JP3978652B2 - Porous metal, metal composite using the same, and method for producing the same - Google Patents

Description

【００５０】
Ｎｏ．１は第２の熱処理工程の温度が低く、Ｎｏ．７は第２の熱処理工程の温度が高いため、それ以外の金属多孔体に比べ、上記特性において劣っていた。
【００５１】
【表２】

【００５２】
以上の結果から、第２の熱処理工程の温度が低いと、骨格部の平均気孔率が大きくなり、３点曲げ強度が低下する。また、表面積も増加するので酸化による耐熱性が低下する。逆に温度が高すぎると金属骨格が保てず、密度が増加するが、３点曲げ強度は低下する。金属多孔体の密度はスラリーの塗着量により左右される。以上より、第２の熱処理温度としては、９５０〜１３５０℃が好ましく、熱処理を２段階工程で行なうのが更に好ましい。
【００５３】
実施例２
表３に示す平均粒径を有するＦｅ₂Ｏ₃粉末５０質量％、平均粒径８μｍのＦｅＣｒ（Ｃｒ６０％）合金粉末２３質量％、熱硬化性樹脂として６５％フェノール樹脂水溶液１７質量％、分散剤としてＣＭＣ２質量％及び水８質量％の配合比率でスラリーを作製した。このスラリーを厚さ１０ｍｍ、孔径３４０μｍのポリウレタンフォームに含浸塗布し、金属ロールで過剰のスラリーを絞り出して除去した。その後、大気中１２０℃で１０分乾燥した。次にＮ₂中８００℃で２０分熱処理する工程によりポリウレタンとフェノール樹脂を炭化した後、Ｈ₂中１２００℃で３０分還元焼結し、ＦｅＣｒ合金の金属多孔体を得た。出来上がった金属多孔体の密度、骨格部の平均空孔率、３点曲げ強度、酸化増分率について調べた結果を表４に示す。
なお、作製した金属多孔体の孔径は２７０μｍであった。
【００５４】
【表３】

【００５５】
【表４】

【００５６】
表３及び表４から、Ｆｅ酸化物の平均粒径が大きいと骨格部の平均空孔率が３０％を超え、引張強度が低下する。Ｆｅ酸化物の平均粒径が大きいほど出来上がった金属多孔体の骨格の表面積も増大するほか、金属の密度、引張強度が低下し、この結果、耐熱性の尺度である酸化増分率が大きくなる。従ってＦｅ酸化物の平均粒径は５μｍ以下が好ましく、１μｍ以下がより好ましい。
【００５７】
実施例３
実施例２と同様の製造手順で平均粒径０．７μｍのＦｅ₂Ｏ₃粉末を用いて、スラリー中の熱硬化性樹脂であるフェノール樹脂量を変えて残炭率を変化させた条件での金属多孔体を作製した。この状態を樹脂成分の残炭率Ｘと樹脂成分の酸化物に含まれる酸素に対する質量比Ｙで表現すると表５のようになる。樹脂成分は、フェノール樹脂、ウレタンフォームおよびＣＭＣである。
【００５８】
【表５】

【００５９】
表５のスラリー調製条件により形成された金属多孔体の密度、骨格部の平均空孔率、３点曲げ強度、酸化増分率を調査した結果を表６に示す。
【００６０】
【表６】

【００６１】
表６の結果から、Ｘ×Ｙの値により、製造された金属多孔体の特性に差が生じることが分かる。表６と表５との対比から、Ｘ×Ｙの値が３７より小さい（樹脂成分の残炭率と酸化物に含まれる酸素に対する樹脂分の質量比との積が３７より小さい）と、金属多孔体の特性が劣化することが分かる。特に骨格断面の空孔率が大きめになり、その結果として引張強度の低下や、耐熱性低下により酸化増分率が大きくなる傾向にある。逆にＸ×Ｙの値が１２６より大きい（樹脂成分の残炭率と酸化物に含まれる酸素に対する樹脂分の質量比との積が１２６より大きい）場合でも同様の傾向がある。従って、本実施例の結果から、Ｘ×Ｙの値を３７を超え１２６未満であるような条件にすることにより、より好ましい金属多孔体を得ることができることが分かる。
【００６２】
実施例４
平均粒径０．８μｍのＦｅ₃Ｏ₄粉末５０質量％、平均粒径５μｍのＣｒ粉末を７．９質量％、及び表７に示す種類、量の第三の金属粉末を添加した粉末と、６５％フェノール樹脂水溶液１２質量％、分散剤（ＣＭＣ）２質量％に水を加えて１００質量％にした配合比率のスラリーを作製した。このスラリーを用いて厚さ１５ｍｍ、孔径５００μｍのポリウレタンフォームに含浸塗布し、金属ロールで過剰なスラリーを絞り出して除去した。その後、大気中１２０℃で１０分乾燥した。次いでＮ₂雰囲気で７００℃２５分加熱して樹脂の炭化とＦｅＣｒ複合酸化物を形成し、さらに酸素分圧０．５Ｔｏｒｒの真空中で１１８０℃で３０分加熱して還元焼結を行い、上記第三金属成分を含むＦｅＣｒ合金の金属多孔体を得た。出来上がった金属多孔体を先の実施例同様に評価した。その結果を表８に示す。
なお、作製した金属多孔体の孔径は４００μｍであった。
【００６３】
【表７】

【００６４】
【表８】

【００６５】
表７と表８の結果から、ＦｅＣｒ合金の金属多孔体に第三の金属を含ませて改質することも可能であり、大きく配合を左右する量で無ければ、第三の金属を含んでも、物性、機械強度、耐熱性には悪影響を及ぼさず、さらにその第三成分を増やすことにより、耐熱性、３点曲げ強度等の特性を改善できることが分かる。
【００６６】
実施例５
前記実施例４で用いたＮｏ．２４について、金属酸化物と樹脂成分の量を変化させたスラリーを作製した。なお樹脂成分の内、スラリー中のフェノール樹脂の量のみを変化させた。その他の成分組成はＮｏ．２４と同じとした。
配合比率をＸ及びＹで表９に示す。
【００６７】
【表９】

