JP3703871B2

JP3703871B2 - Copper-based segregation-preventing mixed powder and method for producing the same

Info

Publication number: JP3703871B2
Application number: JP27208794A
Authority: JP
Inventors: 忠司小山; 修岩津
Original assignee: Fukuda Metal Foil and Powder Co Ltd
Current assignee: Fukuda Metal Foil and Powder Co Ltd
Priority date: 1994-11-07
Filing date: 1994-11-07
Publication date: 2005-10-05
Anticipated expiration: 2020-10-05
Also published as: JPH08134502A

Description

【０００１】
【産業上の利用分野】
本発明は、粉末冶金製品の原料粉として使用され、従来技術では有機結合剤が焼結を阻害する銅系において、焼結を阻害されずに偏析を防止できる偏析防止処理混合粉とその製造方法に関するものである。
【０００２】
【従来の技術】
従来から、焼結部品を製造する場合の原料粉としては、主成分粉と副成分粉とを所定の割合で混合したものが用いられている。しかしながら多くの場合、主成分粉と副成分粉の間に比重, 粒度及び粒形等の差があるために、混合粉の輸送, ホッパーへの装入, ホッパーからの流出あるいは金型への充填時に偏析を起こし、得られる焼結部品の寸法精度, 強度等の特性がばらついたり低下したりする。このような混合粉の偏析を防止するために、これまで次の様な方法が開示されている。
(1) 特開昭60−502158に示されている様にトール油などの液体添加剤を粉末混合物に添加する方法。
(2) 特開昭63−103001や特開平2 −217403などで示されている様に有機結合剤を溶剤で溶解して添加し、均一混合した後、溶剤を蒸発させる方法。
【０００３】
しかしながら、上記(1) の方法は、混合粉末の流動性が著しく悪化し、作業性が極めて悪くなる。
また、(2) の方法は、鉄系では実用されているが、有機結合剤が脱脂あるいは焼結中に完全に分解, 揮発せず、極く微量の炭素が残るため、例えば銅系の様に炭素の固溶度がない系では、残留炭素が焼結を著しく阻害する。
このため、従来有機結合剤を使用した偏析防止処理混合粉は鉄粉あるいは鉄系の粉末を主成分とする場合に限られており、銅系など、有機結合剤が焼結を阻害する系の偏析防止処理混合粉とその製造方法は提案されていなかった。
【０００４】
【発明が解決しようとする課題】
本発明は、上記課題を解決し、有機結合剤が阻害する銅系において、焼結を阻害されずに偏析を防止できる粉末冶金用偏析防止処理混合粉とその製造方法を提供しようとするものである。
【０００５】
【課題を解決するための手段】
即ち、本発明の粉末冶金用銅系偏析防止処理混合粉は、主成分として銅粉又は銅合金粉、副成分粉として銅系粉末冶金で使用される錫粉，鉛粉, 亜鉛粉, アルミ粉，黒鉛粉の中から選ばれるいずれか１種を、主成分粉と副成分粉の総重量の0.01〜0.10％の水溶性有機結合剤で結合させた、銅系偏析防止処理混合粉である。また本発明の製造方法は次の３通りの手段を講じたものである。
【０００６】
(1) 先ず、副成分粉に、例えばポリビニルピロリドン(PVP) やポリビニルアルコール(PVA) などの水溶性有機結合剤をコーティングさせる。すなわち、固体結合剤の量が、主成分粉と副成分粉の総重量の0.02〜0.10％となる様に、水溶性有機結合剤の水溶液と副成分粉を混練し、乾燥後, 粉砕して、水溶性有機結合剤でコーティングされた副成分粉を作製する。次に、主成分粉に、主成分粉と副成分粉の総重量の 0.5〜4.0 ％の水を添加、均一混合して主成分粉の周囲に薄い水の層を形成させたものに、上記の水溶性有機結合剤をコーテイングした副成分粉を添加して均一混合した後、乾燥することにより偏析防止処理混合粉を作製する。
【０００７】
(2) 主成分粉に、水溶性有機結合剤の重量が主成分粉と副成分粉の総重量の0.02〜0.05％となる様に水溶性有機結合剤の水溶液を添加, 均一混合し、副成分粉を添加, 再び混合したもの又は、主成分粉と副成分粉の混合粉に、水溶性有機結合剤の重量が主成分粉と副成分粉の総重量の0.02〜0.05％となる様に水溶性有機結合剤の水溶液を添加, 混合したものを、30〜100 kgf/cm2 の圧力で加圧し、乾燥, 解砕して偏析防止処理混合粉を作製する。
【０００８】
(3) 主成分粉と副成分粉の総重量の 0.5〜4.0 ％の水を主成分粉に添加して、主成分粉の周囲に薄い水の層を形成させたものに、水溶性有機結合剤の重量が主成分粉と副成分粉の総重量の0.01〜0.10％となる様に水溶性有機結合剤をコーティングした副成分粉を添加, 混合した後、30〜100 kgf/cm2 の圧力で加圧し、乾燥, 解砕して偏析防止処理混合粉を作製する。
【０００９】
【作用】
(1) の手段の特徴は、水溶性有機結合剤を副成分粉にコーティングしたものを、水で濡らした銅粉と混合した後、乾燥する所にある。従来の鉄系偏析防止処理混合粉では、主成分粉の周囲にも薄い有機結合剤の層ができてしまい、この技術を、銅系など炭素の固溶度がない系に適用すると、わずかに残る有機結合剤中の炭素が焼結を著しく阻害するという問題があるが、本発明方法では、図１にモデル図を示したように、水溶性有機結合剤は、主成分粉の周囲にはほとんど存在せず、焼結を阻害しにくい。また、主成分粉と副成分粉の間の水溶性有機結合剤が厚く、付着力が向上するので、偏析防止効果が良好である。水溶性有機結合剤の量を主成分粉と副成分粉の総重量の0.02〜0.10％としたのは、0.02％以下では十分な偏析防止効果が得られず、0.10％以上では、初め副成分粉の周囲のみに存在していた水溶性有機結合剤が、混合過程中に主成分粉の周囲にも付着するため、焼結を阻害することになる。
【００１０】
主成分粉に添加する水の量を、主成分粉と副成分粉の総重量の 0.5〜4.0 ％としたのは、0.5 ％より少ないと、主成分粉を十分に濡らすことができず、満足する偏析防止効果が得られない。また、4 ％より多いと、余剰な水のため副成分粉同志が凝集してしまい、粗大な副成分粒子ができ、適切でない。(2) の手段は、主成分粉に水溶性有機結合剤の水溶液を添加、混合し、副成分粉を添加、再び混合したもの又は、主成分粉と副成分粉の混合物に水溶性有機結合剤の重量が主成分粉と副成分粉の総重量の0.02〜0.05％となる様に水溶性有機結合剤の水溶液を添加, 混合したものを、加圧することにより、主成分粉と副成分粉の接着性が向上するために、より少量の水溶性有機結合剤で満足できる偏析防止効果が得られ、その結果、水溶性有機結合剤は主成分粉の周囲に存在するものの、焼結を阻害することがない。水溶性有機結合剤の量を主成分粉と副成分粉の総重量の0.02〜0.05％としたのは、0.02％以下では、満足できる偏析防止効果が得られず、0.05％以上では、主成分粉の周囲に存在する水溶性有機結合剤が焼結を阻害するためである。
【００１１】
加圧力を30〜100 kgf/cm2 としたのは、30kgf/cm2 以下では加圧の効果が不十分で、満足できる偏析防止効果が得られず、100 kgf/cm2 以上では、粉末が変形し、元のイレギュラーな形状が壊れるため、成形性が悪くなるためである。(3) の手段は、(1) と(2) の両方の手段を施すもので、(1),(2) の手段より少量の水溶性有機結合剤で十分な偏析防止効果が得られ、また、水溶性有機結合剤を0.10％添加しても、焼結を阻害することがない。水溶性有機結合剤の量を主成分粉と副成分粉の総重量の0.01〜0.10％としたのは、0.01％以下では、十分な偏析防止効果が得られず、0.10％以上では、初め副成分粉の周囲のみに存在していた水溶性有機結合剤が、混合過程中に主成分粉の周囲に付着するため、水溶性有機結合剤が焼結を阻害するためである。
【００１２】
【実施例】
以下、本発明の実施例及び比較例について説明する。
実施例(1) 〜(3) は請求項２の方法、実施例(4) 〜(6) は請求項３の方法、実施例(7) は請求項４の方法の例である。
なお、見掛密度は、ＪＩＳ−Ｚ−２５０４に準じて、流動度はＪＩＳ−Ｚ−２５０２に準じて測定した。偏析についての評価は、粉末 100 gをビーカーに入れ、内製の振動装置により、水平に対して45°の角度に振幅 5mm, 振動数12Hzで30分間振動させた後の目視観察で行った。すなわち、銅−黒鉛系の場合では、黒鉛粉が銅粉と分離して、かなり上の方へ浮き上がるものを×、側面に黒いすじ状の偏析を起こすものを△、偏析をほとんど起こさないものを○とした。
焼結体圧環強さは、粉末をステアリン酸亜鉛を塗布した金型に入れ、圧粉密度が6.5 g/cm³となる様にφ20×φ12×11.8mmの円筒形に成形し、500 ℃で30分間脱脂、800 ℃で30分間焼結した後、ＪＩＳ−Ｚ−２５０７に準じて測定した。
【００１３】
実施例(1) 及び比較例(1)
実施例(1) として、請求項２の方法で作製した本発明粉と従来技術による粉末及び単純混合粉を比較した。
試料Ａとして、次の偏析防止処理粉を作製した。平均粒径10μm の天然黒鉛粉100gに、PVP 2 ％水溶液を125g添加、乳鉢で混練し、オーブンで100 ℃、1 時間乾燥した後、粉砕して、PVP が主成分粉と副成分粉の総重量の0.05％となるようにPVP でコーティングされた黒鉛粉を得た。
次に、平均粒径50μm の粉末冶金用アトマイズ銅粉196 g に水を 2g 添加して、小型混合機で15分混合した後、上記PVP コーティング黒鉛粉を4.10g 添加、さらに15分混合した。混合物を100 ℃で30分間乾燥し、−80meshを試料粉とした。
試料Ｂは、平均粒径50μm のアトマイズ銅粉196 g に、PVP 5 ％水溶液を 2g 添加して小型混合機で15分間混合、平均粒径10μm の天然黒鉛粉 4g を添加し、さらに15分間混合した後、100 ℃で30分間乾燥し、−80meshを試料粉としたものである。
試料Ｃは、平均粒径50μm のアトマイズ銅粉196 g に、平均粒径10μm の天然黒鉛粉 4g とを小型混合機で15分間混合して作製した。
表１に実施例(1) 及び比較例(1) の結果を示す。
【００１４】
【表１】

