WO2015053239A1 - ニオブ造粒粉末の製造方法 - Google Patents
ニオブ造粒粉末の製造方法 Download PDFInfo
- Publication number
- WO2015053239A1 WO2015053239A1 PCT/JP2014/076742 JP2014076742W WO2015053239A1 WO 2015053239 A1 WO2015053239 A1 WO 2015053239A1 JP 2014076742 W JP2014076742 W JP 2014076742W WO 2015053239 A1 WO2015053239 A1 WO 2015053239A1
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- WIPO (PCT)
- Prior art keywords
- niobium
- granulated powder
- yttrium
- producing
- metal oxide
- Prior art date
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- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 239000010955 niobium Substances 0.000 title claims abstract description 79
- 229910052758 niobium Inorganic materials 0.000 title claims abstract description 74
- 239000000843 powder Substances 0.000 title claims abstract description 67
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 30
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 41
- 239000000956 alloy Substances 0.000 claims abstract description 41
- 239000003990 capacitor Substances 0.000 claims abstract description 34
- -1 niobium hydride Chemical compound 0.000 claims abstract description 27
- 238000010438 heat treatment Methods 0.000 claims abstract description 23
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 22
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 22
- 238000005551 mechanical alloying Methods 0.000 claims abstract description 15
- 239000002245 particle Substances 0.000 claims description 52
- 229910052727 yttrium Inorganic materials 0.000 claims description 42
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims description 42
- 238000010298 pulverizing process Methods 0.000 claims description 22
- 239000000463 material Substances 0.000 claims description 18
- 229910052751 metal Inorganic materials 0.000 claims description 14
- 239000002184 metal Substances 0.000 claims description 13
- 238000002156 mixing Methods 0.000 claims description 11
- 239000011148 porous material Substances 0.000 claims description 10
- 238000009826 distribution Methods 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 6
- 229910052768 actinide Inorganic materials 0.000 claims description 4
- 150000001255 actinides Chemical class 0.000 claims description 4
- 229910052747 lanthanoid Inorganic materials 0.000 claims description 4
- 150000002602 lanthanoids Chemical class 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 229910052706 scandium Inorganic materials 0.000 claims description 4
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 claims description 4
- 150000001768 cations Chemical class 0.000 claims description 3
- 230000001186 cumulative effect Effects 0.000 claims description 3
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 2
- 150000001342 alkaline earth metals Chemical class 0.000 claims description 2
- 238000000034 method Methods 0.000 abstract description 29
- 239000000126 substance Substances 0.000 abstract description 8
- 230000015572 biosynthetic process Effects 0.000 abstract description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 27
- 229910052760 oxygen Inorganic materials 0.000 description 27
- 239000001301 oxygen Substances 0.000 description 27
- 239000011324 bead Substances 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 17
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 15
- 125000004429 atom Chemical group 0.000 description 14
- URLJKFSTXLNXLG-UHFFFAOYSA-N niobium(5+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Nb+5].[Nb+5] URLJKFSTXLNXLG-UHFFFAOYSA-N 0.000 description 13
- 239000002994 raw material Substances 0.000 description 13
- 239000001257 hydrogen Substances 0.000 description 12
- 229910052739 hydrogen Inorganic materials 0.000 description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Inorganic materials O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 description 8
- 230000007423 decrease Effects 0.000 description 7
- 239000002904 solvent Substances 0.000 description 7
- 229910052715 tantalum Inorganic materials 0.000 description 7
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 6
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 6
- 239000002253 acid Substances 0.000 description 6
- 239000011159 matrix material Substances 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 238000005275 alloying Methods 0.000 description 5
- 238000001035 drying Methods 0.000 description 5
- 229910000484 niobium oxide Inorganic materials 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 125000004430 oxygen atom Chemical group O* 0.000 description 5
- 230000000704 physical effect Effects 0.000 description 5
- 239000011164 primary particle Substances 0.000 description 5
- 238000005245 sintering Methods 0.000 description 5
- 239000002002 slurry Substances 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical group F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 4
- 239000000292 calcium oxide Substances 0.000 description 4
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 4
- 239000010419 fine particle Substances 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 3
- 239000012298 atmosphere Substances 0.000 description 3
- 239000002612 dispersion medium Substances 0.000 description 3
- 238000005469 granulation Methods 0.000 description 3
- 230000003179 granulation Effects 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 230000004931 aggregating effect Effects 0.000 description 2
- 229910000905 alloy phase Inorganic materials 0.000 description 2
- 238000000498 ball milling Methods 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 239000011361 granulated particle Substances 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- HFLAMWCKUFHSAZ-UHFFFAOYSA-N niobium dioxide Chemical compound O=[Nb]=O HFLAMWCKUFHSAZ-UHFFFAOYSA-N 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- DSSYKIVIOFKYAU-XCBNKYQSSA-N (R)-camphor Chemical compound C1C[C@@]2(C)C(=O)C[C@@H]1C2(C)C DSSYKIVIOFKYAU-XCBNKYQSSA-N 0.000 description 1
- 241000723346 Cinnamomum camphora Species 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910001257 Nb alloy Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- 229960000846 camphor Drugs 0.000 description 1
- 229930008380 camphor Natural products 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000007739 conversion coating Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 238000006392 deoxygenation reaction Methods 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- RHDUVDHGVHBHCL-UHFFFAOYSA-N niobium tantalum Chemical compound [Nb].[Ta] RHDUVDHGVHBHCL-UHFFFAOYSA-N 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- AOLPZAHRYHXPLR-UHFFFAOYSA-I pentafluoroniobium Chemical compound F[Nb](F)(F)(F)F AOLPZAHRYHXPLR-UHFFFAOYSA-I 0.000 description 1
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 239000011802 pulverized particle Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229910001936 tantalum oxide Inorganic materials 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000013519 translation Methods 0.000 description 1
Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/04—Electrodes or formation of dielectric layers thereon
- H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
- H01G9/052—Sintered electrodes
- H01G9/0525—Powder therefor
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/14—Treatment of metallic powder
- B22F1/142—Thermal or thermo-mechanical treatment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/14—Treatment of metallic powder
- B22F1/148—Agglomerating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
- C22C27/02—Alloys based on vanadium, niobium, or tantalum
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
- H01G9/004—Details
- H01G9/04—Electrodes or formation of dielectric layers thereon
- H01G9/048—Electrodes or formation of dielectric layers thereon characterised by their structure
- H01G9/052—Sintered electrodes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
- B22F2009/041—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by mechanical alloying, e.g. blending, milling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
- B22F2009/043—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by ball milling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2302/00—Metal Compound, non-Metallic compound or non-metal composition of the powder or its coating
- B22F2302/25—Oxide
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2304/00—Physical aspects of the powder
- B22F2304/05—Submicron size particles
- B22F2304/058—Particle size above 300 nm up to 1 micrometer
Definitions
- the present invention relates to a method for producing niobium granulated powder. More specifically, an electrolytic capacitor element having a large capacitance and a method for producing niobium granulated powder capable of producing a capacitor, a sintered body of granulated powder obtained by the method, and a capacitor having the sintered body as an anode About.
