JP2004071436A - Vacuum circuit breaker - Google Patents

Vacuum circuit breaker Download PDF

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JP2004071436A
JP2004071436A JP2002230924A JP2002230924A JP2004071436A JP 2004071436 A JP2004071436 A JP 2004071436A JP 2002230924 A JP2002230924 A JP 2002230924A JP 2002230924 A JP2002230924 A JP 2002230924A JP 2004071436 A JP2004071436 A JP 2004071436A
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contact
alloy
less
circuit breaker
ratio
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JP4515696B2 (en
Inventor
Isao Okutomi
奥富　功
Takashi Kusano
草野　貴史
Atsushi Yamamoto
山本　敦史
Yoshiko Minami
南　淑子
Mitsutaka Honma
本間　三孝
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Toshiba Corp
Shibafu Engineering Corp
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Toshiba Corp
Shibafu Engineering Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum circuit breaker having an excellent breaking characteristics and an excellent reignition characteristics by optimizing various metallurgic conditions of Cu-W alloy or Cu-WC alloy. <P>SOLUTION: Each contact of this vacuum circuit breaker is formed of a contact material containing 10-50 wt.% of a conductive constituent phase formed of Cu, and 50-90 wt.% of an arc-resisting constituent formed of W (or WC). The ratio of the difference (T1-T2) value between a fusion start temperature T1 obtained by measuring the conductive constituent phase formed of Cu in the contact material on the Celsius basis in a heating process and a coagulation start temperature T2 obtained by measuring the conductive constituent phase formed of Cu on the Celsius basis in a cooling process after heating it to at least 1,200°C to the temperature T1, that is, [(T1-T2)×100/T1] is set less than 2.8%. Thereby, both the breaking characteristics and the reignition characteristics can be satisfied. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、優れた遮断特性と再点弧特性とを有する接点材料を備えた真空遮断器に関する。
【０００２】
【従来の技術】
（真空バルブの一般的構造）
一般に真空遮断器において、真空中でのア−クの拡散性を利用して高真空中で電流遮断を行わせる真空バルブの接点は、対向する固定、可動の２つの接点から構成されている。
【０００３】
図７に示す如く、絶縁容器１０１の両端開口部を蓋体１０２ａ、１０２ｂにより閉塞した真空容器１０３内に、一対の接点１０４、１０５を対向させて設けると共に、これらを前記蓋体１０２ａ、１０２ｂを貫通させて真空容器１０３内に挿入された通電軸１０６、１０７の端部にそれぞれ装着し、その一方の通電軸１０７を図示しない操作機構により軸方向に移動可能として、前記一方の接点（以下固定接点）１０４に対して、他方の接点（以下可動接点）１０５を接触または開離出来るようにしてある。
【０００４】
この場合、蓋体１０２ｂと通電軸１０７との間には、真空容器１０３内を真空気密に保持し、かつ導電棒１０７の軸方向への移動を可能とするベロ−ズ１０８が設けられる。なお図中１０９は、前記各接点１０４、１０５および通電軸１０６、１０７を包囲する如く設けられたシ−ルドである。
【０００５】
上記真空遮断器は、通常両接点１０４、１０５が接触し通電状態となる。この状態からの動作により通電軸１０７が図中矢印Ｍ方向に移動すると、可動接点１０５が固定接点１０４から開離し、両接点１０４、１０５間にはア−クが発生する。このア−クは陰極例えば可動接点１０５側からの金属蒸気の発生により維持され、電流がゼロ点（零点）に達すると金属蒸気の発生が止まってア−クが維持できなくなり、遮断が完了する。
【０００６】
ところで、上記両接点１０４、１０５間に発生するア−クは、遮断電流が大きいと、ア−ク自身により生じた磁場と外部回路の作る磁場との相互作用により著しく不安定な状態となる。その結果ア−クは接点面上を移動し（接点が電極に取り付けられ一体化している時には、アークは電極面上にも移動している場合もある）、接点の端部或いは周辺部に片寄り、その部分を局部的に過熱し、多量の金属蒸気を放出させて、真空容器１０３内の真空度を低下させる。その結果、真空遮断器の遮断性能は低下する。これらは金属組織などで代表される接点の状態に依存することが多い。
【０００７】
図８は、一対の接点４１、５１を対向させて設けると共に、接点４１の背面には平板型電極４０、接点５１の背面には平板型電極５０をそれぞれ装着した真空バルブである。また接点４１の背面にはコイル電極４０、接点５１の背面にはコイル電極５０をそれぞれ装着してもよい。
【０００８】
（従来の接点材料）
一般に真空遮断器では、大電流遮断性能、耐電圧性能、耐溶着性能の基本的３要件の他に再点弧現象の発生の抑制が重要な要件となっている。
【０００９】
しかしながら、これらの要件の中には相反するものがある関係上、単一の金属種によって総ての要件を満足させることは不可能である。この為、実用されている多くの接点材料に於いては、不足する性能を相互に補うような２種以上の元素を組合せることによって、例えば大電流用、高耐圧用などのように特定の用途に合った接点材料の選択採用が行われ、それなりに優れた特性を持つ真空バルブが開発されているが、それでも一部の機能を犠牲にして対応している製品が多い。さらに強まる要求を充分満足する真空バルブは未だ得られていないのが実情である。
【００１０】
例えば、基本三要件を満たした大電流遮断用接点材料として、ＢｉやＴｅの様な溶着防止成分を５重量％以下含有するＣｕ−Ｂｉ系合金、Ｃｕ−Ｔｅ系合金が知られている（特公昭４１−１２１３１号、特公昭４４−２３７５１号）。Ｃｕ−Ｂｉ合金は結晶粒界に析出した脆いＢｉ、Ｃｕ−Ｔｅ合金は結晶粒界及び粒内に析出した脆いＣｕ２Ｔｅが合金自体を脆化させ低溶着引き外し力が実現したことから大電流遮断特性に優れている。しかしこの合金には、ロウ付け作業性と再点弧特性の安定性に難点がある。
【００１１】
一方、高耐圧・大電流遮断用接点材料として、Ｃｕ−Ｃｒ系合金が知られている。この合金は前記Ｃｕ−Ｂｉ合金、Ｃｕ−Ｔｅ合金よりも、構成成分間の蒸気圧差が少ない為均一な性能発揮を期待し得る利点があり使い方によっては優れたものである。Ｃｒを５０重量％程度含有させたＣｕ−Ｃｒ合金（特公昭４５−３５１０１号）が知られている。この合金は、Ｃｒ自体がＣｕと略同等の蒸気圧特性を保持し、かつ強力なガスのゲッタ作用を示す等の効果で高電圧大電流遮断性を実現し、高耐圧特性と大容量遮断とを両立させ得る接点として多用されている。しかしこの合金は、活性度の高いＣｒを使用していることから、原料粉の選択、不純物の混入、雰囲気の管理などに十分に配慮しながら接点素材を製造（焼結工程など）する時、接点素材から接点片へ加工する時などで、接点製品とするのに細心の配慮を要する。
【００１２】
また、高耐電圧接点材料としてＣｕ−Ｗ系合金が知られている。この合金は高溶融点材料の効果によって優れた耐ア−ク性を発揮している。しかしこの合金では、遮断特性に難点がある。
【００１３】
（再点弧の発生）
真空遮断器には、電流遮断後真空バルブ内で閃絡が発生し接点間が再び導通状態になる（その後放電は継続しない）現象を誘起することがある。この現象を再点弧と呼び、その発生メカニズムは未解明であるが、電気回路が一度電流遮断状態となった後に導通状態に急激に変化する為、異常過電圧が発生しやすい。特にコンデンサバンクの遮断時に再点弧を発生させる実験によれば、極めて大きな過電圧の発生や、過大な高周波電流が流れる為、再点弧の発生抑制技術の開発が求められている。
【００１４】
上記した様に、再点弧現象の発生メカニズムは未だ知られていないが、本発明者らの実験観察によれば、再点弧は真空バルブ内の接点・接点間、接点・ア−クシ−ルド間でかなり高い頻度で発生している。その為、本発明者らは、例えば接点がア−クを受けた時に放出される突発性ガスの抑制技術、接点表面形態の最適化技術など、再点弧の発生抑制に極めて有効な技術を明らかにし、再点弧発生数を大幅に低減化した。しかし、近年の真空バルブに対する高耐電圧化要求、大電流遮断化要求、特に小形化要求には、接点の一層の低再点弧化が必要となってきた。
【００１５】
すなわち近年では、需要家の使用条件の過酷化と共に負荷の多様化が進行している。最近の顕著な傾向として、リアクトル回路、コンデンサ回路などへの適応拡大が挙げられ、それに伴う接点材料の開発、改良が急務となっている。コンデンサ回路では通常の２倍、３倍の電圧が印加される関係上、電流遮断、電流開閉時のア−クによって接点の表面が著しく損傷しその結果接点の表面荒れ、脱落消耗を招き、再点弧発生の一因と考えられるが、しかし再点弧現象は、製品の信頼性向上の観点から重要であるにもかかわらず、未だ防止技術はむろんのこと直接的な発生原因についても明らかにはなっていない。
【００１６】
本発明者らの実験によれば、例えば２０ｋＡ程度の遮断電流では、上記の接点合金のうちＣｕ−Ｗ系合金が再点弧特性に最も有利な傾向がある。
【００１７】
Ｃｕ−Ｗ系合金の加熱過程で放出されるガス総量、ガスの種類並びに放出形態について、再点弧発生との相関を詳細に観察を行ったところ、溶融点近傍で極めて短時間ではあるがパルス状に突発的に放出されるガスが多い接点では、再点弧発生率も高くなることを見出した。そこであらかじめＣｕ−Ｗ系合金をＣｕの溶融温度以上にて加熱するなどして、Ｃｕ−Ｗ合金中の突発的ガスの放出要因を除去しておくことや、Ｃｕ−Ｗ合金の合金中のポアや組織的偏析を抑制する様に焼結技術を改良することなどによって、再点弧現象の発生を低減させた。
【００１８】
しかし近年の更なる再点弧発生抑制要求に対しては、尚改善の必要性を認めると共に他の施策の開発が重要となっている。
【００１９】
【発明が解決しようとする課題】
Ｃｕ−Ｂｉ合金、Ｃｕ−Ｔｅ合金は、真空遮断器用接点材料として、８０〜９０％ＩＡＣＳ級の高い導電性と優れた耐溶着性を持ち、回路電圧が１２ｋＶ以下にて適用した場合には、優れた大電流遮断特性を発揮する。しかし回路電圧が１２ｋＶを越える高電圧回路に適用した場合には、再点弧特性が極端に低下する。
【００２０】
Ｃｕ−Ｃｒ接点は、現在高耐圧接点材料として多用されている。ＣｕとＣｒが高温度での蒸気圧特性が近似していることなどが寄与して、遮断した後でも接点表面は比較的平滑な損傷特性を示し、安定した電気特性を発揮している。しかし近年では、一層の大電流遮断や一層の高電圧が印加される可能性のある回路への適応が日常的に行われる結果、接点として加工した新品時の表面の状態、電流遮断後の接点表面の損傷の状態などによっては、耐電圧不良を示し再点弧発生の一因となったり、次の電流の開閉時の接触抵抗の異常上昇や温度の異常上昇を引起こす原因となり、遮断特性の低下の一因となったりしている。しかし、接点の表面状態を管理しても完全には再点弧発生を抑制することが出来ていないのが現実であり、十分な遮断特性が得られていないのが現実である。
【００２１】
Ｃｕ−Ｗ接点は、上記Ｃｕ−Ｂｉ合金、Ｃｕ−Ｔｅ合金やＣｕ−Ｃｒ合金よりも優れた耐電圧特性を有することから、Ｃｕ−Ｂｉ合金、Ｃｕ−Ｔｅ合金やＣｕ−Ｃｒ合金に優先してＣｕ−Ｗ合金を適用してきたが、さらに強まる低再点弧化の要求に対しては十分な接点材料とはいえない実情である。
【００２２】
Ｃｕ−Ｗ合金の遮断特性と再点弧特性は、合金中のＷ量の変動、Ｗ粒子の粒度分布、Ｗ粒子の偏析の程度、合金中に存在する空孔の程度、接点表面および内部のガスの量や存在状態などに依存し、これらの最適化が重要となっている。これらの最適化を進めているにも拘らず、上述したＣｕ−Ｗ合金でも、より過酷な高電圧領域及び突入電流を伴う回路ではやはり再点弧現象の発生が観察されている。遮断特性にばらつきが発生したり、再点弧発生頻度にもばらつきが見られたりしている。
【００２３】
この様に、上記基本三要件を一定レベルに維持した上で、優れた遮断特性と再点弧特性とを兼備した真空遮断器の実現は未達成であり、これらを両立させた真空遮断器の開発が期待されている。
【００２４】
本発明の目的は、上記の事情に鑑みてなされたもので、Ｃｕ−Ｗ合金、またはＣｕ−ＷＣ合金の冶金的諸条件を最適化することにより、遮断特性と再点弧特性の優れた真空遮断器を提供するにある。
【００２５】
【課題を解決するための手段】
上記目的を達成する為、本発明に係る真空遮断器は、１０〜５０重量％のＣｕから成る導電性成分相と、５０〜９０重量％のＷから成る耐弧成分とを含む接点材料であり、昇温過程での接点材料中のＣｕから成る導電性成分相の摂氏で測定した溶融開始温度（吸熱開始温度）Ｔ１と、少なくとも１２００℃に加熱した後の冷却過程での、Ｃｕから成る導電性成分相の摂氏で測定した凝固開始温度（発熱開始温度）Ｔ２との差（Ｔ１−Ｔ２）値と、溶融開始温度Ｔ１との比率、すなわち、［（Ｔ１−Ｔ２）×１００／（Ｔ１）］が、２．８％以下である接点材料から成る接点を備えたことを特徴とする。
【００２６】
すなわちこの発明によって、Ｃｕ−Ｗ接点を備えた真空遮断器は安定した再点弧特性、遮断特性が得られる。
【００２７】
［（Ｔ１−Ｔ２）×１００／（Ｔ１）］比が２．８％を越えると、再点弧特性の低下とそのバラツキが発生すると共に、遮断特性も低下する。これは、電流遮断後の冷却過程での被ア−ク点には、液相部分（溶融している部分）が長時間存在していることを指す。耐電圧値の低い（耐電圧特性が劣る）液相状態が長時間存在するということは、再点弧の発生を誘発する機会および遮断不能を起こす機会の増大を招き好ましくない。
【００２８】
［（Ｔ１−Ｔ２）×１００／（Ｔ１）］比が２．８％以下なら、安定した再点弧特性、遮断特性が得られる。
【００２９】
［（Ｔ１−Ｔ２）×１００／（Ｔ１）］比が２．８％以下を得る有力な第１の手段は、耐電圧的に欠陥（弱点）となる液相の存在を短時間に制御することが基本となる。原料表面や焼結容器などの清浄化（例えば、原料がＣｕの場合は焼結前に少なくとも８００℃で３０分程度の脱ガス処理を行う。原料がＡｇの場合は焼結前に少なくとも７００℃で３０分程度の脱ガス処理を行うこと）や、原料の高純度化（例えばＣｕ相中に存在するＣｕ以外またはＣｕＡｇ以外の成分の総量を０．３％以下とすること）や、焼結中雰囲気の高品質化（例えば、１０−２Ｐａ．よりも高真空中での焼結処理を行う。−７０℃以下の露点を持つ高純度水素雰囲気中での焼結処理を行うこと）などが、Ｃｕ液相中（Ａｇ液相中）への溶融点降下物質の侵入を制限し、Ｔ２値の極度の低下を抑制する。
【００３０】
［（Ｔ１−Ｔ２）×１００／（Ｔ１）］比が２．８％以下を得る他の有力な第２の手段は、常温にある接点がア−クを受け昇温過程に入る時、被ア−ク点からその周辺への熱の伝達を遅らせ、被ア−ク点近傍の温度の上昇を遅らせることによって、液相の生成時刻を遅らせＴ１値を小とする。熱の伝達を遅らせる施策として、例えばＣｕに対して固溶したり反応したりしない１％以下好ましくは０．１％以下の炭素、酸化物などのＣｕ中での存在が有効である。
【００３１】
なお、従来の製造では、上記の有力な第１及び第２の手段には、十分な配慮がなされない為、［（Ｔ１−Ｔ２）×１００／（Ｔ１）］比は、２．８を越え、再点弧特性と遮断特性の両立が得られない。本発明の実施では上記の有力な第１及び第２の手段は重複して採用される。
