JP3607552B2

JP3607552B2 - Metal-ceramic bonded body and manufacturing method thereof

Info

Publication number: JP3607552B2
Application number: JP2000035746A
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: JP2001220256A

Description

【０００１】
【発明の属する技術分野】
本発明は、真空スイッチ外管等のセラミックチューブに用いられる金属−セラミック接合体、及びその製造方法に関する。
【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、両部材間にろう材を介してろう付け接合する方法が従来用いられている。
【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Ｔｉ等の活性金属を含む場合、ろう材層表面に該活性金属が偏析して、その表面の濡れ性を低下させる場合がある。また、該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たりして、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、接合状態が安定し接合強度の高い金属−セラミック接合体、及び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に、本発明の金属−セラミック接合体の第１の構成は、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、のいずれかにて構成されている金属部材と、セラミック部材とが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間には、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、前記金属部材と前記セラミック部材との接合方向において、前記反応層の厚さが５０μｍ〜３００μｍであり、かつ、前記ろう材層において、前記活性金属成分の含有率が２重量％以下とされていることを特徴とする。
【０００６】
さらに、本発明の金属−セラミック接合体の製造方法は、
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を含む一次ろう材を、セラミック部材の端面部に一次ろう付けメタライズした後、そのろう付けされた一次ろう材の外表面部の所定量を除去し、その後に、一次ろう材よりも低融点で、かつ活性金属元素の含有量が小さい二次ろう材により、セラミック部材の一次ろう付けされた部分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、活性金属元素を含む一次ろう材と、一次ろう材よりも低融点で、かつ活性金属元素の含有量が小さい（望ましくは含有されていない）二次ろう材とに分けて、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において、一次ろう付けを行った後に、その一次ろう材の外表面部の所定量を除去して二次ろう付けを行ったところ、上記のように、ろう材層において、活性金属成分の含有率が２重量％以下とされた金属−セラミック接合体を得ることができた。この場合、上記ろう材層は二次ろう材を主として構成され、上記反応層は一次ろう材を主として構成されている。
【０００８】
一次ろう材（反応層）中に含まれる活性金属成分は、一次ろう付け時に、該一次ろう材（反応層）の層表面側に偏析する場合がある。この層表面に上記二次ろう付けを行う場合、偏析した活性金属成分が二次ろう付けのろう材濡れ性を低下させたり、また、該活性金属成分が二次ろう材（ろう材層）中に拡散して、上記金属成分との間で金属間化合物を形成し、接合強度の低下、接合状態の不安定化を生じたりする問題がある。しかしながら、本発明の金属−セラミック接合体においては、一次ろう材層（反応層）の外表面部を除去することにより、その外表面部に偏析した活性金属成分が除去され、結果的に、ろう材層中の活性金属成分の含有量が２重量％以下となるようにされているため、上記問題が解決され接合部は高い接合強度を呈する。なお、そのような外表面部の除去は、例えば機械的研磨処理により行うことが可能で、該機械的研磨処理としては、例えばラッピング加工、バフ加工、バレル加工等を例示することができる。また、偏析層は一般的に３〜５μｍ程度になることが多く、この場合、例えば除去量は５〜１０μｍ程度とするのがよい。
【０００９】
また、本発明の金属−セラミック接合体の第２の構成は、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、のいずれかにて構成されている金属部材とセラミック部材とが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間には、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、前記金属部材と前記セラミック部材との接合方向において、前記反応層の厚さが５０μｍ〜３００μｍであり、かつ、前記ろう材層の厚さをｔ２とし、そのろう材層中において前記反応層との接合側に形成される前記活性金属成分の濃度傾斜層の厚さをｔ３としたときに、ｔ３／ｔ２が０．２以下とされていることを特徴とする。
【００１０】
この場合、活性金属成分の濃度傾斜層とは、上述した一次ろう材から二次ろう材へ拡散した活性金属成分の層のことである。製造時において一次ろう材の表面に形成された活性金属成分を除去することにより、偏析した活性金属成分は殆ど無くなり、その拡散量も減少するため、結果的に金属−セラミック接合体において、該濃度傾斜層の厚さｔ３がろう材層の厚さｔ２に対して、ｔ３／ｔ２≦０．２を満たすこととなる。このような金属−セラミック接合体は、二次ろう付け時のろう材濡れ性の低下が起こりにくく、また上記金属間化合物が形成されにくくなるため、接合部は安定な接合状態となって高い接合強度を呈する。