- Tantalum is a porous sintered body formed by sintering powder and aluminum is a foil made porous by etching, respectively.
- the anode body with an increased surface area per unit volume and an electrolytic conversion coating formed on them. Used.
- the tantalum electrolytic capacitor and the aluminum electrolytic capacitor are used in different areas in which their performance is fully exhibited, and both coexist in the industry.
- Niobium is an element that belongs to the same group as tantalum and has similar physicochemical behavior. Niobium is abundant in resources and cheaper than tantalum, and it is relatively easy to replace tantalum with niobium because of the balance between density and relative dielectric constant of oxide and the similarity of physical properties. Research and development of niobium powder that replaces has been underway.
- the niobium oxide film that is the dielectric of the niobium electrolytic capacitor is more unstable than the tantalum oxide film. This is because niobium takes the form of various intermediate oxides. The oxygen in the oxide film easily moves, so that the thickness of the effective oxide film that exhibits the dielectric constant changes, or the transferred oxygen becomes a carrier and has a semiconductor property, which increases the leakage current.
- the primary particles of the powder are basically made smaller.
- the binding part between the primary particles becomes thin, so that the conduction part of the binding part is formed when the oxide film is formed by electrolytic formation.
- the area of the portion functioning as the anode decreases.
- an example in which the increase in the capacitance does not succeed has been reported.
- Patent Document 1 Japanese Patent Laid-Open No. 10-214004, US Pat. No. 6,115,235 describes that the niobium powder is partially nitrided to improve the leakage current of the niobium capacitor.
- Patent Document 2 Japanese Patent Laid-Open No. 2002-25864, US6643120 describes that a sintered body and a capacitor having a small specific leakage current are formed by incorporating antimony into niobium powder.
- Patent Document 3 International Publication No. 2002/015208 pamphlet, US6652619) uses niobium alloys of various elements and niobium powder, which has good leakage current characteristics or can produce a capacitor having a large capacitance, A sintered body and a capacitor are described.
- Patent Document 4 Japanese Patent Publication No. 2010-533642, WO2009 / 0121264 describes a powder and an anode capable of obtaining a low specific leakage current by doping various elements in tantalum niobium complex oxide.
- Patent Document 5 Japanese Patent Application Laid-Open No. 2008-156202, US81072159 discloses a dielectric ceramic containing various elements with respect to barium titanate, and a dielectric having a small temperature coefficient of relative permittivity with the contained elements. It is described to obtain porcelain.
- the subject of the present invention is a method for producing an electrolytic capacitor element having a large capacitance and a niobium granulated powder capable of producing a capacitor by a method different from the method in the prior art, and sintering of the granulated powder obtained by the method. And a capacitor using the sintered body as an anode.
- the inventors of the present invention use niobium hydride and a metal oxide, preferably yttrium oxide as raw materials, and after these mechanical alloys are formed by a mechanical alloying method, pulverization treatment and heat treatment are performed. Thus, it was found that a niobium granulated powder capable of producing an electrolytic capacitor and a device having a large electrostatic capacity was obtained, and the present invention was completed.
- the present invention relates to the following niobium granulated powder production method [1] to [9], [10] niobium granulated powder sintered body, [11] anode body, and [12] capacitor. .
- [1] A step of mixing niobium hydride and a metal oxide by a mechanical alloying method to form a mechanical alloy, a step of pulverizing the mechanical alloy, and aggregating the pulverized mechanical alloy by heat treatment. And a step of forming a granulated product.
- a method for producing a niobium granulated powder comprising: [2] The niobium granulated powder according to [1], wherein a metal oxide represented by a composition formula of M 2 O 3 (M represents a metal element that can be a trivalent cation) is used as the metal oxide. Manufacturing method. [3] The method for producing a niobium granulated powder according to [2], wherein M is at least one selected from scandium, yttrium, lanthanoid and actinoid. [4] The method for producing a niobium granulated powder according to [3], wherein M is yttrium.
- niobium structure according to any one of [1] to [8], wherein an oxide of an alkaline earth metal is used as a pore-forming material when the granulated product is formed by heat-treating the mechanical alloy.
