrogenated dehydrogenated titanium powder (so-called HDH titanium powder) obtained by hydrogenating and crushing sponge titanium and then dehydrogenating, or after the above-mentioned crushing. Examples thereof include titanium hydride powder that has not been dehydrogenated.
- the hydrogenated titanium powder which is a pure titanium powder, allows a hydrogen content of up to 5% by mass.
- the average circularity of the titanium-containing powder is preferably 0.93 or less. By setting the average circularity to 0.93 or less, good air permeability and porosity of the porous metal body can be arranged side by side.
- An average circularity of more than 0.93 means that the titanium-containing powder is too close to a sphere. That is, there is a concern that the desired strength cannot be achieved because the porosity of the porous metal body becomes insufficient and the contact points between the powders cannot be sufficiently secured.
- the average circularity of the titanium-containing powder is preferably 0.91 or less, more preferably 0.89 or less.
- the average circularity of the titanium-containing powder is determined as follows. The perimeter (A) of the projected area of the particles is measured using an electron microscope, and the ratio to the perimeter (B) of the circle having the same area as the projected area is defined as the circularity (B / A).
- the average circularity is defined as the peripheral length (A) of the projected area of each particle from 1000 to 1500 individual particle images by flowing particles together with the carrier liquid in the cell and capturing images of a large number of particles with a CCD camera.
- the circumference (B) of a circle having an area equal to the projected area is measured to calculate the circularity (B / A), which is calculated as the average value of the circularity of each particle.
- the numerical value of the circularity increases as the shape of the particle approaches a true sphere, and the circularity of the particle having a perfect spherical shape becomes 1. On the contrary, the value of circularity decreases as the shape of the particle moves away from the true sphere.
- the titanium-containing powder can be only pure titanium powder.
- the titanium-containing powder can be a titanium alloy powder containing titanium and an alloying element.
- the powders thereof are appropriately selected according to the composition of the porous metal body to be produced and the like.
- the titanium content of the titanium-containing powder is preferably 75% by mass or more, and the iron content is preferably 0.08% by mass or less.
- iron may be regarded as an impurity in such a porous metal body, and it may be required that the iron content is sufficiently low.
- the iron content of the titanium-containing powder is even more preferably 0.06% by mass or less.
- the iron content of the titanium-containing powder is typically 0.02% by mass to 0.04% by mass.
- the oxygen content of the titanium-containing powder is preferably 0.40% by mass or less, more preferably 0.15% by mass to 0.30% by mass. With this oxygen content, HDH titanium powder generally available on the market can be applied.
- the carbon content of the porous metal body may be required to be low to some extent.
- the carbon content of the titanium-containing powder is preferably 0.02% by mass or less, particularly 0.01% by mass or less.
- the carbon content of the titanium-containing powder is preferably 0.005% by mass to 0.02% by mass.
- the nitrogen content of the titanium-containing powder is preferably 0.02% by mass or less, for example 0.001% by mass, from the viewpoint of preventing the presence of chemically extremely stable titanium nitride from inhibiting sintering. It is preferably ⁇ 0.02% by mass.
- the average particle size of the titanium-containing powder is preferably 15 ⁇ m to 90 ⁇ m.
- a titanium-containing powder having such an average particle size By using a titanium-containing powder having such an average particle size, a titanium-containing porous metal body having both strength and air permeability at a high level can be obtained. More preferably, a titanium-containing powder having an average particle size of 16 ⁇ m to 30 ⁇ m is used.
- the average particle size means the particle size D50 (median size) of the particle size distribution (volume basis) obtained by the laser diffraction / scattering method.
- the titanium-containing powder as described above is heated to a temperature of 250 ° C. or higher for 30 minutes or longer in an oxygen-containing atmosphere, for example, an atmospheric atmosphere.
- an oxygen-containing atmosphere for example, an atmospheric atmosphere.
- the titanium-containing powder becomes a surface oxide powder in which an oxide layer containing a titanium oxide such as titanium dioxide is formed on the surface thereof.