【００１１】
上記製造方法において、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。この場合、化合物中の活性金属元素が作用してセラミック部材との接合反応に与り、これが１重量％未満の場合は、一次ろう付け時にセラミック部材と一次ろう材間の接合不良が起こりやすくなる。一方、２０重量％を超えると、上記偏析層の除去作業が困難になる場合がある他、該偏析層の除去が不十分となる場合があり、二次ろう付け時に一次ろう材と二次ろう材間の濡れ不良が起こったり、上記金属間化合物が生じたりする場合がある。また、製造される接合体の金属部材とセラミック部材との間の反応層（一次ろう材から形成される）が厚くなりすぎて、接合強度が低下したり、接合部の気密性が低下したりする場合がある。
【００１２】
なお、上記活性金属成分を含む化合物は、例えば水素化物（例えばＴｉＨ_２等）として一次ろう材中に含有すると、活性金属成分（例えばＴｉ等）の酸化、窒化等を防止する上でも好ましく、また、この水素化物（例えばＴｉＨ_２等）の含有量は、好ましくは５〜１０重量％とするのがよい。さらに、一次ろう材の中には、活性金属成分以外にも、例えば、Ａｇ、Ｃｕ、Ａｕ、Ｓｎ等を含んで構成すれば、金属−セラミック接合体の接合部の安定性が一層向上する。その中でも、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。
【００１３】
上記製造方法において、一次ろう付け温度をＴ１＝８４０〜８８０℃とし、二次ろう付け温度をＴ２＝８００〜８２０℃としたときに、それらの差ΔＴ≡（Ｔ１−Ｔ２）が、２０〜８０℃を満足しているのがよい。一次と二次のろう付け時において、このような範囲の温度差があれば、二次ろう付け時に、一次ろう付けされた一次ろう材（反応層）に含まれる除去しきれなかった活性金属元素（活性金属成分）と、金属部材中に含まれる金属元素（金属成分、例えばＮｉ等）との反応を抑制することができるため、ろう材層と金属部材との間に上記金属間化合物が形成されにくくなる。なお、上記各ろう付け温度は、好ましくはＴ１＝８５０〜８７０℃、Ｔ２＝８００〜８２０℃とするのがよい。また、ΔＴは好ましくは３０〜７０℃、さらに好ましくは４０〜６０℃とするのがよい。
【００１４】
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、上記活性金属元素が酸化ないし窒化されたりする場合があり、セラミック部材と活性金属元素とにより安定な反応層が形成されにくくなる場合がある。なお、真空中のみならず、例えばＡｒ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。
【００１５】
また、上記二次ろう材には、例えばＡｇ−Ｃｕ系合金を用いることができる。Ａｇ−Ｃｕ系合金は、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。この範囲外のものは、金属部材とセラミック部材とのろう付け接合に好ましくない。本発明の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。
【００１６】
一方、結果として製造される金属−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、接合層（反応層とろう材層から形成される）が全体として厚くなりすぎて、接合強度が低下する場合がある。なお、上記範囲は望ましくは１５０μｍ〜２００μｍ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。
【００１７】
次に、上記セラミック部材は、アルミナを主成分とするアルミナ系セラミックにて構成されているものを採用することができる。さらに、金属部材は、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、又は、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、のいずれかにて構成することができる。このようにアルミナ系セラミックからなるセラミック部材を用いた場合や、Ｎｉを含有する上記金属部材を用いた場合、本発明の製造方法により、活性金属−Ｎｉ系金属間化合物が可及的に形成されないようになり、接合状態の良好な金属−セラミック接合体を提供することができる。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。
【００１８】
また、セラミック部材において、反応層と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、セラミック部材と反応層との間の接合状態が悪化する場合があり、また、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。また、偏析層除去により一次ろう材の表面の平面度は、０．１ｍｍ以下とされるのがよい。この場合も、平面度が０．１ｍｍを超えると、接合状態が悪化して二次ろう付け時のろう付け不良の原因となり得る。
【００１９】
上記ろう材層は、セラミック部材と金属部材との突き合わせ部において形成されるフィレット（以下、ろう材フィレットとも言う）として形成することができる。そのような金属−セラミック接合体の具体的態様としては、例えば、金属部材及びセラミック部材を、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反応層とろう材層と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。
【００２０】
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。
【００２１】
【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の筒内外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。
【００２２】