- a method for producing granular powder [10] A sintered body of niobium granulated powder obtained by the production method according to any one of [1] to [9]. [11] An anode body made from the sintered body according to [10]. [12] A capacitor having the sintered body according to [10] as an anode.
- the niobium granulated powder obtained by the method of the present invention improves various performances of the dielectric formed product.
- the capacitor using the sintered body of niobium granulated powder according to the present invention as the anode body can increase the capacitor capacity by preventing excessive formation of the dielectric film.
- the binding model of niobium pentoxide (Nb 2 O 5 ) is shown.
- the bond model in the case where a part of niobium (Nb) atoms in niobium pentoxide (Nb 2 O 5 ) is replaced with yttrium (Y) atoms is shown. It is a graph which shows the anode withstand voltage curve in an Example.
- the sintered body made using the niobium granulated powder according to the present invention has many metal elements in the metal oxide in the vicinity of the surface of the niobium particles, niobium is used when electrolytically formed using this sintered body. Oxygen is trapped in the vicinity of the metal element existing in the vicinity of the particle surface, oxygen movement in the niobium oxide film is suppressed, and an increase in leakage current can be prevented. This state will be described in detail while showing an embodiment in the case where the metal element is yttrium.
- niobium pentoxide Nb 2 O 5
- five oxygen (O) atoms are bonded around one niobium (Nb) atom, and each O atom is bonded to an adjacent niobium (Nb) atom. is doing. At this time, O is in a 5 ⁇ 1/2 atomic coordination with respect to the Nb1 atom.
- Nb 2 O 5 niobium pentoxide
- Y yttrium
- the O atom is 1.5-coordinated, and a part of the O atom becomes a double bond with the Nb atom in order to match the charge. Accordingly, in the niobium oxide in which some Nb atoms are substituted with Y atoms, vacancies as shown in FIG. 2 are generated, and the vacancies thus formed migrate in niobium pentoxide. Since oxygen is trapped, it is presumed that there is an effect of suppressing oxygen movement that causes a decrease in capacity.
- yttrium oxide when the content of yttrium oxide is large and the ratio of yttrium oxide in the niobium pentoxide matrix is excessive, the yttrium oxide alone takes a matrix structure, so that the atomic ratio of O atoms to Y atoms is around that. It is considered that vacancies are not formed in equilibrium. Therefore, it is assumed that the abundance of yttrium oxide needs to be adjusted appropriately.
- a capacitor produced by using the niobium granulated powder of the present invention and having an appropriately distributed yttrium oxide in the niobium pentoxide matrix suppresses the movement of oxygen in the oxide film and increases the capacity. Can do. Even if the metal element is scandium, lanthanoid, or actinoid other than yttrium, the same effect as described above is expected, and it is assumed that the movement of oxygen is suppressed.
- the method for producing niobium granulated powder according to the present invention includes a step of mixing niobium hydride and a metal oxide by a mechanical alloying method to form a mechanical alloy, a step of pulverizing the mechanical alloy, a pulverized mechanical A step of aggregating the alloy by heat treatment to form a granulated product.
- the mechanical alloying method is a method of finely mixing by repeatedly causing folding and rolling of powders using ball collision energy during ball milling in an inert atmosphere.
- the mechanical alloy formed by the mechanical alloying technique can be mixed to the atomic order in the limit, and therefore, a unique alloy phase that cannot be obtained by the conventional method may be formed.
- the mechanical alloy in the present invention means a mixture of niobium hydride and a metal oxide containing yttrium or the like by a mechanical alloying technique, and may contain a plurality of types of alloy phases.
- a process for producing a mechanical alloy by a mechanical alloying technique is essential. It is presumed that the performance of the dielectric-formed product of the niobium granulated powder produced is improved by forming an appropriate concentration gradient between niobium and the metal element of the metal oxide inside the mechanical alloy.
- Niobium hydride which is a raw material, generally uses a niobium ingot that has been occluded by heating under a hydrogen atmosphere, but the niobium reduced powder obtained by sodium reduction of niobium fluoride is hydrofluoric acid.
- the raw material manufacturing method is not particularly limited as long as it is a niobium powder that has become hydrogen embrittled, such as one that has been washed with hydrofluoric acid and stored with hydrogen.
- niobium powder with a low hydrogen occlusion degree or dehydrogenated by vacuum heat treatment loses brittleness and develops malleable ductility, so that the powder is not flattened and flattened in the subsequent milling process. Many of these shapes are difficult to granulate.
- the hydrogen concentration of niobium hydride for obtaining hydrogen embrittlement is 0.4 to 1.0% by mass, preferably 0.7 to 1.0% by mass.
- a metal oxide which is the other raw material a metal oxide represented by a composition formula of M 2 O 3 which is a metal element having an electron configuration in which M is a trivalent cation is effective.
- M include scandium (Sc), yttrium (Y), lanthanoids, and actinoids. Among them, yttrium oxide having an atomic radius close to that of niobium is more effective.
- Commercially available ceramic additive materials, general reagents, etc. can be used as yttrium oxide without any particular limitation, but the particle size described later is an important factor for efficiently forming the mechanical alloy that is an embodiment of the present invention. .
- the mixing ratio of niobium hydride to metal oxide is 997: 3 to 970: 30 (0.3 to 30 atomic% in the case of yttrium), and preferably 997: 3 to 990: 10. (In the case of yttrium, 0.3 to 1.0 atomic%), more preferably 997: 3 to 995: 5 (in the case of yttrium, 0.3 to 0.5 atomic%).