【００６８】
これらのスラリーを用いて実施例４の製造条件と同じ条件で金属多孔体を作製した。出来た金属多孔体を先の実施例同様に評価した。その結果を表１０に示す。 なお、作製した金属多孔体の孔径は４００μｍであった。
【００６９】
【表１０】

【００７０】
表９と表１０の結果から、Ｘ×Ｙの値が３７を超え、１２６未満である範囲の配合比率を用いるとより優れた金属多孔体が形成されることが分かる。
【００７１】
実施例６〜１０
平均粒径０．６μｍのＦｅ₂Ｏ₃粉末５２質量％、平均粒径７μｍのＦｅＣｒ合金（Ｃｒ６３％）粉末２３質量％、熱硬化性樹脂として６５％フェノール樹脂水溶液１３質量％、分散剤（ＣＭＣ）を１．５質量％、水を１０．５質量％とした組成で混合しスラリーとした。
このスラリーを厚さ１０ｍｍ、孔径３４０μｍのポリウレタンフォームシートに含浸した。引き上げ時に金属ロールで過剰に付着したスラリーを絞り出して除去し、大気中１２０℃で１０分乾燥した。このシートを表１１に示す条件で熱処理し、金属多孔体を得た。出来上がった金属多孔体の特徴を表１２に示す。
なお、表１２中の「最小曲率半径」についての評価は、板状の金属多孔体（１４０ｍｍ×９０ｍｍ×３ｍｍｔ）の一端を固定し、他の端を曲げて固定端に近づけていき、破断したときの曲率半径を測定して、これを「最小曲率半径」とした。曲率半径の大きい製品では実施例９程度のものでも問題がないが、φ８０ｍｍの円筒に加工する場合には実施例９程度のものは使用できない。
【００７２】
【表１１】

【００７３】
【表１２】

【００７４】
表１２に示された結果から、カーボン含有量によって金属多孔体の密度は変化はしないが、曲げ加工においては炭素量が多くなると最小曲率半径が１０ｃｍを超えるようになり、加工性が低下することが分かる。硬さについては、残留炭素量の増加に従って硬くなることが分かる。なお、ここで「カーボン含有量」及び「残炭率」について説明すると以下の通りである。
残炭率 ：熱処理を２段階に分けて実施する工程において、骨格樹脂、スラリーに使用された熱硬化性樹脂等の樹脂成分合計量に対して１段目の熱処理において炭化されたウレタンフォーム及び熱硬化性樹脂の残留した量の質量割合。
カーボン含有量：上記残炭率で２段目の熱処理を実施した場合、殆どの炭素は酸化物の還元に利用されるが、この２段目の熱処理の後に残った炭素量の、最終製品である金属多孔体に対する質量割合。
【００７５】
本発明による金属多孔体は、加工性がよく、且つ金属多孔体の硬さを要求されるので、カーボン含有量が適量であることが必要である。
【００７６】
実施例１２〜１４、比較例１〜３
実施例６で用いた成分・組成のスラリーを基準にして、熱硬化性樹脂の配合量を変化させ、金属酸化物との質量比率を変えた各種スラリーを用意した（熱硬化性樹脂の配合量は表１３の第２列に示した。）。このスラリーを用いてスラリー含浸以降は実施例６と同じ条件で金属多孔体を作製した。なおこれら金属多孔体の樹脂残炭率（ａ）、熱硬化性樹脂の酸化物に含まれる酸素に対する質量比（ｂ）を確認して同じく表１３に示す。
得られた多孔体の特性を表１４に示す。
【００７７】
【表１３】

【００７８】
【表１４】

【００７９】
ａ×ｂの値が、１７以下の場合、金属多孔体中のカーボン含有量は０．１質量％よりも小さくなり、加工性が低下する。（２）式を満たす条件で作製した場合、金属多孔体中のカーボン含有量を０．１質量％以上３．５質量％以下に制御することができ、その範囲の金属多孔体の最小曲率半径が小さくなり、種々の曲げ加工が容易になる。また３７以上の場合、カーボン含有量は３．５質量％を超えるとともに最小曲率半径が大きくなり、成形上の制約が大きくなる。さらに金属骨格の硬度も高くなる傾向にある。以上の結果から、好ましいカーボン含有量を０．１質量％以上３．５質量％以下に制御するには、ａ×ｂの値を制御することで達成できることが分かる。
【００８０】
実施例１７〜２０、比較例４
平均粒径０．５μｍのＦｅ₂Ｏ₃粉末５４質量％、平均粒径５μｍのＦｅＣｒ合金（Ｃｒ６３％）粉末１６質量％、分散剤（ＣＭＣ）１．５質量％と熱硬化性樹脂として６５％フェノール樹脂水溶液を表１５に示す量加え、これに水を加えて１００質量％にした配合比率のスラリーを作製した。
このスラリーを厚み１２ｍｍ、孔径４２０μｍのポリウレタンフォームシートに含浸したのち、金属ロールで過剰のスラリーを絞り出して除去し、大気中１２０℃で１０分乾燥した。このシートを表１１の実施例９の条件で熱処理し、金属多孔体を作製した。作製した金属多孔体の特性を表１６に示す。
なお、金属多孔体の孔径は３４０μｍであった。
【００８１】
【表１５】