- the surface oxidized powder has a higher oxygen concentration than the titanium-containing powder. Therefore, the increase in oxygen concentration can be used as an index for grasping the approximate thickness of the oxide layer.
- the oxygen concentration in the atmosphere when the titanium-containing powder is heated in the surface oxidation step can be, for example, 18% by volume or more.
- the heating temperature of the titanium-containing powder is 250 ° C. or higher, preferably 300 ° C. or higher.
- the heating temperature may be, for example, 450 ° C. or lower, typically 400 ° C. or lower, and further 350 ° C. or lower.
- the holding time is preferably 30 minutes or more, and the holding time is preferably 600 minutes or less.
- the upper limit side of the holding time is, for example, 480 minutes or less, typically 360 minutes or less, whereby an oxide layer such as an oxide film can be efficiently applied to the surface of the titanium-containing powder.
- the holding time may be 180 minutes or less, particularly 120 minutes or less.
- the surface oxidation powder obtained in the above surface oxidation step is deposited on a flat surface such as the bottom of a molding mold in a dry manner rather than in a liquid (wet), and in that state, the surface oxidation powder is deposited.
- a porous metal body can be produced as a sintered body.
- usually only the surface oxidized powder is deposited by a dry method.
- the sintering process it is heated to a temperature higher than the ⁇ transformation point.
- a temperature higher than the ⁇ transformation point For example, in the case of pure titanium, if the temperature is 950 ° C, the temperature is higher than the ⁇ transformation point.
- oxygen in the oxide layer existing on the surface of each particle of the surface oxidized powder is first dissolved in the inside of the particles.
- the titanium on the surface diffuses and bonds between adjacent particles, and sintering occurs.
- the powder is sintered in a state where oxygen is distributed deep inside each particle of the surface oxidized powder used as a raw material, so that a porous metal body having high strength as a sintered body can be obtained.
- the sintering is performed using pure titanium powder instead of the surface oxide powder, oxygen does not reach deep inside each particle constituting the pure titanium powder even if the oxidation treatment is performed after the sintering. , Oxygen solidification enhancement as in the embodiment of the present invention cannot be expected. If further sintering is performed after the sintered body is formed, the voids may be reduced due to excessive sintering, and the air permeability or liquid permeability may be lowered. Further, if the existing titanium oxide powder and pure titanium powder are mixed and sintered instead of the surface oxide powder, the particle size of the titanium oxide powder is finer than that of the pure titanium powder, so that both powders are uniform.
- the titanium oxide powder Since it is difficult to mix, the titanium oxide powder is agglomerated, and oxygen is localized at the agglomerated portion of the titanium oxide powder after sintering, the oxygen solid solution strengthening as in the embodiment of the present invention cannot be expected. As a result, even in this case, it is not possible to achieve both the desired strength and air permeability or liquid permeability.
- surface oxide powder is deposited on a flat surface.
- the method of depositing the surface oxidized powder more specifically, for example, using a container-shaped sintering setter or mold made of carbon or the like provided with a side wall of a predetermined height surrounding the bottom surface.
- the surface oxidized powder is shaken off and deposited inside the side wall from the upper side thereof.
- a flat plate-shaped spatula or the like is moved along the upper surface of the side wall, and the surface oxidation rises above the upper surface of the side wall. A portion of the powder is removed to the outside of the sidewall.
- the surface oxidized powder is not intentionally pressurized in the deposition direction.
- the surface oxidized powder can be deposited inside the side wall of the sintering setter by the height of the side wall.
- a porous metal body having a shape such as a sheet corresponding to the internal space of the container-shaped sintering setter can be obtained.
- the thickness of the sheet-shaped porous metal body can be adjusted by changing the height of the side wall of the sintering setter or the like.
- the surface oxidized powder is sintered in the sintering step under a reduced pressure atmosphere such as vacuum or in an inert atmosphere.
- a reduced pressure atmosphere such as vacuum or in an inert atmosphere.