【００１５】
本発明に比べ、従来技術による粉末は、主成分粉と副成分粉の間の有機結合剤が少ないため、偏析防止効果が劣り、また、主成分の周囲に存在する薄い有機結合剤の層が、焼結を阻害するため、圧環強さが低い。単純混合粉は微細な黒鉛粉のために、流動性が悪く、振動を与えると著しく偏析を起こし、また、成分が不均一なため、本発明粉よりも圧環強さが低い。
【００１６】
実施例(2) 及び比較例(2)
実施例(2) として、水溶性有機結合剤を主成分粉と副成分粉の総重量の0.02％から0.10％に限定した理由を示した。平均粒径10μm の天然黒鉛粉100gに水溶性有機結合剤としてPVP 2 ％水溶液を25〜300g 添加、乳鉢で混練し、オーブンで100 ℃、１時間乾燥した後粉砕して、PVP が主成分粉と副成分粉の総重量の0.01〜0.12％となるようにPVP でコーティングされた黒鉛粉を得た。次に、平均粒径50μm の粉末冶金用アトマイズ銅粉196 g に水を 2g 添加して、小型混合機で15分間混合した後、上記PVP コーティング黒鉛粉を4.02g 〜4.24g添加して、さらに15分混合し、オーブンで100 ℃で30分間乾燥し、−80meshを試料粉とした。結果を表２に示す。
【００１７】
【表２】

【００１８】
試料Ａは、水溶性有機結合剤が少な過ぎ、主成分粉である銅粉と副成分粉である黒鉛粉との接着が十分できないため、流動性が悪く、偏析が激しい。試料Ｅは、水溶性有機結合剤の量が多すぎるため、焼結を阻害し、圧環強さが低い。
実施例(3) 及び比較例(3)
実施例(3) として、主成分粉に添加する水の量を成分粉と副成分粉の総重量の0.5〜4.0 ％に限定した理由を示す。平均粒径50μm の粉末冶金用アトマイズ銅粉196 g に水を0.4 〜12.0g 添加して、小型混合機で15分混合した後、実施例(1) で作製した、PVP が主成分粉と副成分粉の総重量の0.05％となるようにPVP でコーティングされた黒鉛粉を4.10g 添加、さらに15分間混合し、100 ℃で30分間乾燥し、−80meshを試料粉とした。結果を表３に示す。試料Ａは、水の添加量が少ないため、銅粉を十分に濡らすことができず、黒鉛粉の付着が十分でない。試料Ｅは、水の添加量が多すぎるため、余剰な水が黒鉛粉のみを凝集させ、粗大な黒鉛粒子ができ、粉末に振動を与えると、粗大な黒鉛粒子が著しく偏析を起こし、また、焼結体の強度も低い。
【００１９】
【表３】

【００２０】
実施例(4) 及び比較例(4)
実施例(4) として、請求項３の方法で作製した本発明粉と従来技術による粉末及び単純混合粉を比較した。
試料Ａとして、次の偏析防止混合粉を作製した。平均粒径50μm の粉末冶金用アトマイズ銅粉 196 g にPVP 5 ％水溶液を1.6 g 添加し、小型混合機で15分混合して、平均粒径10μm の天然黒鉛 4g を添加、さらに15分混合した。次に、これを金型に入れてプレス機で60 kgf/cm²の圧力を加えた後に取り出して、オーブンで100 ℃、１時間乾燥し、乳鉢にて軽く解砕して−80meshを試料粉とした。
試料Ｂは、試料Ａの加圧工程がないものである。
試料Ｃは、同様の銅粉と黒鉛粉を小型混合機で15分間混合したものである。
表４にこれらの結果を示す。
【００２１】
【表４】