【００８２】
【表１６】

【００８３】
表１６に示されている実施例１７〜２０の金属多孔体の密度と、表１２及び表１４で示されている実施例６〜１０、１２〜１４の金属多孔体の密度とが異なるのは、素材に用いられたウレタンフォームシートの気孔率等の違いによるものである。カーボン含有量と最小曲率半径（加工性を示す）および硬さとの関係は、表１４の結果と類似する。カーボン含有量が３．５質量％を超えると表１６の最小曲率半径のデータから明らかなように加工性が低下する。ただし、このように比較的高残留炭素の金属多孔体は、加工度が低くても問題がなく、かつ耐摩耗性を重視する用途には適している。また、カーボン含有量が少ない実施例１７のような場合は、硬度が低いので、軽合金と複合化される金属複合材にするには良い結果をもたらさない可能性がある。
【００８４】
実施例２２〜２６、２８〜３０、３３〜３６（金属複合材製造例１）及び比較例５〜９
前記実施例６〜１０、１２〜１４、１７〜２０、比較例５〜８で得られた金属多孔体の一部を金型に入れ、７５０℃に加熱したアルミニウム合金（ＡＣ８Ｃ）溶湯を３９．２ＭＰａの加圧下で多孔体に含浸させてアルミニウム複合材を作製した。出来たアルミニウム複合材を図５（ａ）に示す矩形のサンプル（１５ｍｍ×１５ｍｍ×１０ｍｍ）に切り出し、図５（ｃ）に示す試験装置にてローラーピン摩耗試験に供した。具体的には、同図に示すように評価するサンプルを（ａ）図に示す形状に加工し、（ｂ）図に示すローラ形状に加工した相手材と接触させて、所定条件でローラーを回転させることにより摩耗性能について評価を行った。
【００８５】
ローラーピン摩耗試験の条件は、以下の通りである。
相手材 ： 硬度がＨｖ１０００の窒化鋼で、直径８０ｍｍ、幅１０ｍｍの回転ローラー
回転数 ： ２００ｒｐｍ
押しつけ加重 ： ６０ｋｇ
時 間 ： ２０分
潤滑油 ： ＳＡＥ１０Ｗ３０
滴下量 ： ５ｍｌ／分
【００８６】
なおこの試験では、作製したアルミニウム複合材試片が垂直に回転する相手材に対して、上部から押しつけ加重を負荷した状態で押しつけられるため発熱する。したがって、双方の接触部分に潤滑油を滴下することでローラーと複合材サンプルとが溶着しないようにした。負荷後、２０分経過後、相手材の回転を停止し、サンプルの摩耗深さを測定し、表１７に示すような結果を得た。なお、ここで比較例１としてアルミニウム合金（ＡＣ８Ｃ）を矩形に切り出して用いた。
【００８７】
このローラーピン摩耗試験では、組み合わせるローラー材との組合せもテスト結果に影響するが、表１７に示すように複合化された本発明の材料では耐摩耗性が顕著に改善されることが分かる。カーボン含有量が極端に少ない場合は、複合化の効果が減少し、カーボン含有量が多くなるほど耐摩耗性が向上する。このテストでは実施例の金属多孔体を加工する操作はしていないが、複雑に加工される場合は加工性も問題になるので、耐摩耗性と加工性はカーボン含有量が多い範囲ではどちらを重視するかにより、カーボン含有量を調整選択することが必要である。
【００８８】

【００８９】
以上の結果より、本発明の多孔体は、ＦｅとＣｒからなる合金中にＦｅ炭化物もしくはＦｅＣｒ炭化物が均一分散相として存在するため、骨格自体が高い硬度を有し、それ自体が耐摩耗性、機械的な強度に優れていることが分かる。したがって、これを骨格としてＡｌ合金と複合化された本実施例の複合材は耐摩耗性に優れている。
【００９０】
実施例３８〜４２、４４〜４６、４９〜５２（金属複合材製造例２）及び比較例２
金属複合材製造例１と同様に実施例６〜１０、１２〜１４、１７〜２０、比較例５〜８で得られた金属多孔体を用いて、これにマグネシウム合金を用いた複合化を実施した。実施例の各金属多孔体の一部を金型に入れ、７５０℃に加熱したマグネシウム合金（ＡＺ９１Ａ）の溶湯を２４．５ＭＰａの加圧下で注入し、マグネシウム複合材を作製した。出来た複合材を矩形に切り出し、ローラーピン摩耗試験機を用いて耐摩耗性を測定した。
【００９１】
ローラーピン摩耗試験の条件は、以下の通りである。
相手材 ：硬度がＨｖ１０００の窒化鋼で、直径８０ｍｍ、幅１０ｍｍの回転ローラー窒化鋼 （製造例１と同じ）
回転数 ： ３００ｒｐｍ
押しつけ加重 ： ５０ｋｇ
時 間 ： １５分
潤滑油 ： ＳＡＥ１０Ｗ３０
滴下量 ： ５ｍｌ／分
【００９２】
この試験方法も金属複合材製造例１と同様に実施し、結果を表１８に示す。ここで用いた比較例２は、マグネシウム合金（ＡＺ９１Ａ）を矩形に切り出したものである。表１８で示すように、カーボン含有量が少ない場合は、複合化しなかった比較例２の摩耗深さに近づく値となる。しかしながら、カーボン含有量が増えると、耐摩耗性が向上する。
残留炭素量と摩耗量の相関はアルミニウム複合材と同様にカーボン含有量が多くなると硬さが増し、耐摩耗性が向上する傾向にある。
【００９３】
【表１８】

【００９４】
本発明の金属多孔体は、ＦｅとＣｒからなる合金中にＦｅ炭化物もしくはＦｅＣｒ炭化物が均一分散相として存在するため、骨格自体の高い硬度を有し、それ自体が耐摩耗性、機械的な強度に優れている。したがって、これを骨格としてＭｇ合金と複合化された本実施例の複合材は、耐摩耗性に優れている。
【００９５】
実施例５４〜５８
平均粒径０．４μｍのＦｅ₂Ｏ₃粉末５０質量％、平均粒径５μｍのＦｅＣｒ（Ｃｒ６３％）合金粉末１４．５質量％、表１９に示す種類、量の金属粉末を添加した粉末と、６５％フェノール樹脂水溶液１２質量％、分散剤（ＣＭＣ）１．５質量％に水を加えて１００質量％にした配合比率のスラリーを作製した。このスラリーを厚さ１０ｍｍ、孔径が３４０μｍのポリウレタンフォームに含浸したのち、金属ロールで過剰に付着したスラリーを除去し、１２０℃で１０分乾燥した。このシートを表１１の実施例９に示す熱処理条件で処理し、金属多孔体を作製した。出来上がった金属多孔体の密度、カーボン含有量及びビッカース硬度を表２０に示す。
【００９６】
【表１９】