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。
【００２３】
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（ろう材層）５ａの厚さｔ２は、例えば、３０μｍ〜１００μｍ（本実施例では、８０μｍ）とされている。
【００２４】
反応層４の厚さｔ１とろう材接合層（ろう材層）５ａの厚さｔ２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６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（ろう材層）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。
【００２５】
本実施例の接合体１においては、ろう材層５ａには、上記Ｔｉ等の活性金属成分が殆ど含有されておらず、多くともろう材層全体の２重量％以下とされている。また、上記ろう材層５ａの厚さをｔ２とし、そのろう材層中において上記反応層４との接合側に形成される活性金属成分の濃度傾斜層２５（図６）の厚さをｔ３としたときに、ｔ３／ｔ２が０．２以下とされている。
【００２６】
また、ろう材フィレット５と金属部材３との間には、上記活性金属成分と金属成分（例えばＮｉ）とを含有する金属間化合物、例えばＴｉ−Ｎｉ系化合物が可及的に形成されていない。これは、換言すれば、金属部材中のＮｉ成分と、反応層を構成する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６において、活性金属成分Ａの線分析を行ったときに、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。
【００２７】
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）に示すような一次ろう材層１０４ｂを形成する。図５（ａ）に示すように、一次ろう材層１０４ｂの表層部付近には活性金属成分４１，４２が偏析する場合が多く、この偏析層４１，４２は後の二次ろう付けに際して接合不良を引き起こすため、本発明の製法においては、この活性金属成分（偏析層）４１，４２のうち、セラミック部材２と対向する側の偏析層４１を研磨除去するものとされている。特に本実施例の製造方法においては、例えば偏析層の厚みは３〜４μｍ程度とされており、研磨量は厚み５〜１０μｍ程度としている。研磨後には、図５（ｂ）に示すように、外表面部の偏析層４１が除去されたろう材層４が形成される。なお、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、例えば活性金属成分以外をＡｇ，Ｃｕとすることができ、該成分が主体となって一次ろう材本体層４３を構成している。活性金属成分としては、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。
【００２８】
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。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。
【００２９】
ところで、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を有する金属部材（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（上記反応層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。
【００３０】
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、この場合も上述の偏析層を除去することが好ましく、その後、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。
【００３１】
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段階に行い、その２段階の間に偏析層除去工程を行っている。したがって、二次ろう付け時の濡れ性が良く、ろう材層５ａ（ろう材フィレット５）と金属筒状体１３との間に金属間化合物（例えばＴｉ−Ｎｉ系の金属間化合物）がほとんど形成されないので、接合強度に優れたものとなる。なお、図２において、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。
【００３２】
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。
【００３３】
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。
【００３４】
（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）製で、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。
【００３５】
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。
【００３６】
一次ろう付けに際して、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。さらに、金属筒状体の接合側の端面は、レース加工時に平面度が０．１ｍｍとなるように切削した。
【００３７】
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。この一次メタライズ層について、二次ろう材との接合側端面を、ラップ研磨により約１０μｍの厚さを除去した。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（反応層）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。
【００３８】
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。
【００３９】
【表１】

