JPH0130881B2 - - Google Patents
Info
- Publication number
- JPH0130881B2 JPH0130881B2 JP10000079A JP10000079A JPH0130881B2 JP H0130881 B2 JPH0130881 B2 JP H0130881B2 JP 10000079 A JP10000079 A JP 10000079A JP 10000079 A JP10000079 A JP 10000079A JP H0130881 B2 JPH0130881 B2 JP H0130881B2
- Authority
- JP
- Japan
- Prior art keywords
- powder
- sintering
- minutes
- pure
- atmosphere
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000843 powder Substances 0.000 claims description 33
- 238000005245 sintering Methods 0.000 claims description 23
- 239000002245 particle Substances 0.000 claims description 13
- 238000002844 melting Methods 0.000 claims description 11
- 230000008018 melting Effects 0.000 claims description 11
- 239000007789 gas Substances 0.000 claims description 10
- 239000011261 inert gas Substances 0.000 claims description 8
- 239000003990 capacitor Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims 1
- 238000000034 method Methods 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 239000011148 porous material Substances 0.000 description 4
- UFWIBTONFRDIAS-UHFFFAOYSA-N Naphthalene Chemical compound C1=CC=CC2=CC=CC=C21 UFWIBTONFRDIAS-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 230000001010 compromised effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
Landscapes
- Powder Metallurgy (AREA)
Description
【発明の詳細な説明】
本発明はコンデンサ等に供せられるAl多孔質
焼結体の製造法に係り、詳しくは、ほとんど不純
物を含まず、実質的にAlのみから成る純Al粉末
からコンデンサ等に供せられる多孔質焼結体を製
造する方法に係る。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an Al porous sintered body to be used in capacitors, etc., and more specifically, it relates to a method for producing an Al porous sintered body to be used in capacitors, etc., from pure Al powder containing almost no impurities and consisting essentially only of Al. The present invention relates to a method for producing a porous sintered body to be used for.
最近、タンタル等の金属粉末を焼結して成る多
孔質焼結体を利用したコンデンサが広く用いられ
ているが、高価であるため、タンタルに代つて、
Al粉末の多孔質焼結体を利用したコンデンサが
提案されている。しかし、Al粉末の表面は、硬
くかつ難還元性の酸化皮膜によつておおられるた
め、多孔質焼結体を製造することが困難であると
云われている。 Recently, capacitors that use porous sintered bodies made by sintering tantalum or other metal powders have been widely used, but because they are expensive, they have been replaced with tantalum.
A capacitor using a porous sintered body of Al powder has been proposed. However, it is said that it is difficult to produce a porous sintered body because the surface of Al powder is covered with a hard and difficult to reduce oxide film.
そこで、例えば、特願昭45−114989号明細書に
記載される通り、ナフタリン等の様な揮発性物質
をAl粉末中に混合し、これらを真空中で加熱、
焼結して、Al粉末粒子間の揮発性物質が飛散し
て孔隙を形成して多孔質焼結体を製造する方法が
提案されている。この方法によると、焼結中に揮
発性物質が飛散して雰囲気が阻害され、焼結性が
大巾に損なわれる。 Therefore, for example, as described in Japanese Patent Application No. 114989/1989, a volatile substance such as naphthalene is mixed into Al powder, and the mixture is heated in a vacuum.
A method has been proposed in which a porous sintered body is produced by sintering, and volatile substances between Al powder particles are scattered to form pores. According to this method, volatile substances are scattered during sintering, the atmosphere is disturbed, and sinterability is significantly impaired.