【００９７】
【表２０】

【００９８】
実施例５９〜６３（金属複合材製造例３）及び比較例３
上記実施例５４〜５８で作製した金属多孔体を金型にセットし、７６０℃に加熱したアルミニウム合金（ＡＣ８Ａ）溶湯を２０ｋｇ／ｃｍ²で加圧注入することによりアルミニウム複合材を作製した。得られた複合材についてローラーピン摩耗試験を行った。また、比較例３としてアルミニウム合金（ＡＣ８Ａ）を矩形に切り出したものを用い同様の摩耗試験を行なった。結果を表２１に示す。
なお、摩耗試験条件は下記の通りである。
相手材 ： 硬度がＨｖ１０００の窒化鋼で、直径８０ｍｍ、幅１０ｍｍの回転ローラー（製造例１と同じ）
回転数 ： ５０ｒｐｍ
押しつけ加重 ： １００ｋｇ
時 間 ： ２０分
潤滑油 ： ＳＡＥ１０Ｗ３０
滴下量 ： １ｍｌ／分
【００９９】
【表２１】

【０１００】
実施例６４〜６５及び比較例４〜５
平均粒径０．４μｍのＦｅ₂Ｏ₃粉末５０質量％、平均粒径５μｍのＦｅＣｒ（Ｃｒ６３％）合金粉末１４．５質量％、平均粒径２．８μｍのＮｉ粉末４．４質量％と、６５％フェノール樹脂溶液１２質量％、分散剤（ＣＭＣ）１．５質量％に水を加えて１００質量％にした配合比率のスラリーを作製した。このスラリーを表２２に示すポリウレタンフォームに含浸したのち、金属ロールで過剰に付着したスラリーを絞り出して除去し、１２０℃で１０分乾燥した。このシートを表１１の実施例９に示す熱処理条件で処理し、金属多孔体を作製した。出来あがった金属多孔体の密度、カーボン含有量、孔径及び３点曲げ強度を表２３に示す。孔径が０．５ｍｍ以下のサンプルでは、孔径が０．６４ｍｍと比較して１．５倍以上の曲げ強度があることが分かる。
【０１０１】
【表２２】

【０１０２】
【表２３】

【０１０３】
実施例６６〜６８（金属複合材製造例４）及び比較例６〜７
上記実施例５４、６４、６５及び比較例４、５で作製した金属多孔体を金型にセットし、７６０℃に加熱したアルミニウム合金（ＡＣ８Ａ）溶湯を２０ｋｇ／ｃｍ²で加圧注入することによりアルミニウム複合材を作製した。得られた複合材について焼付き試験を行った結果を表２４に示す。
なお、焼付き試験条件は下記の通りである。
相手材 ： 窒化鋼、直径１１．３ｍｍ、先端Ｒ＝１０ｍｍ
荷重 ： １ｋｇｆから開始し、１分毎に１ｋｇｆづつ加重を増加させる
ストローク： ５０ｍｍ
試験速度 ： ２００ｃｐｍ
雰囲気 ： 油（ＳＡＥ１０Ｗ−３０）塗布後、拭き取り
【０１０４】
【表２４】

【０１０５】
実施例６９〜７５及び比較例８〜１１
実施例５４の金属多孔体を、表２５に示す固体潤滑剤を含む水溶液に浸せきし、取り出した後に７０℃、１時間乾燥させた金属多孔体を金型にセットし、７６０℃に加熱したアルミニウム合金（ＡＣ８Ａ）溶湯を２０ｋｇ／ｃｍ²で加圧注入することによりアルミニウム複合材を作製した。得られた複合材について金属複合材製造例４での焼付き試験と同じ条件で試験を行なった。
比較例として、孔径が７００μｍのポリウレタンフォームを用いて実施例１８と同様に金属多孔体を作製した以外は実施例６９と同様にして複合材を作製し、試験を行なった。結果を表２６に示す。
なお、固体潤滑剤を含む水溶液中の固体潤滑剤濃度は、５０％であり、浸せき後の固体潤滑剤添加量は、金属多孔体重量の１０〜１５％である。
【０１０６】
【表２５】

【０１０７】
【表２６】

【０１０８】
評価結果から、固体潤滑剤を金属多孔体表面に添加することで、耐焼付き性がさらに向上することが判る。なお、図６に骨格表面に付与した固体潤滑剤の模式図を示す。
【０１０９】
実施例７６〜８４
実施例５５の金属多孔体について、Ｃｒ、Ｍｏ及びＮｉの配合比を変えて作製した金属多孔体を表２７に示す。これらの金属多孔体について、硫酸浸せき試験を実施した結果を表２８に示す。配合比を変えることで飛躍的に耐食性が向上することが判る。
【０１１０】
なお、耐食試験条件は以下の通りである。
溶液 ： 硫酸（１Ｎ）
温度 ： 室温
時間 ： ２４時間
評価方法： １Ｎ硫酸中にサンプルを浸せきし、２４時間後に取出し重量変化を測定する
【０１１１】
【表２７】

