JP3607553B2

JP3607553B2 - Metal-ceramic bonded body and manufacturing method thereof

Info

Publication number: JP3607553B2
Application number: JP2000035747A
Authority: JP
Inventors: 庸晃高嶋
Original assignee: NGK Spark Plug Co Ltd
Current assignee: NGK Spark Plug Co Ltd
Priority date: 2000-02-14
Filing date: 2000-02-14
Publication date: 2005-01-05
Anticipated expiration: 2020-02-14
Also published as: JP2001220253A

Description

【０００１】
【発明の属する技術分野】
本発明は、金属−セラミック接合体と、その製造方法とに関する。
【０００２】
【従来の技術】
セラミック部材は優れた耐熱性、耐衝撃性及び絶縁性を有するため、その特性を生かして種々の分野に利用されつつある。例えば、セラミックチューブを使用した真空スイッチ外管等においては、筒状のセラミック部材の開口端部を、蓋体を備えた筒状の金属部材で溶接封着した構成にて用いられている。このようなセラミック部材と金属部材との接合に際しては従来より、両部材の突き合わせ端部同士をろう付け接合する方法が用いられている。金属部材としては、耐食性と高温強度とを確保するために、Ｎｉを含有した鉄合金が使用されることが多い。
【０００３】
【発明が解決しようとする課題】
しかしながら従来の金属部材とセラミック部材とのろう付け接合においては、例えばろう材中に含まれるＴｉ等の活性金属が、金属部材中のＮｉ金属等と反応して金属間化合物を形成することがある。この場合、その金属間化合物が形成された箇所において接合強度が低下したり、セラミック部材と反応する活性金属が不足して、セラミック部材とろう材との界面付近の接合状態が不安定になる問題が生じている。
【０００４】
本発明の課題は、接合状態が安定し、かつ接合強度の高い金属−セラミック接合体と、その製造方法を提供することにある。
【０００５】
【課題を解決するための手段及び作用・効果】
上記課題を解決するための本発明の金属−セラミック接合体は、Ｎｉを含有する金属部材とセラミック部材とが１つのろう材層を介して接合されるとともに、そのろう材層と前記セラミック部材との双方に接して、Ｔｉ，Ｚｒ，Ｈｆから選択される１種又は２種以上の活性金属成分を含む反応層が形成されてなり、他方、前記ろう材層と金属部材との間における、前記活性金属成分とＮｉとを含有した金属間化合物の形成量が、接合部の断面に対し、微小Ｘ線回折等により結晶構造解析を行ったとき、回折ピークが確認されない程度に小さくしたことを特徴とする。
【０００６】
また、本発明の金属−セラミック接合体の製造方法は、Ｎｉを含有する金属部材とセラミック部材とをろう材層を介して接合した金属−セラミック接合体の製造方法であって、Ｔｉ，Ｚｒ，Ｈｆから選択される１種又は２種以上の活性金属成分を含む一次ろう材を用いて、セラミック部材の接合面にメタライズ処理する一次ろう付けを行い、その後に、一次ろう材よりも低融点で、かつ活性金属成分の含有量が小さい二次ろう材により、セラミック部材のメタライズ処理された端面部に金属部材を二次ろう付けすることを特徴とする。
【０００７】
すなわち、上記課題に鑑みて本発明者らが鋭意検討した結果、上記製法に記した通り、セラミック部材と金属部材とを接合するろう材を、活性金属成分を含む一次ろう材と、一次ろう材よりも低融点で、かつ活性金属成分の含有量が小さい（望ましくは含有されていない）二次ろう材とに分け、それぞれ個々にろう付けする二段階のステップろう付けを行ったところ、上記のように、ろう材層と金属部材との間に形成される前記活性金属成分とＮｉとを含有した金属間化合物の量を可及的に小さくした金属−セラミック接合体を製造することが可能となった。
【０００８】
すなわち、一次ろう付けにおいては、活性金属を含有する一次ろう材によりセラミック部材側の接合面にメタライズ処理することで、セラミック部材の接合面には、活性金属とセラミック成分との反応層が形成される。反応層は、セラミックとろう材層中の活性金属以外のろう材金属成分とのいずれに対しても親和性に優れ、ろう材層とセラミック部材との間に強固な接合構造を形成するための中心的な役割を果たす。そして、二次ろう付け時においては、一次ろう材よりも低融点であり、かつ活性金属成分の含有量が低い（望ましくは含有しない）二次ろう材により、一次ろう付け時よりも低温でろう付けを行うため、該反応層からの活性金属成分のろう材層側への拡散が抑制され、ろう材層を介して接合される金属部材中のＮｉ成分と、反応層（すなわち一次ろう材）からの活性金属成分との反応が極めて生じにくくなる。その結果、活性金属成分とＮｉとを含有した金属間化合物が殆ど形成されなくなり、ひいては、接合界面において接合状態が安定し、接合強度の高い金属−セラミック接合体が得られるようになる。
【０００９】
上記製造方法において、一次ろう付け温度Ｔ１は、使用するろう材の種別にもよるが、８４０〜８８０℃とするのがよい。同様に、二次ろう付け温度Ｔ２は、８００〜８２０℃とするのがよい。そして、それらの差ΔＴ≡Ｔ１−Ｔ２は、２０〜８０℃を満足しているのがよい。すなわち、二次ろう付け温度Ｔ２を、一次ろう付け温度Ｔ１よりも上記ΔＴ程度低く設定することによって、一次ろう付けにより形成される反応層中の活性金属成分が、二次ろう付け時にろう材層を経て金属部材中に含まれるＮｉ成分と反応することを効果的に抑制でき、ひいては、ろう材層と金属部材との間に活性金属−Ｎｉ系金属間化合物が形成されにくくなる。Ｔ１及びＴ２が上記の範囲に設定されるとき、ΔＴが２０℃未満であると、上記の効果が不十分となる。他方、８０℃を超えると、二次ろう付け温度が低くなりすぎて、ろう材層の形成が不完全となり、却って接合強度を低下させることにもつながる。ΔＴは、望ましくは３０〜７０℃、さらに望ましくは４０〜６０℃程度とするのがよい。
【００１０】