- a vacuum degree was allowed to reach 10 -4 Pa ⁇ 10 -2 Pa in a vacuum oven, it is possible to perform sintering under vacuum atmosphere.
- sintering can be performed in an inert atmosphere while the atmosphere is argon gas.
- the nitrogen gas does not correspond to the inert gas.
- the maximum temperature reached during sintering is 950 ° C or higher. If this is set to less than 950 ° C., the decomposition of the oxide layer becomes insufficient, the oxygen distribution in the porous metal body becomes more non-uniform, and the strength of the porous metal body may not be appropriately increased.
- the maximum temperature reached is preferably 1000 ° C. or higher.
- the maximum temperature reached is preferably 1200 ° C. or lower, more preferably 1100 ° C. or lower.
- the sintering step it is preferable to maintain the above-mentioned maximum temperature reached for 30 minutes to 480 minutes, and further for 60 minutes to 360 minutes. That is, for example, it is preferable to hold the time at 950 ° C. or higher for 30 minutes to 480 minutes, further 60 minutes to 360 minutes as described above.
- the retention time of the maximum temperature too short, after the oxide layer on the surface of the surface oxide powder disappears, the titanium of the adjacent surface oxide powder is sufficiently firmly bonded to each other, and the strength of the porous metal body is increased. It can be further enhanced.
- the holding time too long the densification of the porous metal body due to excessive sintering can be suppressed, and the porous metal body can satisfactorily exhibit the required air permeability or liquid permeability. Will be.
- porous metal body The porous metal body that can be produced as described above has both strength and air permeability or liquid permeability, which have been trade-offs in the past, at a relatively high level.
- such a porous metal body has a solid-dissolved oxygen content of 0.35% by mass to 0.70% by mass due to a surface oxidation step performed before the sintering step at the time of manufacture. It is preferably 0.37% by mass to 0.60% by mass, and more preferably 0.37% by mass to 0.55% by mass.
- the solid solution oxygen amount means a value obtained by subtracting the surface oxygen concentration from the oxygen concentration of the entire porous metal body.
- the oxygen concentration of the entire porous metal body the value measured by the inert gas melting-infrared absorption method is used.
- the surface oxygen concentration a value obtained by multiplying the specific surface area (m 2 / g) obtained by the BET method using Kr gas by the thickness of the surface oxide film and the oxygen concentration is used. At this time, the calculation is performed assuming that the thickness of the surface oxide film is 10 nm and the oxygen concentration in the surface oxide film is 40% by mass. In this case, the specific surface area (m 2 / g) is multiplied by a coefficient of 1.71. The value is the surface oxygen concentration (mass%).
- BELSORP-Max manufactured by Microtrac Bell can be used.
- the composition of the porous metal body may be a titanium alloy, and the proportion of titanium may be 75% by mass or more.
- the proportion of titanium in the porous metal body may be 98% by mass or more.
- the iron content is preferably 0.08% by mass or less.
- the iron content of the porous metal body made of titanium alloy can be 0.08% by mass or less. When the iron content is about this level, it is particularly suitable when the porous metal body is used as the conductive material.
- the iron content of the porous metal body is even more preferably 0.06% by mass or less.
- the iron content of the porous metal body is typically 0.02% by mass to 0.04% by mass.
- the oxygen content of the porous metal body is preferably 0.40% by mass to 0.80% by mass, and more preferably 0.45% by mass to 0.65% by mass. As a result, it is possible to prevent embrittlement due to excessive strength improvement while obtaining an appropriate strength improvement effect due to the solid solution of oxygen. Since the oxygen content of the porous metal body includes the above solid solution oxygen content, the oxygen content of the porous metal body usually exceeds the above solid solution oxygen content.
- the nitrogen content of the porous metal body is preferably 0.2% by mass or less, for example, 0.001% by mass to 0.1% by mass. When the nitrogen content is in this range, embrittlement of the porous metal body due to the solid solution of nitrogen can be prevented, and the formation of nitrides having poor corrosion resistance is suppressed.