【０１１２】
【表２８】

【０１１３】
以上の実施例の通り、合金組成を変えることにより、強酸中での耐食性レベルを設計することが出来る。これらの金属多孔体は、固体高分子型燃料電池等の強酸雰囲気での電極材料として適用出来る。
また本発明のＣｒ炭化物相は、これらの電極材料として適用された場合、接触抵抗を低減させる効果がある。
【０１１４】
【発明の効果】
上記で述べたように、本発明の製法によれば、金属炭化物が均一分散されたＦｅＣｒ合金の金属多孔体を得ることが可能であり、かつ強度的にも耐熱性においても優れた特性を有することが出来る。さらに金属多孔体の特性を改善する第三の金属を合金化した金属多孔体を得ることも可能である。
又、本発明による金属多孔体は、骨格中に金属炭化物の相を均一分散させることで、適当な加工性と硬さを保有するので、Ａｌ又はＭｇのような軽金属を主成分とする合金との複合材を得る際の骨格としても適している。本発明の金属多孔体を用いることにより、得られた複合材は、耐摩耗性が改善され、適宜加工することも可能となる。特に、骨格となる金属多孔体の孔径を５００μｍ以下に小さく抑えることによって、軽合金と複合化後の素材を摺動部材として用いた場合、耐焼付き性が顕著に改善される。
【図面の簡単な説明】
【図１】本発明の製法になる金属多孔体の拡大模式図である。
【図２】金属多孔体の骨格断面を説明する図である。
【図３】本発明の金属多孔体の骨格断面中に分散する金属炭化物の存在を示す図である。
【図４】本発明の金属多孔体を用いた金属複合材の断面を拡大したものである。
【図５】本発明実施例のローラーピン摩耗試験装置ならびにその試験片を示す図である。
【図６】本発明の金属多孔体の骨格表面に付与した固体潤滑剤の模式図である。
【符号の説明】
１ 金属骨格
２ 空孔
３ マトリックス
４ 炭化物相
５ Ａｌ合金マトリックス
６ 金属多孔体骨格
７ ローラーピン摩耗試験片
８ 相手材ローラー
９ 荷重印加装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a porous metal body made of an alloy excellent in high strength, corrosion resistance and heat resistance, applied to an electrode substrate, a catalyst carrier, a filter, a metal composite, and the like, a metal composite using the same, and a method for producing the same About.
[0002]
[Prior art]
Conventionally, a metal porous body is used for various applications such as a filter requiring heat resistance, a battery electrode plate, a catalyst carrier, and a metal composite material. Therefore, the manufacturing technique of a metal porous body has been known by many well-known literatures. Further, products using CELMET (registered trademark) manufactured by Sumitomo Electric, which is already a metal porous body based on Ni, have been sufficiently used in the industry.
[0003]
A conventional porous metal body is obtained by forming a metal layer on the surface of a foamed resin or the like, and then baking and removing the resin portion and reducing the metal layer. For example, in the method described in JP-A-57-174484, a conductive layer is subjected to a conductive treatment on the surface of a porous core such as a foamed resin, and then a metal layer is formed by a plating method. Further, in the method described in, for example, Japanese Examined Patent Publication No. 38-17554, a metal preliminary layer is formed by attaching a slurry containing metal powder to the surface of a core made of foamed resin or the like and drying it.
[0004]
The conductive treatment in the case of forming the metal layer by the former plating method is performed by adhesion of a conductive material, vapor deposition of a conductive material, surface modification with a chemical agent, or the like. Next, formation of a metal layer that finally becomes a porous metal body is performed by electrolytic plating, electroless plating, or the like. Finally, a porous metal body is obtained by baking and removing the resin portion, which is a porous core. Further, when an alloyed porous body is obtained, after forming a different kind of metal plating layer, the metal diffusion treatment is performed by heating.
[0005]
In the latter method, a slurry containing a metal powder and a resin is prepared in advance, and this becomes a metal preliminary layer. In this means, an alloy powder is used for the metal powder of the slurry, or a mixed metal powder composed of a plurality of metal species having an alloy composition is used to obtain an alloyed metal porous body through heating after drying. be able to.
However, the alloyed metal porous body obtained in this way has a particularly excellent adhesion between metal powder particles compared to the former metal porous body combined with post-plating diffusion alloying treatment. And the mechanical strength of the porous body is reduced.
[0006]
Japanese Examined Patent Publication No. 6-89376 introduces an improvement example for an iron alloy porous body. According to this method, a certain amount of carbon is contained in the iron powder in the slurry prepared in advance and the surface thereof is forcibly oxidized. By doing in this way, the oxidation-reduction reaction of the oxygen in the oxide at the time of baking and contained carbon arises, As a result, the adhesiveness of metal powder particles improves.
[0007]
JP-A-9-231983 also discloses a sintered iron porous body having a dense metal skeleton using iron oxide powder as a raw material. However, even in this case, in order to use the porous body for a structural member in which mechanical strength, heat resistance and wear resistance are emphasized, it is necessary to further modify the metal itself. For example, as described in the publication, since mechanical strength, corrosion resistance, and heat resistance are insufficient, these properties are improved by alloying.
[0008]
Furthermore, the utilization of the metal porous body is advancing by compositing with a casting such as Al die cast. This technique is a method in which a light metal casting is infiltrated into a void portion of a porous metal body, and is widely used as a means for reducing the weight by replacing an Al alloy with a casting. In this case, further improvement of the characteristics can be expected by alloying the portion mainly composed of Al combined with the porous body mainly composed of iron. Therefore, the same can be expected when compounding with other light metal alloys such as Mg.
[0009]
Japanese Patent Application Laid-Open No. 9-122877 discloses a detailed technique related to composite using a metal porous body. According to the description of the publication, such a composite light metal alloy is used particularly in a severe use part such as a sliding part. For this reason, the characteristic of the metal porous body itself used for the composite is required to be suitable for the intended use.
[0010]
The above-mentioned CELMET has already been used as the porous metal body used for the composite with the light metal as described above, but a technique for obtaining a material with even better performance is disclosed in JP-A-10-251710. Are listed. In this metal porous body, a slurry containing a metal powder and a ceramic powder is applied to a member made of a fire-resistant foamed resin, and then the resin content is burned down in a reducing gas atmosphere containing water vapor / carbon dioxide gas. It is heated and fired in a reducing atmosphere. As a result, ceramic particles are dispersed in the skeleton of the completed metal porous body, and a metal porous body having excellent characteristics of ceramics is formed.
In addition, a porous metal body is disclosed in which a metal powder described in JP-A-8-319504 is molded and sintered so as not to become dense, and a gap between the powders is used. In this method, the volume ratio of the metal porous body is 30 to 88%, which is higher than that of the present invention. For example, when it is combined with Al, a high pressure is required to allow the molten Al to enter the porous body. Furthermore, since the ratio of the porous metal body in the composite material increases, there is a problem that the merit of weight reduction is not obtained. Here, the volume ratio indicates the volume ratio of the skeleton portion in the total volume of the porous body.