【００２２】
本発明粉は、加圧により、銅粉と黒鉛粉がよく接着しているため偏析を起こさず、その結果、焼結体の成分分布が均一で強度が向上することがわかる。
実施例(5) 及び比較例(5)
実施例(5) として、水溶性有機結合剤量を主成分粉と副成分粉の総重量の0.02〜0.05％に限定した理由を示した。
【００２３】
平均粒径50μm の粉末冶金用アトマイズ銅粉にPVP 5 ％水溶液0.4 〜2.8 g を添加、小型混合機で15分間混合し、これに、平均粒径10μm の天然黒鉛4gを添加、さらに15分間混合した。次に、これを金型に入れてプレス機で 60kgf/cm²の圧力を加えた後、取り出して、オーブンで100 ℃、1 時間乾燥し、乳鉢で軽く解砕して、−80meshを、PVP を主成分粉と副成分粉の総重量の0.01〜0.07％含んだ試料粉とした。
結果を表５に示す。
【００２４】
【表５】

【００２５】
PVP 添加量が0.02％より少ないと、偏析防止効果が低下し、0.07％以上になると、PVP が焼結を阻害し、焼結体強度が低下する。
実施例(6) 及び比較例(6)
実施例(6) として、加圧力を30〜100 kgf/cm²に限定した理由を示した。
平均粒径50μm の粉末冶金用アトマイズ銅粉にPVP 5 ％溶液を 2 g添加し、小型混合機で15分間混合し、これに、平均粒径10μm の天然黒鉛 4 gを添加して、さらに15分間混合した。次に、これを金型に入れてプレス機で20〜120kgf/cm²の圧力を加えた後、取り出して、オーブンで100 ℃、1 時間乾燥し、乳鉢で軽く解砕して、−80meshを試料粉とした。
結果を表６に示す。
【００２６】
【表６】

【００２７】
加圧力が30kgf/cm2 より小さいと、銅粉と黒鉛粉の接着が不十分で、偏析を起こしやすくなり、その結果、焼結体の強度が低下する。加圧力が100kgf/cm2より大きくなると、粉末が変形して、元のイレギュラーな形状が壊れるため、成形時に粉末同志のからみが少なくなり、その結果、焼結体の強度が低下する。
実施例(7) 及び比較例(7)
実施例(7) として、請求項４の方法で作製した本発明粉の水溶性有機結合剤の量について示す。
【００２８】
平均粒径10μm の天然黒鉛100gに水溶性有機結合剤として、PVP 2 ％溶液を12.5及び25g 添加、乳鉢で混練し、オーブンにて100 ℃、1 時間乾燥した後、粉砕して、PVP が粉末冶金用アトマイズ銅粉と天然黒鉛の総重量の0.005 及び0.01％となるようにPVP でコーティングされた黒鉛粉を得た。次に、平均粒径50μm の粉末冶金用アトマイズ銅粉196 に水を 2 g添加して、小型混合機で15分間混合した後、上記PVP コーテイング黒鉛粉を4.01g 及び4.02g添加し、さらに15分間混合した。
【００２９】
【表７】