一次ろう材には、具体的にＴｉ、Ｚｒ、Ｈｆから選択される１種又は２種以上の活性金属元素から構成される単体及び／又は化合物が１〜２０重量％含有されているものとすることができる。活性金属成分としては、多くのセラミックに対して優れた接合性能を発揮でき、かつ価格的にも比較的安価なことから、Ｔｉを特に好適に使用できる。この場合、上記のＴｉ成分の反応活性を高めるため、一次ろう材中のＴｉ成分は水素化チタン（一般組成式はＴｉＨ_２であるが、化学量論化合物に限られるものではない）の形で含有されていることが望ましい。また、ＴｉＨ_２として一次ろう材中に含有させることで、Ｔｉの酸化あるいは窒化等も効果的に防止することができる。一次ろう材中の上記活性金属成分の含有量が１重量％未満の場合は、反応層の形成が不十分となり、接合不良が起こりやすくなる場合がある。一方、活性金属成分の含有量が２０重量％を超えると、二次ろう付け時に一次ろう材と二次ろう材との間の濡れ不良が起こることがあり、また、反応層が過度に厚くなりすぎて接合強度が却って低下したり、接合部の気密性が低下したりする場合がある。なお、一次ろう材中の活性金属成分の含有量は、好ましくは５〜１０重量％とするのがよい。
【００１１】
また、上記製造方法において、一次ろう付けは真空中で行うのがよく、その真空度は１．０×１０^−３Ｔｏｒｒ以下とするのがよい。一次ろう付けを１．０×１０^−３Ｔｏｒｒを超える条件下で行うと、一次ろう材の濡れ不良が生じたり、上記活性金属成分が酸化あるいは窒化されて、安定な反応層が形成されにくくなる場合がある。なお、一次ろう付けの雰囲気は真空雰囲気に限られるものではなく、例えばＡｒガス雰囲気等の不活性ガス雰囲気中で一次ろう付けを行っても、安定な反応層を形成することが可能である。
【００１２】
例えば、一次ろう付けによるメタライズ処理では、一次ろう材中の活性金属成分がセラミック部材と反応して反応層を形成する一方、残余の金属成分は、この反応層を密着形態で覆う一次メタライズ層を形成する場合がある。例えば、一次ろう材としては、活性金属以外の成分（以下、ベース成分という）、換言すれば一次メタライズ層を構成すべき成分を、Ａｇ，Ｃｕ，Ａｕ，Ｓｎ等としたものが使用できるが、二次ろう付けに使用する二次ろう材は、上記ベース成分に基づく一次メタライズ層との濡れ性あるいは親和性に優れたもの、例えば一次メタライズ層と類似組成のろう材を使用することが望ましいといえる。このような二次ろう材として、具体的には、Ａｇ−Ｃｕ系合金を用いることができる。Ａｇ−Ｃｕ系合金は、Ｔｉ等の活性金属成分と反応して金属間化合物を形成することも少なく、融点が低く、金属部材との接合性も良いため、本発明の二次ろう材として適している。なお、Ａｇ−Ｃｕ系合金におけるＡｇとＣｕとの含有比率は、Ａｇ１００重量部に対してＣｕ３０〜５０重量部とするのがよい。Ｃｕが３０重量部未満では、ろう材の融点が高くなりすぎ、例えば反応層からの活性金属成分の拡散により前記した金属間化合物等の形成により接合強度が低下する場合がある。他方、５０重量部を超えた場合も、ろう材の高融点化による同様の問題のほか、ろう材層の耐酸化性が損なわれて、高温接合強度等が損なわれる場合がある。なお、上記のようなＡｇ−Ｃｕ系合金としては、例えばＪＩＳ−Ｚ３２６１に記載された銀ろう：ＢＡｇ−８等を用いることができる。
【００１３】
金属−セラミック接合体においては、金属部材とセラミック部材との接合方向において、反応層の厚さが、５０μｍ〜３００μｍとされているのがよい。反応層厚さが、５０μｍ未満の場合、反応層の不足により接合性が低下する場合があり、３００μｍを超えると、反応層が厚くなりすぎて接合強度が却って低下する場合がある。なお、上記反応層の厚さの範囲は望ましくは１５０μｍ〜２００μｍとすることで、金属−セラミック接合体の接合状態が一層安定し、接合強度もさらに向上する。
【００１４】
また、上記金属−セラミック接合体において、ろう材層の、反応層側の端面と金属部材の接合端面との間の厚さ（以下、ろう材接合厚さという）は、３０μｍ〜１００μｍとされているのがよい。該厚さが、３０μｍ未満の場合、活性金属成分と金属部材との間に金属間化合物が形成されやすくなり接合強度の低下を招く場合がある。また、１００μｍを超えると、ろう材層が厚くなりすぎて、接合強度が却って低下する場合がある。なお、上記範囲は望ましくは５０μｍ〜８０μｍとするのがよく、この場合、金属−セラミック接合体の接合状態が一層安定し、接合強度もさらに向上する。
【００１５】
次に、セラミック部材は、アルミナを主成分とするアルミナ系セラミックが、高温強度及び高温耐食性あるいは耐薬品性に優れ、かつ、比較的安価であることから本発明に好適に使用することができる。他方、金属部材は、線膨張係数が比較的小さく、セラミック部材との間の熱応力が比較的生じにくいこと、さらには、真空スイッチ等へ適用する場合は、耐熱性や耐食性の確保できること等が、材料選定上のポイントとなる。具体的には、Ｆｅを主成分とし、最も含有率の高い副成分がＮｉ及びＣｏの一方であり、２番目に含有率の高い副成分がＮｉ及びＣｏの他方であるＦｅ−Ｎｉ−Ｃｏ系合金、Ｆｅを主成分とし、最も含有率の高い副成分がＮｉであるＦｅ−Ｎｉ系合金等を使用できる。なお、Ｆｅ−Ｎｉ−Ｃｏ系合金としては、例えば、Ｆｅ：５４％，Ｎｉ：２９％，Ｃｏ：１７％を含有するもの（商品名：コバール）等、また、Ｆｅ−Ｎｉ系合金としては、例えば、Ｆｅ：５８％，Ｎｉ：４２％を含有するもの（通称：４２アロイ）等を用いることができる。なお、本明細書において、「主成分とする」、「主に」あるいは「主体とする」等は、特に断りのない限り、着目している物質中にて重量含有率の最も高い成分をいう。
【００１６】
次に、セラミック部材の接合面の平面度は０．１ｍｍ以下にするのがよい。平面度が０．１ｍｍを超えると、反応層の形成が不完全となったり、二次ろう付け時のろう付け不良の原因ともなり、結果として製造される接合体の接合強度の低下を招く場合がある。
【００１７】
次に、上記金属−セラミック接合体の具体的態様としては、例えば金属部材とセラミック部材との突き合わせ部を高強度に接合できる態様として、ろう材層を、セラミック部材と金属部材との突き合わせ部に形成されるフィレット（以下、ろう材フィレットともいう）とする態様を例示できる。例えば、各々筒状に構成された金属部材とセラミック部材とを接合する構造として、各々、少なくとも片側の端面が開放する金属筒状体及びセラミック筒状体とし、該金属筒状体とセラミック筒状体とを開放端面側にて同軸状に突き合わせ、その突き合わせ部を環状のろう材層（ろう材フィレット）を介して接合したものとすることができる。なお、この場合、金属筒状体及びセラミック筒状体をいずれも円筒状に形成し、半径方向において金属筒状体側の接合端面をセラミック筒状体側の接合端面の略中央に位置決めすることができる。このように筒状部材同士をろう付け接合する場合、本発明の接合体の導入により、接合層（反応層とろう材層から構成される）に接合ムラがなく良好な接合状態で、接合強度及び接合部の気密性の高いものを提供することが可能である。
【００１８】