- the mixing ratio is less than 997: 3 (less than 0.3 atomic%), the effect of the metal is small.
- the mixing ratio exceeds 990: 10 (exceeds 1.0 atomic%), the leakage current tends to increase.
- the niobium-to-metal atomic ratio of the granulated powder and the anode body is measured by a general elemental analysis method such as atomic absorption method after completely dissolving the sample.
- a mechanical alloying method specifically a stirred ball mill method, in which the raw materials can be refined and mixed at the same time.
- a stirring ball mill for example, an attrition ball mill and a bead mill are preferable.
- the raw material particles used are niobium hydride that has passed through a sieve having an opening of 1 mm, and yttrium oxide has a particle size of 0.4 to 100 ⁇ m, preferably 0.4 to 1 ⁇ m.
- the bead diameter for pulverizing the particles becomes large, the dead space in the mill increases, and pulverization becomes inefficient.
- the bead filling amount is preferably 60 to 90% of the volume in the pot of the mill. If it is less than 60%, the number of collisions between the beads and the raw material is small and the crushing efficiency is inferior. If it exceeds 90%, the number of collisions increases too much and the apparatus itself becomes overloaded and stops.
- the stirring speed is preferably 20 to 30 Hz. If it is less than 20 Hz, the collision speed between the beads and the raw material is small and the pulverization efficiency is inferior. If it exceeds 30 Hz, the collision speed is too high and the apparatus itself may be damaged.
- the material of the beads needs to be higher than that of yttrium oxide, but many commercially available beads such as zirconia, yttria-stable zirconia, and silicon nitride correspond to this condition and can be used.
- the grinding environment is an inert gas atmosphere when grinding dry and liquefaction when grinding wet.
- Conduct under gas, water or organic solvent In particular, a method of using water as a dispersion medium by wet pulverization that can be continuously charged and discharged into a bead mill and can be handled as a slurry thereafter is preferable.
- the temperature in the pot of the mill is preferably not lower than the freezing point and not higher than 10 ° C.
- the end point of pulverization is judged by determining the average particle size of the material.
- a laser diffraction particle size distribution meter is preferably used as the quickest and most convenient method.
- a sample is taken at regular intervals during pulverization and a D 50 value (50% cumulative particle size value based on volume), which is an average particle size, is obtained, there is an exponential relationship between the pulverization time and the average particle size.
- the pulverization time to reach the desired primary particle size can be estimated in advance, and efficient work can be performed.
- the D 50 value of the mechanical alloy particles thus pulverized is preferably 0.7 ⁇ m or less, and more preferably 0.5 ⁇ m or less. If the average particle size exceeds 0.7 ⁇ m, there will be few chances of collision between the beads used and the material, and a sufficient mechanical alloy cannot be obtained.
- the slurry of mechanical alloy particles that has been pulverized is an aggregate of particles. If the dispersion medium is removed as it is, the particles are normally packed densely. If heat treatment is performed in this state, all of them are integrated and do not function as a capacitor powder, so it is necessary to granulate appropriately. Therefore, at this time, it is preferable to use a pore forming material after mechanical alloying so that the particles after heat treatment become porous.
- the pore forming material is not particularly limited as long as it is a material that is not reactive with a mechanical alloy and can be easily removed, but is preferably a material that can be directly added to the slurry.
- Specific examples include oxides, inorganic salts, organic compounds, etc., but alkaline earth metal oxides that have a high melting point and do not evaporate by heat treatment and can be easily removed by acid cleaning are preferred, such as calcium oxide and magnesium oxide. More preferred.
- the pulverized mechanical alloy is then agglomerated by heat treatment to form a granulated product.
- Granulation is performed to improve the physical properties of the powder and facilitate transfer.
- Non-granulated powder is a lump with an indeterminate particle shape and inferior in fluidity, while granulated powder is round and rich in fluidity, and it causes die leakage and die galling in the molding process to form capacitors. This is preferable because it exhibits a stable effect.
- the heat treatment temperature is preferably 1000 to 1300 ° C.
- the diffused atoms are excessively directed in the direction of decreasing the surface energy, so that the specific surface area is reduced. This is directly linked to a decrease in the electrostatic capacity of the powder, so that the heat treatment conditions are naturally determined by setting the electrostatic capacity in an appropriate range.
- yttrium initially exists in the state of being applied to the grain boundary surface of niobium particles, which is a matrix component, but during the heat treatment, it is slightly in the surface direction of the niobium particles and the internal direction of the grain structure. Spread. Therefore, yttrium is basically present near the surface of the niobium particle and at the grain interface, and not in the deep part of the particle. The vicinity of the particle surface is a portion where an electrolytic conversion film is formed in the capacitor, and the movement of oxygen in the oxide film can be suppressed by collecting yttrium efficiently here.
- the alloy After the heat treatment is completed, the alloy will be agglomerated, so it will be crushed into particles by an appropriate method and the particle size distribution will be adjusted.
- a roll granulator, a pin mill, a speed mill, etc. can be used for the crusher.
- the particle size can be adjusted by using a sieve in combination so as to obtain a powder having a particle size distribution in the required range. Further, at this time, the fragments of the pulverized particles become fine particles, and this strongly affects the physical property values related to the dynamic characteristics of the powder such as the angle of repose and fluidity. Therefore, it is desirable to adjust the particle size particularly on the fine particle side.
- the pore forming material is preferably removed at this stage.
- the pore forming material is an inorganic salt, it is removed with an appropriate solvent, and when it is an oxide, it is removed with an appropriate acid, alkali or chelating agent.
- heat of reaction is generated during the removal, and niobium and yttrium both have a high affinity with oxygen, so the alloy surface may be oxidized.