【００３２】
なお、本発明の実施での凝固開始温度Ｔ２の決定に際して、「少なくとも１２００℃」を選択する理由とその効果は、Ｔ２測定値の真値を得ることと測定値のバラツキを無くする為に、温度測定中の接点の全体がＣｕ相の融解温度を完全かつ確実に上回る様に、純銅の溶融温度１０８３℃を大幅に越えさせた測定条件を採用するのが好ましい為である。
【００３３】
また、本発明に係る真空遮断器は、１０〜５０重量％のＣｕから成る導電性成分相と、５０〜９０重量％のＷＣから成る耐弧成分とを含む接点材料であり、昇温過程での接点材料中の前記Ｃｕから成る導電性成分相の摂氏で測定した溶融開始温度（吸熱開始温度）Ｔ１と、少なくとも１２００℃に加熱した後の冷却過程での、前記Ｃｕから成る導電性成分相の摂氏で測定した凝固開始温度（発熱開始温度）Ｔ２との差（Ｔ１−Ｔ２）値と、前記溶融開始温度Ｔ１との比率、すなわち、［（Ｔ１−Ｔ２）×１００／（Ｔ１）］が、２．８％以下である接点材料から成る接点を備えたことを特徴とする。
【００３４】
すなわちこの発明によって、Ｃｕ−ＷＣ接点を備えた真空遮断器は安定した再点弧特性、遮断特性が得られる。
【００３５】
しかし、［（Ｔ１−Ｔ２）×１００／（Ｔ１）］比が２．８％を越えると、再点弧特性の低下とそのバラツキが発生すると共に、遮断特性も低下する。これに対して、［（Ｔ１−Ｔ２）×１００／（Ｔ１）］比が２．８％以下なら、安定した再点弧特性、遮断特性が得られる。
【００３６】
［（Ｔ１−Ｔ２）×１００／（Ｔ１）］比が２．８％を越えると、電流遮断後の冷却過程での被ア−ク点には、液相部分（溶融している部分）が長時間存在していることを指す。耐電圧値の低い（耐電圧特性が劣る）液相状態が長時間存在するということは、再点弧の発生を誘発する機会および遮断不能を起こす機会の増大を招き好ましくない。
【００３７】
［（Ｔ１−Ｔ２）×１００／（Ｔ１）］比が２．８％以下では、耐電圧的に欠陥（弱点）となる液相の存在を短時間に制御する。原料表面や焼結容器などの清浄化（例えば、焼結前に少なくとも１０００℃で３０分程度の脱ガス処理）や、原料の高純度化（例えばＣｕ以外の成分の総量を０．３％以下とする）や、焼結中雰囲気の高品質化（例えば、１０−２Ｐａ．よりも高真空中での処理、−７０℃以下の露点を持つ高純度水素雰囲気）が、液相中への溶融点降下物質の侵入を制限し、極度のＴ２値の低下を抑制し、２．８％以下の比率を達成する有力な手段の１つである。他の手段として、常温にある接点がア−クを受け昇温過程に入る時、被ア−ク点からその周辺への熱の伝達を遅らせ、被ア−ク点近傍の温度の上昇を遅らせることによって、液相の生成時刻を遅らせＴ１値を小とする。熱の伝達を遅らせる手段として、例えばＣｕに対して固溶したり反応したりしない１％以下好ましくは０．１％以下の炭素、酸化物などのＣｕ中での存在が有効である。
【００３８】
【発明の実施の形態】
以下、本発明の実施形態について詳細に説明する。
【００３９】
本発明の実施形態の主旨は、例えば、Ｃｕ−Ｗ（５０〜９０％）接点に対して、Ｃｕ相（高導電性成分相）の溶融開始温度（示差熱分析に於いて吸熱開始温度として測定される）Ｔ１と、凝固開始温度（示差熱分析に於ける発熱開始温度）Ｔ２との差（Ｔ１−Ｔ２）値を小さくした接点材料から成る接点を真空遮断器に搭載し、再点弧発生と遮断特性の安定化を図ることである。
【００４０】
本発明の実施形態で対象とする接点は、Ｃｕ、Ａｇの少なくとも１つから成る１０〜５０重量％（以下重量％を、単に％と表示する）の高導電性成分相と、Ｗ、Ｍｏの少なくとも１つ（またはＷＣ、ＭｏＣの少なくとも１つ）から成る５０〜９０％の耐弧成分（必要によりＢｉ、Ｔｅなどの耐溶着性成分）とを含む接点材料に対して適応する時に効果を発揮する。
【００４１】
耐弧成分の総量が９０％を越えると（以下耐弧成分としてＷを代表例とし、高導電性成分相としてＣｕを代表例としたＣｕ−Ｗ合金について説明する。他の合金系でも同様の傾向である）、２０ｋＡを越える大電流を遮断すると、盛んな熱電子放出によって、遮断特性が保てない。さらに定格電流の開閉および大電流の遮断によって、接点部もしくは遮断器端子部の温度上昇特性や接触抵抗特性の低下を招き好ましくない。一方、Ｗの総量が５０％未満の接点では、電流遮断時に耐ア−ク性の低下で、遮断後の接点表面は著しいア−ク損傷を受け（Ｗの脱落やＣｕ部分の選択的蒸発、飛散により形成される被アーク点近傍の凹凸や荒れ）を受け再点弧特性の低下を招き好ましくない。
【００４２】
本発明の実施形態で対象とする接点で使用するＷ粒子粒は、０．１〜９μｍの範囲の平均粒子直径（以下粒径）が好ましく、この範囲にあるＷ粒子が少なくとも５０％（容積％）を占める時には、さらに安定した再点弧特性を発揮する（Ｗ以外のＷＣ、Ｍｏ、ＭｏＣであっても同様）。
【００４３】
本発明の他の望ましい実施形態は、ＷにＭｏ及びＦｅを一体化してＷＭｏＦｅとした。その結果ＣｕとＷとの間の濡れ性を改良しＷ粒子とＣｕとの密着強度を向上させた。更に一体化したＷＭｏＦｅによって囲まれるＣｕ相の大きさも好ましい範囲である１０μｍ以下の領域が所定面積以上占める様に制限し接点合金組織の均一化を図った。
【００４４】
その結果、ア−クを受けた時に選択的に優先して蒸発、飛散するＣｕを少なくなる様に制御するのみならず、被ア−ク時の熱衝撃によっても接点面上には、再点弧発生に対して有害な著しい亀裂発生も抑止され、Ｗ粒子の飛散脱落も軽減された。この様に合金組織の均一化、Ｍｏ、Ｆｅの一体化等の改良を図ったので、ア−クを受けた後でも接点表面の溶融、飛散損傷が少なくなり、再点弧抑止に重要な影響を及ぼす接点表面荒れを少なくした。これらの相乗的効果によって、遮断電流特性を維持した上でＣｕ−Ｗ合金の再点弧発生頻度の抑制を得た。
【００４５】
接点片を用いた発明者らの基礎的実験によれば、固体状態にある１対のＣｕ−２７％Ｗ接点を対向させ、一方の接点を加熱しながら、耐電圧特性（暗電流対ギャップ特性）を連続測定すると、接点の一部に液相が出現する温度に到達すると、耐電圧値は大幅に低下（約１０〜５０％低下）する。引き続いてこのＣｕＷ接点を冷却すると耐電圧値は回復する（ほぼ元の耐電圧値に戻る）現象を確認している。
【００４６】
液相の出現は、ア−ク点近傍の熱物性の変化や表面（凹凸）の変化に影響を与えると共に、液相が存在している期間中は、接点蒸気の放出状況、液状接点の噴出状況を左右し、その結果耐電圧特性に影響を与える。従って、液相の出現量の大小や液相が存在している期間（液相の存在時間）の大小が、真空遮断器の耐電圧特性に影響を与えていることを示し、これは再点弧の引き金ともなる可能性があると共に、当然、遮断特性にも影響を与えると考えられる。
【００４７】
本発明は、この知見に基づき、遮断により接点に液相が存在している時間の大小に注目したものである。すなわち液相が存在している時間は、接点が昇温してゆき液相を生成し始めた時の温度（溶融開始温度）Ｔ１と、融解温度以上に加熱された接点を冷却してゆき、接点から液相が消失した時の温度（凝固開始温度）Ｔ２との、両者の差（Ｔ１−Ｔ２）を、液相が存在している時間と定義する。Ｔ１の値は、主としてＣｕ相中のＣｕ以外の成分の種類とその量によって変動するので、ある程度の正確さを持った数値把握が可能である。しかしＴ２の値は、融解温度以上に加熱された時に加熱環境（周囲雰囲気からのガスや不純物の侵入固溶による凝固温度の変動）から影響を受け、その都度変動する為、Ｔ２値は十分には把握出来ない。そこで本発明では、数値把握が可能なＴ１を基本として、これに対するＴ１、Ｔ２との差（Ｔ１−Ｔ２）との関係を求めた。すなわち本発明は、溶融開始温度Ｔ１と凝固開始温度Ｔ２との差（Ｔ１−Ｔ２）と、Ｔ１との比率を制御するものである。
【００４８】
前記した様に、遮断によって昇温過程にある接点面（被ア−ク点やア−ク点近傍）は著しく高温度となり、接点面の一部に液相を生ずるに至る。遮断完了と共に接点温度はやがて降下し、液相は固体（凝固）となり消滅する。液相が発生してから消滅するまでの時間（液相が存在している時間）の大小は、遮断特性、再点弧特性の維持向上に対して、好ましくない高温度状態に止まっている期間（時間）の大小を指す。一般には、接点材料の状態（材料物性など）、接点材料の製造条件（焼結温度、冷却条件など）、遮断器の機械的条件（投入速度、開極速度、接触圧力など）などによって変動する。従って、高い温度状態に止まっている時間の大小は、真空遮断器の遮断特性、再点弧特性を左右する目安となると共に重要な意味を持つ。
【００４９】
そこで、昇温過程でのＣｕ−Ｗ接点（実質的には同合金中のＣｕ相）の溶融開始温度（示差熱分析に於ける吸熱開始温度）Ｔ１と、少なくとも１２００℃に加熱した後、これを冷却させた時の冷却過程での前記Ｃｕ相の凝固開始温度（示差熱分析に於ける発熱開始温度）Ｔ２との差（Ｔ１−Ｔ２）と、溶融開始温度Ｔ１との比率、すなわち、［（Ｔ１−Ｔ２）／（Ｔ１）］比が重要な意味を持つ。なおここで、Ｃｕ相の凝固温度１０８３℃よりはるかに高い温度、すなわち「少なくとも１２００℃」とする理由は、正確なＴ２値（液相が存在している時間）を決定する為の選択である。実際の真空遮断器での被ア−ク点やア−ク点近傍の温度は、３０００〜６０００℃に達するが、Ｔ２値の決定の為に、わざわざ３０００〜６０００℃に加熱する必要なく、凝固開始温度の測定は１２００℃で十分に安定した数値を得る。
【００５０】
遮断特性、再点弧特性を両立せるのには、（Ｔ１−Ｔ２）値を小さくすることが必要で、その為にはＴ１値を小とするか、Ｔ２値を大とする必要がある。
【００５１】
Ｔ１値を小とするには、一例として、Ｃｕ−Ｗ接点中に存在するＣが、被ア−ク点が受けた熱入力を、他の部分へ熱伝達するのを一定の時間だけ、（熱伝達を）妨害する効果、すなわち接点が溶融を始めるまでの時刻を遅らせる効果を発揮し、Ｔ１を小とする１つの手段となっている（手段１）。
【００５２】
Ｔ２値を大とするには、液相状態となった時のＣｕ液相中のＣｕの純度を高め、純Ｃｕの凝固温度になるべく近い温度で凝固させる。すなわちＣｕ液相中への溶融点を降下させる物質の侵入量が少なくなる様に、高純度原料の使用、清浄部品（焼結容器など）の使用、清浄雰囲気での焼結作業などの配慮を行うことが、Ｔ２値を大とする１つの手段となっている（手段２）。
【００５３】
なお、再点弧の発生を抑制もしくは軽減化する補助技術として、純度、清浄度など品質的に好ましい状態の原料粉［Ｃｕ］と原料粉［Ｗ］とを、清浄雰囲気中で得た後、これらを解砕・分散・混合しながら均一で微細な［Ｃｕ・Ｗ］混合粉体を清浄雰囲気中で得る。これによって投入、遮断で生成する接点表面の微細な凹凸や損傷の発生を低減化させ、電極空間への微小金属粒子の放出、飛散を低減化させる基本効果を得る。これらの基本効果とＴ１とＴ２との制御効果とを重畳させることによって、再点弧特性と遮断特性との両立を一層確実なものにする。
【００５４】
真空バルブの再点弧特性、遮断特性の安定化には、従来から種々の技術が開発されてきた。例えば接点材料の組成、成分量の変動、ガス量、組織形態（粒度、粒度分布、偏析の程度、合金中に存在する空孔の程度）、接点の表面形態などに依存すると考えられこれらを最適化した。さらに発明者らの観察によれば、再点弧特性のより一層の安定化には、上記に加えてＣｕ−Ｗ合金中のＣｕ相のＴ１（溶融開始温度）とＴ２（冷却過程での凝固開始温度）との差（Ｔ１−Ｔ２）値と、Ｔ１との比率　［（Ｔ１−Ｔ２）／Ｔ１］比が深く関与していることが判った。
【００５５】
この場合のＴ１及びＴ２は、便宜上（℃）で示す数値で計測した。
【００５６】
以下に本発明を実施例と比較例とで詳細に説明する。評価条件と評価結果を図１〜６に示す。
【００５７】
（１）Ｔ１、Ｔ２値の計測
固体状態にある先端が５ｍｍ×長さ３０ｍｍの曲率半径を持つ針状のＣｕＷ電極と、固体状態にある直径２０ｍｍ×厚さ５ｍｍの板状のＣｕＷ試験片電極とを、真空度１０−４Ｐａ．の高真空中で対向させる。板状のＣｕＷ試験片電極表面の一部を例えばレーザ照射法によって、局部的に連続的に昇温して行くと共に、昇温中のその温度を赤外線温度計によって非接触法で計測する。昇温過程にある両電極間に電圧をゼロから絶縁破壊するまで連続印加し、板状ＣｕＷ片の温度と対応した耐電圧値（一定のギャップ間での電圧特性）を連続測定する。昇温過程で接点の一部に液相が出現する温度に到達すると、耐電圧値は大幅に低下（約１０〜１００％程度低下）する。赤外線温度計で計測した温度値と、別途ＣｕＷ片のみを電気炉で加熱しながら示蓋熱分析装置を用いて求めた吸熱開始温度Ｔ１（溶融開始温度）、発熱開始温度Ｔ２（凝固開始温度）とを対比させながらＴ１、Ｔ２値を決定する。
【００５８】
（２）再点弧特性
直径３０ｍｍ、厚さ５ｍｍの円板状接点片を、ディマウンタブル型真空バルブに装着し、２４ｋＶ×５００Ａの回路を２０００回遮断した時の再点弧発生頻度を測定した。尚、数値は、実施例４の値を基準とした時の相対値を、バラツキ幅を持って示した。
【００５９】
再点弧発生頻度が、０．１倍未満を評価（Ａ）、０．１〜０．８倍未満を評価（Ｂ）、　　０．８〜１．２倍未満を評価（Ｃ）、１．２〜１．５倍未満を評価（Ｄ）、１．５〜１０倍未満を評価（Ｘ）、１０〜１００倍未満を評価（Ｙ）、１００倍以上を評価（Ｚ）とした。
【００６０】
なお、評価（Ａ）〜（Ｄ）を「合格」、評価（Ｘ）〜（Ｚ）を「不良」の目安とした。
【００６１】
（３）遮断特性
直径７０ｍｍの接点を装着した遮断テスト用実験バルブを開閉装置に取り付けると共にベーキング、電圧エージング等を与えた後、２４ｋＶ、５０Ｈｚの回路に接続し、電流をほぼ１ｋＡずつ増加しながら遮断限界を真空バルブ３本につき評価した。尚、数値は実施例４の値を１．０とした時の比較値を、バラツキ幅を持って示したもので、評価の目安は倍率がＯ．９倍以上は合格、０．９倍未満は不合格である。
【００６２】
（４）遮断テスト用実験バルブの組立ての概要
遮断テスト用実験バルブの組立ての概要を示す。端面の平均表面粗さを約１．５μｍに研磨したセラミックス製絶縁容器（主成分：ＡＬ２Ｏ３）を用意し、このセラミックス製絶縁容器については、組立て前に１６００℃の前加熱処理を施した。封着金具として、板厚さ２ｍｍの４２％Ｎｉ−Ｆｅ合金を用意した。ロウ材として、厚さＯ．１ｍｍの７２％Ａｇ−Ｃｕ合金板を用意した。上記用意した各部材を被接合物間（セラミックス製絶縁容器の端面と封着金具）に気密封着接合が可能なように配置して、５×１０−４Ｐａ．の真空雰囲気で封着金具とセラミックス製絶縁容器との気密封着工程に供した。
【００６３】
（５）供試接点合金の製造方法
Ｃｕ−Ｗ合金に於ける［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％とした上で、耐弧性成分として所定の粒子直径（好ましくは０．１〜９μｍ）を持つＷと、導電性成分として所定量のＣｕを準備する。これらを均一に分散する様に非酸化性雰囲気中で混合し成型した後、非酸化性雰囲気中で焼結熱処理（例えば１０３０℃）または焼結熱処理と溶浸熱処理（例えば１０００℃と１１５０℃を順次）行い、Ｃｕ−Ｗ接点素材（実施例１〜４、比較例１〜２）を準備した。
【００６４】
Ｃｕ−Ｗ合金のＣｕ相とＷ粒子との界面に、補助成分として粒子直径が好ましくは５μｍ以下のＣが存在するＣｕ−Ｗ−Ｃ接点素材（実施例５〜８、比較例３）を準備した。
【００６５】
耐弧成分としてＷの一部または総てをＭｏで置換したＣｕ−Ｗ接点素材（実施例９〜１２）、他の耐弧成分としてＷＣの一部または総てをＭｏＣで置換したＣｕ−Ｗ接点素材（実施例１３〜１５）を準備した。
【００６６】
また、導電性成分としてＣｕの一部または総てをＡｇで置換したＡｇ−Ｗ接点素材（実施例１６〜１７）を準備した。
【００６７】
第１の補助成分としてＣｏ、Ｆｅ、Ｎｉの１つを含有したＣｕ−Ｗ接点素材（実施例１８〜２１、比較例４）を準備した。第２の補助成分としてＢｉ、Ｓｂの１つを含有したＣｕ−Ｗ接点素材（実施例２２〜２４、比較例５）を準備した。第３の補助成分としてＴｅ、Ｓｅの１つを含有したＣｕ−Ｗ接点素材（実施例２５〜２７、比較例６）を準備した。
【００６８】
次いで、［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を（０．０１〜０．１％）、（０．９〜１．１％）、（１．９〜２．１％）、（２．７〜２．８％）、（５．５〜５．６％）としたＣｕ−Ｗ接点素材（実施例２８〜３１、比較例７）を準備した。
【００６９】
接点製造に於ける［（Ｔ１−Ｔ２）／Ｔ１］比を調整する１つの方法としては、前述の（手段１）、（手段２）のいずれかまたは両者を選択した上で、例えば▲１▼Ｃｕ−Ｗ合金中のＣｕ相中に存在する主成分以外の微量成分の種類とその総量の制御で達成する。すなわちＣｕとＷとの界面に存在するＣを制御する（Ｃ量をＣｕ−Ｗ合金に対して、０．０８％以下とする）。
【００７０】
接点製造に於ける［（Ｔ１−Ｔ２）／Ｔ１］比を調整する他の方法として、例えば▲２▼焼結処理の温度と時間の制御で達成する。すなわち焼結処理の温度をＴ１値近傍（Ｔ１値±５０℃程度。Ｃｕ−Ｗでは１０３０〜１１３０℃、Ａｇ−ＷＣでは９１０〜１０１０℃）の様に高目の温度を選択すると、ＣｕおよびＷ表面の活性化、ＣｕとＷとの界面（ＡｇとＷＣとの界面）の清浄化を達成し、［（Ｔ１−Ｔ２）／Ｔ１］比を小とする。
【００７１】