Such composite technology has made rapid progress.
[0011]
[Problems to be solved by the invention]
The above research on metal composite technology has solved several problems in using metal composite materials. Such a metal composite material has recently been attracting attention and being used as a material for reducing the weight of engine parts such as automobiles. However, for these types of parts, the demand for materials related to exhaust gas regulations and the like is becoming increasingly severe. For example, more excellent wear resistance is required particularly for parts used in the piston wear-resistant ring portion of a diesel engine. As such a component, a composite material using a metal porous body containing the ceramic particles can be cited as one candidate material. However, since this material contains ceramic particles in the skeleton of the porous body, it is difficult to perform the preform processing as compared with a porous body made of only a normal metal, and the shape that can be processed is limited.
In particular, in the case of parts that are used under high-speed sliding conditions at high temperatures, such as the bore material of an engine block, for example, the wearable material and the excellent formability that can be used for near-net preform molding, especially the mating material that slides Improvement of seizure resistance is an extremely important issue.
[0012]
[Means for Solving the Problems]
The present invention has been made as a result of studies based on a series of requirements in such applications, and an object of the present invention is to provide a composite material having an unprecedented seizure resistance particularly under sliding.
[0013]
The first is to provide a metal porous body that meets the above-mentioned purpose, and the porous body has a foamed structure, and its framework is Fe and Cr in which Cr carbide and / or FeCr carbide is uniformly dispersed. And has a pore diameter of 500 μm or less. The amount of the metal carbide contained can be determined by the amount of carbon, and the carbon content in the skeleton of the porous metal body has particularly preferable characteristics when it is 0.1% by mass or more and 3.5% by mass or less. The metal porous body having the above-described composition and structure provides excellent mechanical strength that has never been obtained. In particular, it is preferable if the amount of carbide is within the above range in terms of carbon content. When the amount of carbon is less than 0.1% by mass, the amount of carbide in the skeleton is small, so that the wear resistance is inferior. When the amount exceeds 3.5% by mass, the skeleton itself becomes hard and it becomes difficult to perform the preform processing. There is a possibility that the attacking property against the mating sliding member is increased.
The amount of carbon is more preferably in the range of 0.3% by mass to 2.5% by mass.
In the preferable carbon amount range, that is, in the range of 0.1 to 3.5% by mass, the Vickers hardness of the skeleton portion of the porous metal body is in the range of 140 to 350, particularly the workability after forming the composite alloy. Give good results in wear resistance.
[0014]
When one or more selected from the group consisting of Ni, Cu, Mo, Al, P, B, Si and Ti is included in the skeleton of the porous metal body of the present invention, the toughness is increased and more preferable results are obtained. These desirable contents are 25% by mass or less in total.
In the porous body of the present invention, the pore size of the metal skeleton is further controlled to be 500 μm or less. This significantly improves the seizure resistance especially after the compounding with the light metal. In particular, when it is controlled in the range of 100 μm or more and 350 μm or less, it is more preferable from the viewpoint of improving seizure resistance while facilitating impregnation of the molten metal.
[0015]
The second object of the present invention is to provide a composite material composed of a metal porous body and a light metal alloy that meets the above-mentioned purpose, and the composite material is a void within the above pore diameter range of the metal porous body described above. The hole is filled with Al alloy or Mg alloy. A method for producing this composite material will be described later, but it can be obtained by pressure-impregnating molten metal of Al alloy or Mg alloy into the pores of the metal porous body whose pore diameter is controlled.
[0016]
By making the pore size of the metal skeleton 500 μm or less, the Al or Mg base region surrounded by the metal skeleton can be miniaturized, and the contact area between the counterpart material and the base region can be reduced, and the seizure phenomenon can be caused. The frequency of occurrence can be reduced. Furthermore, by reducing the seizure area in the base region by reducing the pore size of the metal skeleton to 350 μm or less, the surface damage due to seizure is reduced by reducing the adhesion force when seizure occurs between the composite material and the counterpart material. Can be suppressed.
Furthermore, when a solid lubricant is applied to the surface of the skeleton, the seizure resistance is greatly improved. Here, when the pore diameter of the metal porous body is larger than 500 μm, the internal surface area associated therewith decreases, so that the amount of solid lubricant added becomes less than 500 μm or less, and the effect of improving seizure resistance cannot be expected. As the solid lubricant, it is preferable to use at least one selected from the group consisting of graphite, molybdenum disulfide, tungsten disulfide, boron nitride, molybdenum trioxide, and iron oxide.
[0017]
When the pore diameter is smaller than 100 μm, a higher pressure is required for impregnating Al and Mg, which makes it difficult to manufacture. There is also a problem that it is difficult to apply the solid lubricant to the surface.
When a composite material with Al or Mg is used, depending on the hole diameter of the metal skeleton, it becomes a difficult-to-cut material and may damage the cutting edge of the cutting tool. However, when the pore size of the metal skeleton is set to 500 μm or less, the metal skeleton itself becomes small, so that blade wear can be reduced.
In addition, in this specification, the general name of the industry using the average diameter of a pore (pore) is used as the pore diameter of the metal porous body.
[0018]
The method for producing a porous metal body of the present invention will be described below.
A slurry having an average particle diameter of 5 μm or less, a powder mainly composed of one or more powders selected from metal Cr, Cr alloy, and Cr oxide, a thermosetting resin, and a diluent as a main component is prepared. Is applied to a resin core having a foam structure of 625 μm or less and dried, followed by firing including a heat treatment step at 950 ° C. to 1350 ° C. in a non-oxidizing atmosphere.
