JP4309999B2

JP4309999B2 - Composite member and manufacturing method thereof

Info

Publication number: JP4309999B2
Application number: JP18422599A
Authority: JP
Inventors: 恒久畑; 裕介豊田; 武雄伊藤; 捷彌長瀬; 英男清水
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1999-06-29
Filing date: 1999-06-29
Publication date: 2009-08-05
Anticipated expiration: 2019-06-29
Also published as: JP2001009564A

Description

【０００１】
【発明の属する技術分野】
本発明は複合部材、特に、部材本体と、その部材本体の鋳造過程で、それに接合された被鋳ぐるみ材とよりなる複合部材およびその製造方法に関する。
【０００２】
【従来の技術】
従来、この種の複合部材としては、例えばディーゼルエンジン用ピストンが知られている。このピストンにおいて、部材本体としてのピストン本体はＡｌ合金よりなり、また被鋳ぐるみ材としての第１圧縮リング溝形成用環状体はニレジスト鋳鉄よりなる環状主体と、その主体に形成されたＡｌ系メッキ層とより構成される。このＡｌ系メッキ層は、アルフィン法の一工程として溶融メッキ処理により形成されたものである。
【０００３】
【発明が解決しようとする課題】
しかしながら前記溶融メッキ処理においては、Ａｌ系メッキ層と環状主体との間に、Ａｌ系溶湯と環状主体を構成するニレジスト鋳鉄との反応により金属間化合物が層状に形成され、この金属間化合物層はＡｌ系メッキ層とは強く接合しているが、環状主体との接合が弱いことから、そこが破断し易く、したがってピストン本体と環状体との接合強度が低い、という問題があった。
【０００４】
【課題を解決するための手段】
本発明は部材本体と被鋳ぐるみ材との接合強度を大いに向上させた前記複合部材を提供することを目的とする。
【０００５】
前記目的を達成するため本発明によれば、Ａｌ合金製の部材本体と、その部材本体の鋳造過程で、該部材本体に接合された被鋳ぐるみ材とよりなる複合部材において、前記被鋳ぐるみ材がニレジスト鋳鉄製の主体と、その主体の前記部材本体側の表面に形成された硬質クロムメッキ層とよりなり、前記被鋳ぐるみ材は、底部が前記主体に達するように前記硬質クロムメッキ層を貫通していて前記部材本体との接合界面に開口する１以上の凹部を、また前記部材本体は前記凹部に嵌合する１以上の凸部をそれぞれ有していると共に、前記凹部が、前記凸部を形成するＡｌ合金組成の溶湯と前記被鋳ぐるみ材との反応により生じたものであって、開口部分が窄まっており、前記硬質クロムメッキ層の部材本体側は、該硬質クロムメッキ層とＡｌ合金組成の溶湯との反応で生じたＣｒＡｌ系金属間化合物層に変化していて、そのＣｒＡｌ系金属間化合物層の外面が前記接合界面となっており、また前記各凸部の外周部分は、Ａｌ合金組成の溶湯とニレジスト鋳鉄との反応により生じたＦｅＡｌ系金属間化合物より構成されると共に、その各凸部の基端部分は、前記凹部の開口部分の窄まりに対応してくびれていることを特徴とする複合部材が提供される。
【０００６】
前記のように構成すると、Ａｌ合金製の部材本体と一体の各凸部が、ニレジスト鋳鉄製の主体とその表面に形成された硬質クロムメッキ層とよりなる被鋳ぐるみ材における開口部分が窄まった各凹部に抜止め嵌合しているので、部材本体と被鋳ぐるみ材との接合強度が高められる。また各凹、凸部は前記のような反応に伴うものであるからそれらの密着性が高く、したがって部材本体および被鋳ぐるみ材間の熱伝導性が良好である。これは複合部材がディーゼルエンジン用ピストン等の高温環境で使用される部材であって、良好な冷却性を求められる場合に有効である。
【０００７】
また本発明は前記複合部材を確実に得ることができる前記製造方法を提供することを目的とする。
【０００８】
前記目的を達成するため本発明によれば、Ａｌ合金製の部材本体と、その部材本体の鋳造過程で、該部材本体に接合された被鋳ぐるみ材とよりなる複合部材であって、前記被鋳ぐるみ材がニレジスト鋳鉄製の主体と、その主体の前記部材本体側の表面に形成された硬質クロムメッキ層とよりなる複合部材を製造するに当り、前記被鋳ぐるみ材の前記主体に前記硬質クロムメッキ層を形成すると共に、その硬質クロムメッキ層に、その表面から前記主体に達する１以上のクラックを層全体に亘って発生させる第１の工程と、前記メッキ層表面にＡｌ合金組成の溶湯を付与して、前記部材本体を成形する溶湯との相溶性の良い皮膜を前記メッキ層と一体に形成し、またその溶湯の一部を前記クラックを通じて前記被鋳ぐるみ材の前記主体まで到達させることによって、前記硬質クロムメッキ層と溶湯との反応による前記クラックの拡幅および前記主体と溶湯との反応による該主体の侵食をそれぞれ惹起させて、その侵食により前記主体に１以上の小凹部を形成する第２の工程と、前記被鋳ぐるみ材を鋳型内に設置して、前記皮膜を取込んだ前記部材本体を鋳造し、また前記クラックの拡幅および前記主体の侵食の進行により、前記被鋳ぐるみ材に、前記部材本体との接合界面に開口し且つその開口部分が窄まっている１以上の凹部を形成すると共に、前記部材本体に、前記凹部に嵌合する１以上の凸部を形成する第３の工程とを用い、前記第１の工程では、前記硬質クロムメッキ層に前記クラックが発生するように、該硬質クロムメッキ層の厚さｔ ₁ が１．５μｍ≦ｔ ₁ ≦８μｍに設定されることを特徴とする複合部材の製造方法が提供される。