具体的にそれらセラミック筒状体と金属筒状体を一層高強度に接合するための構造として、下記のものを例示できる。すなわち、突き合わせ部において、金属筒状体とセラミック筒状体との接合端面はそれぞれ平面状に形成されるとともに、それら金属筒状体とセラミック筒状体との軸線を含む任意の断面において、金属筒状体の接合端面（以下、金属側接合端面という）の幅がセラミック筒状体の接合端面（以下、セラミック側接合端面という）の幅よりも小さくされ、前記断面においてフィレットは、金属筒状体の端部を埋没させる形でその厚さ方向両側を覆うとともに、金属筒状体の端部内面側及び外面側の双方においてその断面外形が、該金属筒状体側からセラミック筒状体側に向けて裾拡がりとなる形状を呈するものとする。そして、本発明の接合体構造の適用により、筒状部材同士の突き合わせ接合において、接合ムラが少なく、接合強度と気密性に優れた接合構造が得られるようになる。例えば、上記のような構造の金属−セラミック接合体は、真空スイッチへの応用が特に有効である。この場合、その筒状のセラミック部材を真空スイッチ用の外管として用いることができ、金属部材は、その真空スイッチ外管を覆う金属製蓋部として使用することができる。この場合、本発明の適用により、高い気密性を有し、かつ接合強度の高い真空スイッチ外管を提供することが可能となる。
【００１９】
【発明の実施の形態】
以下、本発明の実施の形態を、図面に示す実施例を参照して説明する。
図１は本発明の一実施例たる金属−セラミック接合体１の接合部を、拡大して示す断面図である。金属部材３とセラミック部材２とが、それらの突き合わせ部において、セラミック部材２と接する反応層４と、金属部材３と接するろう材フィレット（ろう材層）５とを介して接合されている。各部材２，３の接合端面、すなわちセラミック側接合端面６、金属側接合端面７はそれぞれ平面状に形成され、特にセラミック側接合端面６の平面度は０．１ｍｍ以下とされている。また、金属側接合端面７はセラミック側接合端面６よりも小さくされている。一方、ろう材フィレット５は、金属部材３の接合側端部を埋没させる形態で該端部の全周縁を覆うとともに、金属部材３の両側においてその断面外形が金属部材３側からセラミック部材２側に向けて裾拡がりとなる形状を呈している。なお、本実施例においては、金属部材３の接合端面の幅が、セラミック部材の接合端面の幅よりも小さくされている。
【００２０】
セラミック部材２は、例えばアルミナを主成分とするアルミナ系セラミックにて構成され、金属部材３は、例えばＦｅ：５４％，Ｎｉ：２９％，Ｃｏ：１７％を含有するＦｅ−Ｎｉ−Ｃｏ系合金にて構成されている。反応層４は、活性金属成分としてＴｉを含有し、ろう材フィレット５はＡｇ−Ｃｕ系合金を主体に構成される。
【００２１】
金属−セラミック接合体１において、反応層４の厚さｔ１は、例えば、５０μｍ〜３００μｍ（本実施例では、１５０μｍ）とされ、また、ろう材フィレット５において、反応層４側の端面８と金属部材３の接合端面７との間の厚さ、すなわちろう材接合層５ａの厚さｔ２は、例えば、３０μｍ〜１００μｍ（本実施例では、８０μｍ）とされている。
【００２２】
反応層４の厚さｔ１とろう材接合層５ａの厚さｔ２とは、例えば電子プローブ・マイクロ・アナライザ（ＥＰＭＡ）、エネルギー分散型Ｘ線分光（ＥＤＳ）、波長分散型Ｘ線分光（ＷＤＳ）等の公知の方法により測定することができる。本発明では、以下のように定義する。図５に示すように、セラミック部材の最も含有率の高いカチオン成分（例えば、Ｘ線光電子分光（ＸＰＳ）等により分析したときに正の価数を示す元素成分であり、アルミナであればＡｌ、窒化珪素であればＳｉである）をＱとし、金属部材の最も含有率の高い金属成分をＭとする一方、活性金属成分をＡとする。そして、接合部の断面を走査電子顕微鏡（ＳＥＭ）により観察し、さらに各部の接合方向において、上記カチオン成分Ｑと、金属成分Ｍと、活性金属成分Ａとについて該ＳＥＭ付属のＥＰＭＡにより線分析を行なったとする。この場合、成分Ｑ、成分Ｍ及び成分Ａの各含有量は、それぞれ対応する特性Ｘ線の検出強度に比例すると考えられる。このとき、成分Ｑに基づく特性Ｘ線強度の最大値がＩＱｍａｘ（金属部材側の最低値をバックグラウンドとして、そのバックグラウンドからの高さにて測定する）であり、成分Ｍに基づく特性Ｘ線強度の最大値がＩＭｍａｘ（セラミック部材側の最低値をバックグラウンドとして、そのバックグラウンドからの高さにて測定する）であり、成分Ａに基づく特性Ｘ線強度の最大値がＩＡｍａｘ（セラミック部材側ないし金属部材側の最低値をバックグラウンドとして、そのバックグラウンドからの高さにて測定する）であったとすれば、０．８ＩＱｍａｘとなる位置をセラミック部材と反応層との境界ＢＣ−Ｒとして、０．８ＩＡｍａｘとなる位置を反応層とろう材層との境界ＢＲ−Ｗとして、また、０．８ＩＭｍａｘとなる位置をろう材層と金属部材との境界ＢＷ−Ｍとして定める。そして、反応層４の厚さｔ１は境界ＢＣ−ＲとＢＲ−Ｗとの間の距離として、また、ろう材接合層５ａの厚さｔ２は境界ＢＲ−ＷとＢＷ−Ｍとの間の距離として、それぞれ定める。
【００２３】
また、ろう材フィレット５と金属部材３との間には、活性金属成分とＮｉとを含有する金属間化合物、例えばＴｉ−Ｎｉ系化合物がほとんど形成されていない。これは、換言すれば、金属部材中のＮｉ成分と、反応層を作るＴｉ成分との間の反応がほとんど生じていないことを意味する。このことを具体的に確認するための手段としては、例えば接合部の断面に対し、微小Ｘ線回折等により結晶構造解析を行い、例えばＴｉ_２Ｎｉ、ＴｉＮｉあるいはＮｉ_３Ｔｉ等のＴｉ−Ｎｉ系化合物の回折ピークが確認されなければ、Ｔｉ−Ｎｉ系化合物が形成されていないものと考えることができる。また、図５において、活性金属成分Ａの線分析を行なったときに、ろう材層と金属部材との界面において観察される活性金属成分Ａの特性Ｘ線強度のピーク値Ｉ’Ａｍａｘの、反応層におけるピーク値ＩＡｍａｘに対する比Ｉ’Ａｍａｘ／ＩＡｍａｘは、０．０１以下（望ましくは測定ばらつきの範囲内にて略ゼロ）となっていることが望ましい。
【００２４】
以下、上記金属−セラミック接合体１の製造方法について説明する。まず、図４（ａ）に示すように、活性金属成分としてＴｉを含む一次ろう材１０４のペーストを、セラミック部材２の端面部（接合面）に配置し、雰囲気加熱炉内にて所定の雰囲気及び温度で加熱することによりメタライズ処理して、図４（ｂ）に示すような反応層４を形成する。なお、活性金属成分以外のろう材成分が、反応層４を密着形態で覆う一次メタライズ層５ｂを形成する場合がある。一次ろう付けの条件は、ろう付け温度Ｔ１が８４０〜８８０℃（本実施例では８６０℃）で、真空度が１．０×１０^−３Ｔｏｒｒ以下（本実施例では、例えば１．０×１０^−４Ｔｏｒｒ）の真空中にて行うことができる。一次ろう材の組成は、例えば活性金属以外の部分をＡｇ，Ｃｕとすることができ、活性金属成分として、例えばＴｉを、ＴｉＨ_２の形で１〜２０重量％（本実施例では５重量％）含有させたものを使用できる。