- the carbon content of the porous metal body is higher than that in the case of using the slurry.
- the amount will be small. This is suitable when used in applications where a porous metal body having a low carbon content is required.
- the carbon content of the porous metal body is preferably 0.03% by mass or less, more preferably 0.001% by mass to 0.03% by mass, and further preferably 0.001% by mass to 0.02% by mass. ..
- the outer shape of the porous metal body may be sheet-like as a whole. In this case, it is also possible to obtain a thin porous metal body having a thickness of 5.0 mm or less. Even such a thin porous metal body has relatively high strength while ensuring the required air permeability or liquid permeability.
- the thickness of the porous metal body may be 0.3 mm to 1.0 mm. The thickness of the porous metal body is measured with a thickness gauge, and can be measured using, for example, an ABS Digimatic Thickness Gauge 547-321 manufactured by Mitutoyo Co., Ltd.
- the porosity of the porous metal body is preferably 30% to 70%, more preferably 35% to 65%. By setting the porosity within the range as described above, air permeability or liquid permeability can be realized depending on the application.
- HDH titanium powder titanium content 99% by mass or more, D50: 18 ⁇ m, D90: 28 ⁇ m, average circularity 0.89 or less
- any special treatment such as surface oxidation treatment or mixing of titanium oxide powder
- the coefficient k is a coefficient, and if the air permeability P is constant, the larger the coefficient k, the larger the bending strength B, that is, it can be considered that the strength and the air permeability are compatible at a relatively high level. Therefore, it can be evaluated that the strength of the porous metal body is improved and the dimension of both strength and air permeability is increased depending on the magnitude of the coefficient k.
- the meaning of the coefficient k in the natural sciences is not always clear, but it can be understood as an index showing the strength of the bond between the titanium-containing powders. In the present invention, the value of the coefficient k can be appropriately improved by increasing the amount of solid solution oxygen, and relatively high strength and air permeability with respect to the thickness can be realized.
- the bending strength of the porous metal body is measured by a three-point bending test.
- the porous metal body to be subjected to the three-point bending test has a width of 15 mm and a length of 60 mm, an indenter diameter of 5 mm, a fulcrum diameter of 5 mm, and a distance between fulcrums of 25 mm.
- Air permeability is measured using a Garley densometer. Arbitrary values are selected for the air capacity and the air permeation hole diameter so that the air permeation time falls within the range of 3 to 100 seconds.
- a universal testing machine manufactured by Shimadzu Corporation can be used for the three-point bending test, and a Garley type densometer manufactured by Toyo Seiki Seisakusho Co., Ltd. can be used for measuring the air permeability.
- HDH titanium powder (titanium content of 99% by mass or more and average circularity of 0.89 or less) having a particle size distribution of D50: 18 ⁇ m and D90: 28 ⁇ m and an oxygen content of 0.26% by mass was prepared.
- This HDH titanium powder was heated at 200 ° C., 250 ° C., 300 ° C., and 350 ° C. under an air atmosphere (oxygen concentration of 18% by volume or more). The oxygen content of the powder obtained in each was measured. The time for heating to the temperature was 60 minutes or 180 minutes. The oxygen concentration of the powder after the heat treatment was determined, and the results are shown in Table 1 (“ ⁇ ” in Table 1 indicates that the measurement was not performed).
- the iron content of the HDH titanium powder was 0.04% by mass or less, the carbon content was 0.01% by mass or less, and the nitrogen content was 0.02% by mass or less.
- the oxygen content of the powder obtained by heating at 200 ° C. was hardly increased to 1.2 times that of the HDH titanium powder, but the powder obtained by heating at 250 ° C. or higher did not increase.
- the oxygen content increased about 1.4 times to 2.4 times. Therefore, it is considered that the oxide layer was well formed on the particle surface of the HDH titanium powder when heated at 250 ° C. or higher.
- HDH titanium powder having a particle size and an oxygen content of 0.26% by mass shown in Table 2 was prepared.