【０００９】
前記方法によれば所期の目的を達成することができる。
【００１０】
【発明の実施の形態】
図１において、複合部材１は部材本体２と、その部材本体２の鋳造過程で、それに接合された被鋳ぐるみ材３とよりなる。被鋳ぐるみ材３は部材本体２との接合界面４に開口する１以上のスロット状凹部５を、また部材本体２は凹部５に嵌合する１以上のビード状凸部６をそれぞれ有する。各凹部５は各凸部６を形成する溶湯と被鋳ぐるみ材３との反応により生じたものであって、開口部分７が窄まっている。
【００１１】
部材本体２はＡｌ合金よりなる。被鋳ぐるみ材３は、ニレジスト鋳鉄よりなる主体８と、その表面に形成されたメッキ層としての硬質クロムメッキ層９とより構成される。その硬質クロムメッキ層９の部材本体２側は、Ａｌ合金組成の溶湯との反応で生じたＣｒＡｌ系金属間化合物層１０に変化しており、その金属間化合物層１０の外面が部材本体２との接合界面４である。各凸部６の外周部分は、Ａｌ合金組成の溶湯と、主としてニレジスト鋳鉄との反応により生じたＦｅＡｌ系金属間化合物１１より構成され、またその基端部分は凹部５の開口部分７の窄まりに対応してくびれている。
【００１２】
前記のように構成すると、部材本体２と一体の各凸部６が、被鋳ぐるみ材３における開口部分７が窄まった各凹部５に抜止め嵌合しているので、部材本体２と被鋳ぐるみ材３との接合強度が高められる。また各凹、凸部５、６は前記のように反応に伴うものであるからそれらの密着性が高く、したがって部材本体２および被鋳ぐるみ材３間の熱伝導性が良好である。これは複合部材１がディーゼルエンジン用ピストン等の高温環境で使用される部材であって、良好な冷却性を求められる場合に有効である。
【００１３】
複合部材１の製造に当っては次のような方法が採用される。
【００１４】
（１）図２（ａ）、図３に示すように、前処理後の被鋳ぐるみ材３の主体８に電気メッキ処理により硬質クロムメッキ層９を形成すると共にその硬質クロムメッキ層９に、その表面から主体８に達する１以上のクラック１２を層全体に亘って発生させる。
【００１５】
（２）図２（ｂ）、（ｃ）に示すように、溶融メッキ処理等により硬質クロムメッキ層９表面にＡｌ合金組成の溶湯１３を付与して、部材本体２を成形する溶湯との相溶性の良い皮膜１４を硬質クロムメッキ層９と一体に形成する。またその溶湯１３の一部をクラック１２を通じて被鋳ぐるみ材３の主体８まで到達させることによって、硬質クロムメッキ層９と溶湯１３との反応によるクラック１２の拡幅および主体８と溶湯１３との反応によるその主体８の侵食をそれぞれ惹起させる。硬質クロムメッキ層９の表層側と溶湯１３との反応によりＣｒＡｌ系金属間化合物層１０が形成される。また前記侵食により主体８に１以上の小凹部５₀が形成されると共にＦｅＡｌ系金属間化合物１１が生成される。
【００１６】
（３）被鋳ぐるみ材３を鋳型内に設置して、皮膜１４を取込んだ部材本体２を鋳造する。またクラック１２の拡幅および主体８の侵食の進行により、図１に示したように被鋳ぐるみ材３に、部材本体２との接合界面４に開口し、且つその開口部分７が窄まっている１以上の凹部５を形成すると共に部材本体２に、凹部５に嵌合する１以上の凸部６を形成する。
【００１７】
被鋳ぐるみ材３の主体８に対する前処理は、溶剤脱脂→アルカリ脱脂→水洗→酸洗→水洗の順序で行われ、水洗後の主体８はそのままメッキ浴に入れられる。また硬質クロムメッキ層９の厚さｔ₁は１．５μｍ≦ｔ₁≦８μｍに設定される。このように設定すると、その層９にはそれを貫通するようにクラック１２が自然に発生する。
【００１８】
部材本体２および皮膜１４をＪＩＳＡＣ８ＡといったＡｌ合金より構成する場合、溶融メッキ処理における溶湯温度Ｔ_Eは６９５℃≦Ｔ_E≦７２５℃に、また浸漬時間Ｔ_Iは１０５sec ≦Ｔ_I≦１８０sec にそれぞれ設定される。この場合、溶湯温度Ｔ_EがＴ_E＞７２５℃であるか、浸漬時間Ｔ_IがＴ_I＞１８０sec である場合には硬質クロムメッキ層９の拡散が激しくなるため凹、凸部５、６を形成することができず、一方、溶湯温度Ｔ_EがＴ_E＜６９５℃であるか、浸漬時間Ｔ_IがＴ_I＜１０５sec である場合には溶湯１３と硬質クロムメッキ層９との濡れ性が悪化して接合不良を招く。
【００１９】
部材本体２の鋳造に当っては、被鋳ぐるみ材３を溶融メッキ処理後一旦冷却し、次いで予熱してから鋳型内に設置するか、または被鋳ぐるみ材３を、溶融メッキ処理における溶湯１３中より取出した後直ちに鋳型内に設置する、といった方法が採用される。後者の場合、皮膜１４は溶融状態にある。なお、皮膜１４の厚さｔ₂は、５０μｍ≦ｔ₂≦３００μｍである。
【００２０】
以下、具体例について説明する。
【００２１】
〔Ｉ〕接合界面４における凹部５の占有率Ａと接合強度Ｓとの関係
被鋳ぐるみ材３の主体８として、縦８０mm、横５０mm、厚さ５mmのニレジスト鋳鉄製板材を選択した。このニレジスト鋳鉄は、２．５ｗｔ％Ｃ、２ｗｔ％Ｓｉ、１ｗｔ％Ｍｎ、１５ｗｔ％Ｎｉ、６ｗｔ％Ｃｕ、２ｗｔ％Ｃｒおよび残部不可避不純物を含むＦｅよりなる。
【００２２】
８枚の主体８に前処理を施した後、それらに電気メッキ処理を施して硬質クロムメッキ層９を形成し、被鋳ぐるみ材３の例１〜８を得た。例１〜８の電気メッキ処理条件は表１、２の通りである。
【００２３】
【表１】