【００４０】
【表２】

【００４１】
【表３】

【００４２】
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に固定して、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している。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、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。
【００４３】
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％に固定して、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。
【００４４】
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％に固定して、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。
【００４５】
（実施例２）
次に、上記実施例１と同様の方法により、金属−セラミック接合体を作製し、セラミック部材の接合側端面の平面度を０．０５ｍｍ、一次ろう材中のＴｉＨ_２の含有量を１重量％、一次ろう付け時の真空度を１．０×１０^−３Ｔｏｒｒとして、一次ろう材のセラミック部材との接合面とは反対側の端面（二次ろう付け側端面）に対する研磨加工の有無により接合強度、気密性について評価した。一方、セラミック部材の接合側端面の平面度を０．１ｍｍ、一次ろう材中のＴｉＨ_２の含有量を２０重量％、一次ろう付け時の真空度を１．０×１０^−４Ｔｏｒｒとしたものについても、一次ろう材の二次ろう付け側端面に対する研磨加工の有無により接合強度、気密性について評価した。結果を表４に示す。
【００４６】
【表４】

【００４７】
製造時において一次ろう付け後に、一次ろう材層の二次ろう付け側端面を研磨除去しない接合体（Ｎｏ．１７，１９）に比べ、一次ろう材層の二次ろう付け側端面を研磨除去した接合体（Ｎｏ．１６，１８）は、優れた接合強度と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優良であることも示された。なお、接合体（Ｎｏ．１６，１８）についてろう材層中の活性金属成分Ｔｉの含有率を解析したところ、２重量％以下であった。また、接合体（Ｎｏ．１７，１９）についてろう材層中の活性金属成分Ｔｉの含有率を解析したところ、２重量％を超える値であった。さらに、上記ろう材層の厚さｔ２と、濃度傾斜層の厚さｔ３との関係ｔ３／ｔ２について解析したところ、接合体（Ｎｏ．１６，１８）は０．２以下の値を示し、接合体（Ｎｏ．１７，１９）は０．２を超える値を示した。
【００４８】
なお、上記実施例１，２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−セラミック接合体の製造方法における研磨処理工程を説明する図。
【図６】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
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 assembly used for a ceramic tube such as a vacuum switch outer tube and a method for manufacturing the same.
[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, a method of brazing and joining between both members via a brazing material is conventionally used.
[0003]
[Problems to be solved by the invention]
However, in the conventional brazing joint between a metal member and a ceramic member, for example, when an active metal such as Ti is contained in the brazing material, the active metal is segregated on the surface of the brazing material layer to reduce the wettability of the surface. There is a case to let you. In addition, the active metal may react with Ni metal or the like 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 arisen.
[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 first configuration of the metal-ceramic bonded body of the present invention is: An Fe—Ni—Co-based alloy containing Fe as a main component, the subcomponent with the highest content being one of Ni and Co, and the second subcomponent with the second highest content being the other of Ni and Co, mainly Fe It is composed of any one of the Fe-Ni-based alloys, which are Ni and the subcomponent with the highest content is Ni. The metal member and the ceramic member are joined via the brazing material layer, and one or more kinds of activities selected from Ti, Zr, and Hf are interposed between the brazing material layer and the ceramic member. A reaction layer containing a metal component is formed; In the joining direction of the metal member and the ceramic member, the thickness of the reaction layer is 50 μm to 300 μm, and In the brazing material layer, the content of the active metal component is 2% by weight or less.
[0006]
Furthermore, the manufacturing method of the metal-ceramic bonding body of the present invention includes:
After primary brazing metal containing one or more active metal elements selected from Ti, Zr, and Hf is first brazed metallized to the end face of the ceramic member, the outer surface of the brazed primary brazing material After removing a predetermined amount of the portion, the secondary brazing material is submerged to the primary brazed portion of the ceramic member with a secondary brazing material having a lower melting point than the primary brazing material and a low active metal element content. It is characterized by brazing.
[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 primary brazing material containing an active metal element, a lower melting point than the primary brazing material, and the content of the active metal element In the two-stage step brazing, which is divided into small brazing materials (which are preferably not contained) and brazed individually, after the primary brazing, the outer surface portion of the primary brazing material When a predetermined amount was removed and secondary brazing was performed, as described above, a metal-ceramic bonding body in which the content of the active metal component was 2% by weight or less in the brazing material layer could be obtained. . In this case, the brazing material layer is mainly composed of a secondary brazing material, and the reaction layer is composed mainly of a primary brazing material.
[0008]
The active metal component contained in the primary brazing material (reaction layer) may segregate on the surface side of the primary brazing material (reaction layer) during primary brazing. When the secondary brazing is performed on the surface of this layer, the segregated active metal component reduces the brazing filler wettability of the secondary brazing, and the active metal component is contained in the secondary brazing material (brazing material layer). And thus forming an intermetallic compound with the above-described metal component, resulting in a decrease in bonding strength and destabilization of the bonding state. However, in the metal-ceramic bonded body according to the present invention, the active metal component segregated on the outer surface portion is removed by removing the outer surface portion of the primary brazing filler metal layer (reaction layer). Since the content of the active metal component in the material layer is 2% by weight or less, the above problem is solved and the joint exhibits high joint strength. Note that such removal of the outer surface portion can be performed by, for example, mechanical polishing, and examples of the mechanical polishing include lapping, buffing, barrel processing, and the like. In general, the segregation layer is often about 3 to 5 μm. In this case, for example, the removal amount is preferably about 5 to 10 μm.