接点製造に於ける［（Ｔ１−Ｔ２）／Ｔ１］比を調整する他の方法として、例えば▲３▼焼結処理時の処理温度とその後の冷却速度の制御で達成する。すなわち、固相焼結では１０００℃近傍、固相・溶浸焼結では１１００℃近傍を通過する際の冷却速度を、０．１℃〜１０℃／分を選択すると、Ｃｕ相中の内蔵ガス量、Ｗの吸着ガスの両者を、より多く放出させ　［（Ｔ１−Ｔ２）／Ｔ１］比は小さくなる。０．１℃／分未満の速度の選択では、生産性が劣る。１０℃／分を越えた速度を選択すると［（Ｔ１−Ｔ２）／Ｔ１］比は大きくなる傾向を示す。実際には、［（Ｔ１−Ｔ２）／Ｔ１］比を一層小さくする為に、前述の（手段１）、（手段２）と、上記▲１▼▲２▼▲３▼の条件とを適宜組み合わせながら実施することが好ましい。
【００７２】
（実施例１〜４、比較例１〜２）
本発明接点のポイントは、遮断器の遮断特性、再点弧特性の両立に対して、Ｃｕ−Ｗ合金中のＣｕ相の溶融開始温度Ｔ１と冷却過程での凝固開始温度Ｔ２との差（Ｔ１−Ｔ２）値とＴ１との比率、すなわち［（Ｔ１−Ｔ２）／Ｔ１］比を制御することがポイントとなる。
【００７３】
本発明技術がその効果を効果的に発揮する為のＣｕ−Ｗ合金中のＣｕ量の範囲を明らかとする為に［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７（％）で一定とした接点を製造する。工業的には、製造技術上の理由と経済的な理由から［（Ｔ１−Ｔ２）×１００／Ｔ１］比率は、３（％）以上や５（％）程度のものが生産される。
【００７４】
＜再点弧特性＞
接点中の総Ｃｕ量を５０％（５０％Ｗ）としたＣｕ−５０％Ｗ接点を搭載した複数の遮断器を２４ｋＶ、２０００回遮断した時の再点弧発生頻度は、１０〜２０回の範囲であった。本発明ではこの特性を性能上の許容範囲とし、この接点の特性を基準とし、実施例４とした。
【００７５】
接点中の総Ｃｕ量を５％（９５％Ｗ）としたＣｕ−９５％Ｗ接点では、一部では１．２〜１．５倍未満（評価Ｄ）を示し合格の判定であったが、多くは１０以上〜１００倍（評価Ｙ）を示した如く、バラツキの大きな再点弧発生となり好ましくない再点弧特性を示した（比較例１）。遮断電流によって接点面が過大に温度上昇したことが一因と考えられる。
【００７６】
接点中の総Ｃｕ量を１０％（９０％Ｗ）としたＣｕ−９０％Ｗ接点では、前記実施例４を基準として比較した再点弧発生頻度は、１．２〜１．５倍未満（評価Ｄ）を示し、良好な再点弧特性を示した（実施例１）。
【００７７】
接点中の総Ｃｕ量を２５％（７５％Ｗ）としたＣｕ−７５％Ｗ接点でも、前記実施例４と比較した再点弧発生頻度は、０．１〜０．８倍未満（評価Ｂ）を示し、良好な再点弧特性を示した（実施例２）。
【００７８】
接点中の総Ｃｕ量を４０％（６０％Ｗ）としたＣｕ−６０％Ｗ接点でも、前記実施例４と比較した再点弧発生頻度は、０．８〜１．２倍未満（評価Ｃ）を示し、良好な再点弧特性を示した（実施例３）。
【００７９】
これに対して、接点中の総Ｃｕ量を７５％（２５％Ｗ）としたＣｕ−２５％Ｗ接点では、［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％としたにもかかわらず、前記実施例４と比較した再点弧発生頻度は、一部では１．２〜１．５倍未満（評価Ｄ）を示し合格の判定であったが、多くは１．５以上〜１０倍（評価Ｘ）を示した如く、バラツキの大きな再点弧発生となり好ましくない再点弧特性を示した（比較例２）。遮断による接点面には激しい荒損が見られている。
【００８０】
以上から本発明技術は、１０〜５０％Ｃｕを含有したＣｕ−Ｗ合金に対して適用する時、再点弧特性にその効果を発揮する。
【００８１】
＜遮断特性＞
接点中の総Ｃｕ量を１０％（９０％Ｗ）としたＣｕ−９０％Ｗ接点では、前記実施例４と比較した遮断特性は、０．９〜０．９５倍を示し、良好な遮断特性を示した（実施例１）。
【００８２】
接点中の総Ｃｕ量を２５％（７５％Ｗ）としたＣｕ−７５％Ｗ接点では、前記実施例４と比較した遮断特性は、０．９倍から１．０５倍を示し、良好な遮断特性を示した（実施例２）。
【００８３】
接点中の総Ｃｕ量を４０％（６０％Ｗ）としたＣｕ−６０％Ｗ接点では、前記実施例４と比較した遮断特性は、１．０〜１．１倍を示し、極めて良好な遮断特性を示した（実施例３）。
【００８４】
接点中の総Ｃｕ量を５０％（５０％Ｗ）としたＣｕ−５０％Ｗ接点を基準接点とし、遮断特性を１．０とした（実施例４）。
【００８５】
これに対して、接点中の総Ｃｕ量を５％（９５％Ｗ）としたＣｕ−９５％Ｗ接点では、［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％としたにもかかわらず、前記実施例４と比較した遮断特性は、Ｏ．３〜０．６倍に大幅な低下を示し、極めて劣る遮断特性を示した（比較例１）。
【００８６】
更に、接点中の総Ｃｕ量を更に増加し７５％（２５％Ｗ）としたＣｕ−２５％Ｗ接点では、前記実施例４と比較した遮断特性は、０．７〜０．８倍を示し、やや劣る遮断特性を示した（比較例２）。
【００８７】
以上の様に、［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を制御して、Ｃｕ−Ｗ合金の遮断特性、再点弧特性を向上させる為には、Ｃｕ量が１０〜５０％のＣｕ−Ｗ合金に対して適応するのが好ましい。
【００８８】
（実施例５〜８、比較例３）
前記実施例１〜４、比較例１〜２では、本発明技術を適応する接点として、Ｃｕ量が１０〜５０％のＣｕ−Ｗ合金が好ましいことを示した。本発明では、Ｃｕ−Ｗ合金中のＣｕ相とＷとの界面に補助成分を存在させたＣｕ−Ｗ−Ｃ合金としても同等の効果を発揮する。Ｃの補助成分を存在させることによって、ア−ク点から周辺（接触面および接点内部）への熱伝達を遅らせ（微少領域に限っての熱伝導度を小さくし、ア−クを受けてから液相を生成させる時刻を遅らせる）、結果的に液相の存在期間（存在時間）を短縮し、（Ｔ１−Ｔ２）値を小さく調整する結果、再点弧特性、遮断特性に好ましい状態とする。本発明では、この様な補助成分としてＣの存在効果を確認した。
【００８９】
Ｃｕ−Ｗ合金中への適量のＣを存在させる方法としては、次のような方法がある。
【００９０】
第１の方法として、混合作業に於いて、まずＣ量とＣｕ量との比率が容積的に同程度となる様に秤量し、ＣとＣｕとの混合粉を得て、次いで、この混合粉にＣｕのみを追加し混合してゆき、Ｃ量が０．００５％以下、０．０１〜０．１５％に相当する微量のＣをＣｕ−Ｗ中に均一に分散させたＣｕ−Ｗ−Ｃ接点素材を得る。
【００９１】
第２の方法として、有機溶剤で希釈した高分子材料をＣｕ粉の表面層に被覆し、熱分解によってその表面にＣを析出させたＣｕ粉を得て、このＣｕ粉と所定のＷ粉とを混合する。この時希釈する有機溶剤の量と高分子材料の量を調節しながら、Ｃｕ−Ｗ中へのＣの量を調節する。これによって所定量範囲（０．００５％以下、０．０１〜０．１５％）のＣ量をＣｕ−Ｗ中に均一に分散させたＣｕ−Ｗ−Ｃ接点素材を得る。
【００９２】
第３の方法として、Ｃｕ粉とＷ粉とをあらかじめ混合した混合粉を前記第２の方法に従って、有機溶剤で希釈した高分子材料を混合粉表面層に被覆し、熱分解によって混合粉の表面にＣを析出させる。これによって所定量範囲（０．００５％以下、０．０１〜０．１５％）のＣ量をＣｕ−Ｗ中に均一に分散させたＣｕ−Ｗ−Ｃ接点素材を得る。
【００９３】
第４の方法として、前記第１の方法を実施するに於いて、第２の方法で得たＣｕ粉を使用する。これによって所定量範囲（０．００５％以下、Ｏ．０１〜０．１５％）のＣ量をＣｕ−Ｗ中に均一に分散させたＣｕ−Ｗ−Ｃ接点素材を得る。
【００９４】
第５の方法として、前記第１の方法を実施するに於いて、第３の方法で得たＣｕ粉とＷ粉とをあらかじめ混合した混合粉を使用する。これによって所定量範囲（０．００５％以下、０．０１〜０．１５％）のＣをＣｕ−Ｃｒ中に均一に分散させたＣｕ−Ｗ−Ｃ接点素材を得る。
【００９５】
なお、Ｃｕ−Ｗ−Ｃ接点でのＣは、その粒子直径が著しく微細であり、量的には極めて少量であるので、機械的な混合法ではＣ粒子の持つ潤滑性の為に、効果的な混合が行えないなどが原因となって、良質な接点素材が得られない。そこで本発明では、上記した第１〜５の方法を適宜選択し組み合わせることによって、Ｃｕ−Ｗ中のＣの量を所定量範囲（０．００５％以下、０．０１〜０．１５％）とした供試接点を得る。
【００９６】
＜再点弧特性＞
接点中のＣｕ−Ｗ合金中のＣの量を０．００５％、０．０１％、０．０３％、０．０８％とした接点では、基準接点とした実施例４の再点弧特性と比較して、同等かそれ以上の良好な特性、すなわち０．１〜０．８倍（評価Ｂ）、０．８〜１．２倍（評価Ｃ）、１．２〜１．５倍（評価Ｄ）を示した（実施例５〜８）。
【００９７】
これに対して、Ｃｕ−Ｗ合金中のＣの量を０．１５％とした接点では、Ｃｕ−Ｗ中のＣには凝集が見られ、評価した接点によって再点弧の発生頻度に大きなバラツキが見られ、基準接点（実施例４）と比較した再点弧の発生頻度は、１．５倍以上〜１０倍、１００倍以上（評価Ｘ〜Ｚ）を示し、極めて好ましくない再点弧特性を示した（比較例３）。
【００９８】
一方、Ｃｕ−Ｗ合金中のＣの量を０．００５％未満とする接点では、再点弧特性はさらに良好である。０．００５％未満のＣの量を持つＣｕ−Ｗ合金の製造は、原料の精製（熱処理温度の高温度化による不純物の熱分解の促進）、混合および焼結熱処理工程（粉塵混入の防止）、熱処理用容器材質の選択（Ｃの混入の防止）、熱処理雰囲気と温度の調整と熱処理回数の増加などで調整することによって得る。
【００９９】
＜遮断特性＞
遮断特性の評価は、各接点について測定した遮断電流値を、前記実施例４の遮断電流値を１．０とした倍率で示した。
【０１００】
Ｃｕ−Ｗ合金中のＣの量を０．００５％、０．０１％、０．０３％、０．０８％とした接点では、基準接点とした実施例４の遮断特性と比較して、同等以上の良好な遮断特性、すなわち、０．９５〜１．１倍（実施例５）、０．９５〜１．０５倍（実施例６）、０．９〜１．０倍（実施例７）、０．９〜０．９５倍（実施例８）を示した。
【０１０１】
これに対して、Ｃｕ−Ｗ合金中のＣの量を０．１５％とした接点では、Ｃｕ−Ｗ中のＣの凝集によって、評価した接点によって遮断特性に大きなバラツキが見られ、基準接点（実施例４）と比較した遮断特性は、０．２５〜０．５倍を示し、大幅な低下とバラツキを示した（比較例３）。
【０１０２】
実施例５に於いて遮断テストに供した後の接点について、Ｃｕ−Ｗ合金中のＣの分布状態を顕微鏡観察すると、良好な分散を確認した。遮断電流による熱入力に対して断熱効果を十分発揮し、液相が存在する時間を短縮したものと考えられ、その結果遮断特性の向上に寄与したものと考えられる。遮断電流が消滅した時には、Ｃｕ−Ｗ合金中のＣの断熱効果よりも、熱容量の大幅に大きな近接する電極や導電軸の冷却効果が優先し急速に冷却される為、液相が存在する時間（Ｔ１−Ｔ２）の長短は、液相の生成時刻（溶融開始時刻Ｔ１）を遅らせることにのみ依存する。
【０１０３】
以上の様に、再点弧特性、遮断特性に及ぼすＣｕ−Ｗ合金中のＣ量は、明らかに相関性が見られ、０．０８％以下とすることが好ましい。Ｃｕ−Ｗ合金の遮断特性、再点弧特性を向上させる為には、［（Ｔ１−Ｔ２）／Ｔ１］比率を制御した上で、０．０８％以下のＣ量とした１０〜５０％Ｃｕ−Ｗ−Ｃ合金によって対応するのが好ましい。
【０１０４】
すなわち、Ｃｕ−Ｗ合金中のＣ量を０．０８％以下としたＣｕ−Ｗ−Ｃ合金に対して、［（Ｔ１−Ｔ２）×１００／Ｔ１］を２．８％以下とすることによって、遮断特性、再点弧特性は好ましい特性を示す。Ｃｕ−Ｗ接点中のＣ量が０．０８％を越えると、［（Ｔ１−Ｔ２）×１００／Ｔ１］を２．８％以下としても、Ｃは凝集した状態となって存在する傾向にあり、素材特性の均質性を損なう結果、再点弧発生頻度にはバラツキを伴う傾向を示すと共に、遮断特性も低下させ、両特性の両立は得られない。
【０１０５】
この様に、Ｃｕ−Ｗ合金中のＣ量が０．０８％以下の場合には、低い再点弧発生頻度を発揮すると共に、遮断特性にも好影響を与えている。Ｃｕ−Ｗ接点中のＣ量を好ましい０．０８％以下とする為には、原料の必要以上の吟味や、特に加熱処理時の雰囲気の制御を要する。
【０１０６】
なお、Ｃｕ−Ｗ接点中のＣの粒子直径（形状が球形でない場合には球に換算した時の直径）または集合体の直径は、５μｍ以下（形状が球形でない場合には球に換算した時の直径）であることが望ましい。Ｃの粒子直径が５μｍ以下では、再点弧の発生頻度のバラツキが少なくなると共に、遮断時の電流による熱流のバランスが良くなり、遮断特性のバラツキも少なくなる。
【０１０７】
（実施例９〜１２）
前記実施例１〜８、比較例１〜３では、Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点について、耐弧成分としてＷを選択した例を示したが、本発明技術では耐弧成分としてＷの一部または総てをＭｏとしてもその効果を発揮する。すなわち２５％Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点に於いて、耐弧成分としてＷの一部をＭｏで置換しＷＭｏ（Ｗ：Ｍｏ＝重量比９９．９９：０．０１、Ｗ：Ｍｏ＝重量比９０：１０、Ｗ：Ｍｏ＝重量比５０：５０、Ｗ：Ｍｏ＝重量比０．０１：９９．９９）としたＣｕ−ＷＭｏ接点を製造した。
【０１０８】
＜再点弧特性＞
基準接点とした実施例４の再点弧特性と比較して、いずれも極めて良好な特性０．１倍未満（評価Ａ）ないし０．１〜０．８未満（評価Ｂ）を示した（実施例９〜１２）。
【０１０９】
＜遮断特性＞
基準接点とした実施例４の遮断特性と比較して、いずれも良好な特性０．９〜１．１倍を示し合格の範囲である（実施例９〜１２）。
【０１１０】
ＷＭｏの形成によって、Ｗ粒子の熱的安定性および機械的特性を改善し、その結果再点弧発生の一因となる遮断時のＷ粒子の脱落を抑制する。また適量のＭｏの存在は、遮断時のＷの粒子成長を抑制し、Ｗの微細分散化にも有益に作用する。遮断後の接点面のＳＥＭ観察によれば、脱落したＷ粒子の付着が減少している。
【０１１１】
すなわち、Ｃｕ−Ｗ接点中のＷの一部または総てをＭｏで置換しても、前記［（Ｔ１−Ｔ２）×１００／（Ｔ１）］が２．８％以下という条件を満たす時には、同様に安定した再点弧特性、遮断特性が得られる。
【０１１２】
（実施例１３〜１５）
前記実施例１〜８、比較例１〜３では、Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点について、耐弧成分としてＷの選択した例を示したが、本発明技術では耐弧成分としてＷの総てをＷＣとしても、またＷＣの一部または総てをＭｏＣとしてもその効果を発揮する。
【０１１３】
すなわち２５％Ｃｕ−ＷＣ合金の　［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点に於いて、耐弧成分としてＷＣの一部をＭｏＣで置換し、ＷＣＭｏＣ（ＷＣ：ＭｏＣ＝重量比９９．９９：０．０１、ＷＣ：ＭｏＣ＝重量比５０：５０、ＷＣ：ＭｏＣ＝重量比０．０１：９９．９９）としたＣｕ−ＷＣＭｏＣ接点を製造した（実施例１３〜１５）
＜再点弧特性＞
基準接点とした実施例４の再点弧特性と比較して、いずれも良好な特性０．１〜０．８未満（評価Ｂ）ないし０．８〜１．２未満（評価Ｃ）を示した（実施例１３〜１５）。
【０１１４】
＜遮断特性＞
基準接点とした実施例４の遮断特性と比較して、いずれも良好な特性０．９〜１．０５倍を示し合格の範囲である（実施例１３〜１５）。
【０１１５】
すなわちＣｕ−Ｗ接点中のＷの総てをＷＣとしても、またＷＣの一部または総てをＭｏＣで置換しても、前記［（Ｔ１−Ｔ２）×１００／Ｔ１］が２．８％以下という条件を満たす時には、同様な安定した再点弧特性、遮断特性が得られる。（なおここでのＭｏＣとは、Ｍｏ炭化物の意味であって、Ｍｏ２Ｃを含むものである。）
（実施例１６〜１７）
前記実施例１〜１５、比較例１〜３では、Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点について、導電成分としてＣｕを選択した例を示したが、本発明技術では導電成分としてＡｇ、ＡｇＣｕとしてもその効果を発揮する。
【０１１６】
すなわち４０％Ａｇ−Ｗ合金、４０％ＡｇＣｕ（２０Ａｇ＋２０Ｃｕ）−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点を製造した（実施例１６〜１７）。
【０１１７】
＜再点弧特性＞
基準接点とした実施例４の再点弧特性と比較して、いずれもほぼ同等の特性０．８〜１．２未満（評価Ｃ）を示した（実施例１６〜１７）。
【０１１８】
＜遮断特性＞
基準接点とした実施例４の遮断特性と比較して、いずれも同等の特性０．９〜１．０倍を示し合格の範囲である（実施例１６〜１７）。
【０１１９】
すなわち、Ｃｕ−Ｗ接点中のＣｕの一部または総てをＡｇで置換しても、前記［（Ｔ１−Ｔ２）×１００／Ｔ１］が２．８％以下という条件を満たす時には、同様に安定した再点弧特性、遮断特性が得られる。なお、Ｃｕ−ＷＣ接点中のＣｕの一部または総てをＡｇで置換しても、同様の効果が得られる。
【０１２０】
（実施例１８〜２１、比較例４）
前記実施例１〜１７、比較例１〜３では、ＣｕやＡｇなどからなる導電成分と、ＷやＭｏなどからなる耐弧成分とで構成され［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点について、再点弧特性、遮断特性との関係を示したが、本発明技術ではこれら導電成分と耐弧成分との構成のみならずＣｏ、Ｆｅ、Ｎｉの１つからなる補助成分（１）を存在させても同等の効果を発揮する。