【００２４】
【表２】

【００２５】
次いで、例１〜８を、７１０℃のＪＩＳＡＣ８Ａ組成の溶湯中に１２０sec 浸漬した。その後、例１〜８を溶湯中から取出して直ちに鋳型内に設置し、ＪＩＳＡＣ８Ａ組成の溶湯を鋳型に注入して部材本体２を鋳造すると共にそれに被鋳ぐるみ材３を鋳ぐるんで複合部材１の例１〜８を得た。これらの例１〜８は被鋳ぐるみ材３の例１〜８にそれぞれ対応する。
【００２６】
複合部材１の例１〜８について、接合界面４における凹部５の占有率Ａを求め、また部材本体２および被鋳ぐるみ材３間の接合強度Ｓを求めた。前記占有率Ａは、接合界面４における任意長さをＡ₁とし、また図１に示すように凹部５の最大幅をａとして、前記長さＡ₁内に存する全凹部５の最大幅ａの和をＡ₂としたとき、Ａ＝（Ａ₂／Ａ₁）×１００（％）として求められた。また接合強度Ｓについては、図４に示すようにテストピースＴｐにおける被鋳ぐるみ材３の両端を２つの支持台１５上に載せ、被鋳ぐるみ材３の中央に形成された孔１６に加圧部材１７を嵌めて部材本体２を押圧し、その部材本体２が被鋳ぐるみ材３から離脱したときの加荷重Ｌ_Oを求め、接合部の面積をＡ_S（ただし、孔１６の断面積は除かれる）としてＳ＝Ｌ_O／Ａ_Sを算出した。
【００２７】
表３は、複合部材１の例１〜８における硬質クロムメッキ層９の厚さｔ₁および凹部５の占有率Ａと接合強度Ｓとの関係を示す。
【００２８】
【表３】

【００２９】
図５は表３に基づいて、凹部５の占有率Ａと接合強度Ｓとの関係をグラフ化したものである。
【００３０】
表３、図５から明らかなように、例２〜７のごとく、硬質クロムメッキ層９の厚さｔ₁を１．５μｍ≦ｔ₁≦８μｍに設定すると、凹部５の占有率Ａを５％≦Ａ≦９５％にして、３６ＭＰａ≦Ｓ≦５６ＭＰａといった比較的大きな接合強度Ｓを得ることができる。例１の場合は接合界面４の面積が過少であることに起因して接合強度Ｓが低く、また例８の場合は硬質クロムメッキ層９の厚さが大となって前記のような貫通クラックが存在しないことから凹部５が形成されなかったものである。
【００３１】
なお、例２〜７において、凹部５の存在率Ｂ（後述）はＢ≧１０％の範囲にあり、また凹部５の最大幅ａの平均値ａ₁（後述）は１５μｍ≦ａ₁≦２００μｍの範囲にあり、さらに硬質クロムメッキ層９のクラック密度Ｄ（後述）は１４０クラック数／cm≦Ｄ≦７５０クラック数／cmの範囲にあった。
【００３２】
〔II〕凹部５の存在率Ｂと接合強度Ｓとの関係
前記同様の４枚の主体８に前処理を施した後、それらに電気メッキ処理を施して、厚さｔ₁が４．５μｍの硬質クロムメッキ層９を形成し、被鋳ぐるみ材３の例９〜１２を得た。例９〜１２の電気メッキ処理条件は表４、５の通りである。
【００３３】
【表４】

【００３４】
【表５】

【００３５】
次いで、例９〜１２における凹部５の存在率Ｂを変化させるべく、それら例９〜１２を、所定温度のＪＩＳＡＣ８Ａ組成の溶湯中に所定時間浸漬した。その後、例９〜１２を溶湯中から取出して直ちに鋳型内に設置し、ＪＩＳＡＣ８Ａ組成の溶湯を鋳型に注入して部材本体２を鋳造すると共にそれに被鋳ぐるみ材３を鋳ぐるんで複合部材１の例９〜１２を得た。これらの例９〜１２は被鋳ぐるみ材３の例９〜１２にそれぞれ対応する。
【００３６】
複合部材１の例９〜１２について、接合界面４における凹部５の存在率Ｂを求め、また部材本体１および被鋳ぐるみ材３間の接合強度Ｓを前記同様の方法で求めた。前記存在率Ｂは、接合界面４の任意長さＡ₁内において、開口部分７が窄んでいる凹部５および開口部分が窄んでいない凹部を含む全部の凹部の数をＢ₁とし、また開口部分７が窄んでいる全凹部５の数をＢ₂としたとき、Ｂ＝（Ｂ₂／Ｂ₁）×１００（％）として求められた。
【００３７】
表６は、複合部材１の例９〜１２における溶湯への浸漬条件、凹部５の存在率Ｂおよび接合強度Ｓの関係を示す。
【００３８】
【表６】

【００３９】
図６は表６に基づいて、凹部５の存在率Ｂと接合強度Ｓとの関係をグラフ化したものである。
【００４０】
表６、図６から明らかなように、例１０〜１２のごとく、凹部５の存在率ＢをＢ≧１０％に設定すると、Ｓ≧３８ＭＰａといった比較的大きな接合強度Ｓを得ることができる。
【００４１】
なお、例１０〜１２において、凹部５の占有率Ａは５％≦Ａ≦９５％の範囲にあり、また凹部５の最大幅ａの平均値ａ₁（後述）は１５μｍ≦ａ₁≦２００μｍの範囲にあり、さらに硬質クロムメッキ層９のクラック密度Ｄ（後述）は１４０クラック数／cm≦Ｄ≦７５０クラック数／cmの範囲にあった。
【００４２】
〔III 〕凹部５の最大幅ａの平均値ａ₁と接合強度Ｓとの関係
前記同様の７枚の主体８に前処理を施した後、それらに電気メッキ処理を施して厚さｔ₁が４．５μｍの硬質クロムメッキ層９を形成し、被鋳ぐるみ材３の例１３〜１９を得た。例１３〜１９の電気メッキ処理条件は表７、８の通りである。
【００４３】
【表７】