更に詳しく説明すると、Al粉末表面の酸化皮
膜は、水素等の還元性雰囲気中で焼結しても、還
元除去することが困難のため、酸化皮膜を機械的
に破壊除去することが一般に行なわれ、このため
には、例えば２トン／cm2以上で加圧してグリーン
コンパクトを形成することが必要である。このよ
うに加圧してグリーンコンパクト体を形成するこ
とが必要であると、多数の孔隙を形成することが
困難で、例えば、特願昭45−114989号明細書に示
す如く、揮発性物質を混合し、成形時に所要の圧
力を加えてグリーンコンパクトを形成しても、焼
結時に揮発性物質が飛散し、孔隙が形成できる方
法が提案される。しかしながら、この方法では揮
発性物質の飛散のために、焼結雰囲気が汚染され
て調整がむずかしく、焼結反応が十分に進行しな
い。 To explain in more detail, the oxide film on the surface of Al powder is difficult to reduce and remove even when sintered in a reducing atmosphere such as hydrogen, so it is generally done to mechanically destroy and remove the oxide film. For this purpose, it is necessary to pressurize, for example, 2 tons/cm 2 or more to form a green compact. If it is necessary to form a green compact body under pressure in this way, it is difficult to form a large number of pores. However, a method is proposed in which even if a green compact is formed by applying the required pressure during molding, volatile substances are scattered during sintering and pores are formed. However, in this method, the sintering atmosphere is contaminated due to the scattering of volatile substances, making adjustment difficult, and the sintering reaction does not proceed sufficiently.
本発明は上記欠点の解決を目的とし、具体的に
は、焼結前に加圧してグリーンコンパクトを形成
することなく、実質的無加圧で成型して焼結し、
Al粒子間に多数の孔隙が形成される多孔質焼結
体を製造する方法を提案する。 The present invention aims to solve the above-mentioned drawbacks, and specifically, the present invention does not apply pressure to form a green compact before sintering, but molds and sinters with substantially no pressure,
We propose a method for manufacturing porous sintered bodies in which many pores are formed between Al particles.
以下、本発明法について詳しく説明する。 The method of the present invention will be explained in detail below.
まず、純Al粉末を、その粉末表面の少なくと
も一部が接触する状態に、実質的に無加圧の状態
で成型し、その後、不活性ガス雰囲気中で純Al
粉末の融点若しくはその近傍において焼結し、こ
の際に、不活性ガスは流動させる。純Al粉末は、
Alを99.99％以上含んで残余としてほとんど不純
物を含まないものである。すなわち、Al多孔質
焼結体を固体コンデンサ用の基材として用いる場
合は、99.99％以上のAl純度が必要である。表面
の酸化皮膜の構造がAl純度によつて変化し、Al
純度が高いほど緻密になり、漏洩電流が小さくな
る。また、Al粉末は加圧してグリーンコンパク
トを形成することなく、無加圧若しくは圧力を加
えても僅かの圧力を加えて、つまり、実質的に無
加圧の状態で成型し、更に、その融点若しくはそ
の近傍で、例えば、N2ガスの如き不活性雰囲気
中で一部液相の状態を焼結する。 First, pure Al powder is molded under substantially no pressure so that at least a portion of the powder surface is in contact with the pure Al powder, and then pure Al powder is molded in an inert gas atmosphere.
Sintering is carried out at or near the melting point of the powder, and at this time an inert gas is allowed to flow. Pure Al powder is
It contains 99.99% or more of Al and almost no impurities as a remainder. That is, when using an Al porous sintered body as a base material for a solid capacitor, an Al purity of 99.99% or more is required. The structure of the oxide film on the surface changes depending on the Al purity.
The higher the purity, the more dense the material, and the smaller the leakage current. In addition, Al powder can be molded without pressurizing it to form a green compact, with no pressure applied or with a slight pressure applied, that is, with virtually no pressure applied, and furthermore, its melting point The partially liquid state is sintered at or near it in an inert atmosphere such as N 2 gas.
更に詳しく説明すると、例えば、99.99％Alの
如く、高純度Al粉を、その融点若しくはその近
傍で焼結すると、組成ならびに組織が粒子全体に
わたり均一であることから、比較的僅かの時間で
全体が溶融する。このため、高純度Al粉では
仲々一部液相焼結が実現できなと云われている。
この点、純Al粉は、他のAl合金粉と違つて、表
面は厚さ100Å程度の酸化皮膜に覆われているこ
ともあつて、表面の接触部分に加えられた熱が集
積し、この部分から溶融が開始される。つまり、
酸化皮膜の熱伝導率はAlに比べて相当高く、熱
容量も大きく、なかでも、粉末粒子接触部分の酸
化皮膜に熱が集中的に蓄積され、この部分がはじ
めに溶解される。その上、粉末粒子の接触部分
は、次の(1)式によつて融点が降下し、その度合
（ΔT）が求められる。 To explain in more detail, for example, when high-purity Al powder such as 99.99% Al is sintered at or near its melting point, the composition and structure are uniform throughout the particle, so the entire particle is sintered in a relatively short time. melt. For this reason, it is said that liquid phase sintering cannot be achieved with high-purity Al powder.