【０１２１】
すなわち２７％Ｃｕ−Ｗ合金の　［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点に於いて、補助成分（１）として０．２％〜５％のＣｏ、０．２％のＦｅ、０．２％のＮｉとしたＣｕ−Ｗ−Ｃｏ、Ｃｕ−Ｗ−Ｆｅ、Ｃｕ−Ｗ−Ｎｉ接点を製造した。なお、原料に起因する不可避的な程度の微量の補助成分（１）のＣｏ、Ｆｅ、Ｎｉなどの成分は、前記実施例１〜１７、比較例１〜３中にも存在している。ここではこれらの量を越えた量の添加が対象である。
【０１２２】
＜再点弧特性＞
補助成分（１）として０．２％〜１％のＣｏの場合では、基準接点とした実施例４の再点弧特性と比較して、同等以上の良好な特性Ｏ．１未満ないし０．１〜０．８未満（評価Ａ〜Ｂ）を示した。素材自体の相対密度の改善と安定化が寄与した（実施例１８〜１９）。
【０１２３】
これに対して、補助成分（１）として５％のＣｏの場合では、遮断特性は向上しているものの、Ｃｏの偏析が避けられず０．１〜０．８未満（評価Ｂ）と１．５以上〜１０倍（評価Ｘ）の再点弧特性を示し、大きなバラツキが見られ再点弧特性と遮断特性との両立は得られず好ましくない（比較例４）
なお、補助成分（１）として０．２％のＦｅ、Ｎｉの場合でも、基準接点とした実施例４の再点弧特性と比較して、同等の良好な特性０．１〜０．８未満（評価Ｂ）ないし０．８〜１．２未満（評価Ｃ）を示し合格である（実施例２０〜２１）。
【０１２４】
＜遮断特性＞
補助成分（１）として０．２％〜１％のＣｏの場合では、基準接点とした実施例４の遮断特性と比較して、同等以上の特性１．０５〜１．１５倍を示し向上した（実施例１８〜１９）。なお補助成分（１）として５％のＣｏの場合では、遮断特性はさらに向上し、１．１〜１．２５倍未満を示した（比較例４）が、上記の様に再点弧特性に大きなバラツキが見られている。
【０１２５】
なお、補助成分（１）として０．２％のＦｅ、Ｎｉの場合でも、基準接点とした実施例４の遮断特性と比較して、良好な特性０．９５〜１．１倍を示し合格である（実施例２０〜２１）。
【０１２６】
すなわち、１％以下のＣｏ、Ｎｉ、Ｆｅの少なくとも１つから成る補助成分（１）を含有させると、焼結後の被焼結体（接点合金）の密度を幅広く調節でき、健全な焼結体とし、一層安定した再点弧特性、遮断特性が得られる。１％を越えて補助成分（１）が存在すると、導電性の低下に伴って遮断特性の低下を招くと共に、［（Ｔ１−Ｔ２）×１００／Ｔ１］を２．８％以下とした時に得られる効果が十分には発揮されない。
【０１２７】
なお、Ｃｕ−ＷＣ接点中に１％以下のＣｏ、Ｎｉ、Ｆｅの少なくとも１つから成る補助成分（１）を含有させても、同様の効果が得られる。
【０１２８】
（実施例２２〜２４、比較例５）
前記実施例１〜１７、比較例１〜３では、ＣｕやＡｇなどからなる導電成分と、ＷやＭｏなどからなる耐弧成分とで構成され［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点について、再点弧特性、遮断特性との関係を示したが、本発明技術ではこれら導電成分と耐弧成分との構成のみならずＢｉ、Ｓｂの１つからなる補助成分（２）を存在させても同等の効果を発揮する。すなわち２７％Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点に於いて、補助成分（２）として０．１％〜５．０％のＢｉ、０．１％のＳｂとしたＣｕ−Ｗ−Ｂｉ、Ｃｕ−Ｗ−Ｓｂ接点を製造した。
【０１２９】
＜再点弧特性＞
補助成分（２）として０．１％〜１％のＢｉの場合では、基準接点とした実施例４の再点弧特性と比較して、同等程度の特性（評価Ｂ〜Ｃないし評価Ｃ〜Ｄ）を示し合格の範囲である（実施例２２〜２３）。
【０１３０】
これに対して、補助成分（２）として５％のＢｉの場合では、Ｂｉの偏析が避けられず、再点弧特性は評価（Ｙ）ないし評価（Ｚ）を示し、大幅な低下が見られ好ましくない（比較例５）。
【０１３１】
なお、補助成分（２）として０．１％のＳｂの場合でも、基準接点とした実施例４の再点弧特性と比較して、同等程度の特性（評価Ｂ〜Ｃ）を示し合格の範囲である（実施例２４）。
【０１３２】
＜遮断特性＞
補助成分（２）として０．１％〜１％のＢｉの場合では、耐溶着性も改善した上に、基準接点とした実施例４の遮断特性と比較して、同等の遮断特性０．９〜１．０倍を示し合格の範囲である（実施例２２〜２３）。
【０１３３】
これに対して、補助成分（２）として５％のＢｉの場合では、Ｂｉの偏析が避けられず、耐溶着性は改善されるものの、遮断特性は０．４〜０．５５倍未満を示し大幅な低下が見られ好ましくない（比較例５）。
【０１３４】
なお、補助成分（２）として０．１％のＳｂの場合でも、基準接点とした実施例４の遮断特性と比較して、同等の遮断特性０．９〜０．９５倍を示し合格の範囲である（実施例２４）。
【０１３５】
すなわち、１％以下のＢｉ、Ｓｂの少なくとも１つから成る補助成分（２）を含有させると、接点合金の耐溶着性を調節する結果、遮断後に引き外した接点面は平滑性を持ち、一層安定した再点弧特性、遮断特性が得られる。１％を越えて補助成分（２）が存在すると、材料自体が脆い性質を示し逆に遮断後に引き外した接点面は粗となり平滑性を損ない、遮断後の再点弧特性の低下を招くと共に、［（Ｔ１−Ｔ２）×１００／Ｔ１］を２．８％以下として得られる効果が十分には発揮されない。
【０１３６】
なお、Ｃｕ−ＷＣ接点中に１％以下のＢｉ、Ｓｂの少なくとも１つから成る補助成分（２）を含有させても、同様の効果が得られる。
【０１３７】
（実施例２５〜２７、比較例６）
前記実施例１〜１７、比較例１〜３では、ＣｕやＡｇなどからなる導電成分と、ＷやＭｏなどからなる耐弧成分とで構成され［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点について、再点弧特性、遮断特性との関係を示したが、本発明技術ではこれら導電成分と耐弧成分との構成のみならずＴｅ、Ｓｅの１つからなる補助成分（３）を存在させても同等の効果を発揮する。すなわち２７％Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％で一定とした接点に於いて、補助成分（３）として０．５％〜１０％のＴｅ、０．５％のＳｅとしたＣｕ−Ｗ−Ｔｅ、Ｃｕ−Ｗ−Ｓｅ接点を製造した。
【０１３８】
＜再点弧特性＞
補助成分（３）として０．５％〜５％のＴｅの場合では、基準接点とした実施例４の再点弧特性と比較して、同等程度の特性（評価Ｃ〜Ｄ）ないし許容範囲の（評価Ｄ）を示し合格の範囲である（実施例２５〜２６）。
【０１３９】
これに対して、補助成分（３）として１０％のＴｅの場合では、Ｃｕ２Ｔｅの偏析が避けられず、再点弧特性は（評価Ｚ）を示し、極端な低下が見られ好ましくない（比較例６）。
【０１４０】
なお、補助成分（３）として０．５％のＳｅの場合でも、基準接点とした実施例４の再点弧特性と比較して、同等程度の特性（評価Ｃ〜Ｄ）を示し合格の範囲である（実施例２７）。
【０１４１】
＜遮断特性＞
補助成分（３）として０．５％〜５％のＴｅの場合では、耐溶着性も改善した上に、基準接点とした実施例４の遮断特性と比較して、同等の遮断特性０．９〜１．０倍を示し合格の範囲である（実施例２５〜２６）。
【０１４２】
これに対して、補助成分（３）として１０％のＴｅの場合では、Ｃｕ２Ｔｅの偏析が避けられず、耐溶着性は改善されるものの、遮断特性は０．４〜０．５５倍未満を示し大幅な低下が見られ好ましくない（比較例６）。
【０１４３】
なお、補助成分（３）として０．５％のＳｅの場合でも、基準接点とした実施例４の遮断特性と比較して、同等の遮断特性０．９〜０．９５倍を示し合格の範囲である（実施例２７）。
【０１４４】
すなわち、５％以下のＴｅ、Ｓｅの少なくとも１つから成る補助成分（３）を含有させると、接点合金の耐溶着性を調節する結果、遮断後に引き外した接点面は平滑性を持ち、一層安定した再点弧特性、遮断特性が得られる。５％を越えて補助成分（３）が存在すると、材料自体が脆い性質を示し逆に遮断後に引き外した接点面は粗となり平滑性を損ない、遮断後の再点弧特性の低下を招くと共に、［（Ｔ１−Ｔ２）×１００／Ｔ１］を２．８％以下として得られる効果が十分には発揮されない。
【０１４５】
なお、Ｃｕ−ＷＣ接点中に５％以下のＴｅ、Ｓｅの少なくとも１つから成る補助成分（３）を含有させても、同様の効果が得られる。
【０１４６】
（実施例２８〜３１、比較例７）
前記実施例１〜２７では、［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％の範囲に近似した状態の接点を選択した上で、遮断特性、再点弧特性への影響を検討した。
【０１４７】
このようにＴ１とＴ２を一定範囲とする効果的な手段の１つは、あらかじめ原料Ｃｕを移動速度１ｃｍ／６０分程度の一方向溶解によって、Ｔ１、Ｔ２値に影響を与える成分やガス状成分などＣｕ中の余分な成分を特に十分に小さくしておくこと、あらかじめ原料Ｗ粉を真空中で少なくとも１３５０℃の温度で加熱処理しておくこと、これらの凝固温度近傍を通過する際の冷却速度を十分に小に制御すること、次いでこれら原料を汚染させずに焼結して接点を得ること、焼結熱処理に際してその表面に同程度以上に清浄な状態のＣｕを被覆した容器を選択して使用することなどを基本として、［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．６〜１．７％の範囲に調整した。
【０１４８】
しかし、本発明技術を実施する場合に於いて、Ｔ１とＴ２とは１．６〜１．７の範囲のみに限ることなくその効果を発揮する。すなわち上記した手段の１つまたは複数を組合せることによって、Ｔ１とＴ２とを広く調整した接点を製造した。
【０１４９】
＜再点弧特性＞
Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を０．０１〜０．１％とした場合には、基準接点とした実施例４の再点弧特性と比較して、極めて良好な特性０．１倍未満（評価Ａ）ないし０．１〜０．８倍未満（評価Ｂ）を示した（実施例２８）。
【０１５０】
Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を０．９〜１．１％とした接点を得た。基準接点とした実施例４の再点弧特性と比較して、良好な特性０．１〜０．８倍未満（評価Ｂ）を示した（実施例２９）。
【０１５１】
Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．９〜２．１％とした接点を得た。基準接点とした実施例４の再点弧特性と比較して、０．１〜０．８倍未満（評価Ｂ）ないし０．８〜１．２倍未満（評価Ｃ）を示した（実施例３０）。
【０１５２】
Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を２．７〜２．８％とした接点を得た。基準接点とした実施例４の再点弧特性と比較して、０．８〜１．２倍未満（評価Ｃ）ないし１．２〜１．５倍未満（評価Ｄ）を示した（実施例３１）。
【０１５３】
これに対して、Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を５．５〜５．６％とした接点では、基準接点とした実施例４の再点弧特性と比較して、１．５以上〜１０倍未満（評価Ｘ）ないし１００倍以上（評価Ｚ）の如く、大きなバラツキと極めて好ましくない再点弧特性を示した（比較例７）。
【０１５４】
＜遮断特性＞
Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を０．０１〜０．１％とした場合には、基準接点とした実施例４の遮断特性と比較して、１．１５〜１．２５倍の極めて良好な遮断特性を示した（実施例２８）。
【０１５５】
Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を０．９〜１．１とした接点では、基準接点とした実施例４の遮断特性と比較して、１．０〜１．１倍の良好な遮断特性を示した（実施例２９）。
【０１５６】
Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を１．９〜２．１％とした接点を得た。基準接点とした実施例４の遮断特性と比較して、良好な特性０．９５〜１．１倍を示した（実施例３０）。
【０１５７】
Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を２．７〜２．８％とした接点を得た。基準接点とした実施例４の遮断特性と比較して、良好な特性０．９〜０．９５倍を示した（実施例３１）。
【０１５８】
これに対して、Ｃｕ−Ｗ合金の［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を５．５〜５．６％とした接点では、基準接点とした実施例４の再点弧特性と比較して、０．５〜０．６倍を示し、大幅な遮断特性の低下を示した（比較例７）。
【０１５９】
以上の様に、［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を２．８％以下に制御したＣｕ−Ｗ合金に於いて、遮断特性、再点弧特性の両立が得られる。
【０１６０】
なお、Ｃｕ−ＷＣに於いても、［（Ｔ１−Ｔ２）×１００／Ｔ１］比率を２．８％以下に制御することにより、遮断特性、再点弧特性の両立が得られる。
【０１６１】
【発明の効果】
本発明によれば、遮断によって接点面の一部分が溶融してから、これが消滅するまでの間の時間（液相が存在している時間）を短く制御したので、再点弧特性と遮断特性とを両立させた真空遮断器を提供することができる。
【図面の簡単な説明】
【図１】本発明に係る真空遮断器の実施例１〜８および比較例１〜３の評価条件を示す表図。
【図２】本発明に係る真空遮断器の実施例９〜２１および比較例４の評価条件を示す表図。
【図３】本発明に係る真空遮断器の実施例２２〜３１および比較例５〜７の評価条件を示す表図。
【図４】本発明に係る真空遮断器の実施例１〜８および比較例１〜３の評価結果を示す表図。
【図５】本発明に係る真空遮断器の実施例９〜２１および比較例４の評価結果を示す表図。
【図６】本発明に係る真空遮断器の実施例２２〜３１および比較例５〜７の評価結果を示す表図。
【図７】代表的な真空バルブの構成を示す図。
【図８】代表的な真空バルブの他の構成を示す図。
【符号の説明】
４０…電極（接点４１の背面）
４１…固定接点
５０…電極（接点５１の背面）
５１…可動接点
１０１…絶縁容器
１０２ａ…固定側蓋体
１０２ｂ…可動側蓋体
１０３…真空容器
１０４…固定接点
１０５…可動接点
１０６…固定通電軸
１０７…可動通電軸
１０８…ベロ−ズ
１０９…ア−クシ−ルド
Ｍ…通電軸１０７の移動方向[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vacuum circuit breaker provided with a contact material having excellent breaking characteristics and restriking characteristics.
[0002]
[Prior art]
(General structure of vacuum valve)
In general, in a vacuum circuit breaker, the contact of a vacuum valve for interrupting a current in a high vacuum utilizing the diffusivity of an arc in a vacuum is composed of two fixed and movable contacts facing each other.
[0003]
As shown in FIG. 7, a pair of contacts 104 and 105 are provided facing each other in a vacuum container 103 in which openings at both ends of an insulating container 101 are closed by lids 102a and 102b, and these are connected to the lids 102a and 102b. Each of the energized shafts 106 and 107 inserted into the vacuum container 103 is inserted into the end of the energized shaft, and one of the energized shafts 107 is axially movable by an operation mechanism (not shown). The other contact (hereinafter referred to as a movable contact) 105 can be brought into contact with or separated from the contact 104.
