JP2004035993A

JP2004035993A - Metal-impregnated carbon sliding material

Info

Publication number: JP2004035993A
Application number: JP2002198734A
Authority: JP
Inventors: Kazumi Kokaji; 小鍜治　和己; Koichi Ueda; 上田　浩一
Original assignee: Hitachi Chemical Co Ltd
Current assignee: Showa Denko Materials Co Ltd
Priority date: 2002-07-08
Filing date: 2002-07-08
Publication date: 2004-02-05
Anticipated expiration: 2022-07-08
Also published as: JP4214451B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal-containing carbon sliding material which has sliding properties equal to those of a lead-impregnated carbon sliding material without incorporating lead therein. <P>SOLUTION: The metal-impregnated carbon sliding material is obtained by impregnating a carbon base material having an open porosity of 7 to 25 vol.% with an alloy comprising, by weight, 20 to 25% Zn and 2 to 10% Cu, and the balance Sn. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、各種ポンプ、圧縮機等の軸受及びシール、真空ポンプのベーンなどに使用される金属含浸カーボン摺動材に関する。
【０００２】
【従来の技術】
従来の金属含浸カーボン摺動材は、例えば（石川敏功、長沖通）著、近代編集社発行の「新炭素工業」などに示されるように、人造黒鉛、天然黒鉛、カーボンブラック、コークス、カーボンファイバー等の骨材の一種以上と、タールピッチ、コールタール、クレオソート等の結合剤の一種以上を適宜配合し、これらを混練機に投入し、最高温度１５０℃〜３００℃の温度で混練する。
【０００３】
次に、この混練物を室温まで冷却した後、平均粒径が１０μｍ〜３００μｍに粉砕し、次いで５０ＭＰａ〜２００ＭＰａの圧力で成形、８００℃〜３０００℃の非酸化雰囲気中で焼成又は必要に応じて黒鉛化し、さらにこの焼成品又は黒鉛化品に鉛、銅等の金属を含浸する。特に、鉛は低融点金属であり含浸作業が容易であるばかりでなく、摩擦係数を下げ、摩耗量を減少させ、さらに耐焼付性を向上させるため、水中ポンプなどの軸受として、鉛含浸カーボン摺動材が広く使用されている。
【０００４】
前記に示す鉛含浸カーボン摺動材は、温度が４００℃〜５００℃、減圧真空度が５ｔｏｒｒ以下の条件で鉛溶融中に前記の焼成品又は黒鉛化品を浸漬した後、窒素、アルゴンガス等の不活性ガスにより０．５ＭＰａ〜１．０ＭＰａまで加圧して、焼成品又は黒鉛化品に有する気孔に鉛を含浸させる。この後、鉛溶融中から引き上げて冷却した後、大気圧に戻して含浸を完了することにより得ることができる。そして得られた鉛含浸カーボン摺動材を機械加工して軸受などに供している。
【０００５】
しかしながら、前記のような鉛含浸カーボン摺動材を用いると重金属である鉛は環境汚染が心配され、廃棄品の市場からの回収が必要となるばかりでなく、鉛そのものの使用を制限するか又は廃止するようになってきている。
【０００６】
【発明が解決しようとする課題】
本発明は、鉛を含有せずに、鉛含浸カーボン摺動材と同等の摺動特性を有する金属含浸カーボン摺動材を提供するものである。
【０００７】
【課題を解決するための手段】
本発明は次のものに関する。
（１）開気孔率が７体積％〜２５体積％のカーボン基材に、Ｚｎ２０重量％〜２５重量％、Ｃｕ２重量％〜１０重量％、残部Ｓｎを含む合金を含浸してなる金属含浸カーボン摺動材に関する。
（２）合金の含浸率が、カーボン基材に対して２５重量％〜６５重量％である前記の金属含浸カーボン摺動材に関する。
【０００８】
【発明の実施の形態】
本発明になる金属含浸カーボン摺動材は、鉛に替わる含浸金属として、Ｚｎ２０重量％〜２５重量％、Ｃｕ２重量％〜１０重量％及び残部Ｓｎを含む合金、好ましくはＺｎ２１重量％〜２４重量％、Ｃｕ３重量％〜９重量％及び残部Ｓｎを含む合金を使用することを特徴とするもので、Ｚｎの量が２０重量％未満であると硬くて脆い合金になり、２５重量％を超えると合金を溶解したときの流動性が悪くなるためカーボン基材の気孔深部へ浸入し難くなり、十分に含浸ができない（含浸率が低い）という問題点が生じる。またＣｕの量が２重量％未満であると柔らかい合金となり、１０重量％を超えると逆に硬くて脆い合金となり、摺動材としての耐摩耗性、耐荷重性、なじみ性、埋収性等が損なわれる。
【０００９】
カーボン基材の開気孔率は、７体積％〜２５体積％、好ましくは７体積％〜２３体積％の範囲とされ、７体積％未満であると溶融した合金が細孔に浸入できず、十分な含浸率が得られなくなり、摺動材として使用した場合に摩耗が大きくなる。一方、２５体積％を超えるとカーボン基材の機械的強度が低くなり、かつ摩擦係数が大きくなる。前記の合金を含浸して機械的強度を向上させると共に耐摩耗性を向上させるためには、カーボン基材の気孔を合金によって埋めつくすことが重要であり、開気孔が少しでも残っていると十分な液膜の形成ができず、摩耗量の増大を引き起こすおそれがある。
【００１０】