【００３０】
この、混合物を金型に入れてプレス機で 60kgf/cm2の圧力を加えた後にとり出して、オーブンにて100 ℃、 1時間乾燥し、乳鉢で軽く解砕して−80meshを試料粉とした。結果を表７に示す。試料Ａは、水溶性有機結合剤が少な過ぎ、振動により偏析を起こす。本発明品である、試料Ｂは、水溶性有機結合剤の0.01％の添加で偏析を起こさず、成分分布の均一性により、焼結体強度も良好である。
【００３１】
【発明の効果】
本発明によれば、有機結合剤が焼結を阻害する銅系において、焼結を阻害されずに偏析を防止できる粉末冶金用偏析防止処理混合粉を提供することが可能となった。
【図面の簡単な説明】
【図１】請求項１の方法で作製した偏析防止粉と従来技術のモデル図。
【符号の説明】
１主成分粉
２副成分粉
３有機結合剤[0001]
[Industrial application fields]
The present invention is used as a raw material powder for powder metallurgy products, and in a copper system in which organic binders inhibit sintering in the prior art, a segregation-preventing mixed powder capable of preventing segregation without inhibiting sintering and a method for producing the same It is about.
[0002]
[Prior art]
Conventionally, as a raw material powder in the case of manufacturing a sintered part, a mixture of main component powder and subcomponent powder at a predetermined ratio has been used. However, in many cases, there are differences in specific gravity, particle size, and particle shape between the main component powder and subcomponent powder, so mixed powder transport, charging into the hopper, outflow from the hopper, or filling into the mold Segregation sometimes occurs, and characteristics such as dimensional accuracy and strength of the resulting sintered parts vary or decrease. In order to prevent such segregation of the mixed powder, the following methods have been disclosed so far.
(1) A method of adding a liquid additive such as tall oil to a powder mixture as disclosed in JP-A-60-502158.
(2) A method in which an organic binder is dissolved and added in a solvent as shown in JP-A-63-103001 and JP-A-2-217403, and the solvent is evaporated after uniform mixing.
[0003]
However, in the method (1), the fluidity of the mixed powder is remarkably deteriorated and workability is extremely deteriorated.
The method (2) is practically used for iron-based materials, but the organic binder does not completely decompose and volatilize during degreasing or sintering, and a very small amount of carbon remains. In a system having no carbon solid solubility, residual carbon significantly inhibits sintering.
For this reason, the segregation-preventing mixed powder using an organic binder is limited to the case where the main component is iron powder or iron-based powder. No segregation-preventing mixed powder and its production method have been proposed.
[0004]
[Problems to be solved by the invention]
The present invention is intended to solve the above-mentioned problems and provide a segregation preventing treatment mixed powder for powder metallurgy that can prevent segregation without inhibiting sintering in a copper system that an organic binder inhibits, and a method for producing the same. is there.
[0005]
[Means for Solving the Problems]
That is, the copper-based segregation preventing mixed powder for powder metallurgy according to the present invention is composed of copper powder or copper alloy powder as a main component, tin powder, lead powder, zinc powder, aluminum powder used as copper powder metallurgy as an auxiliary component powder. , A copper-based segregation-preventing mixed powder obtained by binding any one selected from graphite powder with a water-soluble organic binder in an amount of 0.01 to 0.10% of the total weight of the main component powder and subcomponent powder. The manufacturing method of the present invention employs the following three means.
[0006]
(1) First, the subcomponent powder is coated with a water-soluble organic binder such as polyvinyl pyrrolidone (PVP) or polyvinyl alcohol (PVA). That is, the aqueous solution of the water-soluble organic binder and the subcomponent powder are kneaded so that the amount of the solid binder is 0.02 to 0.10% of the total weight of the main component powder and subcomponent powder, dried, and then pulverized. A subcomponent powder coated with a water-soluble organic binder is prepared. Next, 0.5% to 4.0% of the total weight of the main component powder and subcomponent powder is added to the main component powder and mixed uniformly to form a thin water layer around the main component powder. After adding the subcomponent powder coated with the water-soluble organic binder and uniformly mixing, the mixture is dried to produce a segregation preventing mixed powder.
[0007]
(2) the main component powder, adding an aqueous solution of a water-soluble organic binder as the weight of the water-soluble organic binder is 0.02 to 0.05% by weight of the total weight of the main component powder and the auxiliary component powder, and uniformly mixed, secondary Ingredient powder added, mixed again, or mixed powder of main ingredient powder and sub ingredient powder so that the weight of water-soluble organic binder is 0.02 to 0.05% of the total weight of main ingredient powder and sub ingredient powder An aqueous solution of a water-soluble organic binder is added and mixed at a pressure of 30 to 100 kgf / cm2, dried and crushed to produce a segregation-prevented mixed powder.
[0008]
(3) Water- soluble organic bonds are formed by adding 0.5 to 4.0% of the total weight of the main component powder and subcomponent powder to the main component powder to form a thin water layer around the main component powder. Add the auxiliary powder coated with water-soluble organic binder so that the weight of the additive is 0.01-0.10% of the total weight of the main ingredient powder and auxiliary ingredient powder, and after mixing, at a pressure of 30-100 kgf / cm2 Pressurize, dry and crush to produce a segregation-prevented mixed powder.
[0009]
[Action]