[0004]
In this case, a bellows 108 is provided between the lid 102b and the energizing shaft 107 to keep the inside of the vacuum vessel 103 airtight and to allow the conductive rod 107 to move in the axial direction. In the figure, reference numeral 109 denotes a shield provided so as to surround the contacts 104 and 105 and the conducting shafts 106 and 107.
[0005]
In the vacuum circuit breaker, both the contacts 104 and 105 are normally in contact with each other and are in an energized state. When the energizing shaft 107 moves in the direction of the arrow M in the drawing by the operation from this state, the movable contact 105 is separated from the fixed contact 104, and an arc is generated between the two contacts 104, 105. This arc is maintained by the generation of metal vapor from the cathode, for example, the movable contact 105 side. When the current reaches a zero point (zero point), the generation of metal vapor stops, the arc cannot be maintained, and the interruption is completed. .
[0006]
By the way, the arc generated between the contacts 104 and 105 becomes extremely unstable due to the interaction between the magnetic field generated by the arc itself and the magnetic field generated by the external circuit when the interruption current is large. As a result, the arc moves over the contact surface (when the contact is attached to and integrated with the electrode, the arc may also move over the electrode surface) and a piece is placed at the end or periphery of the contact. Then, the portion is locally heated, and a large amount of metal vapor is released, so that the degree of vacuum in the vacuum vessel 103 is reduced. As a result, the breaking performance of the vacuum circuit breaker decreases. These often depend on the state of the contact represented by a metal structure or the like.
[0007]
FIG. 8 shows a vacuum valve in which a pair of contacts 41 and 51 are provided to face each other, and a flat electrode 40 is mounted on the back of the contact 41 and a flat electrode 50 is mounted on the back of the contact 51, respectively. The coil electrode 40 may be mounted on the back of the contact 41, and the coil electrode 50 may be mounted on the back of the contact 51.
[0008]
(Conventional contact material)
In general, in a vacuum circuit breaker, in addition to the three basic requirements of large current interruption performance, withstand voltage performance, and welding resistance performance, suppression of occurrence of a re-ignition phenomenon is an important requirement.
[0009]
However, because some of these requirements are conflicting, it is not possible to satisfy all requirements with a single metal species. For this reason, in many contact materials that are in practical use, by combining two or more types of elements that complement each other for insufficient performance, specific contact points such as those for large current and high withstand voltage can be obtained. Selection and use of contact materials suitable for the application have been made, and vacuum valves with excellent characteristics have been developed. However, there are still many products that sacrifice some functions. In fact, a vacuum valve that sufficiently satisfies the growing demand has not yet been obtained.
[0010]
For example, Cu—Bi-based alloys and Cu—Te-based alloys containing 5% by weight or less of an anti-welding component such as Bi or Te are known as high-current interrupting contact materials that satisfy the three basic requirements (particularly). No. 41-12131, and No. 44-23751). Cu-Bi alloy is brittle Bi precipitated at the grain boundaries, Cu-Te alloy is brittle Cu precipitated at the grain boundaries and in the grains. 2 Te is excellent in large current interrupting characteristics because the alloy itself is embrittled and a low welding peeling force is realized. However, this alloy has difficulty in brazing workability and stability of restrike characteristics.
[0011]
On the other hand, a Cu—Cr alloy is known as a contact material for high withstand voltage and large current interruption. This alloy has an advantage that a uniform performance can be expected due to a smaller vapor pressure difference between the constituent components than the Cu-Bi alloy and the Cu-Te alloy, and is superior in some usages. A Cu-Cr alloy containing about 50% by weight of Cr (Japanese Patent Publication No. 45-35101) is known. This alloy realizes high voltage and large current interruption by the effect that Cr itself has almost the same vapor pressure characteristics as Cu, and shows a strong gas gettering effect. Are often used as contacts that can achieve both. However, since this alloy uses highly active Cr, when producing contact materials (sintering process, etc.) while giving due consideration to the selection of raw material powder, contamination of impurities, management of atmosphere, etc. Great care must be taken to make a contact product, for example, when processing contact material into contact pieces.
[0012]
A Cu-W alloy is known as a high withstand voltage contact material. This alloy exhibits excellent arc resistance due to the effect of the high melting point material. However, this alloy has a drawback in its blocking properties.
[0013]
(The occurrence of restriking)
In a vacuum circuit breaker, a flashover may occur in the vacuum valve after the current is cut off, and a phenomenon may be induced in which the contacts become conductive again (discharge does not continue thereafter). This phenomenon is called re-ignition, and the mechanism of its occurrence is unclear. However, since the electric circuit suddenly changes to the conducting state after being in the current interruption state, abnormal overvoltage is likely to occur. In particular, according to an experiment in which re-ignition occurs when the capacitor bank is cut off, an extremely large overvoltage is generated and an excessive high-frequency current flows. Therefore, development of a technique for suppressing re-ignition is required.
[0014]
As described above, the mechanism of the occurrence of the re-ignition phenomenon is not yet known, but according to the experimental observations of the present inventors, the re-ignition occurs between the contacts in the vacuum valve, and between the contacts and the arc. It occurs at a fairly high frequency between countries. Therefore, the present inventors have developed a technology that is extremely effective in suppressing the occurrence of restriking, such as a technology for suppressing a sudden gas released when a contact receives an arc and a technology for optimizing a contact surface shape. As a result, the number of restriking occurrences has been significantly reduced. However, in recent years, demands for a high withstand voltage and a demand for a large current interruption, particularly a demand for a miniaturization of a vacuum valve have necessitated a further reduction in re-ignition of a contact.
[0015]
That is, in recent years, diversification of loads has been progressing along with severer use conditions of consumers. As a recent remarkable tendency, application to reactor circuits, capacitor circuits, and the like has been expanded, and accordingly, development and improvement of contact materials have been urgently required. In the capacitor circuit, since the voltage is applied twice or three times the normal voltage, the contact surface is significantly damaged due to the current interruption and the current switching operation, resulting in the contact surface being roughened, falling off and being worn out. Although it is considered to be one of the causes of ignition, the re-ignition phenomenon is important from the viewpoint of improving product reliability. Not.
[0016]
According to experiments by the present inventors, at a cutoff current of, for example, about 20 kA, among the above contact alloys, a Cu—W alloy tends to be most advantageous in restriking characteristics.
[0017]
A detailed observation of the correlation between the total amount of gas released during the heating process of the Cu-W alloy, the type of gas, and the release form and the occurrence of restriking revealed that the pulse near the melting point was very short. It has been found that the re-ignition occurrence rate increases at the contact point where a large amount of gas is suddenly released. Therefore, the cause of sudden gas release in the Cu-W alloy is removed by heating the Cu-W alloy at a temperature equal to or higher than the melting temperature of Cu, or pores in the Cu-W alloy are removed. The occurrence of restriking has been reduced by improving the sintering technology so as to suppress or systematic segregation.
[0018]
However, in recent years, the need for further suppression of restriking has been recognized, and the development of other measures has become important.
[0019]
[Problems to be solved by the invention]
Cu-Bi alloy and Cu-Te alloy have high conductivity of 80-90% IACS class and excellent welding resistance as contact materials for vacuum circuit breakers, and when applied at a circuit voltage of 12 kV or less, Demonstrates excellent large current cutoff characteristics. However, when applied to a high voltage circuit having a circuit voltage exceeding 12 kV, the re-ignition characteristics are extremely reduced.
[0020]
Cu-Cr contacts are currently widely used as high withstand voltage contact materials. Due to the fact that the vapor pressure characteristics of Cu and Cr at high temperatures are similar, the contact surface shows relatively smooth damage characteristics even after interruption, and exhibits stable electric characteristics. However, in recent years, adaptation to circuits where higher current interruption or higher voltage may be applied is performed on a daily basis, and as a result, the state of the surface when new as a contact, the contact after current interruption Depending on the state of surface damage, it may indicate a withstand voltage failure and cause reignition, or may cause an abnormal increase in contact resistance or temperature when the next current is opened or closed. Has contributed to the decline. However, in reality, even if the surface condition of the contact is managed, it is not possible to completely suppress the occurrence of restriking, and in reality, it is not possible to obtain a sufficient breaking characteristic.
[0021]
Cu-W contacts have higher withstand voltage characteristics than the above-mentioned Cu-Bi alloys, Cu-Te alloys and Cu-Cr alloys, and therefore have priority over Cu-Bi alloys, Cu-Te alloys and Cu-Cr alloys. Although a Cu-W alloy has been applied, it cannot be said that it is a sufficient contact material for the demand for a further reduction in re-ignition.
[0022]
The breaking characteristics and restriking characteristics of the Cu-W alloy include variations in the amount of W in the alloy, the particle size distribution of the W particles, the degree of segregation of the W particles, the degree of vacancies present in the alloy, the contact surface and the inside of the alloy. These optimizations are important depending on the amount of gas and the state of existence. Despite the progress of these optimizations, even with the Cu-W alloy described above, the occurrence of a re-ignition phenomenon has been observed in a circuit with a severer high voltage region and a rush current. There are variations in the cutoff characteristics and variations in the frequency of restriking.
[0023]
Thus, while maintaining the above three basic requirements at a certain level, the realization of a vacuum circuit breaker having both excellent breaking characteristics and restriking characteristics has not been achieved yet. Development is expected.
[0024]
The object of the present invention has been made in view of the above circumstances, and by optimizing the metallurgical conditions of a Cu-W alloy or a Cu-WC alloy, a vacuum having excellent cut-off characteristics and re-ignition characteristics. To provide a circuit breaker.
[0025]
[Means for Solving the Problems]
To achieve the above object, a vacuum circuit breaker according to the present invention is a contact material including a conductive component phase composed of 10 to 50% by weight of Cu and an arc-resistant component composed of 50 to 90% by weight of W. A melting onset temperature (endothermic onset temperature) T1 of the conductive component phase of Cu in the contact material in the temperature rising process measured in Celsius, and a conductivity of Cu in the cooling process after heating to at least 1200 ° C. Ratio of the difference (T1-T2) between the solidification onset temperature (exothermic onset temperature) T2 and the melting onset temperature T1, measured in degrees Celsius of the active ingredient phase, ie, [(T1-T2) × 100 / (T1) ] Has a contact made of a contact material of 2.8% or less.
[0026]
That is, according to the present invention, a vacuum circuit breaker having a Cu-W contact can obtain stable re-ignition characteristics and interruption characteristics.
[0027]
If the ratio of [(T1−T2) × 100 / (T1)] exceeds 2.8%, the re-ignition characteristic is reduced and its variation occurs, and the cutoff characteristic is also reduced. This means that a liquid phase portion (melted portion) has been present for a long time at the arc receiving point in the cooling process after the current interruption. The existence of a liquid state having a low withstand voltage value (poor withstand voltage characteristics) for a long time is not preferable because it increases the chances of inducing the occurrence of restriking and the possibility of causing interruption.
[0028]
If the ratio of [(T1−T2) × 100 / (T1)] is 2.8% or less, stable re-ignition characteristics and cutoff characteristics can be obtained.
[0029]
A powerful first means for obtaining a [(T1−T2) × 100 / (T1)] ratio of 2.8% or less controls the existence of a liquid phase that becomes a defect (weak point) in withstand voltage in a short time. That is the basis. Clean the surface of the raw material and the sintering container (for example, if the raw material is Cu, perform a degassing treatment at least at 800 ° C. for about 30 minutes before sintering. If the raw material is Ag, at least 700 ° C. before sintering) Degassing for about 30 minutes), purifying the raw material (for example, reducing the total amount of components other than Cu or CuAg present in the Cu phase to 0.3% or less), and sintering. Quality improvement of medium atmosphere (for example, 10 -2 Pa. Sintering in a higher vacuum. Sintering in a high-purity hydrogen atmosphere having a dew point of −70 ° C. or less) restricts the intrusion of the melting point depressing substance into the Cu liquid phase (in the Ag liquid phase) and reduces the T2 value. Suppress extreme decline.
[0030]
Another influential second means for obtaining a ratio of [(T1−T2) × 100 / (T1)] of 2.8% or less is that when a contact at room temperature receives an arc and enters a heating process, it is damaged. By delaying the transfer of heat from the arc point to its surroundings and delaying the temperature rise near the arc point, the liquid phase generation time is delayed and the T1 value is reduced. As a measure for delaying the transfer of heat, for example, the presence of 1% or less, preferably 0.1% or less of carbon or oxide in Cu that does not form a solid solution or react with Cu is effective.
[0031]
In the conventional manufacturing, since the above-mentioned influential first and second means are not sufficiently considered, the [(T1−T2) × 100 / (T1)] ratio exceeds 2.8. In addition, it is impossible to obtain both the re-ignition characteristic and the cutoff characteristic. In the practice of the present invention, the above-mentioned powerful first and second means are adopted redundantly.
[0032]
In determining the solidification start temperature T2 in the practice of the present invention, the reason for selecting “at least 1200 ° C.” and its effect are to obtain the true value of the T2 measured value and to eliminate the dispersion of the measured value. This is because it is preferable to employ measurement conditions that greatly exceed the melting temperature of pure copper, 1083 ° C., so that the entire contact during temperature measurement completely and reliably exceeds the melting temperature of the Cu phase.
[0033]
The vacuum circuit breaker according to the present invention is a contact material containing a conductive component phase composed of 10 to 50% by weight of Cu and an arc-resistant component composed of 50 to 90% by weight of WC. A melting onset temperature (endothermic onset temperature) T1 of the conductive component phase of Cu in the contact material measured in degrees Celsius, and a conductive component phase of Cu in a cooling process after heating to at least 1200 ° C. The ratio of the difference (T1-T2) from the solidification start temperature (exothermic start temperature) T2 measured in degrees Celsius to the melting start temperature T1, that is, [(T1-T2) × 100 / (T1)] And 2.8% or less of a contact material.
[0034]
That is, according to the present invention, the vacuum circuit breaker provided with the Cu-WC contact can obtain stable restriking characteristics and breaking characteristics.
[0035]
However, when the [(T1−T2) × 100 / (T1)] ratio exceeds 2.8%, the re-ignition characteristic is reduced and its variation occurs, and the cutoff characteristic is also reduced. On the other hand, if the [(T1−T2) × 100 / (T1)] ratio is 2.8% or less, stable re-ignition characteristics and cutoff characteristics can be obtained.
[0036]
If the [(T1−T2) × 100 / (T1)] ratio exceeds 2.8%, a liquid phase portion (molten portion) is formed at an arc point in the cooling process after current interruption. Refers to existence for a long time. The existence of a liquid state having a low withstand voltage value (poor withstand voltage characteristics) for a long time is not preferable because it increases the chances of inducing the occurrence of restriking and the possibility of causing interruption.
[0037]
If the [(T1−T2) × 100 / (T1)] ratio is 2.8% or less, the presence of a liquid phase that becomes a defect (weak point) in withstand voltage is controlled in a short time. Purification of the raw material surface and sintering container (for example, degassing treatment at least at 1000 ° C. for about 30 minutes before sintering) and purification of the raw material (for example, reducing the total amount of components other than Cu to 0.3% or less) ) Or improving the quality of the atmosphere during sintering (for example, 10 -2 Pa. Treatment in a higher vacuum than in a high-purity hydrogen atmosphere having a dew point of −70 ° C. or less, restricts the intrusion of the melting point depressing substance into the liquid phase, suppresses an extremely low T2 value, It is one of the leading means to achieve a ratio of .8% or less. As another means, when a contact at normal temperature receives an arc and enters a heating process, it delays the transfer of heat from the arc point to its surroundings and delays the temperature rise near the arc point. Thus, the generation time of the liquid phase is delayed to reduce the T1 value. As a means for delaying the transfer of heat, for example, the presence of 1% or less, preferably 0.1% or less of carbon or oxide in Cu that does not form a solid solution or react with Cu is effective.
[0038]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0039]
The gist of the embodiment of the present invention is that, for example, a melting start temperature of a Cu phase (highly conductive component phase) (measured as an endothermic start temperature in differential thermal analysis) with respect to a Cu-W (50 to 90%) contact point. A contact made of a contact material having a small difference (T1-T2) between T1 and a solidification onset temperature (exothermic onset temperature in differential thermal analysis) T2 is mounted on a vacuum circuit breaker and re-ignition occurs. And stabilization of the cutoff characteristics.
[0040]
The contact targeted in the embodiment of the present invention includes a highly conductive component phase of 10 to 50% by weight (hereinafter, weight% is simply referred to as%) composed of at least one of Cu and Ag; Effective when applied to a contact material containing at least one (or at least one of WC and MoC) and a 50 to 90% arc resistant component (if necessary, a welding resistant component such as Bi or Te). I do.
[0041]
If the total amount of the arc resistant component exceeds 90% (hereinafter, a Cu-W alloy in which W is a representative example of the arc resistant component and Cu is a representative example of the highly conductive component phase will be described. The same applies to other alloy systems. When a large current exceeding 20 kA is cut off, the cutoff characteristics cannot be maintained due to active emission of thermoelectrons. Further, opening and closing of the rated current and interruption of the large current undesirably lower the temperature rise characteristics and contact resistance characteristics of the contact portion or the breaker terminal portion. On the other hand, in a contact where the total amount of W is less than 50%, the arc resistance is reduced at the time of current interruption, so that the contact surface after the interruption suffers significant arc damage (dropping of W, selective evaporation of Cu part, (Irregularities and roughness in the vicinity of the arc point formed by the scattering) cause the re-ignition characteristic to deteriorate, which is not preferable.
[0042]
The average particle diameter (hereinafter referred to as “particle diameter”) of the W particles used in the contact of interest in the embodiment of the present invention is preferably in the range of 0.1 to 9 μm. ), More stable restriking characteristics are exhibited (the same applies to WC, Mo, and MoC other than W).
[0043]
In another preferred embodiment of the present invention, W and Mo and Fe are integrated into W to form WMoFe. As a result, the wettability between Cu and W was improved, and the adhesion strength between W particles and Cu was improved. Further, the size of the Cu phase surrounded by the integrated WMoFe was also limited so that a region of 10 μm or less, which is a preferable range, occupies a predetermined area or more, thereby achieving a uniform contact alloy structure.