本発明において、合金を含浸するカーボン基材には、必要に応じて鉛が有していた摩擦係数低減効果を得るために、二硫化モリブデン、滑石、雲母等、所謂潤滑性のある固体潤滑剤を該カーボン基材全組成物中に１重量％〜１０重量％、好ましくは２重量％〜７重量％、さらに好ましくは２重量％〜５重量％配合される。上記の固体潤滑剤の配合量が１重量％未満であると十分な摩擦係数低減効果が得られない傾向があり、１０重量％を超えるとカーボン基材の機械的強度が低下する傾向がある。
【００１１】
本発明において、カーボン基材への合金の含浸率は、２５重量％〜６５重量％の範囲が好ましく、３０重量％〜６０重量％の範囲がさらに好ましい。含浸率が２５重量％未満であると開気孔が残っており、十分な被膜が形成できず摩耗量が増大する傾向があり、６５重量％を超えると摺動面でのカーボンの比率が小さく、摩擦係数が増大する傾向がある。
【００１２】
本発明におけるカーボン基材を製造するための原料としては、平均粒径が１μｍ〜５０μｍ程度の各種黒鉛粉、油煙等のカーボン材を骨材として使用し、それに必要に応じて固体潤滑剤として二硫化モリブデン、滑石、雲母等を配合し、さらに結合剤としてタールピッチ、コールタール等が使用される。
【００１３】
本発明におけるカーボン基材は、上記の各原料を配合し、加熱混練、粉砕、成形、焼成することにより製造することができる。
加熱混練は、双腕型ニーダーなどを用いて、各原料を好ましくは１５０℃〜３００℃、より好ましくは１８０℃〜２７０℃、さらに好ましくは２００℃〜２５０℃の温度で混練する。この際、混練温度が高いと機械的強度が低下する傾向があり、反対に低いと混練時間が長くなる傾向がある。なお混練時間については、混練物の量、骨材、結合剤等の配合割合により変化するので、その都度適宜選定する。また上記の他に例えば１７０℃で第一段階の混練を行った後、温度を２５０℃に上げて第二段階の混練をするなど、混練温度を段階的に引き上げることも可能である。ただし、前記の第一段階及び第二段階の混練温度は最高温度を示す。
【００１４】
粉砕は、加熱混練で得られたものを、各種粉砕機を用いて行うことができる。このとき平均粒径が１０μｍ〜３００μｍ程度、より好ましくは２０μｍ〜２００μｍ、さらに好ましくは２０μｍ〜１００μｍの程度になるように粉砕することが好ましい。１０μｍ未満であると機械強度が低下する傾向があり、３００μｍを超えると緻密性が損なわれる傾向がある。なお平均粒径は、後工程の成形方法や焼成又は黒鉛化後に得られるカーボン基材の特性を考慮し、適宜選択することが可能である。
【００１５】
成形は、粉砕して得られた粉体を、ブロック状に金型プレス等の方法でふ形することにより行われる。成形圧力は、５０ＭＰａ〜２００ＭＰａが好ましく、６０ＭＰａ〜１５０ＭＰａがより好ましく、８０ＭＰａ〜１３０ＭＰａがさらに好ましい。成形圧力が５０ＭＰａ未満であると機械的強度が低下する傾向があり、２００ＭＰａを超えると焼成中に揮発分の散逸が抑制されて成形品に内部圧力が生じ、割れ易くなる傾向がある。
【００１６】
次に、上記により得られた成形品を焼成する。焼成は、窒素、アルゴン等の不活性ガスを用いた非酸化雰囲気下又は成形品の周囲に炭素粉を詰めて還元雰囲気下で焼成することができる。焼成時の最高到達温度は８００℃〜１０００℃が好ましく、８５０℃〜１０００℃がより好ましく、９００℃〜１０００℃がさらに好ましい。焼成温度が８００℃未満であると、炭素化が不充分で十分な摺動特性が得られ難い傾向があり、１０００℃を超えると焼成炉が劣化し易くなる傾向がある。
【００１７】
焼成時間は、原料の配合割合や製品形状又は炉の能力などにより決められ特に制限はないが、生産性及び生産コストの点からできるだけ短時間で終了することがよく、具体的には５時間〜５００時間が好ましく、１０時間〜４００時間がより好ましく、２０時間〜３５０時間がさらに好ましい。得られた焼成品をさらに１０００℃以上の高温で黒鉛化してもよい。黒鉛化することによりさらに潤滑性に優れる。この場合の最高温度は１２００℃〜３０００℃が好ましく、１５００℃〜３０００℃がより好ましく、２５００℃〜３０００℃がさらに好ましい。
得られた焼成品又は黒鉛化品の開気孔率は、水中置換法で測定することができる。
【００１８】
次いで上記で得られた焼成品又は黒鉛化品（カーボン基材）に合金を含浸する。含浸方法としては、次の方法が好ましい。即ち焼成品又は黒鉛化品を、金属含浸容器に入れ５ｔｏｒｒ以下に減圧脱気した後、Ｚｎ２０重量％〜２５重量％、Ｃｕ２重量％〜１０重量％及び残部Ｓｎを含む合金溶湯物を該容器に注入し、上記焼成品又は黒鉛化品を浸漬させる。この後、窒素ガスにより０．５ＭＰａ〜５．０ＭＰａに加圧して金属含浸カーボン摺動材を得ることができる。
このようにして得られた金属含浸カーボン摺動材を機械加工して、軸受、シール、ベーン等所望の製品形状にすることができる。
【００１９】
【実施例】
以下、本発明を実施例により説明する。
実施例１
骨材として、平均粒径が２０μｍの自家製人造黒鉛粉４３重量％に、固体潤滑剤として二硫化モリブデン粉末２重量％、結合剤としてタールピッチ（川崎製鉄（株）製、商品名ＰＫＬ）４５重量％及びコールタール１０重量％を配合し、双腕型ニーダーを用いて温度２５０℃で５時間加熱混練した。
【００２０】
この後、上記の混練物を、平均粒径１３μｍに粉砕した。この粉砕粉を寸法が１５０×２５０×５０ｍｍの金型に入れ、成形圧力１２３ＭＰａの条件で成形した。得られた成形品を、還元雰囲気下で１０００℃まで３５０時間かけて昇温した後冷却した。得られた焼成品（カーボン基材）の開気孔率を水中置換法で測定した結果、７体積％であった。
【００２１】
この焼成品を金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ７５重量％、Ｚｎ２０重量％及びＣｕ５重量％からなる合金の溶湯物を注入し、焼成品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ２５重量％であった。
【００２２】
実施例２
骨材として、平均粒径が２０μｍの自家製人造黒鉛粉５０重量％に、結合剤としてタールピッチ（川崎製鉄（株）製、商品名ＰＫＬ）４０重量％及びコールタール１０重量％を配合し、双腕型ニーダーを用いて温度１７０℃で１時間加熱混練し、次いで２５０℃で５時間加熱混練した。