[0009]
In addition, the second configuration of the metal-ceramic bonded body of the present invention is: An Fe—Ni—Co-based alloy containing Fe as a main component, the subcomponent with the highest content being one of Ni and Co, and the second subcomponent with the second highest content being the other of Ni and Co, mainly Fe It is composed of any one of the Fe-Ni-based alloys, which are Ni and the subcomponent with the highest content is Ni. The metal member and the ceramic member are joined via a brazing material layer, and one or more active metals selected from Ti, Zr, and Hf are interposed between the brazing material layer and the ceramic member. A reaction layer containing components is formed, In the joining direction of the metal member and the ceramic member, the thickness of the reaction layer is 50 μm to 300 μm, and When the thickness of the brazing material layer is t2, and the thickness of the concentration gradient layer of the active metal component formed on the bonding side with the reaction layer in the brazing material layer is t3, t3 / t2 is It is characterized by being 0.2 or less.
[0010]
In this case, the concentration gradient layer of the active metal component is a layer of the active metal component diffused from the primary brazing material to the secondary brazing material. By removing the active metal component formed on the surface of the primary brazing material during the production, the segregated active metal component is almost eliminated and the amount of diffusion is reduced. The thickness t3 of the inclined layer satisfies t3 / t2 ≦ 0.2 with respect to the thickness t2 of the brazing material layer. In such a metal-ceramic bonded body, the brazing material wettability at the time of secondary brazing is hardly lowered, and the intermetallic compound is hardly formed. Exhibits strength.
[0011]
In the above production method, 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. Can be. In this case, the active metal element in the compound acts to affect the bonding reaction with the ceramic member. When this is less than 1% by weight, poor bonding between the ceramic member and the primary brazing material is likely to occur during primary brazing. . On the other hand, if it exceeds 20% by weight, the removal operation of the segregation layer may be difficult, and the removal of the segregation layer may be insufficient. In some cases, poor wetting between materials occurs or the intermetallic compound is generated. In addition, the reaction layer (formed from the primary brazing material) between the metal member and the ceramic member of the joined body that is manufactured becomes too thick, so that the joining strength is reduced or the air tightness of the joined part is reduced. There is a case.
[0012]
The compound containing the active metal component is, for example, a hydride (for example, TiH ₂ Etc.) in the primary brazing material is also preferable for preventing the oxidation, nitridation, etc. of the active metal component (for example, Ti), and this hydride (for example, TiH). ₂ Etc.) is preferably 5 to 10% by weight. Furthermore, if the primary brazing material includes, for example, Ag, Cu, Au, Sn, etc. in addition to the active metal component, the stability of the joint portion of the metal-ceramic joined body is further improved. Among them, Ti can be used particularly suitably because it can exhibit excellent bonding performance with respect to many ceramics and is relatively inexpensive.
[0013]
In the above production method, when the primary brazing temperature is T1 = 840-880 ° C. and the secondary brazing temperature is T2 = 800-820 ° C., the difference ΔT≡ (T1-T2) is 20-80. It is good to satisfy ℃. If there is a temperature difference in such a range between the primary and secondary brazing, the active metal element that could not be completely removed contained in the primary brazing material (reaction layer) that was brazed during the secondary brazing. Since the reaction between the (active metal component) and the metal element (metal component such as Ni) contained in the metal member can be suppressed, the intermetallic compound is formed between the brazing filler metal layer and the metal member. It becomes difficult to be done. The brazing temperatures are preferably T1 = 850 to 870 ° C. and T2 = 800 to 820 ° C. ΔT is preferably 30 to 70 ° C., more preferably 40 to 60 ° C.
[0014]
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 performed under conditions exceeding Torr, the primary brazing filler metal may be poorly wetted or the active metal element may be oxidized or nitrided, and it is difficult to form a stable reaction layer between the ceramic member and the active metal element. There is a case. Note that a stable reaction layer can be formed not only in a vacuum but also in a primary brazing, for example, in an Ar gas atmosphere.
[0015]
Moreover, for example, an Ag—Cu alloy can be used as the secondary brazing material. An Ag-Cu alloy is suitable as a secondary brazing material of the present invention because it has a low melting point and good bondability with a metal member. 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. Those outside this range are not preferable for brazing and joining a metal member and a ceramic member. As the Ag—Cu based alloy of the present invention, for example, silver solder: BAg-8 described in JIS-Z3261 can be used.
[0016]
On the other hand, in the metal-ceramic bonded body produced as a result, the thickness of the reaction layer is preferably 50 μm to 300 μm in the bonding direction of the metal member and the ceramic member. When the reaction layer thickness is less than 50 μm, the bonding property may be deteriorated due to the lack of the reaction layer. When the reaction layer thickness exceeds 300 μm, the bonding layer (formed from the reaction layer and the brazing material layer) becomes too thick as a whole. As a result, the bonding strength may decrease. The above range is desirably 150 μm to 200 μm. In this case, the bonding state of the metal-ceramic bonded body is further stabilized, and the bonding strength is further improved.