- the dissolution removal temperature is desirably less than 50 ° C., particularly preferably 0 to 30 ° C. After removal, the excess solvent is washed with water or alcohol. In the case of an organic compound, it is decomposed during the heat treatment and has already been removed from the particles.
- the solvent is removed from the washed particles with a dryer.
- a general vacuum dryer can be used without limitation.
- the solvent is water
- the drying temperature is desirably 50 ° C. or lower until the solvent is sufficiently evaporated. If water is previously removed with a water-soluble organic solvent, the drying time can be shortened.
- the solvent evaporates it is desirable to raise the temperature to 50 ° C. or higher where the pressure in the dryer decreases and no bumping occurs. At this time, if the inside of the dryer is placed in a nitrogen atmosphere and the temperature is raised to 250 ° C., the surface of the alloy particles can be nitrided, which has an effect of preventing oxidation.
- the particles obtained in this way are ordinary niobium powder for capacitors as yttrium-containing niobium powder for capacitors, molding devices using tantalum powder for capacitors, sintering devices, chemical conversion devices, impregnation devices, paste coating devices, frame mounting devices. Further, it can be used as an alternative without particular limitation in equipment such as a sealing device.
- Example 1 A niobium hydride (hydrogen concentration: 0.94%) lump prepared by storing hydrogen in a niobium ingot was pulverized with an impact mill and classified with a gyro shifter using a sieve having an opening of 1 mm. Niobium hydride particles that passed through the sieve were used as raw materials for the subsequent steps. The hydrogen concentration of the niobium hydride particles at this time was 0.95%.
- the yttrium oxide a commercially available Y 2 O 3 powder having a purity of 99.9% and an average particle diameter of 1.0 ⁇ m was prepared. The yttrium concentration of this compound is 39.4%.
- alloying and refinement were simultaneously performed using a bead mill.
- the bead mill setting conditions were zirconia beads having a diameter of 3 mm, a bead filling amount of 80% by volume, and a stirring rotation speed of 25 Hz.
- Raw materials to be processed are niobium pure and the total amount is 10 kg.
- the D 50 value was 2.3 ⁇ m.
- the bead diameter was replaced with 0.5 mm silicon nitride beads, and pulverization was continued until the D 50 value reached 0.5 ⁇ m.
- a dispersed slurry of mechanical alloy particles was recovered.
- the heat-treated alloy lump was taken out after gradual oxidation and pulverized to a mean particle size of about 100 ⁇ m using a roll granulator.
- Slow oxidation means that a clean metal surface without an oxide film comes into contact with oxygen at a high concentration and does not lead to combustion due to rapid oxidation heat generation. It is a technique for forming an oxide film on the surface.
- the pulverized powder was washed with nitric acid, and calcium oxide remaining in the particles was dissolved and removed to form pores. After the dissolution was completed, it was washed with pure water using a gradient method and fine particles dispersed by a water flow were removed, and the necessary granulated particles of yttrium-containing niobium powder were collected. Finally, the granulated particles were transferred to a container and dried at 50 ° C. under reduced pressure, followed by finishing drying at 250 ° C. to obtain a granulated powder sample.
- Table 1 The physical property values of this sample are shown in Table 1.
- Comparative Example 1 Granulated powder samples were obtained in the same manner as in Example 1 except that the atomic ratio of niobium and yttrium was changed as described in Table 1. In Table 1, various conditions other than the changed part and physical property values of each sample are also shown.
- Example 5 3% camphor was mixed with the granulated sample obtained in Example 1, and a niobium compact was produced using an automatic molding machine. The compact was adjusted so that the volume was about 20 mm 3 and the density of the compact was about 3.0 g / cm 3 , and a niobium wire was planted as an anode lead in the center. This molded body was put in a vacuum sintering furnace and kept at a maximum temperature of 1250 ° C. for 30 minutes at a vacuum degree of 10 ⁇ 3 Pa or less to produce a sintered body. Table 2 shows the buckling strength (N / mm 2 ) of this sintered body. This sintered body is used as an anode, and 1% by mass of a 90 ° C.
- phosphoric acid aqueous solution is used as an electrolytic solution, and electrolytic formation is performed at a current density of 200 mA / g. Produced.
- the anode body was washed with running water, dried, and subjected to various tests. Table 2 shows electric characteristic values of the anode body.
- Example 5 a sintered body and an anode body were prepared in the same manner as in Example 5 except that the powders obtained in Examples 2 to 4 and Comparative Example 1 were used as granulated powder samples, and various tests were performed. It was used for. Table 2 shows the buckling strength of the sintered body and the electrical characteristic values of the anode body.
- Anode body withstand voltage curve display For the anode bodies of Examples 5 to 8 and Comparative Example 2, the element leakage current after 30 seconds was measured when the applied voltage was 1 V. Subsequently, the voltage was increased by 1 V to 2 V, and the element leakage current after 30 seconds was measured in the same manner. In this way, the applied voltage was increased by 1V, and the leakage current of the element was measured up to 20V. The relationship between the applied voltage and the leakage current at this time is shown in FIG. In addition, the leakage current value at 14V according to this measurement is also shown in Table 2.
- Comparative Example 3 According to Example 159 of Patent Document 3, niobium and yttrium were mixed at a ratio of 97: 3 by arc melting, heat treatment and pulverization were performed, and a sintered body was produced using the obtained granulated powder sample. Table 2 shows the leakage current value of this sintered body at 14V.
- yttrium was detected in Examples 1 to 4, but the content thereof was 80 to 90% of the initial input amount. I can say that.