【００４４】
【表８】

【００４５】
次いで、例１３〜１９における凹部５の最大幅ａの平均値ａ₁を変化させるべく、それら例１３〜１９を、所定温度のＪＩＳＡＣ８Ａ組成の溶湯中に所定時間浸漬した。その後、例１３〜１９を溶湯中から取出して直ちに鋳型内に設置し、ＪＩＳＡＣ８Ａ組成の溶湯を鋳型に注入して部材本体２を鋳造すると共にそれに被鋳ぐるみ材３を鋳ぐるんで複合部材１の例１３〜１９を得た。これらの例１３〜１９は被鋳ぐるみ材３の例１３〜１９にそれぞれ対応する。
【００４６】
複合部材１の例１３〜１９について、凹部５の最大幅ａの平均値ａ₁を求め、また部材本体１および被鋳ぐるみ材３間の接合強度Ｓを前記同様の方法で求めた。前記平均値ａ₁は、接合界面４における任意長さＡ₁内に存する全凹部５の数をＢ₂とし、また全凹部５の最大幅ａの和をＡ₂としたとき、ａ₁＝Ａ₂／Ｂ₂として求められた。
【００４７】
表９は、複合部材１の例１３〜１９における溶湯への浸漬条件、凹部５の最大幅ａの平均値ａ₁および接合強度Ｓの関係を示す。
【００４８】
【表９】

【００４９】
図７は表９に基づいて、凹部５の最大幅ａの平均値ａ₁と接合強度Ｓとの関係をグラフ化したものである。
【００５０】
表９、図７から明らかなように、例１４〜１７のごとく、凹部５の最大幅ａの平均値ａ₁を１５μｍ≦ａ₁≦２００μｍに設定すると、３８ＭＰａ≦Ｓ≦５２ＭＰａといった比較的大きな接合強度Ｓを得ることができる。例１３の場合は平均値ａ₁が小さ過ぎ、一方、例１９の場合は平均値ａ₁が大き過ぎることから凹部５によるアンカ効果が減退する。
【００５１】
なお、例１４〜１７において、凹部５の占有率Ａは５％≦Ａ≦９５％の範囲にあり、また凹部５の存在率ＢはＢ≧１０％の範囲にあり、さらに硬質クロムメッキ層９のクラック密度Ｄ（後述）は１４０クラック数／cm≦Ｄ≦７５０クラック数／cmの範囲にあった。
【００５２】
〔IV〕硬質クロムメッキ層９のクラック密度Ｄと接合強度Ｓの関係
前記同様の８枚の主体８に前処理を施した後、それらに電気メッキ処理を施して硬質クロムメッキ層９を形成し、被鋳ぐるみ材３の例２０〜２７を得た。例２０〜２７の電気メッキ処理条件は表１０、１１の通りである。
【００５３】
【表１０】

【００５４】
【表１１】

【００５５】
電気メッキ処理後例２０〜２７について、硬質クロムメッキ層９の厚さｔ₁およびそのメッキ層９を貫通しているクラック１２の密度Ｄ（クラック数／cm）を求めた。次いで、例２０〜２７を、７１０℃のＪＩＳＡＣ８Ａ組成の溶湯中に１２０sec 浸漬した。その後、例２０〜２７を溶湯中から取出して直ちに鋳型内に設置し、ＪＩＳＡＣ８Ａ組成の溶湯を鋳型に注入して部材本体２を鋳造すると共にそれに被鋳ぐるみ材３を鋳ぐるんで複合部材１の例２０〜２７を得た。これらの例２０〜２７は被鋳ぐるみ材３の例２０〜２７にそれぞれ対応する。
【００５６】
複合部材１の例２０〜２７について部材本体１および被鋳ぐるみ材３間の接合強度Ｓを前記同様の方法で求めた。
【００５７】
表１２は、複合部材１の例２０〜２７における硬質クロムメッキ層９の厚さｔ₁およびクラック密度Ｄと接合強度Ｓとの関係を示す。
【００５８】
【表１２】