【００２５】
次に、図４（ｃ）に示すように、上記一次ろう材よりも低融点で、かつ活性金属成分の含有量が小さい、具体的には不可避不純物を除いて活性金属成分を実質的に含有しない二次ろう材の箔１０５を、反応層４（あるいは一次メタライズ層５ｂ）上に重ね、さらに金属部材３の端面（接合面）を突き合わせて、雰囲気加熱炉内にて所定の雰囲気及び温度で加熱することにより、二次ろう付けする。これにより、二次ろう材箔１０５が溶融して、図４（ｄ）に示すろう材フィレット５を形成する。なお、一次メタライズ層５ｂが形成される場合は、その一部又は全部が二次ろう材箔１０５と溶融一体化して、ろう材フィレット５に取り込まれる場合がある。二次ろう付けの条件は、ろう付け温度Ｔ２が８００〜８２０℃（本実施例では８００℃）とされ、上記一次ろう付け温度Ｔ１との差ΔＴ≡Ｔ１−Ｔ２が、２０〜８０℃（本実施例では６０℃）に設定される。なお、二次ろう材としては、ＪＩＳ−Ｚ３２６１に記載された銀ろうＢＡｇ−８（Ａｇ：Ｃｕ＝１８：７）が用いられている。
【００２６】
一方、図２は、上記金属−セラミック接合体１が用いられた真空スイッチ外管の一部分を模式的に断面図にて示している。真空スイッチ外管１０には、セラミックチューブを形成する円筒状のセラミック部材（セラミック筒状体）１２と、蓋部材１４を備えた金属部材（金属筒状体）１３とが気密接合された形態を有している。これらセラミック筒状体１２と金属筒状体１３はそれぞれ開放端面を有する円筒状体であって、該開放端面側にて同軸状に突き合わされており、その突き合わせ部を環状の接合層（反応層４とろう材フィレット５よりなる）１５を介して接合され、本発明に係る金属−セラミック接合体を形成している。なお、突き合わせ部において、金属筒状体１３側の接合端面はセラミック筒状体１２側の接合端面の半径方向略中央に位置決めされている。
【００２７】
このようなセラミック筒状体１２の接合面に一次ろう付けを行う際には、図４（ｅ）に示すように、端面形状に対応した環状の一次ろう材箔１０４を用いることができる。また、二次ろう付けを行う場合は、図４（ｆ）に示すように、セラミック筒状体１２と金属筒状体１３との端面間に、環状の二次ろう材箔１０５を挟み込むようにする。
【００２８】
上記のような真空スイッチにおいては、本発明の金属−セラミック接合体の構造により、セラミック筒状体１２と金属筒状体１３とが接合層１５により密封されて高い気密性が達成され、かつ、ろう付けを上記のように２段階に行うことで、接合層１５（ろう材フィレット５）と金属筒状体１３との間にＴｉ−Ｎｉ系金属間化合物がほとんど形成されないので、接合強度にも優れたものとなる。なお、金属部材１３の蓋部材１４側においては、外向きに膨出する鍔状部１３ａが形成されており、蓋部材１４との間の気密性ならびに接合強度を保っている。
【００２９】
図３は、真空スイッチのさらに具体的な構成例を示している。この真空バルブ５０は、絶縁容器５５（セラミック部材）の両端開口部に蓋付きの金属製エンドプレート５７，５７（金属部材）を気密封着して容器状に構成されている。この真空容器内には、接点６０，６１が、接点６１を固定とし、接点６０を可動として接離自在に設けられ、固定接点６１の固定電極棒５２がエンドプレート５７に気密に取付けられ、可動接点６０の可動電極棒５６がベローズ５８を介してエンドプレート５７に可動自在にかつ気密に取付けられている。また、固定接点６１、可動接点６０の周りはアークシールド５４で囲まれ、さらにベローズ５８のベローズカバー５９は可動電極棒５６に取付けられている。
【００３０】
このような真空バルブ５０は、図示しない操作機構により、可動電極棒５６が引き外し方向に操作され、接点６０，６１が離間する。これら接点６０，６１が離間しても、その距離が小さい間は両接点間にアークが発生し、電流は流れ続けるが、一定以上に距離が大きくなると発生するアークは電流ゼロ点を迎えて真空中に拡散され、接点間の電流が遮断される。ここで、上記エンドプレート（金属部材）５７と絶縁容器（セラミック部材）５５とを、本発明の金属−セラミック接合体としてろう付け接合することができる。これにより、その接合部において高い気密性、接合強度を有し、真空バルブとして優れた性能を発揮することが可能となる。
【００３１】
（実施例１）
本発明の効果を確かめるために、以下の実験を行った。まず、図２に示すセラミック筒状体１２として、アルミナ系セラミック（アルミナ含有量９２重量％、密度３．６ｇ／ｃｍ^３）製の、内径５１ｍｍ、外径６１ｍｍ、長さ９１ｍｍのものを用意した。他方、図２に示す金属筒状体１３として、Ｆｅ：５４重量％−Ｎｉ：２９重量％−Ｃｏ：１７重量％の合金（コバール）製で、内径５５ｍｍ、接合面側外径５７．５ｍｍ、ツバ側外径６２ｍｍ、長さ１０ｍｍのものを用意した。
【００３２】
また、一次ろう材としては、Ａｇを７２重量部、Ｃｕを２８重量部含む合金粉末（活性金属成分以外の残部をなす合金粉末である）に対し、活性金属成分としてのＴｉＨ_２粉末を各種の割合で含有配合し、溶媒及び分散剤を加えて一次ろう材ペーストを作製した。また、二次ろう材として、内径５１ｍｍ、外径６０ｍｍ、厚さ０．１３ｍｍの環状のＢＡｇ−８ろう材箔を用意した。さらに、セラミック筒状体の接合側の端面を、グラインダ及びラップ研磨により各種平面度となるように研磨した。また、金属筒状体の接合側の端面は、レース加工（切削）時に平面度が０．１ｍｍとなるように切削した。
【００３３】
そして、セラミック筒状体の接合側端面に前述の一次ろう材ペーストを厚さ２００μｍにて塗布し、雰囲気加熱炉中にて、温度Ｔ１＝８６０℃、真空度＝１×１０^−４〜１×１０^−２Ｔｏｒｒにて一次ろう付けし、一次メタライズ層を形成した。次に、前述の二次ろう材箔を間に挟む形で、一次メタライズ層の形成されたセラミック筒状体の接合側端面と、金属筒状体の接合側端面とを突き合わせ、温度Ｔ２＝８００℃、真空度＝１．０×１０^−４Ｔｏｒｒにて二次ろう付けした。
【００３４】
こうして得られた各接合体の接合強度を、オートグラフを用いた引張試験にて測定し、強度値が３０００ｋｇ以上のものを◎、２０００〜３０００ｋｇのものを○、２０００ｋｇ以下のものを△、として評価した。また、気密度は、Ｈｅリークディテクタを用いたＨｅリーク試験により測定し、Ｈｅリーク量が１０^−９Ｐａ・ｍ^３／ｓｅｃ以下のものを◎、１０^−９〜１０^−８Ｐａ・ｍ^３／ｓｅｃのものを○、１０^−８Ｐａ・ｍ^３／ｓｅｃ以上のものを△として評価した。以上の結果を表１〜３に示す。
【００３５】
【表１】