The feature (1) is characterized in that a water-soluble organic binder coated on a subcomponent powder is mixed with copper powder wetted with water and dried. With conventional iron-based segregation-prevented mixed powder, a thin organic binder layer is also formed around the main component powder. When this technology is applied to a system with no carbon solid solubility such as copper, Although there is a problem that carbon in the remaining organic binder significantly inhibits sintering, in the method of the present invention, as shown in the model diagram in FIG. 1, the water-soluble organic binder is not present around the main component powder. Almost does not exist and does not hinder sintering. Moreover, since the water-soluble organic binder between the main component powder and the subcomponent powder is thick and the adhesion is improved, the segregation preventing effect is good. The amount of the water-soluble organic binder is 0.02 to 0.10% of the total weight of the main component powder and subcomponent powder . If 0.02% or less, sufficient segregation prevention effect cannot be obtained, and if it is 0.10% or more, the subcomponent is initially Since the water-soluble organic binder present only around the powder adheres to the periphery of the main component powder during the mixing process, the sintering is inhibited.
[0010]
The amount of water added to the main component powder is 0.5-4.0% of the total weight of the main component powder and sub-component powder. If the amount is less than 0.5%, the main component powder cannot be sufficiently wetted and satisfied. The effect of preventing segregation is not obtained. On the other hand, if it is more than 4%, the secondary component powder aggregates due to excess water, resulting in coarse secondary component particles, which is not appropriate. (2) means that an aqueous solution of a water-soluble organic binder is added to and mixed with the main component powder, and the auxiliary component powder is added and mixed again, or the mixture of the main component powder and the auxiliary component powder is dissolved in water. Add and mix an aqueous solution of water-soluble organic binder so that the weight of the agent is 0.02 to 0.05% of the total weight of the main component powder and subcomponent powder. As a result, the segregation prevention effect can be obtained with a smaller amount of water-soluble organic binder. As a result, water-soluble organic binder is present around the main component powder but inhibits sintering. There is nothing to do. The amount of the water-soluble organic binder is 0.02 to 0.05% of the total weight of the main component powder and subcomponent powder . If 0.02% or less, a satisfactory segregation preventing effect cannot be obtained. This is because the water-soluble organic binder present around the powder inhibits the sintering.
[0011]
The reason why the applied pressure was 30 to 100 kgf / cm2 is that the effect of pressurization is insufficient at 30 kgf / cm2 or less, and a satisfactory segregation preventing effect cannot be obtained, and at 100 kgf / cm2 or more, the powder is deformed, This is because the original irregular shape is broken and the moldability is deteriorated. The means (3) applies both the means (1) and (2), and a sufficient amount of segregation prevention effect can be obtained with a smaller amount of water-soluble organic binder than the means (1) and (2). Moreover, even if 0.10% of a water-soluble organic binder is added, sintering is not hindered. The amount of the water-soluble organic binder is set to 0.01 to 0.10% of the total weight of the main component powder and the sub component powder. When the amount is 0.01% or less, sufficient segregation prevention effect cannot be obtained. This is because the water-soluble organic binder that exists only around the component powder adheres to the periphery of the main component powder during the mixing process, so that the water-soluble organic binder inhibits sintering.
[0012]
【Example】
Examples of the present invention and comparative examples will be described below.
Examples (1) to (3) are examples of the method of claim 2, examples (4) to (6) are examples of the method of claim 3, and example (7) is an example of the method of claim 4.
The apparent density was measured according to JIS-Z-2504, and the fluidity was measured according to JIS-Z-2502. Evaluation of segregation was performed by visual observation after putting 100 g of powder into a beaker and vibrating it with an in-house vibration device at an angle of 45 ° with respect to the horizontal at an amplitude of 5 mm and a frequency of 12 Hz for 30 minutes. That is, in the case of the copper-graphite system, the graphite powder separates from the copper powder and floats up to the upper side x, the one causing black stripe-like segregation on the side face, and the one causing little segregation. ○.
The sintered compact crushing strength is determined by placing the powder in a die coated with zinc stearate and forming it into a cylindrical shape of φ20 × φ12 × 11.8 mm so that the green density is 6.5 g / cm ^3. After degreasing for 30 minutes and sintering at 800 ° C. for 30 minutes, the measurement was performed according to JIS-Z-2507.
[0013]
Example (1) and Comparative Example (1)
As Example (1), the powder of the present invention produced by the method of claim 2 was compared with the powder of the prior art and the simple mixed powder.
As sample A, the following segregation preventing powder was prepared. 125 g of PVP 2% aqueous solution is added to 100 g of natural graphite powder with an average particle size of 10 μm, kneaded in a mortar, dried in an oven at 100 ° C. for 1 hour, pulverized, and PVP is the total of the main component powder and subcomponent powder. A graphite powder coated with PVP so as to be 0.05% by weight was obtained.
Next, 2 g of water was added to 196 g of atomized copper powder for powder metallurgy having an average particle size of 50 μm, mixed for 15 minutes with a small mixer, and then added with 4.10 g of the above PVP-coated graphite powder and further mixed for 15 minutes. The mixture was dried at 100 ° C. for 30 minutes, and −80 mesh was used as sample powder.
For sample B, add 196 g of atomized copper powder with an average particle size of 50 μm to 2 g of PVP 5% aqueous solution, mix for 15 minutes with a small mixer, add 4 g of natural graphite powder with an average particle size of 10 μm, and mix for another 15 minutes Then, it is dried at 100 ° C. for 30 minutes, and −80 mesh is used as a sample powder.
Sample C was prepared by mixing 196 g of atomized copper powder having an average particle size of 50 μm with 4 g of natural graphite powder having an average particle size of 10 μm for 15 minutes using a small mixer.
Table 1 shows the results of Example (1) and Comparative Example (1).
[0014]
[Table 1]