[0044]
As a result, not only is control performed so that the amount of Cu that evaporates and scatters preferentially when an arc is received is reduced, but also the contact surface is re-positioned due to thermal shock during the arc. The generation of remarkable cracks, which are harmful to the occurrence of arcs, was also suppressed, and the scattering and falling of W particles were reduced. In this way, the alloy structure has been made uniform and the Mo and Fe have been integrated, so that even after receiving the arc, melting and scattering damage of the contact surface are reduced, which is an important influence on the suppression of restriking. To reduce the contact surface roughness. By these synergistic effects, the frequency of restriking of the Cu-W alloy was suppressed while maintaining the breaking current characteristics.
[0045]
According to the basic experiments performed by the inventors using contact pieces, a pair of Cu-27% W contacts in a solid state are opposed to each other, and while one of the contacts is heated, a withstand voltage characteristic (dark current versus gap characteristic) is obtained. ), When the temperature reaches a temperature at which a liquid phase appears at a part of the contact, the withstand voltage value is greatly reduced (about 10 to 50% reduction). Subsequently, when the CuW contact is cooled, the withstand voltage value is recovered (substantially returns to the original withstand voltage value).
[0046]
The appearance of the liquid phase affects the change in thermophysical properties and surface (irregularity) near the arc point, and during the period in which the liquid phase exists, the release state of the contact vapor and the ejection of the liquid contact It affects the situation, and as a result, affects the withstand voltage characteristics. Therefore, it is shown that the magnitude of the appearance of the liquid phase and the magnitude of the period during which the liquid phase exists (the duration of the liquid phase) affect the withstand voltage characteristics of the vacuum circuit breaker. It can be a trigger for the arc and, of course, is considered to affect the breaking characteristics.
[0047]
The present invention is based on this finding, and focuses on the length of time during which a liquid phase is present at a contact point due to interruption. That is, while the liquid phase is present, the temperature of the contact increases and the temperature at which the liquid phase starts to be generated (melting start temperature) T1, and the contact heated to the melting temperature or higher is cooled. The difference (T1-T2) between the temperature (solidification start temperature) T2 when the liquid phase disappears from the contact point is defined as the time during which the liquid phase exists. Since the value of T1 mainly varies depending on the type and amount of components other than Cu in the Cu phase, it is possible to grasp numerical values with a certain degree of accuracy. However, the value of T2 is affected by the heating environment (fluctuation of the solidification temperature due to penetration of gas and impurities from the ambient atmosphere and solid solution) when heated above the melting temperature, and fluctuates each time. Can not grasp. Therefore, in the present invention, the relationship between the difference T1 and T2 (T1−T2) is determined based on T1 that can be grasped as a numerical value. That is, the present invention controls the ratio of T1 to the difference (T1-T2) between the melting start temperature T1 and the solidification start temperature T2.
[0048]
As described above, the temperature of the contact surface (in the vicinity of an arc point or an arc point) in the process of raising the temperature becomes extremely high due to the interruption, and a liquid phase is generated on a part of the contact surface. With the completion of the cutoff, the contact temperature gradually drops, and the liquid phase becomes solid (solidified) and disappears. The amount of time from the generation of the liquid phase to the disappearance (the time during which the liquid phase is present) depends on the period during which the high-temperature state remains unfavorable for maintaining and improving the cutoff characteristics and the re-ignition characteristics. (Time). Generally, it fluctuates depending on the state of the contact material (material properties, etc.), the manufacturing conditions of the contact material (sintering temperature, cooling conditions, etc.), the mechanical conditions of the circuit breaker (input speed, opening speed, contact pressure, etc.). . Therefore, the magnitude of the time during which the high temperature state is maintained serves as a guide for determining the breaking characteristics and restriking characteristics of the vacuum circuit breaker and has an important meaning.
[0049]
Therefore, the melting start temperature (endothermic start temperature in differential thermal analysis) T1 of the Cu-W contact (substantially the Cu phase in the same alloy) in the temperature rising process, and after heating to at least 1200 ° C. The ratio of the difference (T1-T2) between the solidification start temperature of the Cu phase (the heat generation start temperature in the differential thermal analysis) T2 and the melting start temperature T1 in the cooling process when is cooled, that is, [ The (T1-T2) / (T1)] ratio is important. The reason why the temperature is much higher than the solidification temperature of 1083 ° C. of the Cu phase, that is, “at least 1200 ° C.” is a selection for determining an accurate T2 value (time during which the liquid phase exists). . The temperature at the arcing point or near the arcing point in the actual vacuum circuit breaker reaches 3000 to 6000 ° C, but it is not necessary to heat to 3000 to 6000 ° C to determine the T2 value. For the measurement of the starting temperature, a sufficiently stable numerical value is obtained at 1200 ° C.
[0050]
It is necessary to reduce the value of (T1−T2) in order to achieve both the cutoff characteristic and the re-ignition characteristic. To this end, it is necessary to reduce the T1 value or increase the T2 value.
[0051]
In order to reduce the T1 value, as an example, it is necessary for C existing in the Cu-W contact to transfer the heat input received by the arc point to the other portion for a certain period of time. This has the effect of obstructing the heat transfer, that is, the effect of delaying the time until the contacts start melting, and is one means for reducing T1 (means 1).
[0052]
To increase the T2 value, the purity of Cu in the Cu liquid phase at the time of the liquid phase state is increased, and the Cu is solidified at a temperature as close as possible to the solidifying temperature of pure Cu. That is, use of high-purity raw materials, use of clean parts (such as a sintering container), and sintering work in a clean atmosphere are performed so that the intrusion of the substance that lowers the melting point into the Cu liquid phase is reduced. This is one means for increasing the T2 value (means 2).
[0053]
As an auxiliary technique for suppressing or reducing the occurrence of restriking, after obtaining raw material powder [Cu] and raw material powder [W] in a quality-preferred state such as purity and cleanliness in a clean atmosphere, While crushing, dispersing and mixing these, a uniform and fine [Cu.W] mixed powder is obtained in a clean atmosphere. As a result, it is possible to obtain a basic effect of reducing the occurrence of minute irregularities and damage on the contact surface generated by turning on and off, and reducing the emission and scattering of fine metal particles into the electrode space. By superimposing these basic effects and the control effects of T1 and T2, it is possible to further ensure compatibility between the restriking characteristic and the cutoff characteristic.
[0054]
Various techniques have been conventionally developed for stabilizing the re-ignition characteristics and cutoff characteristics of a vacuum valve. For example, it is thought that it depends on the composition of the contact material, the variation of the component amount, the gas amount, the structure morphology (grain size, particle size distribution, the degree of segregation, the degree of vacancy present in the alloy), the surface morphology of the contact, etc. It has become. According to observations made by the present inventors, in order to further stabilize the re-ignition characteristics, in addition to the above, T1 (melting start temperature) and T2 (solidification during the cooling process) of the Cu phase in the Cu-W alloy It was found that the difference (T1-T2) from the (starting temperature) and the ratio of T1 [(T1-T2) / T1] ratio were deeply involved.
[0055]
In this case, T1 and T2 were measured by numerical values shown in (° C.) for convenience.
[0056]
Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. Evaluation conditions and evaluation results are shown in FIGS.
[0057]
(1) Measurement of T1 and T2 values
A needle-shaped CuW electrode having a radius of curvature of 5 mm × length 30 mm in a solid state and a plate-shaped CuW test piece electrode having a diameter of 20 mm × thickness 5 mm in a solid state and a vacuum degree of 10 -4 Pa. In a high vacuum. A part of the surface of the plate-shaped CuW test piece electrode is locally and continuously heated by, for example, a laser irradiation method, and the temperature during the heating is measured by a non-contact method by an infrared thermometer. A voltage is continuously applied between the two electrodes in the process of raising the temperature from zero to dielectric breakdown, and a withstand voltage value (voltage characteristics between fixed gaps) corresponding to the temperature of the plate-shaped CuW piece is continuously measured. When the temperature reaches a temperature at which a liquid phase appears at a part of the contact during the temperature rising process, the withstand voltage value is significantly reduced (about 10 to 100% lower). Temperature value measured with an infrared thermometer, endothermic start temperature T1 (melting start temperature), exothermic start temperature T2 (solidification start temperature) obtained by using a lid thermal analyzer while heating only the CuW piece separately in an electric furnace. T1 and T2 values are determined by comparing
[0058]
(2) Restriking characteristics
A disk-shaped contact piece having a diameter of 30 mm and a thickness of 5 mm was attached to a demountable vacuum valve, and the frequency of restriking when a circuit of 24 kV × 500 A was interrupted 2,000 times was measured. Note that the numerical values are relative values based on the values of Example 4 with a variation width.
[0059]
The frequency of occurrence of restriking is less than 0.1 times (A), 0.1 to less than 0.8 times (B), and 0.8 to less than 1.2 times (C). An evaluation of 2 to less than 1.5 times (D), an evaluation of 1.5 to less than 10 times (X), an evaluation of 10 to less than 100 times (Y), and an evaluation of 100 times or more were evaluation (Z).
[0060]
The evaluations (A) to (D) were used as “pass”, and the evaluations (X) to (Z) were used as “inferior”.
[0061]
(3) Cut-off characteristics
An experimental valve for a cutoff test equipped with a contact having a diameter of 70 mm was attached to the switchgear and subjected to baking, voltage aging, etc., and then connected to a 24 kV, 50 Hz circuit. Each of the three was evaluated. The numerical values are comparative values when the value of Example 4 is set to 1.0 with a variation width. 9 times or more is a pass, and less than 0.9 times is a reject.
[0062]
(4) Overview of assembling an experimental valve for shut-off test
The outline of the assembly of the experimental valve for the shut-off test is shown. Ceramic insulating container with the average surface roughness of the end face polished to about 1.5 μm (main component: AL 2 O 3 ) Was prepared, and this ceramic insulating container was subjected to a preheating treatment at 1600 ° C. before assembling. A 42% Ni-Fe alloy having a plate thickness of 2 mm was prepared as a sealing metal. As a brazing material, a thickness of O.D. A 1 mm 72% Ag-Cu alloy plate was prepared. Each of the prepared members is arranged between the objects to be joined (the end face of the insulating container made of ceramics and the sealing metal) so as to be able to be hermetically sealed and joined. -4 Pa. In a vacuum atmosphere, and subjected to an airtight sealing process between the sealing fitting and the ceramic insulating container.
[0063]
(5) Method of manufacturing test contact alloy
After setting the [(T1-T2) × 100 / T1] ratio in the Cu—W alloy to 1.6 to 1.7%, a predetermined particle diameter (preferably 0.1 to 9 μm) is used as an arc-resistant component. ) And a predetermined amount of Cu as a conductive component. After they are mixed and molded in a non-oxidizing atmosphere so as to be uniformly dispersed, sintering heat treatment (for example, 1030 ° C.) or sintering heat treatment and infiltration heat treatment (for example, 1000 ° C. and 1150 ° C.) are performed in a non-oxidizing atmosphere. Sequentially) to prepare Cu-W contact materials (Examples 1 to 4 and Comparative Examples 1 and 2).
[0064]
Prepare a Cu-WC contact material (Examples 5 to 8 and Comparative Example 3) in which C having a particle diameter of preferably 5 µm or less is present as an auxiliary component at the interface between the Cu phase and the W particles of the Cu-W alloy. did.
[0065]
Cu-W contact material in which part or all of W is substituted with Mo as an arc-resistant component (Examples 9 to 12), and Cu-W in which part or all of WC is substituted with MoC as another arc-resistant component Contact materials (Examples 13 to 15) were prepared.
[0066]
Ag-W contact materials (Examples 16 and 17) in which part or all of Cu was replaced with Ag as a conductive component were prepared.
[0067]
A Cu-W contact material (Examples 18 to 21, Comparative Example 4) containing one of Co, Fe, and Ni as a first auxiliary component was prepared. A Cu-W contact material (Examples 22 to 24, Comparative Example 5) containing one of Bi and Sb as a second auxiliary component was prepared. A Cu-W contact material (Examples 25 to 27, Comparative Example 6) containing one of Te and Se as a third auxiliary component was prepared.
[0068]
Next, the [(T1-T2) × 100 / T1] ratio was set to (0.01 to 0.1%), (0.9 to 1.1%), (1.9 to 2.1%), (2 0.7-2.8%) and (5.5-5.6%) Cu-W contact materials (Examples 28-31, Comparative Example 7) were prepared.
[0069]
One method for adjusting the [(T1-T2) / T1] ratio in the production of contacts is to select either (Means 1) or (Means 2) or both, and then, for example, (1) This is achieved by controlling the types of trace components other than the main components present in the Cu phase in the Cu-W alloy and the total amount thereof. That is, C existing at the interface between Cu and W is controlled (the amount of C is set to 0.08% or less with respect to the Cu-W alloy).
[0070]
Another method of adjusting the [(T1-T2) / T1] ratio in the production of contacts is achieved by, for example, (2) controlling the temperature and time of the sintering process. That is, if the temperature of the sintering process is selected to be higher than the T1 value (T1 value ± 50 ° C .; 1030 to 1130 ° C. for Cu-W, 910 to 1010 ° C. for Ag-WC), Cu and W Activation of the surface and purification of the interface between Cu and W (the interface between Ag and WC) are achieved, and the [(T1-T2) / T1] ratio is reduced.
[0071]
Another method of adjusting the [(T1-T2) / T1] ratio in the production of contacts is achieved by, for example, controlling the processing temperature during sintering and the cooling rate thereafter. That is, if the cooling rate when passing through near 1000 ° C. in solid phase sintering and near 1100 ° C. in solid phase / infiltration sintering is selected from 0.1 ° C. to 10 ° C./min, the built-in gas in the Cu phase Both the amount and the amount of W adsorbed gas are released more, and the [(T1-T2) / T1] ratio decreases. Selecting a rate less than 0.1 ° C./min results in poor productivity. When a rate exceeding 10 ° C./min is selected, the [(T1-T2) / T1] ratio tends to increase. Actually, in order to further reduce the [(T1-T2) / T1] ratio, the above-mentioned (means 1) and (means 2) are appropriately combined with the above conditions (1), (2) and (3). It is preferable to carry out while.
[0072]
(Examples 1-4, Comparative Examples 1-2)
The point of the contact point of the present invention is that the difference between the melting start temperature T1 of the Cu phase in the Cu-W alloy and the solidification start temperature T2 in the cooling process (T1 The point is to control the ratio between the (-T2) value and T1, that is, the [(T1-T2) / T1] ratio.
[0073]
In order to clarify the range of the amount of Cu in the Cu-W alloy for the technique of the present invention to exhibit its effect effectively, the ratio of [(T1-T2) × 100 / T1] is set to 1.6 to 1.7. Manufacture a contact with a constant (%). Industrially, [(T1−T2) × 100 / T1] ratios of 3 (%) or more or about 5 (%) are produced for manufacturing technology reasons and economic reasons.
[0074]
<Reignition characteristics>
When a plurality of circuit breakers equipped with Cu-50% W contacts with the total Cu content in the contacts being 50% (50% W) are interrupted 2,000 times at 24 kV, the re-ignition frequency is 10 to 20 times. Range. In the present invention, this characteristic was set as an allowable range in performance, and the characteristic of this contact was used as a reference, and a fourth embodiment was made.
[0075]
In the Cu-95% W contact where the total Cu amount in the contact was 5% (95% W), the result was 1.2 to less than 1.5 times (evaluation D) and was judged to be acceptable. In many cases, re-ignition occurred with a large variation, as shown by 10 to 100 times (evaluation Y), and undesirable re-ignition characteristics were exhibited (Comparative Example 1). One possible reason is that the temperature of the contact surface was excessively increased by the breaking current.
[0076]
In the Cu-90% W contact where the total Cu content in the contact was 10% (90% W), the frequency of restriking compared with Example 4 was 1.2 to less than 1.5 times ( Evaluation D) was shown, and good restriking characteristics were shown (Example 1).
[0077]
Even with a Cu-75% W contact where the total Cu content in the contact was 25% (75% W), the frequency of restriking compared to Example 4 was less than 0.1 to 0.8 times (evaluation B ), Indicating good restriking characteristics (Example 2).
[0078]
Even with a Cu-60% W contact where the total Cu content in the contact was 40% (60% W), the frequency of restriking compared to Example 4 was 0.8 to less than 1.2 times (evaluation C ) And good restriking characteristics (Example 3).
[0079]
On the other hand, in a Cu-25% W contact where the total Cu content in the contact is 75% (25% W), the ratio of [(T1-T2) × 100 / T1] is 1.6 to 1.7%. In spite of the above, the re-ignition occurrence frequency compared with Example 4 was 1.2 to less than 1.5 times (evaluation D) in some cases, and was judged to be acceptable. As shown in Table 1, the re-ignition with large variation was observed, and unfavorable re-ignition characteristics were exhibited (Comparative Example 2). Severe damage has been observed on the contact surface due to the interruption.
[0080]
As described above, when the present technology is applied to a Cu-W alloy containing 10 to 50% Cu, it exhibits its effect on restriking characteristics.
[0081]
<Blocking characteristics>
In the case of the Cu-90% W contact where the total Cu content in the contact was 10% (90% W), the cutoff characteristic as compared with the above Example 4 was 0.9 to 0.95 times, showing a good cutoff characteristic. (Example 1).
[0082]
In the case of the Cu-75% W contact where the total Cu content in the contact was 25% (75% W), the breaking characteristic as compared with the above Example 4 was 0.9 to 1.05 times, indicating good breaking. The characteristics were shown (Example 2).
[0083]
In the case of the Cu-60% W contact where the total Cu content in the contact was 40% (60% W), the breaking characteristics as compared with the above Example 4 showed 1.0 to 1.1 times, and extremely good breaking. The characteristics were shown (Example 3).
[0084]
A Cu-50% W contact having a total Cu content of 50% (50% W) in the contact was used as a reference contact, and the breaking characteristic was set to 1.0 (Example 4).