【００３６】
【表２】

【００３７】
【表３】

【００３８】
表１は、セラミック部材の接合側端面の平面度を０．０５ｍｍに固定し、また、一次ろう付け時の真空度を１．０×１０^−４Ｔｏｒｒに固定し、使用する一次ろう材中のＴｉＨ_２の含有量を各種変化させた場合の結果を示す。ＴｉＨ_２の含有量を１．０〜２０．０重量％とすることで、十分な接合強度と、高い気密性とが両立できていることがわかる。また、この場合、接合部を軸線方向に切断した断面を投影機により外観観察したところ、接合ムラのない良好な接合状態であることも確認できた。一方、ＴｉＨ_２の含有量が上記範囲外の接合体（Ｎｏ．１，６，７）は、上記接合体（Ｎｏ．２〜５）に比べて接合強度が低く、かつ気密性にも若干の低下がみられた。
【００３９】
表２は、一次ろう付け時の真空度を１．０×１０^−４Ｔｏｒｒに固定し、さらに、一次ろう材中のＴｉＨ_２の含有量を１２重量％に固定し、セラミック部材の接合側端面の平面度を０．０５〜０．１５ｍｍの各種値に変化させた場合の結果である。平面度を０．１ｍｍ以下とすることで、接合強度及び気密性の双方に優れた接合構造が実現されていることがわかる。また断面観察結果も実施例１と同様、良好であった。一方、平面度が０．１ｍｍを超える接合体（Ｎｏ．３，４）は、接合強度がやや低く、かつ気密性にも若干の低下がみられた。
【００４０】
表３は、セラミック部材の接合側端面の平面度を０．０５ｍｍに固定し、さらに、一次ろう材中のＴｉＨ_２の含有量を１２重量％に固定し、一次ろう付け時の真空度を１．０×１０^−４〜１．０×１０^−２Ｔｏｒｒの各種値に変化させた場合の結果である。一次ろう付け時の真空度が１．０×１０^−３Ｔｏｒｒ以下の条件で作製された接合体（Ｎｏ．１２，１３）は、十分な接合強度を示し、Ｈｅリーク試験により高い気密性を有していることが示され、また断面観察により接合状態が良好であることも示された。一方、真空度が１．０×１０^−３Ｔｏｒｒを超える条件で作製された接合体（Ｎｏ．１４，１５）は、接合強度がやや低く、かつ気密性にも若干の低下がみられた。
【００４１】
なお、上記実施例において、金属部材として、Ｆｅ−Ｎｉ系合金（Ｆｅ：５８％，Ｎｉ：４２％を含有）を用いて、上記各実施例と同様の試験を行った。その結果、コバールを用いた場合と全く同様の傾向を示すことが確認できた。
【図面の簡単な説明】
【図１】本発明の金属−セラミック接合体の一実施例を示す拡大断面模式図。
【図２】図１の金属−セラミック接合体を用いた一実施形態を示す断面模式図。
【図３】本発明の金属−セラミック接合体を真空スイッチ外管として用いる一実施例を示す断面図。
【図４】本発明の金属−セラミック接合体の製造方法について説明する図。
【図５】本発明の金属−セラミック接合体において、反応層及びろう材層の厚さを決定するための説明図。
【符号の説明】
１金属−セラミック接合体
２，１２セラミック部材
３，１３金属部材
４反応層
５ろう材フィレット（ろう材層）
６セラミック側接合端面
７金属側接合端面
１０真空スイッチ外管
１５接合層（反応層及びろう材層）
５０真空バルブ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal-ceramic bonded body and a manufacturing method thereof.
[0002]
[Prior art]
Ceramic members have excellent heat resistance, impact resistance, and insulation, and are being used in various fields by taking advantage of their characteristics. For example, in a vacuum switch outer tube or the like using a ceramic tube, the opening end of a cylindrical ceramic member is welded and sealed with a cylindrical metal member having a lid. In joining such a ceramic member and a metal member, conventionally, a method of brazing and joining the butted ends of both members has been used. As the metal member, an iron alloy containing Ni is often used in order to ensure corrosion resistance and high temperature strength.
[0003]
[Problems to be solved by the invention]
However, in conventional brazing joining of a metal member and a ceramic member, for example, an active metal such as Ti contained in the brazing material may react with Ni metal in the metal member to form an intermetallic compound. . In this case, the bonding strength decreases at the location where the intermetallic compound is formed, or the active metal that reacts with the ceramic member is insufficient, and the bonding state near the interface between the ceramic member and the brazing material becomes unstable. Has occurred.
[0004]
An object of the present invention is to provide a metal-ceramic bonded body having a stable bonding state and high bonding strength, and a method for producing the same.
[0005]
[Means for solving the problems and actions / effects]
In order to solve the above problems, the metal-ceramic bonded body of the present invention comprises a metal member containing Ni and a ceramic member. One It is joined via the brazing material layer, and the brazing material layer and the ceramic member In contact with both A reaction layer containing one or more active metal components selected from Ti, Zr, and Hf is formed; On the other hand Amount of intermetallic compound containing the active metal component and Ni between the brazing filler metal layer and the metal member However, when the crystal structure analysis is performed on the cross section of the joint by micro X-ray diffraction or the like, the diffraction peak is not confirmed. Characterized by being made smaller.
[0006]
The method for producing a metal-ceramic bonded body according to the present invention is a method for manufacturing a metal-ceramic bonded body in which a metal member containing Ni and a ceramic member are bonded via a brazing material layer, and includes Ti, Zr, A primary brazing material containing one or more active metal components selected from Hf is used to perform a primary brazing process on the joint surface of the ceramic member, followed by a lower melting point than the primary brazing material. The metal member is secondarily brazed to the metallized end surface portion of the ceramic member with a secondary brazing material having a small active metal component content.
[0007]
That is, as a result of intensive studies by the present inventors in view of the above problems, as described in the above production method, a brazing material that joins a ceramic member and a metal member, a primary brazing material containing an active metal component, and a primary brazing material Were divided into secondary brazing materials having a lower melting point and a lower active metal component content (desirably not contained), and each of the two steps of brazing was performed individually. As described above, it is possible to manufacture a metal-ceramic joint in which the amount of the intermetallic compound containing the active metal component and Ni formed between the brazing filler metal layer and the metal member is made as small as possible. became.
[0008]
That is, in the primary brazing, a reaction layer of the active metal and the ceramic component is formed on the bonding surface of the ceramic member by metallizing the bonding surface on the ceramic member side with the primary brazing material containing the active metal. The The reaction layer has an excellent affinity for both the ceramic and the brazing filler metal component other than the active metal in the brazing filler metal layer, and forms a strong joint structure between the brazing filler metal layer and the ceramic member. Play a central role. And, at the time of secondary brazing, the lower melting point than that of the primary brazing material and the content of the active metal component is low (desirably not contained). Therefore, the diffusion of the active metal component from the reaction layer to the brazing filler metal layer side is suppressed, and the Ni component in the metal member joined through the brazing filler metal layer and the reaction layer (that is, the primary brazing filler metal) Reaction with the active metal component from is extremely difficult to occur. As a result, an intermetallic compound containing an active metal component and Ni is hardly formed, and as a result, the bonding state is stabilized at the bonding interface, and a metal-ceramic bonded body with high bonding strength can be obtained.
[0009]
In the above manufacturing method, the primary brazing temperature T1 is preferably 840 to 880 ° C., although it depends on the type of brazing material used. Similarly, the secondary brazing temperature T2 is preferably 800 to 820 ° C. The difference ΔT≡T1−T2 should satisfy 20 to 80 ° C. That is, by setting the secondary brazing temperature T2 lower than the primary brazing temperature T1 by about ΔT, the active metal component in the reaction layer formed by the primary brazing becomes a brazing material layer during the secondary brazing. It is possible to effectively suppress the reaction with the Ni component contained in the metal member through the process, and as a result, the active metal-Ni intermetallic compound is hardly formed between the brazing filler metal layer and the metal member. When T1 and T2 are set in the above range, if ΔT is less than 20 ° C., the above effect is insufficient. On the other hand, when it exceeds 80 ° C., the secondary brazing temperature becomes too low, and the formation of the brazing material layer becomes incomplete, leading to a decrease in the bonding strength. ΔT is preferably about 30 to 70 ° C., more preferably about 40 to 60 ° C.
[0010]
The primary brazing material contains 1 to 20% by weight of a simple substance and / or a compound composed of one or more active metal elements specifically selected from Ti, Zr, and Hf. be able to. As the active metal component, Ti can be used particularly suitably because it can exhibit excellent bonding performance with respect to many ceramics and is relatively inexpensive. In this case, in order to enhance the reaction activity of the Ti component, the Ti component in the primary brazing material is titanium hydride (general composition is TiH ₂ (But not limited to stoichiometric compounds). TiH ₂ As a result, the oxidation or nitridation of Ti can be effectively prevented. When the content of the active metal component in the primary brazing material is less than 1% by weight, the formation of the reaction layer may be insufficient, and bonding failure may easily occur. On the other hand, if the content of the active metal component exceeds 20% by weight, poor wetting between the primary brazing material and the secondary brazing material may occur during secondary brazing, and the reaction layer becomes excessively thick. In some cases, the bonding strength may decrease and the airtightness of the bonding portion may decrease. The content of the active metal component in the primary brazing material is preferably 5 to 10% by weight.
[0011]