The reason why the average particle size of the iron oxide powder used as the starting material is 5 μm or less is to improve the sinterability of the skeleton of the porous body in the subsequent heat treatment step. By using such fine iron powder, the void area ratio of the cross section of the skeleton becomes 30% or less, and as a result, an excellent mechanical strength / heat resistance / corrosion resistance porous body suitable for the purpose of the invention is obtained. can get. The reason why the pore diameter of the resin core having a foam structure is 625 μm or less is that the pore diameter of the metal porous body is 500 μm or less.
[0019]
Moreover, in this invention, a carbide | carbonized_material is produced | generated by reaction with the carbon produced from the thermosetting resin. By doing in this way, unlike the case where a carbon component is added as a metal carbide from the beginning, the metal carbide is uniformly dispersed. Furthermore, the metal carbide phase obtained by the method of the present invention has an average grain size in the range of 2 μm to 50 μm, and exhibits an excellent effect in wear resistance and the like. Furthermore, by using the core body with the above-mentioned pore diameter, the final pore diameter can be suppressed to 500 μm or less, and by being filled and compounded with a light metal alloy such as Al or Mg, it is particularly resistant to seizure. Sexually improved.
[0020]
One or more additive metals selected from the group consisting of Ni, Cu, Mo, Al, P, B, Si, and Ti described above are mixed in the slurry in a powder state. These are alloyed with a base metal mainly composed of Fe or Cr after sintering and incorporated into the skeleton of the porous metal body.
[0021]
A preferred embodiment of the heat treatment step includes a first heat treatment step of carbonizing the resin component of the dried porous resin core after applying the slurry in a non-oxidizing atmosphere, and 950 ° C. or higher in a reducing atmosphere. And a second heat treatment step of heating at a temperature of 1350 ° C. or lower. In the second heat treatment step, the metal oxide is reduced by the carbonized component generated in the first heat treatment step, and a part of one or more components selected from Fe oxide, Cr, Cr alloy, and Cr oxide are used. Is converted into a carbide, and the reduced metal component is alloyed and sintered.
Furthermore, the points to be noted in the production method are the blending amount of the resin serving as the carbon source for forming the carbide and the firing conditions.
[0022]
First, the mass ratio between the resin component in the slurry and the carbonized component generated from the resin core through the first heat treatment step and the Fe oxide and other oxide powder added to the slurry is controlled within a certain range. Preferably, the composition of the slurry is determined based on the relationship. The determination method is based on the following formula (1). That is, a residual carbon ratio X which is a mass ratio of carbon generated from the resin component that can remain in the skeleton of the metal porous body, and oxygen contained in Fe, Cr, and other metal oxides of the resin component at the time of slurry preparation It is preferable that the product with the mass ratio Y is in a range satisfying the following formula (1).
37 <X × Y <126 (1)
X: Residual carbon ratio of resin component (mass%)
Y: Mass ratio to oxygen contained in oxide of resin component
[0023]
The residual carbon ratio of the resin component is a combination of the thermosetting resin added to the slurry and the residual carbon ratio generated from the entire resin component such as a resin porous body serving as an initial skeleton. And the measurement of the residual carbon ratio is a method described in JISK2270. The ratio of the amount of residual carbon component after carbonization to the initial resin weight (total weight of the thermosetting resin component which is a diluent in the resin core and slurry). To tell. In addition, although the quantity of the oxide used by the trial calculation of mass ratio Y is mainly based on Fe oxide, when Cr oxide is also used, the thing by it is also included. By controlling the initial component ratio under such conditions, the reduction of the oxide in the second heat treatment step proceeds in a well-balanced manner, and a porous metal body having excellent mechanical strength can be obtained.
[0024]
When the carbon content in the obtained metal porous body is controlled to be 0.1% by mass or more and 3.5% by mass or less, the compounding ratio of the oxide powder and the thermosetting resin satisfies the following formula (2). It is preferable to blend as described above.
17 <a × b <37 (2)
Here, a is a residual carbon ratio of the thermosetting resin solution added to the slurry, and b is a mass ratio with respect to oxygen contained in the oxide of the thermosetting resin solution added to the slurry.
[0025]
The sintering conditions need to be appropriately changed depending on the carbon source contained in the resin component in the slurry and the amount of oxygen in the metal oxide.
The metal porous body thus obtained has a toughness because the metal carbide phase is uniformly dispersed in the metal phase of the skeleton part, and the metal carbide phase is a carbide phase up to the inside. Has wear resistance.
[0026]
Furthermore, on the surface of the metal porous body, various solid lubricants and resin binders such as phenol are dispersed in a solution such as water, and the metal porous body is put into the solution and impregnated, or sprayed with a spray or the like. A solid lubricant can be applied to the surface by heating and drying.
The porous metal body and the porous metal body with a solid lubricant applied to the surface of the skeleton are suitable for pouring Al alloy or Mg alloy into the pores of the porous body to form a composite. In particular, when an Al alloy or Mg alloy is poured under a pressure of 98 kPa or more to form a composite metal, the metal porous body and the Al alloy or Mg alloy matrix are sufficiently adhered and filled without any gaps, so that a preferable metal composite material is obtained. .
In addition, when the molten metal is poured at a pressure lower than 98 kPa, the gas existing between the metal porous body skeletons cannot be exhausted, and there is a possibility that void defects are generated inside the composite material.
[0027]
Furthermore, alloying according to a use is possible by including a 3rd component other than the alloy of Fe and Cr. That is, when a powder composed of the third metal component or its oxide is added to the raw slurry, the heat resistance, corrosion resistance, wear resistance and mechanical strength of the resulting metal porous body can be improved. For example, Ni, Cu, Mo, Al, P, B, Si, and Ti can be given as typical examples. These third components may be added in any form of a metal powder, an oxide powder, or a mixture thereof. In particular, addition with an oxide is advantageous in that a powder as a raw material can be easily obtained.
In addition, when the third substance is added as an oxide, oxygen contained in the oxide of the third substance is considered in Y of the above relational expression (1) and b in (2). The