[0085]
On the other hand, in the Cu-95% W contact where the total Cu content in the contact is 5% (95% W), the ratio of [(T1-T2) × 100 / T1] is 1.6 to 1.7%. Nevertheless, the blocking characteristics as compared with Example 4 were O.D. It showed a drastic decrease of 3 to 0.6 times, and showed extremely poor blocking characteristics (Comparative Example 1).
[0086]
Further, in the Cu-25% W contact where the total Cu content in the contact was further increased to 75% (25% W), the breaking characteristic as compared with the above Example 4 was 0.7 to 0.8 times. And a slightly inferior barrier property (Comparative Example 2).
[0087]
As described above, in order to control the [(T1−T2) × 100 / T1] ratio and improve the cutoff characteristics and restrike characteristics of the Cu—W alloy, the Cu content is 10 to 50%. Preferably it is adapted for -W alloys.
[0088]
(Examples 5 to 8, Comparative Example 3)
In Examples 1 to 4 and Comparative Examples 1 and 2, it was shown that a Cu-W alloy having a Cu content of 10 to 50% is preferable as a contact to which the present invention is applied. In the present invention, the same effect is exerted as a Cu-WC alloy in which an auxiliary component is present at the interface between the Cu phase and W in the Cu-W alloy. The presence of the auxiliary component of C delays the heat transfer from the arc point to the periphery (the contact surface and the inside of the contact) (reduces the thermal conductivity only in a minute area, and As a result, the existence period (existence time) of the liquid phase is shortened, and the (T1-T2) value is adjusted to be small, so that the re-ignition characteristic and the cutoff characteristic are in a favorable state. . In the present invention, the effect of C as such an auxiliary component was confirmed.
[0089]
As a method for allowing an appropriate amount of C to exist in the Cu-W alloy, there is the following method.
[0090]
As a first method, in the mixing operation, first, a mixture of C and Cu is weighed so that the ratio of the amount of C to the amount of Cu becomes substantially equal in volume to obtain a mixed powder of C and Cu. Cu-W-C in which only C is added and mixed, and a C amount is 0.005% or less, and a trace amount of C corresponding to 0.01 to 0.15% is uniformly dispersed in Cu-W. Obtain contact material.
[0091]
As a second method, a polymer material diluted with an organic solvent is coated on a surface layer of Cu powder to obtain Cu powder in which C is deposited on the surface by thermal decomposition, and this Cu powder and a predetermined W powder are combined. Mix. At this time, the amount of C in Cu-W is adjusted while adjusting the amount of the organic solvent and the amount of the polymer material to be diluted. As a result, a Cu-WC contact material in which a predetermined amount range (0.005% or less, 0.01 to 0.15%) of C is uniformly dispersed in Cu-W is obtained.
[0092]
As a third method, a mixed powder obtained by previously mixing Cu powder and W powder is coated on a mixed powder surface layer with a polymer material diluted with an organic solvent according to the second method, and the surface of the mixed powder is thermally decomposed. To precipitate C. As a result, a Cu-WC contact material in which a predetermined amount range (0.005% or less, 0.01 to 0.15%) of C is uniformly dispersed in Cu-W is obtained.
[0093]
As a fourth method, the Cu powder obtained by the second method is used in performing the first method. As a result, a Cu-WC contact material in which a predetermined amount range (0.005% or less, 0.01 to 0.15%) of C is uniformly dispersed in Cu-W is obtained.
[0094]
As a fifth method, in performing the first method, a mixed powder obtained by previously mixing the Cu powder and the W powder obtained by the third method is used. Thereby, a Cu-WC contact material in which C in a predetermined amount range (0.005% or less, 0.01 to 0.15%) is uniformly dispersed in Cu-Cr is obtained.
[0095]
Note that C in the Cu-WC contact point has an extremely fine particle diameter and is extremely small in quantity. Therefore, in a mechanical mixing method, C is effective due to the lubricity of the C particles. A high quality contact material cannot be obtained due to the inability to perform proper mixing. Therefore, in the present invention, the amount of C in Cu-W is set to a predetermined amount range (0.005% or less, 0.01 to 0.15%) by appropriately selecting and combining the above first to fifth methods. The obtained test contact is obtained.
[0096]
<Reignition characteristics>
In the contact where the amount of C in the Cu-W alloy in the contact was 0.005%, 0.01%, 0.03%, and 0.08%, the restriking characteristics of Example 4 as the reference contact were In comparison, good properties that are equivalent or better, namely 0.1 to 0.8 times (evaluation B), 0.8 to 1.2 times (evaluation C), 1.2 to 1.5 times (evaluation B) D) (Examples 5 to 8).
[0097]
On the other hand, at the contact where the amount of C in the Cu-W alloy was 0.15%, C in the Cu-W was agglomerated, and the occurrence of re-ignition greatly varied depending on the evaluated contact. The frequency of occurrence of re-ignition as compared with the reference contact (Example 4) is 1.5 times or more to 10 times or 100 times or more (evaluation X to Z), which is a very undesirable re-ignition characteristic. (Comparative Example 3).
[0098]
On the other hand, at the contact where the amount of C in the Cu-W alloy is less than 0.005%, the restriking characteristic is further excellent. The production of a Cu-W alloy having an amount of C of less than 0.005% is performed by refining the raw material (promoting the thermal decomposition of impurities by increasing the heat treatment temperature), mixing and sintering heat treatment (prevention of dust contamination). It can be obtained by selecting the material of the heat treatment container (prevention of mixing of C), adjusting the heat treatment atmosphere and temperature, and increasing the number of heat treatments.
[0099]
<Blocking characteristics>
The evaluation of the breaking characteristics is shown by a magnification of the breaking current value measured for each contact point with the breaking current value of Example 4 being 1.0.
[0100]
In the contacts where the amount of C in the Cu-W alloy was 0.005%, 0.01%, 0.03%, and 0.08%, the same as compared with the breaking characteristics of Example 4 as the reference contact. Good blocking characteristics as described above, that is, 0.95 to 1.1 times (Example 5), 0.95 to 1.05 times (Example 6), 0.9 to 1.0 times (Example 7) , 0.9 to 0.95 times (Example 8).
[0101]
On the other hand, in the contact where the amount of C in the Cu-W alloy was 0.15%, a large variation was observed in the breaking characteristics depending on the evaluated contact due to the aggregation of C in Cu-W, and the reference contact ( The blocking characteristics as compared with Example 4) were 0.25 to 0.5 times, showing a significant decrease and variation (Comparative Example 3).
[0102]
Microscopic observation of the distribution state of C in the Cu-W alloy with respect to the contact after subjected to the cutoff test in Example 5 confirmed good dispersion. It is considered that the insulation effect was sufficiently exhibited with respect to the heat input due to the breaking current, and the time during which the liquid phase was present was shortened. As a result, it is considered that the breaking characteristics were improved. When the interruption current disappears, the cooling effect of the adjacent electrodes and conductive shafts having a much larger heat capacity takes precedence over the adiabatic effect of C in the Cu-W alloy, and the cooling effect is rapidly cooled. The length of (T1-T2) depends only on delaying the liquid phase generation time (melting start time T1).
[0103]
As described above, there is a clear correlation between the amount of C in the Cu-W alloy that affects the restriking characteristic and the cutoff characteristic, and it is preferable to set the amount to 0.08% or less. In order to improve the cut-off characteristics and restriking characteristics of the Cu-W alloy, the [(T1-T2) / T1] ratio is controlled, and the C content is set to 0.08% or less. It is preferable to use a WC alloy.
[0104]
That is, [(T1−T2) × 100 / T1] is set to 2.8% or less for a Cu—WC alloy in which the C content in the Cu—W alloy is set to 0.08% or less. The cutoff characteristics and restrike characteristics show preferable characteristics. When the amount of C in the Cu-W contact exceeds 0.08%, even if [(T1-T2) × 100 / T1] is 2.8% or less, C tends to exist in an aggregated state. As a result, the re-ignition frequency tends to vary with the result that the homogeneity of the material characteristics is impaired, and at the same time, the cut-off characteristics are also reduced, so that both characteristics cannot be achieved.
[0105]
As described above, when the C content in the Cu-W alloy is 0.08% or less, a low restriking occurrence frequency is exhibited, and the cutoff characteristics are also positively affected. In order to reduce the C content in the Cu-W contact to 0.08% or less, it is necessary to examine the raw materials more than necessary and to control the atmosphere particularly during the heat treatment.
[0106]
The particle diameter of C in the Cu-W contact (the diameter when converted to a sphere when the shape is not spherical) or the diameter of the aggregate is 5 μm or less (when converted to a sphere when the shape is not spherical). Is preferable. When the particle diameter of C is 5 μm or less, the variation in the frequency of occurrence of restriking is reduced, the balance of the heat flow due to the current at the time of breaking is improved, and the variation in the breaking characteristics is also reduced.
[0107]
(Examples 9 to 12)
In Examples 1 to 8 and Comparative Examples 1 to 3, the arc resistance component of the contact where the [(T1−T2) × 100 / T1] ratio of the Cu—W alloy was constant at 1.6 to 1.7% was used. Although an example in which W is selected as the above is shown, in the present technology, the effect is exhibited even when Mo is used as a part or all of W as the arc resistant component. That is, in a contact where the [(T1-T2) × 100 / T1] ratio of a 25% Cu—W alloy is constant at 1.6 to 1.7%, a part of W is replaced with Mo as an arc-resistant component. WMo (W: Mo = weight ratio 99.99: 0.01, W: Mo = weight ratio 90:10, W: Mo = weight ratio 50:50, W: Mo = weight ratio 0.01: 99.99 ) Was manufactured.
[0108]
<Reignition characteristics>
In comparison with the restriking characteristics of Example 4 which was used as a reference contact point, all showed extremely good characteristics of less than 0.1 times (evaluation A) to 0.1 to less than 0.8 (evaluation B) (implementation). Examples 9 to 12).
[0109]
<Blocking characteristics>
As compared with the shut-off characteristics of Example 4 which was used as the reference contact point, all of them exhibited good characteristics of 0.9 to 1.1 times and were within the acceptable range (Examples 9 to 12).
[0110]
The formation of WMo improves the thermal stability and mechanical properties of the W particles, and thus suppresses the W particles from falling off at the time of interruption, which contributes to the occurrence of restriking. Further, the presence of an appropriate amount of Mo suppresses the growth of W particles at the time of cutoff, and also has a beneficial effect on fine dispersion of W. According to the SEM observation of the contact surface after the interruption, the adhesion of the dropped W particles is reduced.
[0111]
That is, even if part or all of W in the Cu-W contact is replaced with Mo, when [(T1-T2) × 100 / (T1)] satisfies the condition of 2.8% or less, the same applies. In addition, stable re-ignition characteristics and breaking characteristics can be obtained.
[0112]
(Examples 13 to 15)
In Examples 1 to 8 and Comparative Examples 1 to 3, the arc resistance component of the contact where the [(T1−T2) × 100 / T1] ratio of the Cu—W alloy was constant at 1.6 to 1.7% was used. Although the example in which W is selected as above is shown, the effect of the present invention is exerted even if all of W is WC as an arc-resistant component, and part or all of WC is MoC.
[0113]
That is, in a contact where the [(T1-T2) × 100 / T1] ratio of a 25% Cu-WC alloy is constant at 1.6 to 1.7%, part of WC is replaced with MoC as an arc-resistant component. Then, a Cu-WCMoC contact with WCMoC (WC: MoC = weight ratio 99.99: 0.01, WC: MoC = weight ratio 50:50, WC: MoC = weight ratio 0.01: 99.99) is manufactured. (Examples 13 to 15)
<Reignition characteristics>
As compared with the restriking characteristics of Example 4 which was used as the reference contact point, all exhibited good characteristics of 0.1 to less than 0.8 (evaluation B) to 0.8 to less than 1.2 (evaluation C). (Examples 13 to 15).
[0114]
<Blocking characteristics>
As compared with the cutoff characteristics of Example 4 which was a reference contact, all of them exhibited good characteristics 0.9 to 1.05 times, and were within the acceptable range (Examples 13 to 15).
[0115]
That is, even if all of W in the Cu-W contact is replaced by WC, or even if part or all of WC is replaced by MoC, the above [(T1-T2) × 100 / T1] is 2.8% or less. When the condition is satisfied, the same stable re-ignition characteristics and cutoff characteristics can be obtained. (Note that MoC here means Mo carbide, and 2 C is included. )
(Examples 16 to 17)
In Examples 1 to 15 and Comparative Examples 1 to 3, the contact where the [(T1−T2) × 100 / T1] ratio of the Cu—W alloy was constant at 1.6 to 1.7% was used as the conductive component. Although an example in which Cu is selected has been described, in the present technology, Ag and AgCu are also effective as conductive components.
[0116]
That is, a contact was manufactured in which the ratio of [(T1−T2) × 100 / T1] of the 40% Ag—W alloy and the 40% AgCu (20Ag + 20Cu) —W alloy was constant at 1.6 to 1.7% (Example). 16-17).
[0117]
<Reignition characteristics>
As compared with the restriking characteristics of Example 4 which was used as the reference contact point, all of them showed almost the same characteristics of 0.8 to less than 1.2 (evaluation C) (Examples 16 to 17).
[0118]
<Blocking characteristics>
As compared with the cutoff characteristics of Example 4 which was a reference contact, all of them exhibited equivalent characteristics of 0.9 to 1.0 times, and were within the acceptable range (Examples 16 to 17).
[0119]
That is, even if part or all of Cu in the Cu-W contact is replaced with Ag, when [(T1−T2) × 100 / T1] satisfies the condition of 2.8% or less, the same stability is obtained. The re-ignition characteristic and the cutoff characteristic can be obtained. The same effect can be obtained even if part or all of Cu in the Cu-WC contact is replaced with Ag.
[0120]
(Examples 18 to 21, Comparative Example 4)
In Examples 1 to 17 and Comparative Examples 1 to 3, the conductive component composed of Cu or Ag and the arc-resistant component composed of W, Mo, or the like are formed and the [(T1−T2) × 100 / T1] ratio is set. The relationship between the restriking characteristic and the breaking characteristic was shown for the contact point which was constant at 1.6 to 1.7%. However, in the present invention, not only the configuration of the conductive component and the arc-resistant component but also Co, Fe , Ni, the same effect is exerted even when the auxiliary component (1) comprising one of Ni.
[0121]
That is, in a contact where the [(T1-T2) × 100 / T1] ratio of a 27% Cu—W alloy is constant at 1.6 to 1.7%, 0.2% to 5% as an auxiliary component (1). Cu-W-Co, Cu-W-Fe, and Cu-W-Ni contacts were manufactured with% Co, 0.2% Fe, and 0.2% Ni. In addition, components such as Co, Fe, and Ni, which are inevitably trace amounts of auxiliary components (1) caused by the raw materials, are also present in Examples 1 to 17 and Comparative Examples 1 to 3. Here, the addition in amounts exceeding these amounts is targeted.
[0122]
<Reignition characteristics>
In the case of Co of 0.2% to 1% as the auxiliary component (1), the characteristic O.D. Less than 1 to less than 0.1 to 0.8 (evaluation AB) was shown. Improvement and stabilization of the relative density of the material itself contributed (Examples 18 to 19).
[0123]
On the other hand, in the case of 5% Co as the auxiliary component (1), although the barrier properties are improved, segregation of Co is inevitable, but 0.1 to less than 0.8 (evaluation B). It shows a re-ignition characteristic of 5 or more to 10 times (evaluation X), a large variation is observed, and a balance between the re-ignition characteristic and the cutoff characteristic cannot be obtained, which is not preferable (Comparative Example 4).
Even when 0.2% of Fe or Ni is used as the auxiliary component (1), the same good characteristics as those of the fourth embodiment, which is a reference contact, are less than 0.1 to less than 0.8. (Evaluation B) to 0.8 to less than 1.2 (Evaluation C), indicating a pass (Examples 20 to 21).
[0124]
<Blocking characteristics>
In the case of Co of 0.2% to 1% as the auxiliary component (1), the characteristics were equal to or more than 1.05 to 1.15 times and improved compared to the breaking characteristics of Example 4 as the reference contact. (Examples 18 to 19). In addition, in the case of 5% Co as the auxiliary component (1), the cutoff characteristics were further improved and showed 1.1 to less than 1.25 times (Comparative Example 4). Large variations are seen.
[0125]
In addition, even when 0.2% of Fe and Ni were used as the auxiliary component (1), the characteristics were 0.95 to 1.1 times as good as those of the fourth embodiment, which was a reference contact point. (Examples 20 to 21).
[0126]
That is, when the auxiliary component (1) composed of at least one of Co, Ni, and Fe of 1% or less is contained, the density of the sintered body (contact alloy) after sintering can be widely adjusted, and sound sintering can be achieved. A more stable restriking characteristic and cutoff characteristic can be obtained. If the auxiliary component (1) is present in an amount exceeding 1%, the blocking characteristics will be reduced as the conductivity is reduced, and will be obtained when [(T1-T2) × 100 / T1] is set to 2.8% or less. Effect is not sufficiently exhibited.
[0127]
The same effect can be obtained even when the Cu-WC contact contains 1% or less of the auxiliary component (1) composed of at least one of Co, Ni, and Fe.
[0128]
(Examples 22 to 24, Comparative Example 5)
In Examples 1 to 17 and Comparative Examples 1 to 3, the conductive component composed of Cu or Ag and the arc-resistant component composed of W, Mo, or the like are formed and the [(T1−T2) × 100 / T1] ratio is set. The relationship between the restriking characteristic and the breaking characteristic is shown for the contact point that is constant at 1.6 to 1.7%. In the present invention, not only the configuration of the conductive component and the arc-resistant component but also Bi and Sb. The same effect is exhibited even when the auxiliary component (2) consisting of one of the above is present. That is, in the contact where the [(T1-T2) × 100 / T1] ratio of the 27% Cu—W alloy is constant at 1.6 to 1.7%, 0.1% to 5% as the auxiliary component (2). Cu-W-Bi and Cu-W-Sb contacts with 0.0% Bi and 0.1% Sb were manufactured.
[0129]
<Reignition characteristics>
In the case of Bi of 0.1% to 1% as the auxiliary component (2), compared to the restriking characteristic of Example 4 which was used as the reference contact, the characteristics were comparable (evaluation BC to evaluation CD). ) Is within the acceptable range (Examples 22 to 23).