In the above manufacturing method, the primary brazing is preferably performed in vacuum, and the degree of vacuum is 1.0 × 10. ^-3 It should be less than Torr. Primary brazing 1.0 × 10 ^-3 If it is carried out under a condition exceeding Torr, the primary brazing material may be poorly wetted, or the active metal component may be oxidized or nitrided, making it difficult to form a stable reaction layer. Note that the primary brazing atmosphere is not limited to a vacuum atmosphere, and a stable reaction layer can be formed even if primary brazing is performed in an inert gas atmosphere such as an Ar gas atmosphere.
[0012]
For example, in the metallization process by primary brazing, the active metal component in the primary brazing material reacts with the ceramic member to form a reaction layer, while the remaining metal component forms a primary metallization layer that covers the reaction layer in close contact. May form. For example, as the primary brazing material, a component other than the active metal (hereinafter referred to as a base component), in other words, a component that should constitute the primary metallized layer, such as Ag, Cu, Au, Sn, etc. can be used. As the secondary brazing material used for the secondary brazing, it is desirable to use a brazing material having excellent wettability or affinity with the primary metallized layer based on the above base component, for example, a brazing material having a composition similar to that of the primary metallized layer. I can say that. Specifically, an Ag—Cu-based alloy can be used as such a secondary brazing material. Ag-Cu alloys are less likely to react with active metal components such as Ti to form intermetallic compounds, have a low melting point, and have good bondability to metal members, making them suitable as the secondary brazing material of the present invention. ing. Note that the content ratio of Ag and Cu in the Ag-Cu alloy is preferably 30 to 50 parts by weight of Cu with respect to 100 parts by weight of Ag. When Cu is less than 30 parts by weight, the melting point of the brazing material becomes too high, and for example, the bonding strength may be lowered due to the formation of the above-described intermetallic compound or the like due to diffusion of the active metal component from the reaction layer. On the other hand, when the amount exceeds 50 parts by weight, the oxidation resistance of the brazing material layer is impaired in addition to the same problem due to the high melting point of the brazing material, and the high-temperature bonding strength may be impaired. In addition, as said Ag-Cu type-alloy, the silver solder: BAg-8 etc. which were described, for example in JIS-Z3261 can be used.
[0013]
In the metal-ceramic bonded body, the thickness of the reaction layer is preferably 50 μm to 300 μm in the bonding direction between the metal member and the ceramic member. When the reaction layer thickness is less than 50 μm, the bondability may decrease due to the lack of the reaction layer. When the reaction layer thickness exceeds 300 μm, the reaction layer may become too thick and the bonding strength may decrease. The thickness range of the reaction layer is desirably 150 μm to 200 μm, so that the bonded state of the metal-ceramic bonded body is further stabilized and the bonding strength is further improved.
[0014]
In the metal-ceramic bonded body, the thickness of the brazing material layer between the end surface on the reaction layer side and the bonding end surface of the metal member (hereinafter referred to as the brazing material bonding thickness) is 30 μm to 100 μm. It is good to be. When the thickness is less than 30 μm, an intermetallic compound is likely to be formed between the active metal component and the metal member, resulting in a decrease in bonding strength. On the other hand, when the thickness exceeds 100 μm, the brazing material layer becomes too thick, and the bonding strength may decrease instead. The above range is desirably 50 μm to 80 μm. In this case, the bonding state of the metal-ceramic bonded body is further stabilized, and the bonding strength is further improved.
[0015]
Next, as the ceramic member, an alumina-based ceramic containing alumina as a main component is excellent in high-temperature strength, high-temperature corrosion resistance or chemical resistance, and is relatively inexpensive, so that it can be suitably used in the present invention. On the other hand, the metal member has a relatively small coefficient of linear expansion, is relatively less likely to generate thermal stress with the ceramic member, and further, when applied to a vacuum switch or the like, heat resistance and corrosion resistance can be ensured. It becomes a point on material selection. Specifically, an Fe—Ni—Co system in which Fe is the main component, the subcomponent with the highest content is one of Ni and Co, and the subcomponent with the second highest content is the other of Ni and Co. An alloy, such as an Fe—Ni-based alloy whose main component is Fe and whose secondary component with the highest content ratio is Ni, can be used. In addition, as an Fe-Ni-Co type alloy, for example, an alloy containing Fe: 54%, Ni: 29%, Co: 17% (trade name: Kovar), etc., and as an Fe-Ni type alloy, For example, those containing Fe: 58% and Ni: 42% (common name: 42 alloy) can be used. In the present specification, “main component”, “mainly”, “main component” and the like refer to a component having the highest weight content in the material of interest unless otherwise specified. .
[0016]
Next, the flatness of the joining surface of the ceramic member is preferably 0.1 mm or less. If the flatness exceeds 0.1 mm, the formation of the reaction layer may be incomplete, or it may cause a brazing failure during secondary brazing, resulting in a decrease in the joint strength of the manufactured joined body. There is.
[0017]
Next, as a specific mode of the metal-ceramic bonded body, for example, as a mode in which the butted portion of the metal member and the ceramic member can be bonded with high strength, the brazing material layer is formed on the butted portion of the ceramic member and the metal member. An example of a fillet formed (hereinafter also referred to as a brazing filler fillet) can be exemplified. For example, as a structure for joining a metal member and a ceramic member each formed in a cylindrical shape, a metal cylindrical body and a ceramic cylindrical body each having an open end face on at least one side, respectively, the metal cylindrical body and the ceramic cylindrical body The body may be coaxially butted on the open end face side, and the butted portion may be joined via an annular brazing material layer (brazing material fillet). In this case, both the metal cylindrical body and the ceramic cylindrical body can be formed in a cylindrical shape, and the joining end surface on the metal cylindrical body side can be positioned in the approximate center of the joining end surface on the ceramic cylindrical body side in the radial direction. . In this way, when the cylindrical members are joined to each other by brazing, the joining strength of the joining layer (consisting of the reaction layer and the brazing material layer) can be obtained in a good joining state by introducing the joined body of the present invention. In addition, it is possible to provide a joint with high airtightness.
[0018]
Specifically, the following can be exemplified as a structure for joining the ceramic cylindrical body and the metal cylindrical body with higher strength. That is, in the butt portion, the joining end surfaces of the metal cylindrical body and the ceramic cylindrical body are each formed in a planar shape, and in any cross section including the axis of the metal cylindrical body and the ceramic cylindrical body, The width of the joining end face of the cylindrical body (hereinafter referred to as the metal side joining end face) is made smaller than the width of the joining end face of the ceramic cylindrical body (hereinafter referred to as the ceramic side joining end face). Covering both sides in the thickness direction so as to bury the end of the body, and the cross-sectional outer shape of the metal cylindrical body on both the inner surface side and the outer surface side of the metal cylindrical body is directed from the metal cylindrical body side to the ceramic cylindrical body side. The shape will be widened. By applying the joined body structure of the present invention, a joining structure with little joining unevenness and excellent joining strength and airtightness can be obtained in the butt joining of the cylindrical members. For example, the metal-ceramic bonding body having the above structure is particularly effective for application to a vacuum switch. In this case, the cylindrical ceramic member can be used as an outer tube for a vacuum switch, and the metal member can be used as a metal lid that covers the vacuum switch outer tube. In this case, by applying the present invention, it is possible to provide a vacuum switch outer tube having high airtightness and high bonding strength.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to examples shown in the drawings.
FIG. 1 is an enlarged sectional view showing a joint portion of a metal-ceramic joint body 1 according to an embodiment of the present invention. The metal member 3 and the ceramic member 2 are joined to each other through a reaction layer 4 in contact with the ceramic member 2 and a brazing filler fillet (brazing material layer) 5 in contact with the metal member 3. The joining end faces of the