【００２３】
この後、上記の混練物を、平均粒径３００μｍに粉砕した。この粉砕粉を寸法が１５０×２５０×５０ｍｍの金型に入れ、成形圧力１１０ＭＰａの条件で成形した。得られた成形品を、還元雰囲気下で１０００℃まで４００時間かけて昇温した後冷却し、次いで２８００℃で黒鉛化を行った。得られた黒鉛化品（カーボン基材）の開気孔率を水中置換法で測定した結果、２５体積％であった。
【００２４】
この黒鉛化品を金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ７５重量％、Ｚｎ２０重量％及びＣｕ５重量％からなる合金物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ６５重量％であった。
【００２５】
実施例３
骨材として、平均粒径が２０μｍの自家製人造黒鉛粉４５重量％に、結合剤としてタールピッチ（川崎製鉄（株）製、商品名ＰＫＬ）４５重量％及びコールタール１０重量％を配合し、双腕型ニーダーを用いて２５０℃で５時間加熱混練した。
【００２６】
この後、上記の混練物を、平均粒径３００μｍに粉砕した。この粉砕粉を寸法が１５０×２５０×５０ｍｍの金型に入れ、成形圧力１１０ＭＰａの条件で成形した。得られた成形品を、還元雰囲気下で１０００℃まで４００時間かけて昇温した後冷却し、次いで２８００℃で黒鉛化を行った。得られた黒鉛化品の開気孔率を水中置換法で測定した結果、１３体積％であった。
【００２７】
この黒鉛化品を金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ７５重量％、Ｚｎ２０重量％及びＣｕ５重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ４８重量％であった。
【００２８】
実施例４
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ７０重量％、Ｚｎ２５重量％及びＣｕ５重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ３３重量％であった。
【００２９】
実施例５
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ７６重量％、Ｚｎ２２重量％及びＣｕ２重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで浸漬して窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ４０重量％であった。
【００３０】
実施例６
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ６８重量％、Ｚｎ２２重量％及びＣｕ１０重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ４４重量％であった。
【００３１】
実施例７
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、５ｔｏｒｒに減圧脱気した後、Ｓｎ６８重量％、Ｚｎ２２重量％及びＣｕ１０重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．５ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ２６重量％であった。
【００３２】
実施例８
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、０．５ｔｏｒｒに減圧脱気した後、Ｓｎ６８重量％、Ｚｎ２２重量％及びＣｕ１０重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材についてカーボン基材の含浸率を求めたところ５９重量％であった。
【００３３】
比較例１
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、鉛の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して鉛含浸カーボン材を得た。得られた鉛含浸カーボン材について合金の含浸率を求めたところ６４重量％であった。
【００３４】
比較例２
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ７６重量％、Ｚｎ１９重量％及びＣｕ５重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ１８重量％であった。
【００３５】
比較例３
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ７６重量％、Ｚｎ１９重量％及びＣｕ５重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ６７重量％であった。
【００３６】
比較例４
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ７６重量％、Ｚｎ２３重量％及びＣｕ１重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ４０重量％であった。
【００３７】
比較例５
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ６６重量％、Ｚｎ２３重量％及びＣｕ１１重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ４５重量％であった。
【００３８】
比較例６
骨材として、平均粒径が２０μｍの自家製人造黒鉛粉４３重量％に、固体潤滑剤として二硫化モリブデン粉末２重量％、結合剤としてタールピッチ（川崎製鉄（株）製、商品名ＰＫＬ）４５重量％及びコールタール１０重量％を配合し、双腕型ニーダーを用いて温度２５０℃で５時間加熱混練した。
【００３９】