- the iron content of the HDH titanium powder was 0.04% by mass or less
- the carbon content was 0.01% by mass or less
- the nitrogen content was 0.02% by mass or less.
- the titanium content was 99% by mass or more, and the average circularity of the titanium-containing powder was 0.89 or less.
- the above HDH titanium powder was heated at the temperature and time shown in Table 2 under an air atmosphere (oxygen concentration of 18% by volume or more) to form an oxide layer on the surface of the surface oxidized powder. And said. Then, the surface oxide powder was dry-deposited in a sintering setter with a side wall, and this was heated and sintered under the conditions shown in Table 2 to obtain a porous metal body having a thickness of 0.3 mm.
- a sintering setter a setter having a bottom surface inside the side wall having a length of 100 mm and a width of 100 mm and a side wall height of 0.35 mm was used.
- the surface oxide powder was shaken off and deposited on the bottom surface inside the side wall, and then a part of the surface oxide powder raised above the upper surface of the side wall was removed with a flat plate spatula. ..
- the atmosphere was reduced to a reduced pressure, and the degree of vacuum was set to the 10-3 pascal level.
- Example 10 to 13 the above HDH titanium powder was heated at the temperature and time shown in Table 2 under an air atmosphere (oxygen concentration of 18% by volume or more) to form an oxide layer on the surface of the surface oxidized powder. And said. Then, the surface oxide powder is dry-deposited in a sintering setter with a side wall, and this is heated and sintered under the conditions shown in Table 2 to obtain a porous metal body having a thickness of 0.6 mm and 1.0 mm.
- Example 14 a porous metal body was produced in the same manner as in Example 1 except that the temperature at the time of sintering was set to 1050 ° C.
- Examples 15 and 16 a porous metal body was prepared by using HDH titanium powder having a substantially different particle size from the above HDH titanium powder and adopting the conditions shown in Table 2. Other conditions were the same as in Examples 1 to 9.
- Comparative Examples 1 to 4 a porous metal body was produced substantially in the same manner as in Examples except that the HDH titanium powder was heated and sintered without surface oxidation.
- Comparative Example 5 as shown in Table 2, a porous metal body was produced in the same manner as in Example 1 except that the sintering temperature was changed to 900 ° C.
- Comparative Example 6 the above HDH titanium powder and titanium oxide powder (manufactured by Toho Titanium Company (HY0210), having a titanium dioxide purity of 99.9% by mass or more and a D50 of 2.3 ⁇ m) were mixed in a mass ratio of 99.
- a porous metal body was prepared in the same manner as in Example 3 except that the mixture was mixed at 5: 0.5 and the mixed powder was heated and sintered. As shown in FIG. 1, the porous metal body of Comparative Example 6 had black stains scattered on its surface. On the other hand, in the porous metal body of Example 3, such a stain was not found as shown in FIG.
- the porosity, oxygen content, solid solution oxygen amount and coefficient k described above were calculated for the porous metal bodies obtained in each of Examples 1 to 16 and Comparative Examples 1 to 6 described above.
- the results are shown in Table 3.
- the porous metal bodies obtained in Examples 1 to 16 and Comparative Examples 1 to 6 each had a titanium content of 98% by mass or more, an iron content of 0.04% by mass or less, and a carbon content of 0. It was 0.01% by mass or less and the nitrogen content was 0.02% by mass or less.
- the coefficient k was 1.1 ⁇ 10 6 or more, which was a large value of 1.2 ⁇ 10 6 or more. Therefore, both strength and breathability were well-balanced. You can see that it is done. That is, even if the thickness changes, both strength and breathability are compatible at a high level.
- the coefficient k furthermore, 1.5 ⁇ 10 6 or more, was also achieved higher value than such 2.0 ⁇ 10 6 or more.
- Comparative Examples 1-4 the oxygen solid-solution strengthening due to not subjected to surface oxidation treatment is not done, the coefficient k becomes 0.9 ⁇ 10 6 or less.