members

2, 3, that is, the ceramic side joining end face 6 and the metal side joining end face 7 are each formed in a flat shape, and in particular, the flatness of the ceramic side joining end face 6 is 0.1 mm or less. Further, the metal side joining end face 7 is made smaller than the ceramic side joining end face 6. On the other hand, the brazing filler fillet 5 covers the entire peripheral edge of the metal member 3 in such a manner that the joint side end of the metal member 3 is buried, and the cross-sectional outer shape of both sides of the metal member 3 is the metal member 3 side to the ceramic member 2 side It has a shape that expands toward the bottom. In the present embodiment, the width of the joining end face of the metal member 3 is made smaller than the width of the joining end face of the ceramic member.
[0020]
The ceramic member 2 is made of, for example, an alumina-based ceramic whose main component is alumina, and the metal member 3 is an Fe—Ni—Co-based alloy containing, for example, Fe: 54%, Ni: 29%, and Co: 17%. It is composed of. The reaction layer 4 contains Ti as an active metal component, and the brazing filler metal fillet 5 is mainly composed of an Ag—Cu alloy.
[0021]
In the metal-ceramic bonding body 1, the thickness t1 of the reaction layer 4 is, for example, 50 μm to 300 μm (in this embodiment, 150 μm). In the brazing filler fillet 5, the end surface 8 on the reaction layer 4 side and the metal The thickness between the bonding end surface 7 of the member 3, that is, the thickness t <b> 2 of the brazing material bonding layer 5 a is, for example, 30 μm to 100 μm (80 μm in this embodiment).
[0022]
The thickness t1 of the reaction layer 4 and the thickness t2 of the brazing material bonding layer 5a are, for example, an electron probe micro analyzer (EPMA), energy dispersive X-ray spectroscopy (EDS), wavelength dispersive X-ray spectroscopy (WDS). It can measure by well-known methods, such as. In the present invention, the definition is as follows. As shown in FIG. 5, the cation component having the highest content of the ceramic member (for example, an element component showing a positive valence when analyzed by X-ray photoelectron spectroscopy (XPS) or the like; Q is a metal component having the highest content of the metal member, and A is an active metal component. Then, the cross section of the joint is observed with a scanning electron microscope (SEM), and the cation component Q, the metal component M, and the active metal component A in the joining direction of each part are subjected to line analysis with the EPMA attached to the SEM. Suppose you did it. In this case, each content of the component Q, the component M, and the component A is considered to be proportional to the detected intensity of the corresponding characteristic X-ray. At this time, the maximum value of the characteristic X-ray intensity based on the component Q is IQmax (measured at the height from the background with the minimum value on the metal member side as the background), and the characteristic X-ray based on the component M The maximum value of the intensity is IMmax (measured at the height from the background with the minimum value on the ceramic member side as the background), and the maximum value of the characteristic X-ray intensity based on the component A is IAmax (the ceramic member side) Or the minimum value on the metal member side as a background, and measured from the height from the background), the position of 0.8 IQmax is defined as the boundary BC-R between the ceramic member and the reaction layer, The position where 0.8IAmax is defined as the boundary BR-W between the reaction layer and the brazing material layer, and the position where 0.8IMmax is defined as the brazing material layer. Defined as the boundary BW-M with genus member. The thickness t1 of the reaction layer 4 is the distance between the boundaries BC-R and BR-W, and the thickness t2 of the brazing filler metal bonding layer 5a is the distance between the boundaries BR-W and BW-M. Respectively.
[0023]
In addition, an intermetallic compound containing an active metal component and Ni, for example, a Ti—Ni-based compound is hardly formed between the brazing filler fillet 5 and the metal member 3. In other words, this means that there is almost no reaction between the Ni component in the metal member and the Ti component forming the reaction layer. As a means for specifically confirming this, for example, the crystal structure analysis is performed on the cross section of the joint portion by micro X-ray diffraction or the like. ₂ Ni, TiNi or Ni ₃ If a diffraction peak of a Ti—Ni compound such as Ti is not confirmed, it can be considered that a Ti—Ni compound is not formed. Further, in FIG. 5, when the line analysis of the active metal component A is performed, the reaction of the peak value I′Amax of the characteristic X-ray intensity of the active metal component A observed at the interface between the brazing filler metal layer and the metal member. The ratio I′Amax / IAmax to the peak value IAmax in the layer is desirably 0.01 or less (preferably substantially zero within the range of measurement variation).
[0024]
Hereinafter, a method for producing the metal-ceramic bonded body 1 will be described. First, as shown in FIG. 4 (a), a paste of primary brazing filler metal 104 containing Ti as an active metal component is disposed on the end face (joint face) of the ceramic member 2, and a predetermined atmosphere is set in an atmosphere heating furnace. And the metallization process is performed by heating at a temperature to form a reaction layer 4 as shown in FIG. In addition, the brazing filler metal component other than the active metal component may form the primary metallized layer 5b that covers the reaction layer 4 in close contact. The primary brazing conditions are a brazing temperature T1 of 840 to 880 ° C. (860 ° C. in this embodiment) and a vacuum degree of 1.0 × 10 6. ^-3 Torr or less (in this embodiment, for example, 1.0 × 10 ^-4 Torr) vacuum. The composition of the primary brazing material can be, for example, a portion other than the active metal Ag, Cu, and the active metal component can be Ti, for example, TiH ₂ In the form of 1 to 20% by weight (in this example, 5% by weight) can be used.
[0025]
Next, as shown in FIG. 4 (c), the melting point is lower than that of the primary brazing filler metal and the content of the active metal component is small. Specifically, the active metal component is substantially contained except for inevitable impurities. The secondary brazing material foil 105 is overlaid on the reaction layer 4 (or the primary metallized layer 5b), and the end face (joint surface) of the metal member 3 is abutted against each other in an atmosphere heating furnace at a predetermined atmosphere and temperature. Secondary brazing by heating. As a result, the secondary brazing material foil 105 is melted to form the brazing filler fillet 5 shown in FIG. When the primary metallized layer 5 b is formed, part or all of the primary metallized layer 5 b may be melted and integrated with the secondary brazing material foil 105 and taken into the brazing filler fillet 5. The conditions for the secondary brazing are that the brazing temperature T2 is 800 to 820 ° C. (800 ° C. in this embodiment), and the difference ΔT≡T1−T2 from the primary brazing temperature T1 is 20 to 80 ° C. In the embodiment, it is set to 60 ° C.). As the secondary brazing material, silver brazing BAg-8 (Ag: Cu = 18: 7) described in JIS-Z3261 is used.
[0026]
On the other hand, FIG. 2 schematically shows a part of a vacuum switch outer tube in which the metal-ceramic assembly 1 is used in a sectional view. The vacuum switch outer tube 10 has a form in which a cylindrical ceramic member (ceramic cylindrical body) 12 forming a ceramic tube and a metal member (metal cylindrical body) 13 including a lid member 14 are hermetically bonded. Have. Each of the ceramic cylindrical body 12 and the metal cylindrical body 13 is a cylindrical body having an open end surface, and is abutted coaxially on the open end surface side, and the butted portion is formed into an annular bonding layer (reaction layer). 4 and brazing filler fillet 5) 15 to form a metal-ceramic joint according to the present invention. In the abutting portion, the joining end face on the metal cylindrical body 13 side is positioned at the substantially center in the radial direction of the joining end face on the ceramic cylindrical body 12 side.
[0027]
When primary brazing is performed on the joint surface of such a ceramic cylindrical body 12, as shown in FIG. 4E, an annular primary brazing material foil 104 corresponding to the end surface shape can be used. When performing secondary brazing, an annular secondary brazing material foil 105 is sandwiched between the end surfaces of the ceramic cylindrical body 12 and the metal cylindrical body 13 as shown in FIG. To do.
[0028]
In the vacuum switch as described above, the ceramic cylindrical body 12 and the metal cylindrical body 13 are sealed by the bonding layer 15 due to the structure of the metal-ceramic bonded body of the present invention, and high airtightness is achieved, and By performing brazing in two stages as described above, since a Ti—Ni intermetallic compound is hardly formed between the bonding layer 15 (the brazing filler fillet 5) and the metal cylindrical body 13, the bonding strength is also improved. It will be excellent. On the lid member 14 side of the metal member 13, a flange-like portion 13 a that bulges outward is formed, and airtightness and bonding strength with the lid member 14 are maintained.
[0029]
FIG. 3 shows a more specific configuration example of the vacuum switch. The vacuum valve 50 is configured in a container shape by sealingly attaching metal end plates 57 and 57 (metal members) with lids to both ends of an insulating container 55 (ceramic member). In this vacuum vessel, the

contacts

60 and 61 are provided so that the contact 61 is fixed and the contact 60 is movable, and can be contacted and separated. A movable electrode rod 56 of the contact 60 is movably and airtightly attached to the end plate 57 via a bellows 58. The fixed contact 61 and the movable contact 60 are surrounded by an arc shield 54, and the bellows cover 59 of the bellows 58 is attached to the movable electrode rod 56.
[0030]
In such a vacuum valve 50, the movable electrode rod 56 is operated in the direction of pulling out by an operating mechanism (not shown), and the

contacts

60 and 61 are separated. Even if the

contacts

60 and 61 are separated, an arc is generated between the two contacts when the distance is small, and the current continues to flow. However, when the distance becomes larger than a certain distance, the generated arc reaches the current zero point and reaches a vacuum. It diffuses in and the current between the contacts is cut off. Here, the end plate (metal member) 57 and the insulating container (ceramic member) 55 can be brazed and joined as the metal-ceramic joint of the present invention. Thereby, it is possible to exhibit high performance as a vacuum valve having high airtightness and bonding strength at the bonded portion.
[0031]
Example 1
In order to confirm the effect of the present invention, the following experiment was conducted. First, as the ceramic cylindrical body 12 shown in FIG. 2, an alumina-based ceramic (alumina content 92 wt%, density 3.6 g / cm ³ ) With an inner diameter of 51 mm, an outer diameter of 61 mm, and a length of 91 mm was prepared. On the other hand, the metal cylindrical body 13 shown in FIG. 2 is made of an alloy (Kovar) of Fe: 54 wt% -Ni: 29 wt% -Co: 17 wt%, and has an inner diameter of 55 mm and a joining surface side outer diameter of 57.5 mm. A flange-side outer diameter of 62 mm and a length of 10 mm were prepared.
[0032]
Further, as the primary brazing material, an alloy powder containing 72 parts by weight of Ag and 28 parts by weight of Cu (which is an alloy powder forming the remainder other than the active metal component), TiH as an active metal component is used. ₂ The powder was mixed and contained in various proportions, and a solvent and a dispersant were added to produce a primary brazing paste. In addition, an annular BAg-8 brazing foil having an inner diameter of 51 mm, an outer diameter of 60 mm, and a thickness of 0.13 mm was prepared as a secondary brazing material. Furthermore, the end surface on the joining side of the ceramic cylindrical body was polished by a grinder and lapping so as to have various flatnesses. Further, the end surface on the joining side of the metal cylindrical body was cut so that the flatness was 0.1 mm at the time of lace processing (cutting).
[0033]
Then, the above-mentioned primary brazing paste is applied to the joining side end face of the ceramic cylindrical body at a thickness of 200 μm, and the temperature T1 = 860 ° C. and the degree of vacuum = 1 × 10 in an atmosphere heating furnace. ^-4 ~ 1x10 ^-2 Primary brazing was performed with Torr to form a primary metallized layer. Next, the joining side end face of the ceramic cylindrical body on which the primary metallized layer is formed and the joining side end face of the metal cylindrical body are butted together with the above-mentioned secondary brazing material foil interposed therebetween, and the temperature T2 = 800. ° C, degree of vacuum = 1.0 x 10 ^-4 Secondary brazing was performed at Torr.
[0034]
The bonding strength of each joined body thus obtained was measured by a tensile test using an autograph. evaluated. The air density is measured by a He leak test using a He leak detector. ^-9 Pa · m ³ ◎ 10 or less ^-9 -10 ^-8 Pa · m ³ / Sec for ○ / 10 ^-8 Pa · m ³ Those with a / sec or higher were evaluated as Δ. The above results are shown in Tables 1-3.
[0035]
[Table 1]