【００５９】
図８は表１２に基づいて、クラック密度Ｄと接合強度Ｓとの関係をグラフ化したものである。
【００６０】
表１２、図８から明らかなように、例２１〜２５のごとく、硬質クロムメッキ層９の厚さｔ₁を１．５μｍ≦ｔ₁≦８μｍに設定すると、クラック密度Ｄを１４０クラック数／cm≦Ｄ≦７５０クラック数／cmにして、３６ＭＰａ≦Ｓ≦５２ＭＰａといった比較的大きな接合強度Ｓを得ることができる。
【００６１】
なお、例２１〜２５において、凹部５の占有率Ａは５％≦Ａ≦９５％の範囲にあり、また凹部５の存在率ＢはＢ≧１０％の範囲にあり、さらに凹部５の最大幅ａの平均値ａ₁は１５μｍ≦ａ₁≦２００μｍの範囲にあった。
【００６２】
鋳造において、注湯開始から凝固終了までの冷却速度Ｃ_Rは２．５℃／sec ≦Ｃ_R≦５℃／sec であることが望ましい。このような冷却速度Ｃ_Rの設定は、被鋳ぐるみ材３の接合界面４の変化を抑制して凹、凸部５、６の形状を安定化させる上で有効である。
【００６３】
【発明の効果】
本発明によれば前記のように構成することによって、部材本体と被鋳ぐるみ材との接合強度を大いに向上させた複合部材を提供することができる。
【００６４】
また本発明によれば前記のような手段を採用することによって、前記複合部材を確実に得ることが可能な製造方法を提供することができる。
【図面の簡単な説明】
【図１】複合部材の要部拡大断面図である。
【図２】複合部材の製造工程説明図である。
【図３】硬質クロムメッキ層の平面図である。
【図４】接合強度の測定方法説明図である。
【図５】凹部の占有率Ａと接合強度Ｓとの関係を示すグラフである。
【図６】凹部の存在率Ｂと接合強度Ｓとの関係を示すグラフである。
【図７】凹部の最大幅ａの平均値ａ₁と接合強度Ｓとの関係を示すグラフである。
【図８】クラック密度Ｄと接合強度Ｓとの関係を示すグラフである。
【符号の説明】
１複合部材
２部材本体
３被鋳ぐるみ材
４接合界面
５ ₀ 小凹部
５凹部
６凸部
７開口部分
８主体
９硬質クロムメッキ層
１０ＣｒＡｌ系金属間化合物層
１１ＦｅＡｌ系金属間化合物
１２クラック
１３溶湯
１４皮膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composite member, and more particularly, to a composite member including a member main body, and a cast stuffed material joined to the member main body in a casting process of the member main body, and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, as this type of composite member, for example, a piston for a diesel engine is known. In this piston, the piston main body as a member main body is made of an Al alloy, and the first compression ring groove forming annular body as a cast fill material is an annular main body made of Ni-resist cast iron, and an Al-based plating formed on the main body. Composed of layers. This Al-based plating layer is formed by a hot dipping process as one step of the Alfin method.
[0003]
[Problems to be solved by the invention]
However, in the hot-dip plating process, an intermetallic compound is formed in layers between the Al-based plating layer and the annular main body by a reaction between the Al-based molten metal and Niresist cast iron constituting the annular main body. Although it is strongly bonded to the Al-based plating layer, since the bonding with the annular main body is weak, there is a problem that it is easy to break, and therefore the bonding strength between the piston body and the annular body is low.
[0004]
[Means for Solving the Problems]
An object of the present invention is to provide the composite member in which the joint strength between the member main body and the cast-in-place material is greatly improved.
[0005]
In order to achieve the above object, according to the present invention, in a composite member comprising an Al alloy member main body and a cast fill material joined to the member main body in the casting process of the member main body, the cast fill The material consists of a main body made of Ni-resist cast iron and a hard chrome plating layer formed on the surface of the main body of the main body, and the cast stuffed material has the hard chrome plating layer so that the bottom reaches the main body. the extend through openings in the joint interface between the member body 1 or more recesses, also together with the member body has one or more protrusions to be fitted into the recess, respectively, the recess, the It is generated by a reaction between the molten Al alloy composition forming the convex portion and the cast material, the opening portion is narrowed, and the member main body side of the hard chrome plating layer is the hard chrome plating. Layer and Al It has changed to a CrAl-based intermetallic compound layer generated by the reaction with the molten metal of the gold composition, the outer surface of the CrAl-based intermetallic compound layer is the bonding interface, and the outer peripheral portion of each convex portion, It is composed of an FeAl-based intermetallic compound produced by the reaction between the molten Al alloy composition and Ni-resist cast iron, and the base end portion of each convex portion is constricted to correspond to the constriction of the opening portion of the concave portion. A composite member is provided.
[0006]
When configured as described above, each convex portion integrated with the Al alloy member main body is narrowed in the opening portion of the cast swallow material made up of the main body made of Ni-resist cast iron and the hard chromium plating layer formed on the surface thereof. In addition, since it is fitted in each recess, the bonding strength between the member main body and the cast-out material is increased. The respective concave and convex portion and the high adhesion them from those associated with the reaction, such as, hence the heat conductivity between the member body and the insert casting material is good. This is effective when the composite member is a member used in a high-temperature environment such as a piston for a diesel engine and a good cooling property is required.
[0007]
Moreover, this invention aims at providing the said manufacturing method which can obtain the said composite member reliably.
[0008]
In order to achieve the above object, according to the present invention, there is provided a composite member comprising an Al alloy member main body and a to-be-casting material joined to the member main body in a casting process of the member main body. In producing a composite member comprising a main body made of Ni-resist cast iron and a hard chrome plating layer formed on the surface of the main body of the main body, the main body of the to- be-cast base material is the hard body. and forming a chromium plating layer, its hard chrome plating layer, a first step of generating over one or more cracks from the surface reaches the main throughout the layer, the Al alloy composition on the plating layer surface melt Is formed integrally with the plating layer, and a part of the molten metal reaches the main body of the cast blanket through the crack. By, said hard chromium plating layer and the melt and the reaction each was induced erosion of the principal by reaction with widening and the metallic and the melt of the cracks due to the, one or more small recesses in the main by the erosion The second step to be formed , the cast body material is placed in a mold, the member body incorporating the coating is cast, and the crack is widened and the main body is eroded. the casting-material, and forming one or more recesses opened 且 one the opening portion at the bonding interface between said member main body is narrowed, the member main body, one or more protrusions to be fitted into the recess using a third step of forming a, in the first step, the so cracks in the hard chrome plating layer, the thickness t ₁ of the hard chromium plating layer is 1.5 [mu] m ≦ t ₁ ≦ Set to 8μm A method for manufacturing a composite member is provided.
[0009]
According to the method, the intended purpose can be achieved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, the composite member 1 includes a member main body 2 and a cast-up material 3 joined to the member main body 2 during the casting process of the member main body 2. The to-be-cast material 3 has one or more slot-like recesses 5 that open to the joint interface 4 with the member body 2, and the member body 2 has one or more bead-like projections 6 that fit into the recesses 5. Each concave portion 5 is generated by a reaction between the molten metal forming each convex portion 6 and the cast fill material 3, and the opening portion 7 is narrowed.
[0011]
The member body 2 is made of an Al alloy. The to-be-cast material 3 is composed of a main body 8 made of Ni-resist cast iron and a hard chromium plating layer 9 as a plating layer formed on the surface thereof. The member main body 2 side of the hard chrome plating layer 9 is changed to a CrAl-based intermetallic compound layer 10 generated by a reaction with a molten metal having an Al alloy composition, and the outer surface of the intermetallic compound layer 10 is connected to the member main body 2. This is the bonding interface 4. The outer peripheral portion of each convex portion 6 is composed of a FeAl-based intermetallic compound 11 produced mainly by the reaction between the molten Al alloy composition and Ni-resist cast iron, and its base end portion is a constriction of the opening portion 7 of the concave portion 5. Corresponding to.
[0012]
With the above-described configuration, each convex portion 6 integral with the member main body 2 is fitted to each concave portion 5 in which the opening portion 7 in the casted swallow material 3 is narrowed. The joining strength with the cast-in material 3 is increased. Moreover, since each concave and convex