[0017]
Next, what is comprised with the alumina type ceramic which has an alumina as a main component can be employ | adopted for the said ceramic member. Further, the metal member is Fe—Ni—Co whose main component is Fe, 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. It can be composed of any one of an alloy and an Fe—Ni alloy that contains Fe as a main component and Ni is the secondary component having the highest content. In this way, when a ceramic member made of alumina-based ceramic is used, or when the above-mentioned metal member containing Ni is used, the active metal-Ni-based intermetallic compound is not formed as much as possible by the manufacturing method of the present invention. Thus, it is possible to provide a metal-ceramic bonded body having a good bonding state. As the Fe—Ni—Co alloy, for example, one containing Fe: 54%, Ni: 29%, Co: 17%, etc., and as the Fe—Ni alloy, for example, Fe: 58% , Ni: A material containing 42% 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. .
[0018]
In the ceramic member, the flatness of the joint surface with the reaction layer is preferably 0.1 mm or less. If the flatness exceeds 0.1 mm, the bonding state between the ceramic member and the reaction layer may be deteriorated, and it may cause a brazing failure at the time of secondary brazing, resulting in a bonded joint. The joint strength of the body may be reduced. The flatness of the surface of the primary brazing material is preferably 0.1 mm or less by removing the segregation layer. Also in this case, when the flatness exceeds 0.1 mm, the joining state is deteriorated, which may cause a brazing failure at the time of secondary brazing.
[0019]
The brazing filler metal layer can be formed as a fillet (hereinafter also referred to as a brazing filler fillet) formed at a butt portion between the ceramic member and the metal member. As a specific embodiment of such a metal-ceramic bonded body, for example, a metal member and a ceramic member are respectively a metal cylindrical body and a ceramic cylindrical body whose end faces on at least one side are open, and the metal cylindrical body and ceramic The cylindrical body can be abutted coaxially on the open end face side, and the abutted portion can be joined via the reaction layer and the brazing material layer. 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.
[0020]
Specific examples of the structure for joining the ceramic cylindrical body and the metal cylindrical body with higher strength include the following. 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 joint 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.
[0021]
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 5 in contact with the metal member 3 at the abutting portion. 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 periphery of the end of the metal member 3 in a form in which the end of the joining side of the metal member 3 is buried. It has a shape that expands toward the side. 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.
[0022]
The ceramic member 2 is made of an alumina-based ceramic whose main component is alumina, for example, and the metal member 3 is an Fe—Ni—Co-based alloy containing, for example, Fe: 54%, Ni: 29%, 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.
[0023]
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 joining end surface 7 of the member 3, that is, the thickness t <b> 2 of the brazing material joining layer (brazing material layer) 5 a is, for example, 30 μm to 100 μm (80 μm in this embodiment).
[0024]
The thickness t1 of the reaction layer 4 and the thickness t2 of the brazing material bonding layer (brazing material layer) 5a are, for example, an electron probe microanalyzer (EPMA), energy dispersive X-ray spectroscopy (EDS), wavelength dispersive X-ray. It can be measured by a known method such as spectroscopy (WDS). In the present invention, the definition is as follows. As shown in FIG. 6, 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; if alumina, Al, 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 went. In this case, it is considered that each content of the component Q, the component M, and the component A is 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 0.8 IAmax is set as the boundary BR-W between the reaction layer and the brazing material layer, and the position where 0.8 IMmax is set 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 material bonding layer (brazing material layer) 5a is the boundaries BR-W and BW-M. The distance between each is determined.
[0025]
In the joined body 1 of the present embodiment, the brazing material layer 5a contains almost no active metal component such as Ti, and at most 2% by weight or less of the entire brazing material layer. The thickness of the brazing filler metal layer 5a is t2, and the thickness of the active metal component concentration gradient layer 25 (FIG. 6) formed on the bonding side with the reaction layer 4 in the brazing filler metal layer is t3. T3 / t2 is 0.2 or less.
[0026]
Further, between the brazing filler fillet 5 and the metal member 3, an intermetallic compound containing the active metal component and the metal component (for example, Ni), for example, a Ti—Ni-based compound is not formed as much as possible. . In other words, this means that there is almost no reaction between the Ni component in the metal member and the Ti component constituting 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. 6, 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 with respect to the peak value IAmax in the layer is desirably 0.01 or less (preferably substantially zero within the range of measurement variation).
[0027]
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. Then, metallization is performed by heating at a temperature to form a primary brazing filler metal layer 104b as shown in FIG. As shown in FIG. 5A, the