[0036]
[Table 2]

[0037]
[Table 3]

[0038]
Table 1 shows that the flatness of the joining side end face of the ceramic member is fixed to 0.05 mm, and the degree of vacuum during primary brazing is 1.0 × 10 ^-4 TiH in the primary brazing material used by fixing to Torr ₂ The result at the time of changing various content of is shown. TiH ₂ It turns out that sufficient joint strength and high airtightness are compatible by making content of 1.0-20.0 weight%. Further, in this case, when a cross section obtained by cutting the joint portion in the axial direction was externally observed with a projector, it was confirmed that the joint portion was in a good joined state without joining unevenness. On the other hand, TiH ₂ In the joined body (No. 1, 6, 7) whose content is outside the above range, the joining strength is lower than that of the joined body (No. 2 to 5), and the airtightness is slightly reduced. It was.
[0039]
Table 2 shows the vacuum degree during primary brazing at 1.0 × 10 ^-4 Fixed to Torr, and further TiH in the primary brazing material ₂ Is a result when the flatness of the joining side end face of the ceramic member is changed to various values of 0.05 to 0.15 mm. It can be seen that when the flatness is 0.1 mm or less, a bonded structure excellent in both bonding strength and airtightness is realized. The cross-sectional observation result was also good as in Example 1. On the other hand, the joined body (Nos. 3 and 4) having a flatness exceeding 0.1 mm had a slightly low joining strength and a slight decrease in airtightness.
[0040]
Table 3 shows that the flatness of the joining side end face of the ceramic member is fixed to 0.05 mm, and further, TiH in the primary brazing material ₂ Is fixed at 12% by weight, and the degree of vacuum during primary brazing is 1.0 × 10 ^-4 ~ 1.0 × 10 ^-2 It is a result at the time of changing to various values of Torr. The vacuum degree during primary brazing is 1.0 × 10 ^-3 The joined bodies (Nos. 12 and 13) produced under the conditions of Torr and below show a sufficient joining strength, and it is shown by the He leak test that the airtightness is high. It was also shown to be good. On the other hand, the degree of vacuum is 1.0 × 10 ^-3 The joined body (Nos. 14 and 15) produced under conditions exceeding Torr showed a slightly low joining strength and a slight reduction in airtightness.
[0041]
In addition, in the said Example, the test similar to said each Example was done using the Fe-Ni type alloy (Fe: 58% and Ni: 42% containing) as a metal member. As a result, it was confirmed that the same tendency as in the case of using Kovar was shown.
[Brief description of the drawings]
FIG. 1 is an enlarged schematic cross-sectional view showing an embodiment of the metal-ceramic bonded body of the present invention.
FIG. 2 is a schematic cross-sectional view showing an embodiment using the metal-ceramic assembly of FIG.
FIG. 3 is a cross-sectional view showing an embodiment in which the metal / ceramic assembly of the present invention is used as a vacuum switch outer tube.
FIG. 4 is a diagram illustrating a method for producing a metal-ceramic bonded body according to the present invention.
FIG. 5 is an explanatory diagram for determining the thickness of a reaction layer and a brazing filler metal layer in the metal-ceramic bonding body of the present invention.
[Explanation of symbols]
1 Metal-ceramic joint
2,12 Ceramic parts
3,13 Metal member
4 reaction layers
5 Brazing filler fillet
6 Ceramic end face
7 Metal side joint end face
10 Vacuum switch outer tube
15 Bonding layer (reaction layer and brazing material layer)
50 Vacuum valve

Claims

Together and a metal member and a ceramic member containing Ni is joined via one of the braze layer, in contact with both of said ceramic member and the brazing material layer, one selected Ti, Zr, and Hf Alternatively, a reaction layer containing two or more active metal components is formed, while the amount of the intermetallic compound containing the active metal component and Ni between the brazing filler metal layer and the metal member is, A metal-ceramic bonded body characterized in that when a crystal structure analysis is performed on a cross section of a bonded portion by micro X-ray diffraction or the like, a diffraction peak is not confirmed .

2. The metal-ceramic bonded body according to claim 1, wherein the ceramic member is made of an alumina-based ceramic containing alumina as a main component.

The metal member is
A Fe—Ni—Co-based alloy containing Fe as a main component, wherein the subcomponent with the highest content is one of Ni and Co, and the subcomponent with the second highest content is the other of Ni and Co;
The metal-ceramic bonded body according to claim 1 or 2, wherein the metal-ceramic bonded body is composed of any one of an Fe-Ni-based alloy containing Fe as a main component and Ni being the secondary component having the highest content.

The metal-ceramic bonding body according to any one of claims 1 to 3, wherein the brazing material layer is a fillet formed at a butt portion between the ceramic member and the metal member.

The metal member and the ceramic member are respectively formed into a metal cylindrical body and a ceramic cylindrical body whose end surfaces on at least one side are open, and the metal cylindrical body and the ceramic cylindrical body are coaxially butted on the open end surface side. The metal-ceramic bonded body according to any one of claims 1 to 4, wherein the butted portion is bonded via an annular brazing material layer.

The metal cylindrical body and the ceramic cylindrical body are both formed in a cylindrical shape, and a joining end surface on the metal cylindrical body side is positioned at a substantially center of a joining end surface on the ceramic cylindrical body side in a radial direction. 5. The metal-ceramic bonding article according to 5.

In the butting portion, the joining end surfaces of the metal cylindrical body and the ceramic cylindrical body are each formed in a planar shape, and in any cross section including the axis of the metal cylindrical body and the ceramic cylindrical body, The width of the joining end face of the metal cylindrical body (hereinafter referred to as the metal side joining end face) is made smaller than the width of the joining end face of the ceramic cylindrical body (hereinafter referred to as the ceramic side joining end face),
In the cross-section, the fillet covers both sides in the thickness direction so as to bury the end of the metal cylindrical body, and the cross-sectional outer shape on both the inner surface side and the outer surface side of the metal cylindrical body is The metal-ceramic bonded body according to claim 5 or 6, wherein the metal-ceramic bonded body has a shape that expands from the metal cylindrical body side toward the ceramic cylindrical body side.

8. The metal-ceramic joint according to claim 1, wherein the ceramic member is an outer tube for a vacuum switch.

In the manufacturing method of the metal-ceramic joining body of any one of Claim 1 thru | or 8, using the primary brazing material containing the 1 type, or 2 or more types of active metal component selected from Ti, Zr, and Hf. The ceramic member is subjected to a primary brazing process for metallization, and then a secondary brazing material having a melting point lower than that of the primary brazing material and a low content of the active metal component. A method for producing a metal-ceramic assembly, wherein the metal member is secondarily brazed to a metallized end surface portion.

When the primary brazing temperature is T1, and the secondary brazing temperature is T2,
T1: 840-880 ° C.
T2: 800-820 ° C.
The method for producing a metal-ceramic bonded body according to claim 9, wherein the difference (T1-T2) is 20 to 80 ° C.

The primary brazing material contains 1 to 20% by weight of a simple substance and / or a compound composed of one or more active metal elements selected from Ti, Zr, and Hf. The manufacturing method of the metal-ceramic joining body of description.

The method for producing a metal-ceramic bonded body according to any one of claims 9 to 11, wherein the primary brazing is performed in a vacuum, and the degree of vacuum is set to 1.0 x ^10-3 Torr or less.

The method for producing a metal-ceramic bonded body according to any one of claims 9 to 12, wherein an Ag-Cu alloy is used as the secondary brazing filler metal.

The method for producing a metal-ceramic bonded body according to claim 13, wherein the content ratio of Ag and Cu in the Ag-Cu alloy is 30 to 50 parts by weight of Cu with respect to 100 parts by weight of Ag.