part

5 and 6 accompany reaction as mentioned above, those adhesiveness is high, Therefore, the thermal conductivity between the member main body 2 and the to-be-casting material 3 is favorable. This is effective when the composite member 1 is a member used in a high temperature environment such as a piston for a diesel engine, and good cooling performance is required.
[0013]
In manufacturing the composite member 1, the following method is employed.
[0014]
(1) As shown in FIG. 2 (a) and FIG. 3, a hard chrome plating layer 9 is formed by electroplating on the main body 8 of the to-be-cast material 3 after the pretreatment, and the hard chrome plating layer 9 is One or more cracks 12 reaching the main body 8 from the surface are generated over the entire layer.
[0015]
(2) As shown in FIGS. 2 (b) and 2 (c), a phase with the molten metal for forming the member main body 2 by applying a molten alloy 13 of Al alloy composition to the surface of the hard chrome plated layer 9 by a hot dipping process or the like. A film 14 having good solubility is formed integrally with the hard chrome plating layer 9. Further, by causing a part of the molten metal 13 to reach the main body 8 of the cast blank 3 through the crack 12, the crack 12 is widened by the reaction between the hard chromium plating layer 9 and the molten metal 13 and the reaction between the main body 8 and the molten metal 13. Cause erosion of the subject 8 by. A CrAl-based intermetallic compound layer 10 is formed by a reaction between the surface layer side of the hard chromium plating layer 9 and the molten metal 13. The FeAl intermetallic compound 11 is produced with one or more small recesses 5 ₀ mainly 8 is formed by the erosion.
[0016]
(3) The cast body 3 is placed in the mold, and the member body 2 incorporating the coating 14 is cast. Further, due to the widening of the crack 12 and the progress of the erosion of the main body 8, as shown in FIG. One or more concave portions 5 are formed, and one or more convex portions 6 that fit into the concave portions 5 are formed in the member main body 2.
[0017]
The pretreatment for the main body 8 of the cast-in-place material 3 is performed in the order of solvent degreasing → alkali degreasing → water washing → acid washing → water washing, and the main body 8 after water washing is put in a plating bath as it is. The thickness t ₁ of the hard chrome plating layer 9 is set to 1.5 μm ≦ t ₁ ≦ 8 μm. If it sets in this way, the crack 12 will generate | occur | produce naturally in the layer 9 so that it may penetrate.
[0018]
When the member main body 2 and the coating 14 are made of an Al alloy such as JIS AC8A, the molten metal temperature T _E in the hot dipping process is 695 ° C. ≦ T _E ≦ 725 ° C., and the immersion time T _I is 105 sec ≦ T _I ≦ 180 sec. Is set. In this case, when the molten metal temperature T _E is T _E > 725 ° C. or the immersion time T _I is T _I > 180 sec, the diffusion of the hard chrome plating layer 9 becomes intense, so that the concave and

convex portions

5 and 6 are formed. On the other hand, when the molten metal temperature T _E is T _E <695 ° C. or the immersion time T _I is T _I <105 sec, the wettability between the molten metal 13 and the hard chromium plating layer 9 is high. It deteriorates and causes poor bonding.
[0019]
In casting the member body 2, the to-be-casting material 3 is once cooled after the hot dipping treatment and then preheated and then placed in the mold, or the to-be-casting material 3 is melted in the hot dipping process 13. A method is adopted in which it is placed in the mold immediately after taking out from the inside. In the latter case, the coating 14 is in a molten state. The thickness t ₂ of the film 14 is 50 μm ≦ t ₂ ≦ 300 μm.
[0020]
Hereinafter, specific examples will be described.
[0021]
[I] Relationship between Occupancy A of Recess 5 at Joining Interface 4 and Joining Strength S As a main body 8 of the cast-in waist material 3, a Niresist cast iron plate material having a length of 80 mm, a width of 50 mm, and a thickness of 5 mm was selected. This Ni-resist cast iron is made of Fe containing 2.5 wt% C, 2 wt% Si, 1 wt% Mn, 15 wt% Ni, 6 wt% Cu, 2 wt% Cr and the balance unavoidable impurities.
[0022]
After subjecting the eight main bodies 8 to pretreatment, they were subjected to electroplating treatment to form a hard chrome plating layer 9, and Examples 1 to 8 of the cast material 3 were obtained. The electroplating process conditions of Examples 1-8 are as Tables 1 and 2.
[0023]
[Table 1]

[0024]
[Table 2]

[0025]
Next, Examples 1 to 8 were immersed in a molten metal having a JIS AC8A composition at 710 ° C. for 120 seconds. Thereafter, Examples 1 to 8 were taken out from the molten metal and immediately installed in the mold, and the molten metal having the composition of JIS AC8A was poured into the mold to cast the member main body 2 and cast the blank 3 to the composite member 1. Examples 1 to 8 were obtained. These Examples 1 to 8 correspond to Examples 1 to 8 of the cast material 3, respectively.
[0026]
For Examples 1 to 8 of the composite member 1, the occupation ratio A of the concave portion 5 at the bonding interface 4 was determined, and the bonding strength S between the member main body 2 and the cast blank 3 was determined. The occupancy A is any length as A ₁ in the bonding interface 4, and as a maximum width of the recess 5, as shown in Figure 1, the maximum width a of the total recess 5 existing in the length A ₁ When the sum was A ₂ , it was calculated as A = (A ₂ / A ₁ ) × 100 (%). In addition, as shown in FIG. 4, the bonding strength S is placed on the two support bases 15 at both ends of the cast ball material 3 in the test piece Tp, and pressed into the hole 16 formed in the center of the cast ball material 3. The member 17 is fitted and the member main body 2 is pressed, and the applied load L _O is obtained when the member main body 2 is detached from the cast material 3, and the area of the joint is A _S (however, the cross-sectional area of the hole 16 is S = L _O / A _S was calculated.
[0027]
Table 3 shows the relationship between the thickness t ₁ of the hard chromium plating layer 9 and the occupation ratio A of the recess 5 and the bonding strength S in Examples 1 to 8 of the composite member 1.
[0028]
[Table 3]

[0029]
FIG. 5 is a graph showing the relationship between the occupation ratio A of the recesses 5 and the bonding strength S based on Table 3.
[0030]
As apparent from Table 3 and FIG. 5, when the thickness t ₁ of the hard chrome plating layer 9 is set to 1.5 μm ≦ t ₁ ≦ 8 μm as in Examples 2 to 7, the occupation ratio A of the recess 5 is 5%. By setting ≦ A ≦ 95%, a relatively large bonding strength S such as 36 MPa ≦ S ≦ 56 MPa can be obtained. In the case of Example 1, the bonding strength S is low due to the area of the bonding interface 4 being too small, and in the case of Example 8, the thickness of the hard chrome plating layer 9 is increased, resulting in the above-described penetration crack. The recess 5 is not formed because of the absence of.
[0031]
In Examples 2 to 7, the abundance ratio B (described later) of the recess 5 is in the range of B ≧ 10%, and the average value a ₁ (described later) of the maximum width a of the recess 5 is 15 μm ≦ a ₁ ≦ 200 μm. Further, the crack density D (described later) of the hard chromium plating layer 9 was in the range of 140 crack number / cm ≦ D ≦ 750 crack number / cm.
[0032]
[II] Relationship between the abundance ratio B of the recesses 5 and the bonding strength S After the pretreatment is performed on the four main bodies 8 similar to the above, they are subjected to electroplating, and the thickness t ₁ is 4.5 μm. The hard chrome plating layer 9 was formed and Examples 9-12 of the to-be-casting material 3 were obtained. The electroplating process conditions of Examples 9-12 are as Tables 4 and 5.
[0033]
[Table 4]