[0015]
Compared to the present invention, the powder according to the prior art has less organic binder between the main component powder and the subcomponent powder, so the segregation preventing effect is inferior, and a thin organic binder layer around the main component is present. In order to inhibit sintering, the crushing strength is low. Simple mixed powders are fine graphite powders, and therefore have poor fluidity, and when subjected to vibration, segregation occurs remarkably, and since the components are not uniform, the crushing strength is lower than the powders of the present invention.
[0016]
Example (2) and Comparative Example (2)
As Example (2), the reason why the water-soluble organic binder was limited to 0.02% to 0.10% of the total weight of the main component powder and the sub component powder was shown. Add 25 to 300g of PVP 2% aqueous solution as a water-soluble organic binder to 100g of natural graphite powder with an average particle size of 10μm, knead in a mortar, dry in an oven at 100 ° C for 1 hour, and then pulverize. Thus, graphite powder coated with PVP so as to be 0.01 to 0.12% of the total weight of the subcomponent powder was obtained. Next, 2 g of water was added to 196 g of atomized copper powder for powder metallurgy with an average particle size of 50 μm and mixed for 15 minutes with a small mixer, and then 4.02 g to 4.24 g of the above PVP-coated graphite powder was added. The mixture was mixed for 15 minutes and dried in an oven at 100 ° C. for 30 minutes, and −80 mesh was used as a sample powder. The results are shown in Table 2.
[0017]
[Table 2]