この後、上記の混練物を、平均粒径１３μｍに粉砕した。この粉砕粉を寸法が１５０×２５０×５０ｍｍの金型に入れ、成形圧力１２３ＭＰａの条件で成形した。得られた成形品を、２０ＭＰａの条件で加圧しながら還元雰囲気下で１０００℃まで３５０時間かけて昇温した後冷却した。得られた焼成品の開気孔率を水中置換法で測定した結果、６体積％であった。
【００４０】
この焼成品を金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ７５重量％、Ｚｎ２０重量％及びＣｕ５重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ１２重量％であった。
【００４１】
比較例７
骨材として、平均粒径が３０μｍの自家製人造黒鉛粉５０重量％に、結合剤としてタールピッチ（川崎製鉄（株）製、商品名ＰＫＬ）４０重量％及びコールタール１０重量％を配合し、双腕型ニーダーを用いて温度１７０℃で１時間加熱混練し、次いで２５０℃で５時間加熱混練した。
【００４２】
この後、上記の混練物を、平均粒径３００μｍに粉砕した。この粉砕粉を寸法が１５０×２５０×５０ｍｍの金型に入れ、成形圧力１１０ＭＰａの条件で成形した。得られた成形品を、還元雰囲気下で１０００℃まで４００時間かけて昇温した後冷却し、次いで２０００℃で黒鉛化を行った。得られた黒鉛化品の開気孔率を水中置換法で測定した結果、２７体積％であった。
【００４３】
この黒鉛化品を金属含浸容器に入れ、３ｔｏｒｒに減圧脱気した後、Ｓｎ７５重量％、Ｚｎ２０重量％及びＣｕ５重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．９８ＭＰａまで加圧しして金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ６９重量％であった。
【００４４】
参考例１
実施例３で得た黒鉛化品を用い、これを金属含浸容器に入れ、５ｔｏｒｒに減圧脱気した後、Ｓｎ７５重量％、Ｚｎ２０重量％及びＣｕ５重量％からなる合金の溶湯物を注入し、黒鉛化品を浸漬させた。次いで窒素ガスにより０．３ＭＰａまで加圧して金属含浸カーボン摺動材を得た。得られた金属含浸カーボン摺動材について合金の含浸率を求めたところ１４重量％であった。
【００４５】
次に、実施例１〜８、比較例２〜７及び参考例１で得られた金属含浸カーボン摺動材並びに比較例１で得られた鉛含浸カーボン材について、物理特性及び摩耗試験を行った。その結果を表１に示す。
なお、曲げ強さは、厚さが１０ｍｍ、幅が１０ｍｍ及び長さが５０ｍｍの直方体の試験片についてＪＣＡＳ（炭素協会規格）−１０−１９６８に準拠して測定した。
【００４６】
また、硬さについては、ショア硬さ試験機で測定し、水中摩耗試験は、８×１２×１８ｍｍの試験片（摺動面１２×１８ｍｍ）を水中で回転する外径寸法８５ｍｍ（φ）の円板（材質ＳＵＳ３０４）上で摺動させ、周速が１０ｍ／ｓ及び面圧が０．９８ＭＰａの条件で１００時間の試験を行って、摩擦係数及び摩耗量を測定した。
【００４７】
【表１】

【００４８】
表１に示されるように、実施例１〜８の金属含浸カーボン摺動材は、曲げ強さ及び硬さについては何ら問題はなく、また比較例２〜７及び参考例１の金属含浸カーボン摺動材に比較して摩擦係数が小さく、かつ摩耗量も少なく、これらの値はほぼ比較例１の鉛含浸カーボン材と同等又はそれ以上の摺動特性が確認された。
【００４９】
【発明の効果】
本発明の金属含浸カーボン摺動材は、鉛を含有せずに、優れた摺動特性を有し、工業的に極めて好適である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a metal-impregnated carbon sliding material used for various pumps, bearings and seals of compressors and the like, and vanes of vacuum pumps.
[0002]
[Prior art]
Conventional metal-impregnated carbon sliding materials include, for example, synthetic graphite, natural graphite, carbon black, coke, carbon One or more aggregates such as fibers and one or more binders such as tar pitch, coal tar, creosote, etc. are appropriately blended, and these are charged into a kneading machine and kneaded at a maximum temperature of 150 ° C to 300 ° C. .
[0003]
Next, after cooling this kneaded product to room temperature, it is pulverized to an average particle size of 10 μm to 300 μm, and then molded at a pressure of 50 MPa to 200 MPa, fired in a non-oxidizing atmosphere at 800 ° C. to 3000 ° C. or as required. Graphite is formed, and the fired or graphitized product is impregnated with a metal such as lead or copper. In particular, lead is a low-melting-point metal and is not only easy to impregnate, it also reduces the coefficient of friction, reduces wear, and improves seizure resistance. Moving material is widely used.