- yttrium oxide is used as a raw material, and the oxygen atom (O): yttrium atom (Y) ratio of this molecule is 48: 178. Therefore, when yttrium increases by 1 part by mass, oxygen becomes 48 / 178 ⁇ 0.27 parts by mass.
- yttrium is 2800, 4700, and 9300 ppm, respectively, so oxygen increases by about 760, 1270, and 2500 ppm, respectively.
- the measurement results in Table 2 are the properties of the sintered body and anode body produced based on the granulated powder obtained by this method.
- the sintered body strength is 20% larger in Examples 5 to 6 and 10% smaller in Examples 7 to 8.
- the capacitance the blank values increased by 20 to 40% in Examples 5 to 8.
- Examples 7 to 8 differ in the yttrium content by about 3 times, but the capacitance is reversed.
- Comparative Example 2 is the largest and Examples 5 to 8 are small. From this, it can be seen that the presence of yttrium suppresses oxygen movement in the chemical conversion film due to heating.
- niobium oxide includes oxides with low oxygen content, such as niobium dioxide. Since these oxides do not become ferroelectrics, the capacitance is reduced when they are present in a chemical conversion oxide film as a dielectric. . From this result and the results shown in Table 2, in Examples 5 to 7, yttrium is present in the chemical conversion oxide film and prevents the movement of oxygen in the oxide film, so that the oxygen moves and becomes a non-ferroelectric oxide.
- the capacitance is larger than the blank value because the capacitance is prevented from decreasing.
- the abundance of yttrium is excessive, the dielectric constant decreases due to the characteristics of yttrium, and the capacitance is higher than that of Comparative Example 2, but is lower than that of Example 7. Accordingly, in order to obtain the maximum capacitance by the method of the present invention, it can be said that the upper limit of yttrium is more preferably 1 atomic%.
- FIG. 3 is a withstand voltage curve of the anode body elements of Examples 5 to 8 and Comparative Example 2. Based on the comparative example 2 which is a blank value, it is estimated that in Examples 5 to 7, the leakage current is smaller than the blank value up to the vicinity of the applied voltage of 7 V, and the oxygen moving by the electric field is suppressed by yttrium. However, in Example 8, since the uniformity of the chemical conversion oxide film formed by niobium, which is a matrix element with many yttrium atoms, is impaired, the leakage current is increased even at a low voltage. It can be judged from FIG. 3 that the upper limit of yttrium is more preferably 1 atomic%.
- Examples 5 to 7 show values smaller than those of Comparative Example 3.
- the niobium sintered body produced by using the production method of the present invention particularly the niobium sintered body having a yttrium content of 1 atomic% or less is different. It can be confirmed that the leakage current value is lower than that of the sintered body of Comparative Example 3 manufactured by the manufacturing method and exhibits excellent characteristics.