active metal components

41 and 42 often segregate in the vicinity of the surface layer portion of the primary brazing filler metal layer 104b, and the

segregated layers

41 and 42 are poorly bonded during the subsequent secondary brazing. Therefore, in the production method of the present invention, the segregation layer 41 on the side facing the ceramic member 2 out of the active metal components (segregation layers) 41 and 42 is polished and removed. In particular, in the manufacturing method of this embodiment, for example, the thickness of the segregation layer is about 3 to 4 μm, and the polishing amount is about 5 to 10 μm. After the polishing, as shown in FIG. 5B, the brazing filler metal layer 4 from which the segregation layer 41 on the outer surface portion has been removed is formed. 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 may be, for example, Ag and Cu other than the active metal component, and the primary brazing material main body layer 43 is composed mainly of the component. As the active metal component, for example, Ti, TiH ₂ In the form of 1 to 20% by weight (in this example, 5% by weight) can be used.
[0028]
Next, as shown in FIG. 4 (c), the melting point is lower than that of the primary brazing material 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 overlapped on the reaction layer 4, the end surface (joint surface) of the metal member 3 is abutted, and heated in a predetermined atmosphere and temperature in an atmosphere heating furnace to obtain a secondary Braze. As a result, the secondary brazing material foil 105 is melted to form the brazing filler fillet 5 shown in FIG. 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.
[0029]
Incidentally, 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 having a lid member 14 are hermetically joined. doing. 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 (the above reaction layer). The metal-ceramic bonded body according to the present invention is formed by bonding through a layer 15 (consisting of the layer 4 and the brazing filler fillet 5). In the abutting portion, the joining end surface on the metal tubular body 13 side is positioned at the substantially center in the radial direction of the joining end surface on the ceramic tubular body 12 side.
[0030]
When primary brazing is performed on the joint surface of the ceramic cylindrical body 12, an annular primary brazing material foil 104 corresponding to the end surface shape can be used as shown in FIG. 4 (e). Also in this case, it is preferable to remove the segregation layer described above. After that, when secondary brazing is performed, the ceramic cylindrical body 12 and the metal cylindrical body 13 are formed as shown in FIG. An annular secondary brazing foil 105 is sandwiched between the end faces.
[0031]
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 The brazing is performed in two stages as described above, and the segregation layer removing step is performed between the two stages. Therefore, the wettability at the time of secondary brazing is good, and an intermetallic compound (for example, Ti—Ni intermetallic compound) is almost formed between the brazing filler metal layer 5a (the brazing filler fillet 5) and the metal cylindrical body 13. Therefore, the bonding strength is excellent. In FIG. 2, a hook-like portion 13 a that bulges outward is formed on the lid member 14 side of the metal member 13, and airtightness and bonding strength with the lid member 14 are maintained.
[0032]
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 the contact 60 is movable. The fixed electrode rod 52 of the fixed contact 61 is airtightly attached to the end plate 57 and is movable. 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.
[0033]
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 from each other, an arc is generated between the 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 a current zero point and reaches a vacuum. It diffuses in and the current between the contacts is interrupted. 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 has high airtightness and joining strength in the joined part, and it is possible to exhibit excellent performance as a vacuum valve.
[0034]
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. 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, an outer diameter of the joining surface side of 57.5 mm, A flange-side outer diameter of 62 mm and a length of 10 mm were prepared.
[0035]
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. As a secondary brazing material, an annular BAg-8 brazing material foil having an inner diameter of 51 mm, an outer diameter of 60 mm, and a thickness of 0.13 mm was prepared.
[0036]
At the time of primary brazing, 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. Furthermore, the end surface on the joining side of the metal cylindrical body was cut so that the flatness was 0.1 mm during the lace processing.
[0037]
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. About this primary metallized layer, the thickness of about 10 μm was removed from the end surface on the joint side with the secondary brazing material by lapping. Next, in the form of sandwiching the above-mentioned secondary brazing material foil, the joining side end face of the ceramic cylindrical body formed with the primary metallized layer (reaction layer) and the joining side end face of the metal cylindrical body are butted together, Temperature T2 = 800 ° C., degree of vacuum = 1.0 × 10 ^-4 Secondary brazing was performed at Torr.
[0038]
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.
[0039]
[Table 1]

[0040]
[Table 2]

[0041]
[Table 3]

[0042]
Table 1 shows that the flatness of the end surface on the joining side of the ceramic member is fixed at 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 the appearance of a cross section obtained by cutting the joint portion in the axial direction was observed with a projector, it was confirmed that the joint portion was in a good joined state without joining unevenness. On the other hand, the joined bodies (No. 1, 6, and 7) outside the above range had lower joint strength than the above joined bodies (No. 2 to 5), and a slight decrease in airtightness was observed.
[0043]
Table 2 shows the vacuum degree during primary brazing at 1.0 × 10 ^-4 Fixed to Torr, and further TiH in primary brazing ₂ This is a result when the content of is fixed to 12% by weight and the flatness of the end face on the joining side 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.
[0044]
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.
[0045]
(Example 2)
Next, a metal-ceramic bonding body was prepared by the same method as in Example 1, the flatness of the bonding-side end surface of the ceramic member was 0.05 mm, and TiH in the primary brazing material ₂ Content of 1% by weight, and the degree of vacuum during primary brazing is 1.0 × 10 ^-3 As Torr, the bonding strength and airtightness were evaluated based on the presence or absence of polishing on the end surface (secondary brazing side end surface) opposite to the bonding surface of the primary brazing material with the ceramic member. On the other hand, the flatness of the joining side end face of the ceramic member is 0.1 mm, TiH in the primary brazing material ₂ Content of 20% by weight, and the degree of vacuum during primary brazing is 1.0 × 10 ^-4 With respect to the Torr, the bonding strength and hermeticity were evaluated based on the presence or absence of polishing on the secondary brazing side end surface of the primary brazing material. The results are shown in Table 4.
[0046]
[Table 4]