[0130]
On the other hand, in the case of Bi of 5% as the auxiliary component (2), segregation of Bi is inevitable, and the restriking characteristic shows evaluation (Y) or evaluation (Z), and a drastic decrease is seen. Not preferred (Comparative Example 5).
[0131]
In addition, even in the case of 0.1% Sb as the auxiliary component (2), compared with the restriking characteristic of Example 4 which was used as the reference contact point, the characteristics were comparable (evaluation B to C) and the range was acceptable. (Example 24).
[0132]
<Blocking characteristics>
In the case of Bi of 0.1% to 1% as the auxiliary component (2), not only the welding resistance was improved, but also the breaking characteristics equivalent to 0.9 as compared with the breaking characteristics of Example 4 which was used as the reference contact. It shows a value of ~ 1.0 times, which is within the acceptable range (Examples 22 to 23).
[0133]
On the other hand, in the case of 5% Bi as the auxiliary component (2), the segregation of Bi is inevitable, and although the welding resistance is improved, the cutoff characteristic shows 0.4 to less than 0.55 times. A significant decrease is observed, which is not preferable (Comparative Example 5).
[0134]
In addition, even when the auxiliary component (2) is 0.1% of Sb, the equivalent cutoff characteristic is 0.9 to 0.95 times as large as that of the reference contact and the range of the pass. (Example 24).
[0135]
That is, when the auxiliary component (2) composed of at least one of Bi and Sb of 1% or less is contained, the welding resistance of the contact alloy is adjusted. Stable re-ignition characteristics and interruption characteristics are obtained. If the auxiliary component (2) is present in an amount exceeding 1%, the material itself becomes brittle, and on the other hand, the contact surface which is tripped after the interruption is roughened to impair the smoothness, and the re-ignition characteristic after the interruption is lowered, and , [(T1−T2) × 100 / T1] is not sufficiently exerted to obtain the effect of 2.8% or less.
[0136]
Note that the same effect can be obtained even if the Cu-WC contact contains 1% or less of the auxiliary component (2) composed of at least one of Bi and Sb.
[0137]
(Examples 25 to 27, Comparative Example 6)
In Examples 1 to 17 and Comparative Examples 1 to 3, the conductive component composed of Cu or Ag and the arc-resistant component composed of W, Mo, or the like are formed and the [(T1−T2) × 100 / T1] ratio is set. Although the relationship between the re-ignition characteristic and the cutoff characteristic was shown for the contact point that was constant at 1.6 to 1.7%, the present invention technology is not limited to the configuration of the conductive component and the arc-resistant component, but also Te, Se. The same effect is exerted even when the auxiliary component (3) consisting of one of the above is present. That is, in the contact where the [(T1-T2) × 100 / T1] ratio of the 27% Cu—W alloy is constant at 1.6 to 1.7%, 0.5% to 10% as the auxiliary component (3). Cu-W-Te and Cu-W-Se contacts were manufactured with the percentage of Te and 0.5% of Se.
[0138]
<Reignition characteristics>
In the case of 0.5% to 5% of Te as the auxiliary component (3), the characteristics (evaluation C to D) of the comparable degree or the allowable range are compared with the restriking characteristic of the fourth embodiment as the reference contact. (Evaluation D) is shown and is within the acceptable range (Examples 25 and 26).
[0139]
In contrast, in the case of 10% Te as the auxiliary component (3), Cu 2 The segregation of Te is inevitable, and the re-ignition characteristic shows (evaluation Z), which is not preferable because of a drastic decrease (Comparative Example 6).
[0140]
In addition, even when 0.5% of Se is used as the auxiliary component (3), compared with the restriking characteristic of the fourth embodiment as the reference contact point, it shows similar characteristics (evaluation C to D) and shows a pass range. (Example 27).
[0141]
<Blocking characteristics>
In the case of Te of 0.5% to 5% as the auxiliary component (3), not only the welding resistance was improved, but also the equivalent breaking characteristic of 0.9 as compared with the breaking characteristic of Example 4 which was a reference contact. １．０1.0 times, which is within the acceptable range (Examples 25 and 26).
[0142]
In contrast, in the case of 10% Te as the auxiliary component (3), Cu 2 Although segregation of Te is unavoidable and the welding resistance is improved, the barrier property is less than 0.4 to 0.55 times, which is not preferable because a significant decrease is observed (Comparative Example 6).
[0143]
In addition, even when 0.5% of Se is used as the auxiliary component (3), the equivalent breaking characteristic is 0.9 to 0.95 times as compared with the breaking characteristic of the fourth embodiment which is a reference contact, and the range is acceptable. (Example 27).
[0144]
In other words, when the auxiliary component (3) composed of at least one of Te and Se of 5% or less is contained, the welding resistance of the contact alloy is adjusted. Stable re-ignition characteristics and interruption characteristics are obtained. If the auxiliary component (3) is present in an amount exceeding 5%, the material itself becomes brittle, and on the other hand, the contact surface which is tripped after breaking is roughened, impairs smoothness, and causes a reduction in restriking characteristics after breaking. , [(T1−T2) × 100 / T1] is not sufficiently exerted to obtain the effect of 2.8% or less.
[0145]
The same effect can be obtained even when the auxiliary component (3) composed of at least one of Te and Se of 5% or less is contained in the Cu-WC contact.
[0146]
(Examples 28 to 31, Comparative Example 7)
In the first to 27th embodiments, after selecting a contact in a state where the ratio of [(T1−T2) × 100 / T1] is in the range of 1.6 to 1.7%, the cutoff characteristic and the re-ignition characteristic are selected. The effect on the was examined.
[0147]
As described above, one of the effective means for controlling T1 and T2 to be within a certain range is a component which affects the T1 and T2 values or a gaseous component by unidirectional melting of the raw material Cu in advance at a moving speed of about 1 cm / 60 minutes. In particular, the extra components in Cu should be made sufficiently small, the raw material W powder should be previously heat-treated in a vacuum at a temperature of at least 1350 ° C., and the cooling rate when passing through the vicinity of these solidification temperatures Control to sufficiently small, then sintering without contaminating these raw materials to obtain a contact, during the sintering heat treatment, select a container whose surface is coated with Cu that is at least as clean The [(T1-T2) × 100 / T1] ratio was adjusted to a range of 1.6 to 1.7% on the basis of use and the like.
[0148]
However, in implementing the technique of the present invention, T1 and T2 exert their effects without being limited to the range of 1.6 to 1.7. That is, by combining one or more of the above-described means, a contact in which T1 and T2 were adjusted widely was manufactured.
[0149]
<Reignition characteristics>
When the [(T1−T2) × 100 / T1] ratio of the Cu—W alloy was set to 0.01 to 0.1%, the re-ignition characteristics of the reference contact of Example 4 were extremely high. Good characteristics showed less than 0.1 times (evaluation A) to 0.1 to less than 0.8 times (evaluation B) (Example 28).
[0150]
A contact having a [(T1-T2) * 100 / T1] ratio of the Cu-W alloy of 0.9 to 1.1% was obtained. As compared with the restriking characteristic of Example 4 which was used as a reference contact point, good characteristic was 0.1 to less than 0.8 times (evaluation B) (Example 29).
[0151]
A contact having a [(T1-T2) × 100 / T1] ratio of the Cu—W alloy of 1.9 to 2.1% was obtained. Compared with the restriking characteristics of Example 4 as a reference contact, the values were 0.1 to less than 0.8 times (Evaluation B) to 0.8 to less than 1.2 times (Evaluation C) (Example). 30).
[0152]
A contact having a [(T1-T2) * 100 / T1] ratio of the Cu-W alloy of 2.7 to 2.8% was obtained. Compared with the restriking characteristics of Example 4 as a reference contact, the values were 0.8 to less than 1.2 times (evaluation C) to 1.2 to less than 1.5 times (evaluation D) (Example) 31).
[0153]
On the other hand, the contact where the [(T1-T2) × 100 / T1] ratio of the Cu—W alloy was 5.5 to 5.6% was compared with the restriking characteristic of Example 4 which was the reference contact. As a result, large variations and extremely unfavorable restriking characteristics were exhibited, such as 1.5 or more to less than 10 times (evaluation X) to 100 times or more (evaluation Z) (Comparative Example 7).
[0154]
<Blocking characteristics>
When the [(T1−T2) × 100 / T1] ratio of the Cu—W alloy was set to 0.01 to 0.1%, the cutoff characteristic was 1.15 in comparison with the breaking characteristic of the fourth embodiment in which the reference contact was used. A very good shutoff characteristic of １．２1.25 times was exhibited (Example 28).
[0155]
The contact of the Cu—W alloy having the ratio of [(T1−T2) × 100 / T1] of 0.9 to 1.1 was 1.0 to 1 in comparison with the breaking characteristic of the fourth embodiment as the reference contact. .1 times as good as the blocking characteristics (Example 29).
[0156]
A contact having a [(T1-T2) × 100 / T1] ratio of the Cu—W alloy of 1.9 to 2.1% was obtained. As compared with the shut-off characteristics of the fourth embodiment as a reference contact, the good characteristics were 0.95-1.1 times higher (Example 30).
[0157]
A contact having a [(T1-T2) * 100 / T1] ratio of the Cu-W alloy of 2.7 to 2.8% was obtained. As compared with the cutoff characteristics of Example 4 which was used as the reference contact, good characteristics were shown at 0.9 to 0.95 times (Example 31).
[0158]
On the other hand, the contact where the [(T1-T2) × 100 / T1] ratio of the Cu—W alloy was 5.5 to 5.6% was compared with the restriking characteristic of Example 4 which was the reference contact. As a result, the ratio was 0.5 to 0.6 times, indicating a significant decrease in the cutoff characteristics (Comparative Example 7).
[0159]
As described above, in the Cu-W alloy in which the ratio of [(T1−T2) × 100 / T1] is controlled to 2.8% or less, both the cutoff characteristics and the re-ignition characteristics can be obtained.
[0160]
In the case of Cu-WC, by controlling the ratio of [(T1−T2) × 100 / T1] to 2.8% or less, both of the cutoff characteristic and the restriking characteristic can be obtained.
[0161]
【The invention's effect】
According to the present invention, the time from the melting of a part of the contact surface due to the interruption to the disappearance of the contact surface (the time during which the liquid phase exists) is controlled to be short. Can be provided.
[Brief description of the drawings]
FIG. 1 is a table showing evaluation conditions of Examples 1 to 8 and Comparative Examples 1 to 3 of a vacuum circuit breaker according to the present invention.
FIG. 2 is a table showing evaluation conditions of Examples 9 to 21 and Comparative Example 4 of the vacuum circuit breaker according to the present invention.
FIG. 3 is a table showing evaluation conditions of Examples 22 to 31 and Comparative Examples 5 to 7 of the vacuum circuit breaker according to the present invention.
FIG. 4 is a table showing evaluation results of Examples 1 to 8 and Comparative Examples 1 to 3 of the vacuum circuit breaker according to the present invention.
FIG. 5 is a table showing evaluation results of Examples 9 to 21 and Comparative Example 4 of the vacuum circuit breaker according to the present invention.
FIG. 6 is a table showing evaluation results of Examples 22 to 31 and Comparative Examples 5 to 7 of the vacuum circuit breaker according to the present invention.
FIG. 7 is a diagram showing a configuration of a typical vacuum valve.
FIG. 8 is a diagram showing another configuration of a typical vacuum valve.
[Explanation of symbols]
40 ... electrode (back side of contact 41)
41 ... fixed contact
50 ... electrode (back side of contact 51)
51: movable contact
101 ... insulating container
102a: Fixed side lid
102b: movable side lid
103… Vacuum container
104 fixed contacts
105: movable contact
106: Fixed energized shaft
107: movable energized shaft
108 ... bellows
109 ... Arc shield
M: moving direction of energized shaft 107

Claims (10)

１０〜５０重量％のＣｕから成る導電性成分相と、５０〜９０重量％のＷから成る耐弧成分とを含む接点材料であり、昇温過程での前記接点材料中の前記Ｃｕから成る導電性成分相の摂氏で測定した溶融開始温度Ｔ１と、少なくとも１２００℃に加熱した後の冷却過程での、前記Ｃｕから成る導電性成分相の摂氏で測定した凝固開始温度Ｔ２との差（Ｔ１−Ｔ２）値と、前記溶融開始温度Ｔ１との比率、すなわち、［（Ｔ１−Ｔ２）×１００／（Ｔ１）］が、２．８％以下である接点材料から成る接点を備えたことを特徴とする真空遮断器。A contact material comprising a conductive component phase composed of 10 to 50% by weight of Cu and an arc-resistant component composed of 50 to 90% by weight of W, wherein the conductive material composed of Cu in the contact material in a temperature rising process Difference between the melting start temperature T1 measured in degrees Celsius of the conductive component phase and the solidification start temperature T2 measured in degrees Celsius of the conductive component phase composed of Cu in a cooling process after heating to at least 1200 ° C. T2) and a contact made of a contact material having a ratio of the melting start temperature T1, that is, [(T1−T2) × 100 / (T1)] is 2.8% or less. Vacuum circuit breaker. 前記Ｃｕから成る導電性成分相の一部または総てがＡｇであることを特徴とする請求項１に記載の真空遮断器。The vacuum circuit breaker according to claim 1, wherein a part or all of the conductive component phase made of Cu is Ag. 前記Ｗから成る耐弧成分の一部または総てがＭｏであることを特徴とする請求項１または請求項２に記載の真空遮断器。3. The vacuum circuit breaker according to claim 1, wherein a part or all of the arc-resistant component made of W is Mo. 4. １０〜５０重量％のＣｕから成る導電性成分相と、５０〜９０重量％のＷＣから成る耐弧成分とを含む接点材料であり、昇温過程での前記接点材料中の前記Ｃｕから成る導電性成分相の摂氏で測定した溶融開始温度Ｔ１と、少なくとも１２００℃に加熱した後の冷却過程での、前記Ｃｕから成る導電性成分相の摂氏で測定した凝固開始温度Ｔ２との差（Ｔ１−Ｔ２）値と、前記溶融開始温度Ｔ１との比率、すなわち、［（Ｔ１−Ｔ２）×１００／（Ｔ１）］が、２．８％以下である接点材料から成る接点を備えたことを特徴とする真空遮断器。A contact material comprising a conductive component phase composed of 10 to 50% by weight of Cu and an arc-resistant component composed of 50 to 90% by weight of WC, and a conductive material composed of the Cu in the contact material in a temperature rising process. Difference between the melting start temperature T1 measured in degrees Celsius of the conductive component phase and the solidification start temperature T2 measured in degrees Celsius of the conductive component phase composed of Cu in a cooling process after heating to at least 1200 ° C. T2) and a contact made of a contact material having a ratio of the melting start temperature T1, that is, [(T1−T2) × 100 / (T1)] is 2.8% or less. Vacuum circuit breaker. 前記Ｃｕから成る導電性成分相の一部または総てがＡｇであることを特徴とする請求項４に記載の真空遮断器。The vacuum circuit breaker according to claim 4, wherein a part or all of the conductive component phase made of Cu is Ag. 前記ＷＣから成る耐弧成分の一部または総てがＭｏＣであることを特徴とする請求項４または請求項５に記載の真空遮断器。The vacuum circuit breaker according to claim 4 or 5, wherein a part or all of the arc resistant component made of WC is MoC. １％以下のＣｏ、Ｎｉ、Ｆｅの少なくとも１つから成る第１の補助成分を含むことを特徴とする請求項１乃至請求項６のいずれかに記載の真空遮断器。The vacuum circuit breaker according to any one of claims 1 to 6, further comprising 1% or less of a first auxiliary component comprising at least one of Co, Ni, and Fe. １％以下のＢｉ、Ｓｂの少なくとも１つから成る第２の補助成分を含むことを特徴とする請求項１乃至請求項７のいずれかに記載の真空遮断器。The vacuum circuit breaker according to any one of claims 1 to 7, further comprising a second auxiliary component consisting of at least one of Bi and Sb of 1% or less. ５％以下のＴｅ、Ｓｅの少なくとも１つから成る第３の補助成分を含むことを特徴とする請求項１乃至請求項７のいずれかに記載の真空遮断器。The vacuum circuit breaker according to any one of claims 1 to 7, further comprising a third auxiliary component comprising at least one of Te and Se of 5% or less. ０．０８％以下のＣを含むことを特徴とする請求項１乃至請求項９のいずれかに記載の真空遮断器。The vacuum circuit breaker according to any one of claims 1 to 9, further comprising 0.08% or less of C.
JP2002230924A 2002-08-08 2002-08-08 Contact materials for vacuum circuit breakers Expired - Lifetime JP4515696B2 (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013101786A (en) * 2011-11-07 2013-05-23 Toshiba Corp Contact material for vacuum valve
CN106148794A (en) * 2016-08-19 2016-11-23 北京尚华扬电子技术开发有限公司 A kind of copper-tungsten of dopen Nano iron powder and preparation method thereof
RU2769344C1 (en) * 2021-08-04 2022-03-30 Федеральное государственное бюджетное учреждение науки Институт металлургии Уральского отделения Российской академии наук (ИМЕТ УрО РАН) Material for arc-quenching and breaking electrical contacts based on copper and method of its production
US11462367B2 (en) 2017-02-22 2022-10-04 Mitsubishi Electric Corporation Contact material, method of manufacturing same, and vacuum valve

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013101786A (en) * 2011-11-07 2013-05-23 Toshiba Corp Contact material for vacuum valve
CN106148794A (en) * 2016-08-19 2016-11-23 北京尚华扬电子技术开发有限公司 A kind of copper-tungsten of dopen Nano iron powder and preparation method thereof
US11462367B2 (en) 2017-02-22 2022-10-04 Mitsubishi Electric Corporation Contact material, method of manufacturing same, and vacuum valve
RU2769344C1 (en) * 2021-08-04 2022-03-30 Федеральное государственное бюджетное учреждение науки Институт металлургии Уральского отделения Российской академии наук (ИМЕТ УрО РАН) Material for arc-quenching and breaking electrical contacts based on copper and method of its production

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