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Abstract
Description
[1]水素化ニオブと金属酸化物とをメカニカルアロイング法により混合して機械的合金とする工程と、前記機械的合金を粉砕する工程と、粉砕された機械的合金を熱処理により凝集させて造粒物を形成する工程とを含むことを特徴とするニオブ造粒粉末の製造方法。
[2]前記金属酸化物として、M2O3(Mは3価の陽イオンとなり得る金属元素を表す。)の組成式で示される金属酸化物を用いる[1]に記載のニオブ造粒粉末の製造方法。
[3]Mがスカンジウム、イットリウム、ランタノイド及びアクチノイドから選ばれる1種以上である[2]に記載のニオブ造粒粉末の製造方法。
[4]Mがイットリウムである[3]に記載のニオブ造粒粉末の製造方法。
[5]前記ニオブ造粒粉末において、ニオブと、金属酸化物に由来する金属元素との原子比が997:3~970:30の範囲である[1]~[4]のいずれかに記載のニオブ造粒粉末の製造方法。
[6]水素化ニオブとして、目開き1mmのふるいを通過した粉末を用いる[1]~[5]のいずれかに記載のニオブ造粒粉末の製造方法。
[7]水素化ニオブと金属酸化物とを混合する際に撹拌ボールミルを用いる[1]~[6]のいずれかに記載のニオブ造粒粉末の製造方法。
[8]水素化ニオブと金属酸化物とを混合した後、レーザー回折式粒度分布計のD50値(体積基準の50%累積粒径値)が0.7μm以下になるよう粉砕することを含む[1]~[7]のいずれかに記載のニオブ造粒粉末の製造方法。
[9]前記機械的合金を熱処理して造粒物を形成する際に、空孔形成材としてアルカリ土類金属の酸化物を使用する[1]~[8]のいずれかに記載のニオブ造粒粉末の製造方法。
[10][1]~[9]のいずれかに記載の製造方法により得られたニオブ造粒粉末の焼結体。
[11][10]に記載の焼結体から作られた陽極体。
[12][10]に記載の焼結体を陽極とするコンデンサ。
一方、五酸化ニオブ(Nb2O5)の一部のNb原子がイットリウム(Y)原子に置換された場合は、図2に示す結合モデルとなる。このとき、Y原子は+3価のためO原子は1.5配位となり、電荷を合わせるために一部のO原子はNb原子と二重結合となる。これに伴い、一部のNb原子がY原子に置換された酸化ニオブでは、図2に示すような空孔が生じ、このようにして形成された空孔に、五酸化ニオブの中で移動する酸素がトラップされるため、容量減少の原因となる酸素移動を抑制する効果があると推察される。
以上のように、本発明のニオブ造粒粉末を用いて製造した、五酸化ニオブマトリックス内において酸化イットリウムを適度に分布させたコンデンサは酸化膜中の酸素の移動が抑制され、容量を高くすることができる。
金属元素がイットリウム以外のスカンジウム、ランタノイド、アクチノイドでも、上記と同様の作用が期待され、酸素の移動が抑制されると推察される。
本発明に係るニオブ造粒粉末の製造方法は、水素化ニオブと金属酸化物とをメカニカルアロイング法により混合して機械的合金とする工程、前記機械的合金を粉砕する工程、粉砕した機械的合金を熱処理により凝集させて造粒物を形成する工程を含む。
メカニカルアロイング手法とは、不活性雰囲気中でのボールミル時における、ボールの衝突エネルギーを利用して、粉末同士の折り畳みと圧延を繰り返し起こさせることにより、微細に混合する手法である。メカニカルアロイング手法により形成された機械的合金では、極限的には原子オーダーまでの混合が可能であるため、従来法では得られない特異な合金相が形成される場合もある。
また、本発明においては、メカニカルアロイング手法により機械的合金を作製する工程が肝要となる。機械的合金の内部において、ニオブと金属酸化物の金属元素が適切な濃度勾配を形成することにより、製造されるニオブ造粒粉末の誘電体形成物の性能が向上するものと推察される。
なお、造粒粉末、陽極体のニオブ対金属原子比は、共に試料を全溶解し、原子吸光法などの一般的な元素分析方法で測定される。
ビーズの材質としては酸化イットリウムより硬度が大きいものである必要があるが、ジルコニア、イットリア安定ジルコニア、窒化ケイ素など、市販の多くのビーズがこの条件に該当し使用できる。
造粒は粉体物性値を向上させ、移送を容易にするために行われる。非造粒粉末は粒子形状が不定形の塊状であり流動性に劣るのに対し、造粒粉末は丸みを帯びて流動性に富み、コンデンサを形成するための成形工程においてダイス漏れやダイスかじりのない安定的な効果を発揮するので好ましい。
熱処理温度は1000~1300℃が好ましい。1300℃を超えると拡散した原子が表面エネルギーを減少させる方向に過度に向かうため比表面積が減少する。このことは粉末の静電容量が減少することに直結するので、静電容量を適宜の範囲に設定することでおのずと熱処理条件が決まる。
なお、空孔形成材として酸化カルシウムを用いる場合にはリン酸、硫酸以外の鉱酸によって、酸化マグネシウムを用いる場合にはリン酸以外の鉱酸によって除去することが可能である。
実施例及び比較例において、ニオブ(造粒)粉末の酸素及びイットリウム分析(化学分析)、比表面積(m2/g)、かさ密度(g/cm3)、焼結体座屈強度(N/mm2)、及び陽極体静電容量(μFV/g)は以下の方法で測定した。
化学分析:金属中酸素分析装置、及びサンプルを溶解しICP発光分光装置で定量した。
比表面積:BET式比表面積測定器を使用した。
かさ密度:JIS Z 2504かさ密度測定器を使用した。
電気特性:白金黒電極を使用し、測定液30%硫酸、120Hzバイアス電圧1.5Vで計測した。
加熱後測定:コンデンサを基板に半田付けする際のリフロー炉を想定し、陽極体を260℃で20分加熱し、放冷後に電気特性を測定した。
ニオブインゴットに水素吸蔵させて調製した水素化ニオブ(水素濃度0.94%)塊をインパクトミルにて粉砕し、目開き1mmのふるいを用いてジャイロシフターにて分級した。ふるいを通過した水素化ニオブ粒子を原材料とし以降の工程に使用した。このときの水素化ニオブ粒子の水素濃度は0.95%であった。
一方、酸化イットリウムは市販の純度99.9%、平均粒径1.0μmのY2O3粉末を準備した。この化合物のイットリウム濃度は39.4%である。
両者を、純水を分散媒として混合粉砕を行うとともに機械的合金を形成した。機械的合金工程では、ビーズミルを用いて合金化と微細化を同時に行った。ビーズミル設定条件は直径3mmのジルコニアビーズを使用しビーズ充填量80体積%、撹拌回転数25Hzとした。処理する原材料はニオブ純分として総量が10kg、ニオブとイットリウムの原子比が997:3になるように水素化ニオブと酸化イットリウム粉末を準備し、スラリー濃度50%の設定で3時間湿式粉砕処理を行った。2時間後の平均粒径をレーザー回折式粒度分布計で測定するとD50値で2.3μmであった。次にビーズ直径を0.5mmの窒化珪素ビーズに交換し、D50値が0.5μmになるまで続けて粉砕を実施した。6時間後D50値が0.5μmになったところで機械的合金粒子の分散スラリーを回収した。