[0004]
The lead-impregnated carbon sliding material described above is obtained by immersing the calcined product or the graphitized product in a molten state of lead at a temperature of 400 ° C. to 500 ° C. and a reduced pressure of 5 torr or less, and then using nitrogen, argon gas, or the like. Is pressurized to 0.5 MPa to 1.0 MPa with the inert gas described above to impregnate the pores of the fired product or the graphitized product with lead. Thereafter, it can be obtained by pulling up from the molten state of the lead, cooling it, returning it to atmospheric pressure, and completing the impregnation. The obtained lead-impregnated carbon sliding material is machined and used for bearings and the like.
[0005]
However, when a lead-impregnated carbon sliding material as described above is used, lead, which is a heavy metal, is concerned about environmental pollution, not only is it necessary to recover waste products from the market, but also restrict the use of lead itself or It is being abolished.
[0006]
[Problems to be solved by the invention]
The present invention provides a metal-impregnated carbon sliding material that does not contain lead and has sliding characteristics equivalent to those of a lead-impregnated carbon sliding material.
[0007]
[Means for Solving the Problems]
The present invention relates to the following.
(1) A metal-impregnated carbon slide obtained by impregnating an alloy containing 20% to 25% by weight of Zn, 2% to 10% by weight of Cu, and the balance of Sn into a carbon substrate having an open porosity of 7% to 25% by volume. For moving material.
(2) The metal-impregnated carbon sliding material having an alloy impregnation rate of 25% by weight to 65% by weight based on the carbon base material.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The metal-impregnated carbon sliding material according to the present invention is an alloy containing 20% to 25% by weight of Zn, 2% to 10% by weight of Cu, and the balance of Sn as an impregnating metal instead of lead, preferably 21% to 24% by weight of Zn. , Cu 3% to 9% by weight and the balance of Sn are used. If the amount of Zn is less than 20% by weight, the alloy becomes hard and brittle, and if it exceeds 25% by weight, the alloy becomes Since the fluidity when dissolving is deteriorated, it is difficult to penetrate deep into the pores of the carbon base material, which causes a problem that impregnation cannot be sufficiently performed (impregnation rate is low). If the amount of Cu is less than 2% by weight, it becomes a soft alloy, and if it exceeds 10% by weight, it becomes a hard and brittle alloy, and the wear resistance, load resistance, conformability, fillability, etc. as a sliding material. Is impaired.
[0009]
The open porosity of the carbon base material is in the range of 7% by volume to 25% by volume, preferably 7% by volume to 23% by volume. If it is less than 7% by volume, the molten alloy cannot penetrate into the pores. A high impregnation rate cannot be obtained, and when used as a sliding material, abrasion increases. On the other hand, when the content exceeds 25% by volume, the mechanical strength of the carbon base material decreases, and the coefficient of friction increases. In order to improve the mechanical strength by impregnating the alloy and improve the wear resistance, it is important to fill the pores of the carbon base material with the alloy, and it is sufficient if any open pores remain. Liquid film cannot be formed, and the amount of wear may increase.
[0010]
In the present invention, a so-called lubricating solid lubricant such as molybdenum disulfide, talc, mica, etc. is used on the carbon substrate impregnated with the alloy in order to obtain the effect of reducing the coefficient of friction that lead had as necessary. Is contained in the entire carbon base composition in an amount of 1% by weight to 10% by weight, preferably 2% by weight to 7% by weight, and more preferably 2% by weight to 5% by weight. If the amount of the solid lubricant is less than 1% by weight, a sufficient effect of reducing the friction coefficient tends not to be obtained, and if it exceeds 10% by weight, the mechanical strength of the carbon base material tends to decrease.
[0011]
In the present invention, the impregnation rate of the alloy into the carbon substrate is preferably in the range of 25% by weight to 65% by weight, and more preferably in the range of 30% by weight to 60% by weight. If the impregnation rate is less than 25% by weight, open pores remain, and a sufficient coating cannot be formed, and the amount of wear tends to increase. If the impregnation rate exceeds 65% by weight, the ratio of carbon on the sliding surface is small, The coefficient of friction tends to increase.
[0012]
As a raw material for producing the carbon substrate in the present invention, various graphite powders having an average particle diameter of about 1 to 50 μm, carbon materials such as oil smoke, etc. are used as aggregates, and if necessary, solid lubricants are used. Molybdenum sulfide, talc, mica and the like are blended, and tar pitch, coal tar and the like are used as a binder.
[0013]
The carbon substrate in the present invention can be produced by blending the above-mentioned raw materials, kneading with heat, pulverizing, molding and firing.
In the heat kneading, each raw material is kneaded at a temperature of preferably 150 ° C to 300 ° C, more preferably 180 ° C to 270 ° C, still more preferably 200 ° C to 250 ° C using a double-arm kneader or the like. At this time, when the kneading temperature is high, the mechanical strength tends to decrease, and when it is low, the kneading time tends to increase. The kneading time varies depending on the amount of the kneaded material, the mixing ratio of the aggregate, the binder and the like, and is appropriately selected each time. In addition to the above, it is also possible to raise the kneading temperature stepwise, for example, after kneading the first stage at 170 ° C., raise the temperature to 250 ° C. and knead the second stage. However, the kneading temperatures in the first and second stages indicate the highest temperatures.