In this respect, unlike other Al alloy powders, the surface of pure Al powder is covered with an oxide film about 100 Å thick, so the heat applied to the contact area of the surface accumulates, and this Melting starts from that part. In other words,
The thermal conductivity of the oxide film is considerably higher than that of Al, and the heat capacity is also large. Particularly, heat is concentrated in the oxide film in the areas in contact with the powder particles, and this area is melted first. Furthermore, the melting point of the contact area of the powder particles decreases according to the following equation (1), and the degree of this decrease (ΔT) can be determined.
ΔT＝2γ／ｒ−VsTm／ΔHf ……(1)
ただし、
ΔT：溶融温度の降下度合
ΔHf：溶融熱
Vs：Al粉末1molの固体の容積
γ：溶融Alの表面張力
ｒ：Al粉末の粒子半径
Tm：Al粉末の融点
そこで、純度99.99％以上のAl粉末につき、(1)
式に各特性値を代入すると、(2)式が得られ、(2)式
から温度降下の値が具体的に求められる。 ΔT=2γ/r−VsTm/ΔHf...(1) However, ΔT: Degree of fall in melting temperature ΔHf: Heat of fusion Vs: Solid volume of 1 mol of Al powder γ: Surface tension of molten Al r: Particle radius of Al powder Tm: Melting point of Al powder Therefore, for Al powder with a purity of 99.99% or more, (1)
By substituting each characteristic value into the equation, equation (2) is obtained, and the value of temperature drop can be specifically determined from equation (2).
ｒ＝5.46×10-4／−ΔT ……(2)
例えば半径ｒ＝10-3mmの純Al粉末であると、
接触部分の融点が他の部分より0.6℃程度温度降
下する。 r=5.46×10 -4 /-ΔT ...(2) For example, if it is pure Al powder with radius r=10 -3 mm,
The melting point of the contact area is approximately 0.6°C lower than that of other areas.
また、このときに、焼結雰囲気中は少なくとも
酸素がないことが必要であり、この意味では還元
性雰囲気や不活性ガス雰囲気の何れでも良いが、
例えば、H2雰囲気の如き還元性雰囲気であると、
安全性が損なわれ易い。このため、本発明では
N2ガスの如き不活性雰囲気で焼結し、とくに、
N2ガスなどの不活性ガスを流動させ、焼結時に
粉末粒子間に残存する酸素を追出すとともに、こ
の粉末粒子間を不活性ガスで置換して内部を完全
に不活性雰囲気で包囲する。このように完全に不
活性ガス雰囲気にすると、少なくとも接触部分で
優先して溶融したときに、この溶融部分は全く酸
化されることなく、焼結が進行し、併せて、全く
Al酸化物が生成しないため、これらが介在する
ことがなく、強固な多孔質焼結体が得られる。 Also, at this time, it is necessary that there is at least no oxygen in the sintering atmosphere, and in this sense, either a reducing atmosphere or an inert gas atmosphere may be used.
For example, in a reducing atmosphere such as H2 atmosphere,
Safety is likely to be compromised. Therefore, in the present invention,
Sintered in an inert atmosphere such as N2 gas, in particular
By flowing an inert gas such as N 2 gas, oxygen remaining between the powder particles during sintering is expelled, and the space between the powder particles is replaced with an inert gas to completely surround the inside with an inert atmosphere. By creating a completely inert gas atmosphere in this way, when melting occurs preferentially at least in the contact area, sintering progresses without oxidizing this melted area at all, and at the same time, sintering progresses at all.
Since no Al oxide is generated, a strong porous sintered body can be obtained without the presence of these substances.
また、焼結時に、あまり長く融点若しくはその
近傍に保つことは好ましくないが、不活性ガスを
流動させて焼結性を高めるときには、５〜20分程
度である。 Further, during sintering, it is not preferable to maintain the temperature at or near the melting point for too long, but when improving sinterability by flowing an inert gas, the time is about 5 to 20 minutes.