[0018]
Sample A has too little water-soluble organic binder, and cannot sufficiently bond the copper powder as the main component powder and the graphite powder as the subcomponent powder, so the fluidity is poor and segregation is severe. In Sample E, since the amount of the water-soluble organic binder is too large, sintering is inhibited and the crushing strength is low.
Example (3) and Comparative Example (3)
As Example (3), the reason for limiting the amount of water added to the main component powder to 0.5 to 4.0% of the total weight of the component powder and the subcomponent powder will be shown. After adding 0.4 to 12.0 g of water to 196 g of atomized copper powder for powder metallurgy with an average particle size of 50 μm and mixing for 15 minutes with a small mixer, the PVP produced in Example (1) was mixed with the main component powder. 4.10 g of graphite powder coated with PVP so as to be 0.05% of the total weight of the component powder was added, mixed for another 15 minutes, dried at 100 ° C. for 30 minutes, and −80 mesh was used as sample powder. The results are shown in Table 3. Since the sample A has a small amount of water added, the copper powder cannot be sufficiently wetted and the graphite powder is not sufficiently adhered. In sample E, since the amount of water added is too large, excess water aggregates only graphite powder to form coarse graphite particles. When the powder is vibrated, the coarse graphite particles cause significant segregation, The strength of the sintered body is also low.
[0019]
[Table 3]

[0020]
Example (4) and Comparative Example (4)
As Example (4), the powder of the present invention produced by the method of claim 3 was compared with the powder of the prior art and the simple mixed powder.
As sample A, the following segregation-preventing mixed powder was prepared. Add 1.6 g of 5% aqueous solution of PVP to 196 g of atomized copper powder for powder metallurgy with an average particle size of 50 μm, mix for 15 minutes with a small mixer, add 4 g of natural graphite with an average particle size of 10 μm, and mix for another 15 minutes . Next, this was put in a mold, taken out after applying a pressure of 60 kgf / cm ² with a press machine, dried in an oven at 100 ° C. for 1 hour, lightly crushed in a mortar, and −80 mesh was sampled. It was.
Sample B has no pressurizing step for sample A.
Sample C is obtained by mixing the same copper powder and graphite powder for 15 minutes with a small mixer.
Table 4 shows these results.
[0021]
[Table 4]

[0022]
The powder of the present invention does not cause segregation because the copper powder and the graphite powder are well bonded by pressurization, and as a result, it is understood that the component distribution of the sintered body is uniform and the strength is improved.
Example (5) and Comparative Example (5)
As Example (5), the reason why the amount of the water-soluble organic binder was limited to 0.02 to 0.05% of the total weight of the main component powder and the subcomponent powder was shown.
[0023]
Add 0.4 to 2.8 g of PVP 5% aqueous solution to atomized copper powder for powder metallurgy with an average particle size of 50 μm, mix for 15 minutes with a small mixer, add 4 g of natural graphite with an average particle size of 10 μm, and mix for another 15 minutes did. Next, after putting this in a mold and applying a pressure of 60 kgf / cm ² with a press machine, it is taken out, dried in an oven at 100 ° C. for 1 hour, crushed lightly in a mortar, −80mesh is converted into PVP Was used as a sample powder containing 0.01 to 0.07% of the total weight of the main component powder and subcomponent powder.
The results are shown in Table 5.
[0024]
[Table 5]

[0025]
When the amount of PVP added is less than 0.02%, the effect of preventing segregation decreases, and when it exceeds 0.07%, PVP inhibits sintering and the strength of the sintered body decreases.
Example (6) and Comparative Example (6)
As Example (6), the reason why the applied pressure was limited to 30 to 100 kgf / cm ² was shown.
Add 2 g of PVP 5% solution to atomized copper powder for powder metallurgy with an average particle size of 50 μm, mix for 15 minutes with a small mixer, add 4 g of natural graphite with an average particle size of 10 μm, and add 15 Mixed for minutes. Next, after putting it in a mold and applying a pressure of ²⁰ to 120 kgf / cm ² with a press machine, it is taken out, dried in an oven at 100 ° C. for 1 hour, lightly crushed in a mortar, and −80 mesh is obtained. Sample powder was obtained.
The results are shown in Table 6.
[0026]
[Table 6]