[0034]
[Table 5]

[0035]
Next, in order to change the abundance ratio B of the recesses 5 in Examples 9 to 12, the Examples 9 to 12 were immersed in a molten metal having a JIS AC8A composition at a predetermined temperature for a predetermined time. Thereafter, Examples 9 to 12 were taken out from the molten metal and immediately placed in the mold, and the molten metal having the composition of JIS AC8A was poured into the mold to cast the member main body 2 and cast the fill material 3 to the composite member 1. Examples 9 to 12 were obtained. These Examples 9 to 12 correspond to Examples 9 to 12 of the to-be-cast material 3, respectively.
[0036]
With respect to Examples 9 to 12 of the composite member 1, the abundance B of the recesses 5 at the bonding interface 4 was determined, and the bonding strength S between the member main body 1 and the cast blank 3 was determined by the same method as described above. The existence ratio B is optional in the length A _1, and the number of all the recesses including recess recess 5 and the opening portions opening portion 7 is in Lisbon is no Lisbon and B _1, also the opening portion of the bonding interface 4 When the number of all concave portions 5 in which 7 is constricted is B ₂ , B = (B ₂ / B ₁ ) × 100 (%).
[0037]
Table 6 shows the relationship between the immersion conditions in the molten metal, the abundance B of the recesses 5 and the bonding strength S in Examples 9 to 12 of the composite member 1.
[0038]
[Table 6]

[0039]
FIG. 6 is a graph showing the relationship between the abundance B of the recesses 5 and the bonding strength S based on Table 6.
[0040]
As is clear from Table 6 and FIG. 6, when the abundance ratio B of the recesses 5 is set to B ≧ 10% as in Examples 10 to 12, a relatively large bonding strength S such as S ≧ 38 MPa can be obtained.
[0041]
In Examples 10 to 12, the occupation ratio A of the recess 5 is in the range of 5% ≦ A ≦ 95%, and the average value a ₁ (described later) of the maximum width a of the recess 5 is 15 μm ≦ a ₁ ≦ 200 μm. Further, the crack density D (described later) of the hard chromium plating layer 9 was in the range of 140 crack number / cm ≦ D ≦ 750 crack number / cm.
[0042]
[III] Relationship between Average Value a ₁ of Maximum Width a of Recess 5 and Bonding Strength S After subjecting the same seven main bodies 8 to pretreatment, they are subjected to electroplating to obtain a thickness t ₁ A hard chromium plating layer 9 having a thickness of 4.5 μm was formed, and Examples 13 to 19 of the cast material 3 were obtained. The electroplating treatment conditions of Examples 13 to 19 are as shown in Tables 7 and 8.
[0043]
[Table 7]

[0044]
[Table 8]

[0045]
Next, in order to change the average value a ₁ of the maximum width a of the recess 5 in Examples 13 to 19, the Examples 13 to 19 were immersed in a molten metal having a JIS AC8A composition at a predetermined temperature for a predetermined time. Thereafter, Examples 13 to 19 were taken out from the molten metal and immediately installed in the mold, and the molten metal having the composition of JIS AC8A was poured into the mold to cast the member main body 2 and cast the fill material 3 to the composite member 1. Examples 13 to 19 were obtained. These Examples 13 to 19 correspond to Examples 13 to 19 of the to-be-cast material 3, respectively.
[0046]
For example 13 to 19 of the composite member 1, the average value a ₁ of the maximum width a of the recess 5, was also determined the bonding strength S between member main body 1 and the insert casting material 3 in the same manner. Said average value a ₁ is the number of all recesses 5 existing in any length A ₁ and B ₂ at a joint interface 4, also when the sum of the maximum width a of all recesses 5 was A _2, a ₁ = A It obtained as ₂ / B _2.
[0047]
Table 9 shows the relationship between the immersion conditions in the molten metal in Examples 13 to 19 of the composite member 1, the average value a ₁ of the maximum width a of the recess 5, and the bonding strength S.
[0048]
[Table 9]

[0049]
FIG. 7 is a graph showing the relationship between the average value a ₁ of the maximum width a of the recess 5 and the bonding strength S based on Table 9.
[0050]
As can be seen from Table 9 and FIG. 7, when the average value a ₁ of the maximum width a of the recess 5 is set to 15 μm ≦ a ₁ ≦ 200 μm as in Examples 14 to 17, a relatively large joint such as 38 MPa ≦ S ≦ 52 MPa. The strength S can be obtained. In the case of Example 13, the average value a ₁ is too small, whereas in Example 19, the average value a ₁ is too large, so that the anchor effect by the recess 5 is reduced.
[0051]
In Examples 14 to 17, the occupation ratio A of the recesses 5 is in the range of 5% ≦ A ≦ 95%, the existence ratio B of the recesses 5 is in the range of B ≧ 10%, and the hard chromium plating layer 9 The crack density D (described later) was in the range of 140 crack number / cm ≦ D ≦ 750 crack number / cm.
[0052]
[IV] Relationship between Crack Density D and Bond Strength S of Hard Chrome Plating Layer 9 After pre-processing the same eight main bodies 8 as described above, they are electroplated to form a hard chromium plated layer 9 Then, Examples 20 to 27 of the cast material 3 were obtained. The electroplating treatment conditions of Examples 20 to 27 are as shown in Tables 10 and 11.
[0053]
[Table 10]

[0054]
[Table 11]