[0014]
The pulverization can be performed by using various pulverizers obtained by heating and kneading. At this time, it is preferable to pulverize so that the average particle size is about 10 μm to 300 μm, more preferably about 20 μm to 200 μm, and further preferably about 20 μm to 100 μm. If it is less than 10 μm, the mechanical strength tends to decrease, and if it exceeds 300 μm, the denseness tends to deteriorate. The average particle diameter can be appropriately selected in consideration of the molding method in the subsequent step and the characteristics of the carbon substrate obtained after firing or graphitization.
[0015]
The molding is performed by shaping the powder obtained by the pulverization into a block shape by a method such as a mold press. The molding pressure is preferably from 50 MPa to 200 MPa, more preferably from 60 MPa to 150 MPa, even more preferably from 80 MPa to 130 MPa. If the molding pressure is less than 50 MPa, the mechanical strength tends to decrease. If the molding pressure exceeds 200 MPa, the dissipation of volatile components during firing is suppressed, and an internal pressure is generated in the molded product, which tends to cause cracking.
[0016]
Next, the molded article obtained as described above is fired. The firing can be performed under a non-oxidizing atmosphere using an inert gas such as nitrogen or argon, or under a reducing atmosphere by packing carbon powder around the molded article. The maximum temperature at the time of firing is preferably 800 ° C to 1000 ° C, more preferably 850 ° C to 1000 ° C, and even more preferably 900 ° C to 1000 ° C. If the firing temperature is lower than 800 ° C., carbonization tends to be insufficient and sufficient sliding characteristics tend not to be obtained. If the firing temperature exceeds 1000 ° C., the firing furnace tends to deteriorate.
[0017]
The firing time is determined by the mixing ratio of the raw materials, the product shape, the capacity of the furnace, and the like, and is not particularly limited. However, the firing time is preferably as short as possible from the viewpoint of productivity and production cost. 500 hours are preferable, 10 hours to 400 hours are more preferable, and 20 hours to 350 hours are further preferable. The obtained fired product may be further graphitized at a high temperature of 1000 ° C. or higher. By being graphitized, lubricity is further improved. In this case, the maximum temperature is preferably 1200C to 3000C, more preferably 1500C to 3000C, and even more preferably 2500C to 3000C.
The open porosity of the obtained calcined product or graphitized product can be measured by an underwater substitution method.
[0018]
Next, the sintered product or the graphitized product (carbon substrate) obtained above is impregnated with an alloy. The following method is preferable as the impregnation method. That is, the calcined product or the graphitized product is put in a metal impregnation vessel and degassed under reduced pressure to 5 torr or less, and then a molten alloy containing 20% to 25% by weight of Zn, 2% to 10% by weight of Cu, and the balance of Sn is placed in the vessel. Then, the fired product or the graphitized product is immersed. Thereafter, the metal-impregnated carbon sliding material can be obtained by applying a pressure of 0.5 MPa to 5.0 MPa with nitrogen gas.
The thus obtained metal-impregnated carbon sliding material can be machined into a desired product shape such as a bearing, a seal or a vane.
[0019]
【Example】
Hereinafter, the present invention will be described with reference to examples.
Example 1
As an aggregate, 43% by weight of homemade artificial graphite powder having an average particle size of 20 μm, 2% by weight of molybdenum disulfide powder as a solid lubricant, and 45% by weight of tar pitch (PKL manufactured by Kawasaki Steel Corporation) as a binder % And 10% by weight of coal tar, and kneaded by heating at 250 ° C. for 5 hours using a double-arm kneader.
[0020]
Thereafter, the above kneaded material was pulverized to an average particle size of 13 μm. The pulverized powder was placed in a mold having a size of 150 × 250 × 50 mm, and was molded under the condition of a molding pressure of 123 MPa. The obtained molded product was heated to 1000 ° C. over 350 hours in a reducing atmosphere and then cooled. The open porosity of the obtained calcined product (carbon substrate) was measured by an underwater substitution method, and as a result, was 7% by volume.
[0021]
The fired product was placed in a metal impregnation vessel and degassed under reduced pressure to 3 torr. Then, a melt of an alloy composed of 75% by weight of Sn, 20% by weight of Zn and 5% by weight of Cu was injected, and the fired product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the alloy of the obtained metal-impregnated carbon sliding material was 25% by weight.
[0022]
Example 2
As an aggregate, 50% by weight of homemade artificial graphite powder having an average particle diameter of 20 μm, 40% by weight of tar pitch (trade name: PKL, manufactured by Kawasaki Steel Corp.) and 10% by weight of coal tar as a binder were mixed. Using an arm type kneader, the mixture was heated and kneaded at a temperature of 170 ° C. for 1 hour, and then heated and kneaded at 250 ° C. for 5 hours.
[0023]
Thereafter, the above kneaded material was pulverized to an average particle size of 300 μm. This pulverized powder was placed in a mold having a size of 150 × 250 × 50 mm, and was molded under the conditions of a molding pressure of 110 MPa. The obtained molded product was heated in a reducing atmosphere to 1000 ° C. over 400 hours, cooled, and then graphitized at 2800 ° C. The open porosity of the obtained graphitized product (carbon base material) was measured by an underwater substitution method, and as a result, was 25% by volume.