- Comparative Examples 5 and 6 the temperature during sintering is low, or, by obtained by mixing titanium dioxide powder, a range coefficient k in the same manner as in Comparative Example 1-4 is 0.9 ⁇ 10 6 or less It became inside.
- the bending strength of Examples 1 to 16 and Comparative Examples 1 to 6 was in the range of 20 MPa to 470 MPa, and the air permeability P ⁇ thickness t 0.33 was in the range of 50 to 400.
- Porous metal body coefficient k is 1.1 ⁇ 10 6 or more is preferably higher strength.
- the three-point bending strength is preferably 100 MPa or more as in Examples 1 to 15, and particularly 200 MPa or more as in Examples 2, 3, 5 to 7, 9 to 14. More preferred.
- Porous metal body coefficient k is 1.1 ⁇ 10 6 or more, it is preferable that more larger value of air permeability P ⁇ thickness t 0.33.
- the value of air permeability P ⁇ thickness t 0.33 is preferably 50 or more as in Examples 1 to 16, and more preferably 90 or more as in Examples 1, 3 to 6, 8, 12, 15, and 16.
- both strength and breathability or liquid permeability can be compatible at a relatively high level.
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Abstract
Description
この発明の一の実施形態に係る多孔質金属体の製造方法は、チタンを含有する多孔質金属体を製造する方法であって、酸素を含有する雰囲気下で、チタン含有粉末を250℃以上の温度に30分以上にわたって加熱し、表面酸化粉末を得る表面酸化工程と、前記表面酸化粉末を乾式で堆積させ、当該表面酸化粉末を減圧雰囲気もしくは不活性雰囲気の下、950℃以上の温度に加熱して焼結させる焼結工程とが含まれる。
はじめに、チタン含有粉末を準備する。チタン含有粉末としては、チタンを含有するものであれば様々な粉末とすることができるが、たとえば、純チタン粉末、チタン合金粉末を用いることができる。ここでいう純チタン粉末は実質的にチタンのみからなる粉末であってよく、チタン合金粉末はチタン及び合金元素を含む粉末である。
例えば、チタン合金は、チタンとFe、Sn、Cr、Al、V、Mn、Zr、Mo等の金属(合金元素)との合金であり、具体例としては、Ti-6-4(Ti-6Al-4V)、Ti-5Al-2.5Sn、Ti-8-1-1(Ti-8Al-1Mo-1V)、Ti-6-2-4-2(Ti-6Al-2Sn-4Zr-2Mo-0.1Si)、Ti-6-6-2(Ti-6Al-6V-2Sn-0.7Fe-0.7Cu)、Ti-6-2-4-6(Ti-6Al-2Sn-4Zr-6Mo)、SP700(Ti-4.5Al-3V-2Fe-2Mo)、Ti-17(Ti-5Al-2Sn-2Zr-4Mo-4Cr)、β-CEZ(Ti-5Al-2Sn-4Zr-4Mo-2Cr-1Fe)、TIMETAL555、Ti-5553(Ti-5Al-5Mo-5V-3Cr-0.5Fe)、TIMETAL21S(Ti-15Mo-2.7Nb-3Al-0.2Si)、TIMETAL LCB(Ti-4.5Fe-6.8Mo-1.5Al)、10-2-3(Ti-10V-2Fe-3Al)、Beta C(Ti-3Al-8V-6Cr-4Mo-4Cr)、Ti-8823(Ti-8Mo-8V-2Fe-3Al)、15-3(Ti-15V-3Cr-3Al-3Sn)、BetaIII(Ti-11.5Mo-6Zr-4.5Sn)、Ti-13V-11Cr-3Al等が挙げられる。