ニオブとイットリウムの原子比を表1に記載した通りに変更したこと以外は実施例1と同様にして、それぞれ造粒粉サンプルを得た。なお、表1には変更部分以外の各種条件と各サンプルの物性値も併記した。
実施例1で得た造粒物サンプルに樟脳を3%混合し、自動成形機を用いてニオブ成形体を作製した。成形体は体積約20mm3、成形体密度が約3.0g/cm3になるよう調整し、中央に陽極リードとしてニオブワイヤを植立させた。この成形体を真空焼結炉に入れ10-3Pa以下の真空度で最高温度1250℃で30分保持させ焼結体を作製した。この焼結体の座屈強度(N/mm2)を表2に示す。この焼結体を陽極とし、1質量%の90℃リン酸水溶液を電解液とし電流密度200mA/gで電解化成を行い、電圧が20Vに達してから定電圧で3時間保持して陽極体を作製した。この陽極体は流水で洗浄後乾燥させ、各種試験に供した。この陽極体の電気特性値を表2に示す。
実施例5において、造粒粉サンプルとしてそれぞれ実施例2~4、比較例1で得られた粉末を使用した以外は実施例5と同様な工程で焼結体及び陽極体を作製し、各種試験に供した。この焼結体の座屈強度及び陽極体の電気特性値を表2に示す。
実施例5~8及び比較例2の陽極体について、印加電圧を1Vとしたとき30秒後の素子漏れ電流を測定した。続いて電圧を1V加圧して2Vとし、同様に30秒後の素子漏れ電流を測定した。このように印加電圧を1Vずつ加圧し20Vまで素子の漏れ電流を測定した。このときの印加電圧と漏れ電流の関係を図3に示す。なお、本測定による14Vにおける漏れ電流値をそれぞれ表2に併記した。
特許文献3の実施例159に従い、ニオブとイットリウムを97:3の割合で、アーク溶解により混合し、熱処理、粉砕を行い、得られた造粒粉サンプルを用いて焼結体を作製した。この焼結体の14Vにおける漏れ電流値を表2示す。
また、原料に酸化イットリウムを用いており、この分子の酸素原子(O):イットリウム原子(Y)比は48:178なので、イットリウムが1質量部増加すると酸素が48/178≒0.27質量部増加する。例えば実施例1~3において、イットリウムは各々2800、4700、9300ppmであるから酸素は各々約760、1270、2500ppm増加する。ブランク値である比較例2の酸素は3.6%であるから、ここを基準にすると実施例1~3の酸素は各々約3.68、3.73、3.85%となり、多少の誤差はあるが分析値と相関していると言える。
比表面積についてはブランク値である比較例1を基準にすると大きくても1割程度の増加なので、熱処理時における焼結阻害効果は小さいと考えられる。かさ密度はブランク値よりも若干小さいが、造粒添加工程において機械的合金といえども添加物はまだセラミックスの特徴を持っているため、造粒の効果が弱くなっているためであると考えられる。
このことと表2の結果から、実施例5~7ではイットリウムは化成酸化皮膜中に存在し、酸化膜中の酸素の移動を防止するので、酸素が移動して強誘電体でない酸化物になり静電容量が低下することを抑えているため静電容量はブランク値よりも大きくなると推察される。ただし実施例8ではイットリウムの存在量が過剰であり、イットリウムの特性により誘電率が低下し、静電容量が比較例2より高いものの、実施例7よりは低くなっている。
したがって本発明の方法で最大の静電容量を得るためにはイットリウムは上限1原子%であることがより好ましいと言える。
また、表2の14Vにおける漏れ電流値に着目すると、実施例5~7は比較例3よりも小さい値を示すことがわかる。このことから、詳細な条件に若干の差異はあるものの、本発明の製造方法を用いて作製したニオブ焼結体、特にイットリウムの含有量が1原子%以下のニオブ焼結体の方が、異なる製造方法により作製した比較例3の焼結体よりも漏れ電流値が低く、優れた特性を示すことが確認できる。
Claims (12)
- 水素化ニオブと金属酸化物とをメカニカルアロイング法により混合して機械的合金とする工程と、前記機械的合金を粉砕する工程と、粉砕された機械的合金を熱処理により凝集させて造粒物を形成する工程とを含むことを特徴とするニオブ造粒粉末の製造方法。
- 前記金属酸化物として、M2O3(Mは3価の陽イオンとなり得る金属元素を表す。)の組成式で示される金属酸化物を用いる請求項1に記載のニオブ造粒粉末の製造方法。
- Mがスカンジウム、イットリウム、ランタノイド及びアクチノイドから選ばれる1種以上である請求項2に記載のニオブ造粒粉末の製造方法。
- Mがイットリウムである請求項3に記載のニオブ造粒粉末の製造方法。
- 前記ニオブ造粒粉末において、ニオブと、金属酸化物に由来する金属元素との原子比が997:3~970:30の範囲である請求項1~4のいずれかに記載のニオブ造粒粉末の製造方法。
- 水素化ニオブとして、目開き1mmのふるいを通過した粉末を用いる請求項1~5のいずれかに記載のニオブ造粒粉末の製造方法。
- 水素化ニオブと金属酸化物とを混合する際に撹拌ボールミルを用いる請求項1~6のいずれかに記載のニオブ造粒粉末の製造方法。
- 水素化ニオブと金属酸化物とを混合した後、レーザー回折式粒度分布計のD50値(体積基準の50%累積粒径値)が0.7μm以下になるよう粉砕することを含む請求項1~7のいずれかに記載のニオブ造粒粉末の製造方法。
- 前記機械的合金を熱処理して造粒物を形成する際に、空孔形成材としてアルカリ土類金属の酸化物を使用する請求項1~8のいずれかに記載のニオブ造粒粉末の製造方法。
- 請求項1~9のいずれかに記載の製造方法により得られたニオブ造粒粉末の焼結体。
- 請求項10に記載の焼結体から作られた陽極体。
- 請求項10に記載の焼結体を陽極とするコンデンサ。
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US15/027,794 US20160254100A1 (en) | 2013-10-08 | 2014-10-07 | Niobium granulated powder production method |
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US11247269B2 (en) | 2015-05-07 | 2022-02-15 | Teknologian Tutkimuskeskus Vtt Oy | Method for forming powder particles and a product |
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CN114152847A (zh) * | 2021-11-30 | 2022-03-08 | 伊默维科技有限公司 | 一种高压陶瓷电容的取电结构及其制作方法 |
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JPWO2015053239A1 (ja) | 2017-03-09 |
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