[0027]
When the applied pressure is less than 30 kgf / cm 2, the adhesion between the copper powder and the graphite powder is insufficient and segregation is likely to occur, resulting in a decrease in the strength of the sintered body. When the applied pressure is greater than 100 kgf / cm 2, the powder is deformed and the original irregular shape is broken, so that the entanglement between the powders is reduced at the time of molding, and as a result, the strength of the sintered body is reduced.
Example (7) and Comparative Example (7)
As Example (7), it shows about the quantity of the water-soluble organic binder of this invention powder produced by the method of Claim 4.
[0028]
Add 12.5 and 25 g of PVP 2% solution as a water-soluble organic binder to 100 g of natural graphite with an average particle size of 10 μm, knead in a mortar, dry in an oven at 100 ° C. for 1 hour, pulverize, and PVP powder A graphite powder coated with PVP so as to be 0.005 and 0.01% of the total weight of the atomized copper powder for metallurgy and natural graphite was obtained. Next, 2 g of water was added to atomized copper powder 196 for powder metallurgy with an average particle diameter of 50 μm, mixed for 15 minutes with a small mixer, then 4.01 g and 4.02 g of the above PVP coating graphite powder were added, and 15 Mixed for minutes.
[0029]
[Table 7]

[0030]
This mixture was put into a mold, taken out after applying a pressure of 60 kgf / cm2 with a press machine, dried in an oven at 100 ° C. for 1 hour, and lightly crushed in a mortar to obtain −80 mesh as sample powder . The results are shown in Table 7. Sample A has too little water-soluble organic binder and segregates due to vibration. Sample B, which is the product of the present invention, does not cause segregation when 0.01% of the water-soluble organic binder is added, and the sintered compact has good strength due to the uniformity of the component distribution.
[0031]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, in the copper type | system | group with which an organic binder inhibits sintering, it became possible to provide the segregation prevention processed mixed powder for powder metallurgy which can prevent segregation without inhibiting sintering.
[Brief description of the drawings]
FIG. 1 is a model diagram of segregation-preventing powder prepared by the method of claim 1 and a prior art.
[Explanation of symbols]
1 Main ingredient powder 2 Sub ingredient powder 3 Organic binder

Claims

The main component powder is copper powder or copper alloy powder, and the subcomponent powder is any one selected from tin powder, lead powder, zinc powder, aluminum powder and graphite powder used in copper-based powder metallurgy. A copper-based segregation-preventing mixed powder for powder metallurgy combined with 0.01 to 0.10% water-soluble organic binder of the total weight of the powder and subcomponent powder.

The main component in any one selected from copper powder or copper alloy powder as the main component powder and tin powder, lead powder, zinc powder, aluminum powder and graphite powder used in copper-based powder metallurgy as the auxiliary component powder Add 0.5 to 4.0% water of the total weight of the main component powder and subcomponent powder to the powder, mix to form a thin water layer around the main component powder, the weight of the water-soluble organic binder A method for producing a segregation-preventing treatment mixed powder, in which a secondary component powder coated with a water-soluble organic binder is added and mixed so that the total weight of the primary component powder and the secondary component powder is 0.02 to 0.10%.

The main component in any one selected from copper powder or copper alloy powder as the main component powder and tin powder, lead powder, zinc powder, aluminum powder and graphite powder used in copper-based powder metallurgy as the auxiliary component powder Add aqueous solution of water-soluble organic binder to the powder so that the weight of the water-soluble organic binder is 0.02 to 0.05% of the total weight of the main component powder and subcomponent powder, mix, add subcomponent powder, and mix again Or an aqueous solution of a water-soluble organic binder such that the weight of the water-soluble organic binder is 0.02 to 0.05% of the total weight of the main component powder and the sub-component powder in the mixed powder of the main component powder and the sub-component powder. A method for producing a segregation-preventing mixed powder in which a mixture is added and mixed at a pressure of 30 to 100 kgf / cm2 and then dried and crushed.

The main component in any one selected from copper powder or copper alloy powder as the main component powder and tin powder, lead powder, zinc powder, aluminum powder and graphite powder used in copper-based powder metallurgy as the auxiliary component powder Add 0.5 to 4.0% water of the total weight of the main component powder and subcomponent powder to the powder, mix to form a thin water layer around the main component powder, the weight of the water-soluble organic binder Add the secondary component powder coated with water-soluble binder so that the total weight of the main component powder and secondary component powder is 0.01-0.10%, and after mixing, pressurize with a pressure of 30-100 kgf / cm2, A method for producing a segregation-prevented mixed powder that is dried and crushed.