なお、上記において、各合金金属の前に付されている数字は、含有量(質量%)を指す。例えば、「Ti-6Al-4V」とは、合金金属としては、6質量%のAlと4質量%のVとを含有するチタン合金を指す。
チタン含有粉末の平均円形度は、0.93以下であることが好ましい。平均円形度を0.93以下とすることで多孔質金属体の良好な透気度と空隙率の並立を図る。平均円形度が0.93を超えることはチタン含有粉末が球形に近づきすぎることを意味する。すなわち、多孔質金属体の空隙率が不十分となり、粉末同士の接触点を十分に確保できないため所望の強度を達成できない懸念がある。チタン含有粉末の平均円形度は、好ましくは0.91以下であり、より好ましくは0.89以下である。
チタン含有粉末の平均円形度は次のようにして求める。電子顕微鏡を使用して粒子の投影面積の周囲長(A)を測定し、前記投影面積と等しい面積の円の周囲長(B)との比を円形度(B/A)とする。平均円形度は、セル内にキャリア液とともに粒子を流し、CCDカメラで多量の粒子の画像を撮り込み、1000~1500個の個々の粒子画像から、各粒子の投影面積の周囲長(A)と投影面積と等しい面積の円の周囲長(B)を測定して円形度(B/A)を算出し、各粒子の円形度の平均値として求める。上記円形度の数値は粒子の形状が真球に近くなるほど大きくなり、完全な真球の形状を有する粒子の円形度は1となる。逆に、粒子の形状が真球から離れるにつれて円形度の数値は小さくなる。
チタン含有粉末の窒素含有量は、化学的に極めて安定な窒化チタンの存在により焼結が阻害されることを防ぐ観点から、0.02質量%以下であることが好ましく、たとえば0.001質量%~0.02質量%が好ましい。
表面酸化工程では、上述したようなチタン含有粉末を、酸素が含まれる雰囲気、たとえば大気雰囲気下で、250℃以上の温度に30分以上にわたって加熱する。これにより、チタン含有粉末は、その表面に、二酸化チタン等のチタン酸化物を含む酸化物層が形成された表面酸化粉末になる。表面酸化粉末はチタン含有粉末より酸素濃度が高くなる。よって、酸素濃度の上昇は酸化物層のおおよその厚さを把握する指標として利用できる。表面酸化工程でチタン含有粉末を加熱する際の雰囲気中の酸素濃度は、たとえば18体積%以上とすることができる。
焼結工程にて、上記の表面酸化工程で得られた表面酸化粉末を、液体中(湿式)ではなく乾式で、たとえば成形型の底部等の平面上に堆積させ、その状態で当該表面酸化粉末を減圧雰囲気または不活性雰囲気の下、950℃以上の温度に加熱して焼結させる。これにより、焼結体として多孔質金属体を製造することができる。原料である粉末同士が接触し焼結により結合することにより多くの箇所で酸素の固溶拡散効果を確保するため、通常、表面酸化粉末のみを乾式で堆積させる。
また仮に、表面酸化粉末ではなく既存の酸化チタン粉末と純チタン粉末を混合して焼結を行った場合、酸化チタン粉末の粒径が純チタン粉末よりも微細であるために両粉末の均一な混合が難しく、酸化チタン粉の凝集が生じ、焼結後には酸化チタン粉の凝集箇所に酸素が局在するため、この発明の実施形態のような酸素固溶強化は見込めない。それにより、この場合も、所望の強度と通気性もしくは通液性を両立させることができない。
上述したようにして製造され得る多孔質金属体は、従来はトレードオフであった強度と通気性もしくは通液性が比較的高い次元で両立されたものになる。
多孔質金属体の窒素含有量は0.2質量%以下であることが好ましく、たとえば0.001質量%~0.1質量%である。窒素含有量がこの範囲であれば、窒素の固溶による多孔質金属体の脆化を防止できると共に、耐食性に劣る窒化物形成が抑制される。
ε=(1-ρ´/ρ)×100
B=0.81×106・(P・t0.33)-1.902=k・(P・t0.33)-1.902