[0047]
After the primary brazing at the time of production, the secondary brazing side end surface of the primary brazing material layer was polished and removed as compared with the joined body (No. 17, 19) in which the secondary brazing side end surface of the primary brazing material layer was not polished and removed. The joined body (Nos. 16 and 18) was shown to have excellent joining strength and airtightness, and the joining state was also shown to be excellent by cross-sectional observation. In addition, when the content rate of the active metal component Ti in a brazing filler metal layer was analyzed about a joined body (No. 16, 18), it was 2 weight% or less. Moreover, when the content rate of the active metal component Ti in a brazing material layer was analyzed about a joined body (No. 17, 19), it was a value exceeding 2 weight%. Furthermore, when the relationship t3 / t2 between the thickness t2 of the brazing filler metal layer and the thickness t3 of the concentration gradient layer was analyzed, the joined body (Nos. 16 and 18) showed a value of 0.2 or less. The body (No. 17, 19) showed a value exceeding 0.2.
[0048]
In Examples 1 and 2, the same test as in the above Examples was performed using an Fe—Ni alloy (Fe: 58%, Ni: 42% included) as the 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 one embodiment of a 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 view for explaining a method for producing a metal-ceramic bonded body according to the present invention.
FIG. 5 is a view for explaining a polishing process step in the method for producing a metal-ceramic bonded body of the present invention.
FIG. 6 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

An Fe—Ni—Co-based alloy containing Fe as a main component, the subcomponent having the highest content ratio being one of Ni and Co, and the second subcomponent having the second highest content ratio being the other of Ni and Co, mainly Fe As a component, a metal member composed of any one of the Fe-Ni alloys whose subcomponent with the highest content is Ni and a ceramic member are joined together through a brazing material layer, and the brazing Between the material layer and the ceramic member, a reaction layer containing one or more active metal components selected from Ti, Zr, and Hf is formed, and the metal member and the ceramic member Metal-ceramic bonding characterized in that, in the bonding direction, the thickness of the reaction layer is 50 μm to 300 μm, and the brazing material layer has a content of the active metal component of 2% by weight or less. body.

An Fe—Ni—Co-based alloy containing Fe as a main component, the subcomponent having the highest content ratio being one of Ni and Co, and the second subcomponent having the second highest content ratio being the other of Ni and Co, mainly Fe As a component, a metal member composed of any one of Fe—Ni-based alloys in which the secondary component having the highest content is Ni and a ceramic member are joined together via a brazing material layer, and the brazing material A reaction layer containing one or more active metal components selected from Ti, Zr, and Hf is formed between the layer and the ceramic member, and the metal member and the ceramic member are joined together. The active metal component formed on the bonding side with the reaction layer in the brazing material layer, wherein the thickness of the reaction layer is 50 μm to 300 μm in the direction, and the thickness of the brazing material layer is t2. The thickness of the concentration gradient layer is t 3, the metal-ceramic bonded body, wherein t3 / t2 is 0.2 or less.

The metal-ceramic bonding body according to claim 1 or 2, wherein the ceramic member is made of an alumina-based ceramic whose main component is alumina.

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 each a metal cylindrical body and a ceramic cylindrical body each having an open end face on at least one side, and the metal cylindrical body and the ceramic cylindrical body are coaxially butted on the open end face side, The metal-ceramic bonded body according to any one of claims 1 to 4 , wherein the butted portion is bonded through the reaction layer and the 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 flat 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). The both sides in the thickness direction are covered in such a manner that the end portion of the metal cylindrical body is buried, and the cross-sectional outer shape of both ends of the metal cylindrical body on the inner surface side and the outer surface side is from the metal cylindrical body side to the ceramic tube. The metal-ceramic bonding body according to claim 5 or 6, wherein the metal-ceramic bonding body has a shape that expands toward the side of the body.

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

A method for producing a metal-ceramic bonding article according to any one of claims 1 to 8, wherein a primary brazing material containing one or more active metal elements selected from Ti, Zr, and Hf is used. After the primary brazing metallization to the end surface portion of the ceramic member, a predetermined amount of the outer surface portion of the brazed primary brazing material is removed, and then the active metal element having a lower melting point than the primary brazing material and the active metal element A method for producing a metal-ceramic joint, wherein the metal member is secondarily brazed to a primary brazed portion of the ceramic member by a secondary brazing material having a small content of.

The method for producing a metal-ceramic bonding article according to claim 9 , wherein the removal of the outer surface portion of the primary brazing material is to remove the segregation layer of the active metal component formed on the outer surface portion .

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-ceramics assembly as described .

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 the removal of the outer surface portion of the primary brazing material is performed by a mechanical polishing process .