[0024]
This graphitized product was placed in a metal impregnation vessel and degassed under reduced pressure to 3 torr, and then an alloy consisting of 75% by weight of Sn, 20% by weight of Zn and 5% by weight of Cu was injected, and the graphitized product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The alloy impregnation ratio of the obtained metal-impregnated carbon sliding material was 65% by weight.
[0025]
Example 3
45% by weight of homemade artificial graphite powder having an average particle diameter of 20 μm as an aggregate, 45% by weight of tar pitch (PKL manufactured by Kawasaki Steel Corporation) and 10% by weight of coal tar as a binder were mixed. The mixture was heated and kneaded at 250 ° C. for 5 hours using an arm type kneader.
[0026]
Thereafter, the above kneaded material was pulverized to an average particle size of 300 μm. This pulverized powder was placed in a mold having a size of 150 × 250 × 50 mm, and was molded under the conditions of a molding pressure of 110 MPa. The obtained molded product was heated in a reducing atmosphere to 1000 ° C. over 400 hours, cooled, and then graphitized at 2800 ° C. As a result of measuring the open porosity of the obtained graphitized product by a water substitution method, it was 13% by volume.
[0027]
The graphitized product was placed in a metal impregnation vessel and degassed under reduced pressure at 3 torr. Then, a molten metal of an alloy composed of 75% by weight of Sn, 20% by weight of Zn and 5% by weight of Cu was injected, and the graphitized product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the alloy of the obtained metal-impregnated carbon sliding material was 48% by weight.
[0028]
Example 4
The graphitized product obtained in Example 3 was put into a metal-impregnated vessel, degassed under reduced pressure at 3 torr, and then a molten alloy of 70% by weight of Sn, 25% by weight of Zn and 5% by weight of Cu was poured, and graphite was added. The product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The alloy impregnation ratio of the obtained metal-impregnated carbon sliding material was 33% by weight.
[0029]
Example 5
The graphitized product obtained in Example 3 was put into a metal impregnation vessel, deaerated under reduced pressure to 3 torr, and then a molten metal of an alloy consisting of 76% by weight of Sn, 22% by weight of Zn, and 2% by weight of Cu was poured, and graphite was added. The product was immersed. Then, it was immersed and pressurized to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the obtained metal-impregnated carbon sliding material was 40% by weight.
[0030]
Example 6
The graphitized product obtained in Example 3 was put into a metal-impregnated vessel, deaerated under reduced pressure to 3 torr, and then a molten alloy of 68% by weight of Sn, 22% by weight of Zn and 10% by weight of Cu was poured, and graphite was added. The product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the alloy of the obtained metal-impregnated carbon sliding material was 44% by weight.
[0031]
Example 7
The graphitized product obtained in Example 3 was put into a metal-impregnated container, degassed under reduced pressure at 5 torr, and then a molten alloy of 68% by weight of Sn, 22% by weight of Zn, and 10% by weight of Cu was poured, and graphite was added. The product was immersed. Then, the pressure was increased to 0.5 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the alloy of the obtained metal-impregnated carbon sliding material was 26% by weight.
[0032]
Example 8
The graphitized product obtained in Example 3 was placed in a metal-impregnated container, degassed under reduced pressure to 0.5 torr, and then a molten alloy of 68% by weight of Sn, 22% by weight of Zn and 10% by weight of Cu was injected. And the graphitized product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the carbon substrate for the obtained metal-impregnated carbon sliding material was 59% by weight.
[0033]
Comparative Example 1
The graphitized product obtained in Example 3 was used, placed in a metal-impregnated container, degassed under reduced pressure at 3 torr, poured with molten lead, and immersed in the graphitized product. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a lead-impregnated carbon material. The alloy impregnation ratio of the obtained lead-impregnated carbon material was 64% by weight.
[0034]
Comparative Example 2
The graphitized product obtained in Example 3 was put into a metal-impregnated container, deaerated under reduced pressure to 3 torr, and then a molten metal of an alloy consisting of 76% by weight of Sn, 19% by weight of Zn and 5% by weight of Cu was injected, and graphite was added. The product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation rate of the alloy of the obtained metal-impregnated carbon sliding material was 18% by weight.
[0035]
Comparative Example 3
The graphitized product obtained in Example 3 was put into a metal-impregnated container, deaerated under reduced pressure to 3 torr, and then a molten metal of an alloy consisting of 76% by weight of Sn, 19% by weight of Zn and 5% by weight of Cu was injected, and graphite was added. The product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the alloy of the obtained metal-impregnated carbon sliding material was 67% by weight.
[0036]
Comparative Example 4
The graphitized product obtained in Example 3 was put into a metal-impregnated vessel, degassed under reduced pressure at 3 torr, and then a molten metal of an alloy composed of 76% by weight of Sn, 23% by weight of Zn and 1% by weight of Cu was poured, and graphite was added. The product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the obtained metal-impregnated carbon sliding material was 40% by weight.
[0037]
Comparative Example 5
The graphitized product obtained in Example 3 was put into a metal-impregnated container, degassed under reduced pressure to 3 torr, and then a molten alloy of 66 wt% Sn, 23 wt% Zn, and 11 wt% Cu was injected, and graphite was added. The product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The alloy impregnation ratio of the obtained metal-impregnated carbon sliding material was 45% by weight.