tは多孔質金属体の厚み(mm)で、透気度Pにt0.33を乗ずることで、厚みの影響を反映することができる。kは係数で、透気度Pが一定であれば係数kが大きいほど曲げ強度Bが大きくなる、即ち、強度と通気性が比較的高い次元で両立していると見做せる。よって、係数kの大小によって、多孔質金属体の強度が向上し、強度と通気性の両立の次元が高まったことを評価可能である。なお、係数kの自然科学における意味は必ずしも明らかではないが、チタン含有粉末同士の結合の強固さを表す指標と理解できる。本発明では、固溶酸素量を増大することで係数kの値を適切に向上させ、厚みに対する比較的高い強度と透気度を実現できる。
k=B/((P・t0.33)-1.902)
粒度分布がD50:18μm、D90:28μmであり、酸素含有量が0.26質量%であるHDHチタン粉末(チタン含有量は99質量%以上、平均円形度は0.89以下)を準備した。
表2に示す粒径、酸素含有量0.26質量%のHDHチタン粉末を準備した。なお、HDHチタン粉末の鉄含有量は0.04質量%以下、炭素含有量は0.01質量%以下、窒素含有量は0.02質量%以下であった。また、チタン含有量は99質量%以上、チタン含有粉末の平均円形度は0.89以下であった。
比較例5では、表2に示すように、焼結温度を900℃に変更したことを除いて、実施例1と同様にして多孔質金属体を作製した。
なお、この試験結果では、実施例1~16及び比較例1~6の曲げ強度が20MPa~470MPaの範囲内、透気度P×厚みt0.33が50~400の範囲内であった。
係数kが1.1×106以上である多孔質金属体は、より高強度であることが好ましい。具体的には、3点曲げ強度は、実施例1~15のように100MPa以上であることが好ましく、特に実施例2、3、5~7、9~14のように200MPa以上であることがより好ましい。係数kが1.1×106以上である多孔質金属体は、より透気度P×厚みt0.33の値が大きいことが好ましい。透気度P×厚みt0.33の値は、実施例1~16のように50以上が好ましく、特に実施例1、3~6、8、12、15、16のように90以上がより好ましい。
Claims (7)
- チタンを含有する多孔質金属体を製造する方法であって、
酸素を含有する雰囲気下で、チタン含有粉末を250℃以上の温度に30分以上にわたって加熱し、表面酸化粉末を得る表面酸化工程と、
前記表面酸化粉末を乾式で堆積させ、当該表面酸化粉末を減圧雰囲気もしくは不活性雰囲気の下、950℃以上の温度に加熱して焼結させる焼結工程と
を含む、多孔質金属体の製造方法。 - 前記表面酸化工程で用いる前記チタン含有粉末の平均粒径が15μm~90μmである、請求項1に記載の多孔質金属体の製造方法。
- 前記焼結工程で、前記表面酸化粉末を、少なくともその堆積方向に加圧せずに堆積させて焼結する、請求項1又は2に記載の多孔質金属体の製造方法。
- 前記表面酸化工程で、前記チタン含有粉末のチタン含有量が75質量%以上、鉄含有量が0.08質量%以下、酸素含有量が0.40質量%以下、炭素含有量が0.02質量%以下である、請求項1~3のいずれか一項に記載の多孔質金属体の製造方法。
- チタン含有量が75質量%以上、鉄含有量が0.08質量%以下、酸素含有量が0.40質量%~0.80質量%、炭素含有量が0.001質量%~0.03質量%、固溶酸素量が0.35質量%~0.70質量%である多孔質金属体。
- 厚みが5.0mm以下のシート状である請求項5に記載の多孔質金属体。
- 空隙率が30%~70%である請求項5又は6に記載の多孔質金属体。
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EP4227428A4 (en) * | 2020-10-05 | 2024-04-24 | Toho Titanium Co Ltd | MANUFACTURING PROCESS FOR POROUS METAL BODY AND POROUS METAL BODY |
EP4219778A4 (en) * | 2020-09-28 | 2024-04-24 | Toho Titanium Co Ltd | TITANIUM-BASED POROUS BODY AND METHOD FOR PRODUCING A TITANIUM-BASED POROUS BODY |
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