[0055]
With respect to Examples 20 to 27 after the electroplating treatment, the thickness t ₁ of the hard chrome plating layer 9 and the density D (number of cracks / cm) of the cracks 12 penetrating the plating layer 9 were determined. Next, Examples 20 to 27 were immersed in a molten metal having a JIS AC8A composition at 710 ° C. for 120 seconds. Thereafter, Examples 20 to 27 are taken out from the molten metal and immediately installed in the mold, and the molten metal having the composition of JIS AC8A is poured into the mold to cast the member main body 2 and cast the fill material 3 to the composite member 1. Examples 20 to 27 were obtained. These examples 20 to 27 correspond to the examples 20 to 27 of the cast material 3, respectively.
[0056]
For Examples 20 to 27 of the composite member 1, the bonding strength S between the member main body 1 and the casted ball material 3 was determined by the same method as described above.
[0057]
Table 12 shows the relationship between the thickness t ₁ and crack density D of the hard chromium plating layer 9 and the bonding strength S in Examples 20 to 27 of the composite member 1.
[0058]
[Table 12]

[0059]
FIG. 8 is a graph showing the relationship between the crack density D and the bonding strength S based on Table 12.
[0060]
As apparent from Table 12 and FIG. 8, as in Examples 21 to 25, when the thickness t ₁ of the hard chrome plating layer 9 is set to 1.5 μm ≦ t ₁ ≦ 8 μm, the crack density D is 140 cracks / cm. By setting ≦ D ≦ 750 cracks / cm, a relatively large bonding strength S such as 36 MPa ≦ S ≦ 52 MPa can be obtained.
[0061]
In Examples 21 to 25, the occupation ratio A of the recesses 5 is in the range of 5% ≦ A ≦ 95%, the existence ratio B of the recesses 5 is in the range of B ≧ 10%, and the maximum width of the recesses 5 The average value a _{1 of a} was in the range of 15 μm ≦ a ₁ ≦ 200 μm.
[0062]
In casting, the cooling rate C _R from the start of pouring to the end of solidification is preferably 2.5 ° C./sec≦C _R ≦ 5 ° C./sec. Setting of such a cooling rate C _R is effective in stabilizing concave, the shape of the

convex portion

5, 6 to suppress the change in the bonding interface 4 of the insert casting material 3.
[0063]
【The invention's effect】
According to the present invention, by configuring as described above, it is possible to provide a composite member that greatly improves the bonding strength between the member main body and the cast-in-place material.
[0064]
In addition, according to the present invention, it is possible to provide a manufacturing method capable of reliably obtaining the composite member by employing the above-described means.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view of a main part of a composite member.
FIG. 2 is an explanatory diagram of a manufacturing process of a composite member.
FIG. 3 is a plan view of a hard chrome plating layer.
FIG. 4 is an explanatory diagram of a bonding strength measurement method.
FIG. 5 is a graph showing the relationship between the recess occupancy ratio A and the bonding strength S;
6 is a graph showing the relationship between the abundance ratio B and the bonding strength S. FIG.
7 is a graph showing the relationship between the average value a ₁ of the maximum width a of the recess and the bonding strength S. FIG.
FIG. 8 is a graph showing the relationship between crack density D and bonding strength S.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Composite member 2 Member main body 3 Casting material 4 Joining interface
5 ₀ Small recessed portion 5 Recessed portion 6 Convex portion 7 Opening portion 8 Main body 9 Hard chrome plating layer
10 CrAl intermetallic compound layer
11

FeAl intermetallic compound

12 Crack 13 Molten metal 14 Film

Claims

In a composite member consisting of an Al alloy member main body (2) and a to-be-casting material (3) joined to the member main body (2) in the casting process of the member main body (2) ,
The cast stuffed material (3) consists of a main body (8) made of Ni-resist cast iron and a hard chrome plating layer (9) formed on the surface of the main body (8) on the member main body (2) side,
The to-be-cast material (3) passes through the hard chrome plating layer (9) so that the bottom reaches the main body (8 ) and opens at the joint interface (4) with the member body (2). 1 or more recesses (5), also together with the member body (2) has one or more protrusions to be fitted into the recess (5) and (6) respectively, the recess (5) comprises It was generated by the reaction between the molten Al alloy composition (13) forming the convex portion (6) and the cast fill material (3), and the opening portion (7) is narrowed ,
The member main body (2) side of the hard chromium plating layer (9) is formed on the CrAl-based intermetallic compound layer (10) generated by the reaction between the hard chromium plating layer (9) and the molten alloy (13) of the Al alloy composition. The outer surface of the CrAl-based intermetallic compound layer (10) is the bonding interface (4),
The outer peripheral portion of each convex portion (6) is made of FeAl-based intermetallic compound (11) generated by the reaction between the molten Al alloy composition (13) and Ni-resist cast iron, and each convex portion (6 ) Is a base member corresponding to the constriction of the opening (7) of the recess (5) .

The Al alloy member main body (2), in the casting process of the member main body (2), an object to be insert casting material which is joined to the member main body (2) (3) become more complex material (1) The composite material is composed of a main body (8) made of Ni-resist cast iron and a hard chromium plating layer (9) formed on the surface of the main body (8) on the member main body (2) side. In manufacturing the member (1) ,
The hard chrome plating layer (9) is formed on the main body (8) of the cast material (3) , and at least one of the hard chrome plating layer (9) reaches the main body (8) from the surface thereof. A first step of generating a crack (12) of the entire layer;
An aluminum alloy composition molten metal (13) is applied to the surface of the plated layer (9), and a film (14) having good compatibility with the molten metal forming the member body (2) is integrated with the plated layer (9). And the hard chrome plating layer (9) and the molten metal are made to reach the main body (8) of the to-be-cast material (3) through the crack (12). widening and the subject of the cracks due to reaction with (13) (12) (8) and melt the principal by reaction with (13) the erosion of (8) by induced respectively, the main by its erosion (8) A second step of forming one or more small recesses (5 ₀ ) in
The cast body (3) is placed in a mold to cast the member body (2) incorporating the coating (14), and the crack (12) is widened and the main body (8) the progress of erosion, the to be insert casting material (3), said member main body (2) with one or more recesses bonding interface (4) with opened 且 one the opening portion (7) is narrowed (5 ) to form the said members body (2), using a third step of forming one or more protrusions to be fitted into the recess (5) (6),
In the first step, the thickness t _{1 of the} hard chrome plating layer (9) is 1.5 μm ≦ t ₁ ≦ 8 μm so that the crack (12) occurs in the hard chrome plating layer (9). A method for producing a composite member, wherein the composite member is set .