また、上記の如くAl粒子の表面の少なくとも
一部を接触する状態を形成するのには、成形型を
用いてその中にAl粉末粒子を散布し、振動を与
えることによつて達成でき、焼結はこのままで焼
結すれば良い。 In addition, forming a state in which at least a part of the surface of the Al particles is in contact as described above can be achieved by using a mold, scattering Al powder particles into the mold, and applying vibration. You can sinter it as it is.
次に、実施例について説明する。 Next, examples will be described.
まず。99.99％Alから成る純Al粉（粒度150〜
325メツシユのものと325メツシユ以下のもの）を
成形型内に散布、振動を与えて、径２mm、高さ４
mmの円柱状に成型し、660±10℃の範囲で焼結し
た。この際、雰囲気ガスとしてN2ガスを流速１
／分の割合で流動し、焼結時間は昇温後、１
分、４分、５分、８分、10分、15分、20分、23
分、25分に保持し、各時間における焼結状況を観
察した。比較のために、N2ガス雰囲気中でN2ガ
スを流動させることなく、焼結時間を変化させて
焼結した。 first. Pure Al powder consisting of 99.99% Al (particle size 150~
325 mesh and 325 mesh or less) were sprinkled into the mold and vibrated to form a mold with a diameter of 2 mm and a height of 4 mm.
It was molded into a cylindrical shape with a diameter of mm and sintered at a temperature of 660±10°C. At this time, N2 gas was used as the atmospheric gas at a flow rate of 1
/minute, and the sintering time is 1 minute after heating up.
minutes, 4 minutes, 5 minutes, 8 minutes, 10 minutes, 15 minutes, 20 minutes, 23
The sintering conditions were observed at each time. For comparison, sintering was performed in an N2 gas atmosphere without flowing N2 gas and for different sintering times.
この結果、N2ガスを流動させた場合は、焼結
時間５分程度で焼結するが、20分以上になると孔
隙率が大巾に低下し、Al粉末の中心附近まで溶
融した。また、N2ガスを流動させないときは９
分程度でも焼結が不十分で、12分程度で焼結され
たが20分をこえると焼結がばらつき好ましくなか
つた。 As a result, when N 2 gas was flowed, sintering was completed in about 5 minutes, but after 20 minutes or more, the porosity decreased significantly and the Al powder was melted close to the center. Also, when not flowing N2 gas, use 9
Sintering was insufficient even after about 12 minutes, and although sintering was achieved after about 12 minutes, sintering varied and was not desirable after 20 minutes.
Claims (1)
を含まない純Al粉末をこれら粉末粒子の表面の
一部が接触する状態に圧力を加えることなく成型
し、その後、不活性ガス雰囲気中で、不活性ガス
を流動させつつ、純Al粉末の融点若しくは近傍
の温度で焼結することを特徴とするコンデンサ等
に供せられるAl多孔質焼結体の製造法。1 Pure Al powder consisting of 99.99% or more Al and containing almost no impurities is molded without applying pressure so that a part of the surface of these powder particles is in contact with each other, and then in an inert gas atmosphere. A method for producing an Al porous sintered body for use in capacitors, etc., characterized by sintering at a temperature at or near the melting point of pure Al powder while flowing gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10000079A JPS5625906A (en) | 1979-08-06 | 1979-08-06 | Reparation of porous sintered material from pure aluminum powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10000079A JPS5625906A (en) | 1979-08-06 | 1979-08-06 | Reparation of porous sintered material from pure aluminum powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5625906A JPS5625906A (en) | 1981-03-12 |
| JPH0130881B2 true JPH0130881B2 (en) | 1989-06-22 |
Family
ID=14262325
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10000079A Granted JPS5625906A (en) | 1979-08-06 | 1979-08-06 | Reparation of porous sintered material from pure aluminum powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5625906A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101754825B (en) | 2007-07-18 | 2012-04-18 | 株式会社Ihi | Process for producing electrode for discharge surface treatment, and electrode for discharge surface treatment |
| GB0715320D0 (en) * | 2007-08-08 | 2007-09-19 | Bridge Iain | Fused granular structure |
-
1979
- 1979-08-06 JP JP10000079A patent/JPS5625906A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5625906A (en) | 1981-03-12 |
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