[0038]
Comparative Example 6
As an aggregate, 43% by weight of homemade artificial graphite powder having an average particle size of 20 μm, 2% by weight of molybdenum disulfide powder as a solid lubricant, and 45% by weight of tar pitch (PKL manufactured by Kawasaki Steel Corporation) as a binder % And 10% by weight of coal tar, and kneaded by heating at 250 ° C. for 5 hours using a double-arm kneader.
[0039]
Thereafter, the above kneaded material was pulverized to an average particle size of 13 μm. The pulverized powder was placed in a mold having a size of 150 × 250 × 50 mm, and was molded under the condition of a molding pressure of 123 MPa. The obtained molded product was heated under a reducing atmosphere to 1000 ° C. over 350 hours while being pressurized under a condition of 20 MPa, and then cooled. The open porosity of the obtained calcined product was measured by an underwater substitution method, and as a result, was 6% by volume.
[0040]
This calcined product was placed in a metal impregnation vessel and degassed under reduced pressure to 3 torr. Then, a molten alloy of 75% by weight of Sn, 20% by weight of Zn and 5% by weight of Cu was injected, and the graphitized product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the alloy of the obtained metal-impregnated carbon sliding material was 12% by weight.
[0041]
Comparative Example 7
50% by weight of home-made artificial graphite powder having an average particle size of 30 μm as an aggregate, 40% by weight of tar pitch (PKL, manufactured by Kawasaki Steel Corporation) and 10% by weight of coal tar as a binder were mixed. Using an arm type kneader, the mixture was heated and kneaded at a temperature of 170 ° C. for 1 hour, and then heated and kneaded at 250 ° C. for 5 hours.
[0042]
Thereafter, the above kneaded material was pulverized to an average particle size of 300 μm. This pulverized powder was placed in a mold having a size of 150 × 250 × 50 mm, and was molded under the conditions of a molding pressure of 110 MPa. The obtained molded article was heated to 1000 ° C. over 400 hours in a reducing atmosphere, cooled, and then graphitized at 2000 ° C. The open porosity of the obtained graphitized product was measured by an underwater substitution method, and as a result, was 27% by volume.
[0043]
The graphitized product was placed in a metal impregnation vessel and degassed under reduced pressure at 3 torr. Then, a molten metal of an alloy composed of 75% by weight of Sn, 20% by weight of Zn and 5% by weight of Cu was injected, and the graphitized product was immersed. Then, the pressure was increased to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the alloy of the obtained metal-impregnated carbon sliding material was 69% by weight.
[0044]
Reference Example 1
The graphitized product obtained in Example 3 was put into a metal-impregnated container, degassed under reduced pressure at 5 torr, and then a molten metal of an alloy composed of 75% by weight of Sn, 20% by weight of Zn and 5% by weight of Cu was injected, and graphite was added. The product was immersed. Then, the pressure was increased to 0.3 MPa with nitrogen gas to obtain a metal-impregnated carbon sliding material. The impregnation ratio of the obtained metal-impregnated carbon sliding material was determined to be 14% by weight.
[0045]
Next, the metal-impregnated carbon sliding materials obtained in Examples 1 to 8, Comparative Examples 2 to 7 and Reference Example 1 and the lead-impregnated carbon material obtained in Comparative Example 1 were subjected to physical properties and wear tests. . Table 1 shows the results.
The bending strength was measured on a rectangular parallelepiped test piece having a thickness of 10 mm, a width of 10 mm and a length of 50 mm in accordance with JCAS (Carbon Institute of Japan) -10-1968.
[0046]
The hardness was measured by a Shore hardness tester, and the underwater wear test was performed on an outer diameter of 85 mm (φ) by rotating a test piece (sliding surface 12 × 18 mm) of 8 × 12 × 18 mm in water. The test piece was slid on a disk (material: SUS304), and a test was performed for 100 hours under the conditions of a peripheral speed of 10 m / s and a surface pressure of 0.98 MPa to measure a friction coefficient and a wear amount.
[0047]
[Table 1]

[0048]
As shown in Table 1, the metal-impregnated carbon sliding materials of Examples 1 to 8 have no problem in bending strength and hardness, and the metal-impregnated carbon sliding materials of Comparative Examples 2 to 7 and Reference Example 1 do not have any problem. The coefficient of friction was smaller and the amount of wear was smaller than that of the moving material, and these values were confirmed to have sliding characteristics almost equal to or higher than those of the lead-impregnated carbon material of Comparative Example 1.
[0049]
【The invention's effect】
The metal-impregnated carbon sliding material of the present invention does not contain lead, has excellent sliding characteristics, and is industrially extremely suitable.

Claims

A metal-impregnated carbon sliding material obtained by impregnating a carbon base material having an open porosity of 7% by volume to 25% by volume with an alloy containing 20% to 25% by weight of Zn, 2% to 10% by weight of Cu and the balance of Sn.

The metal-impregnated carbon sliding material according to claim 1, wherein the impregnation ratio of the alloy is 25% by weight to 65% by weight based on the carbon substrate.