[0028]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an enlarged view schematically showing a representative example of the porous metal body of the present invention. In appearance, it is the same as the porous resin body, but after applying the slurry to the skeleton of the porous resin body, the metal skeleton 1 has pores 2 in order to dry it and then sinter, By contracting during carbonization sintering, a skeleton cross section as shown in FIG. 2 is obtained.
[0029]
FIG. 3 is a diagram schematically showing a typical example of a skeleton cross section of a porous metal body of the present invention showing a state in which a metal carbide phase 4 is dispersed in a matrix 3 of an alloy phase containing Fe and Cr. It is. As shown in FIG. 2, some pores may exist in the skeleton, but these pores are omitted in FIG. 3. When added as a carbide powder from the beginning, the carbide phase 4 is too large in particle size and does not become sufficiently dispersed in the matrix 3. For example, the particle size of the carbide phase in that case is about 100 μm. However, the skeleton part of the porous body of the present invention is sufficiently adhered to the matrix 3 of the alloy phase because the metal carbide phase 4 is considerably finer and more uniformly dispersed in the alloy phase matrix 3. Properties rich in toughness can be obtained.
[0030]
FIG. 4 schematically shows a representative example of a cross section of a material obtained by combining the porous metal body of the present invention with an Al alloy, as observed with an optical microscope. Although the porous metal skeleton 6 cannot reflect the internal composition due to the reflected light, no gap or the like is observed at the boundary with the Al alloy matrix 5 and the metal porous skeleton 6 is formed in a sufficiently close contact state. By forming such a structure, it is possible to obtain a metal composite material having excellent wear resistance, which is a characteristic of the metal composite material, and excellent workability.
[0031]
In the method for producing a porous metal body of the present invention, the oxide powder is used without using Fe as a component of the slurry. At this time, the average particle size of the Fe oxide is 5 μm or less. Preferably it is 1 micrometer or less. This shortens the time required to reduce the particles to the inside and facilitates sintering during firing. Further, after the first heat treatment, a carbonized component generated from the resin is formed around the main component particles containing Fe and Cr in a uniformly dispersed state, and is uniformly reduced. As a result, it becomes easy to form a skeleton having a uniform composition and a relatively low porosity.
[0032]
As shown in FIG. 2, there are pores inside the skeleton, but the strength decreases when the porosity is large. In the present invention, by using the fine Fe oxide as described above, the porosity, that is, the pore area ratio of the skeleton cross section can be suppressed to 30% or less.
Further, by finely pulverizing, a coating layer of the slurry on the porous resin body can be formed densely and uniformly. Furthermore, since the formation of the FeCr composite oxide is facilitated in the first heat treatment step, the reaction during reduction sintering is promoted. As a result, the heat treatment time can be shortened. In addition, the contact area with the carbon particles generated from the resin is increased by atomization, the carbonization reaction is promoted and carbon can be consumed uniformly, so that it is easy to occur when sintering metal powder in a reducing atmosphere. Adhesion of carbon is difficult to occur. As a result, troubles such as deterioration of the sintering furnace can be suppressed.
[0033]
For Cr as an alloy component, metal Cr, Cr alloy or Cr oxide is used as a feedstock, but the composition after alloying is 30% by mass or less, more preferably, in addition to this, the mass ratio of Fe and Cr Fe / Cr should be in the range of about 1.5-20. When the amount of Cr exceeds 30% by mass, the mechanical strength as a metal porous body is lowered. In order to form a uniform skeleton, the finer the Cr raw material powder is, the better the same as the above raw material as the alloy component Fe, but the finer the metal powder, the higher the price. It is a good idea to use it extremely. In the case of metallic Cr, a powder having an average particle size of 40 μm or less is preferable. More preferably, the thickness is 10 μm or less, which is convenient for alloying with Fe oxide. If it is larger than 40 μm, precipitation during slurry and uneven coating are induced, resulting in non-uniform alloy composition. From the above viewpoint, a particularly preferable starting material as a Cr component is Cr.₂O_ThreeOr FeCr alloy.
[0034]
When at least one metal powder of Ni, Cu, Mo, Al, P, B, Si, Ti or an oxide powder thereof is added as the third component, the heat resistance, corrosion resistance, and mechanical properties of the metal porous body It is preferable because the strength can be improved. The amount that exhibits the effect varies depending on the type of metal, but is preferably 25% by mass or less as a total amount in terms of the element concentration in the product composition. Addition of an amount exceeding 25% by mass adversely affects the improvement of the metal skeleton.
[0035]
What should be noted about the blending ratio in the slurry is the distribution of the amount of oxygen and the amount of thermosetting resin of the oxide of Fe and Cr, and further the oxide as the third component. The role of the thermosetting resin is a carbon source for forming a metal carbide and a function as a binder for attaching the slurry to the resin core having a foam structure. The thermosetting resin is carbonized when heated after coating, and the carbon after carbonization also serves as a carbon source for metal carbide formation. Therefore, the blending amount is related to the ratio between the amount of oxygen atoms present as the metal oxide in the slurry and the amount of carbon atoms in the thermosetting resin component. Most of the resin or other resin component that becomes the core body is burned off during firing, so that the final contribution to the amount of residual carbon in the metal porous body is small.
[0036]
In consideration of these points, it is preferable to determine the blending ratio of the resin component and the metal oxide when preparing the slurry based on the carbonization rate of the total resin including the resin porous body serving as the skeleton. First, the metal weight per unit volume is determined according to the application. The resin component amount is determined from the metal amount. At the same time, the amount of residual carbon resulting from the thermosetting resin component added is determined from the residual carbon ratio of the resin component. Then, a metal alloy is designed from the characteristics such as heat resistance and mechanical strength of the metal, and the amount of Fe, Cr, and a third metal to be added is calculated. The amount of oxide is calculated from the raw material composition, and the amount of oxygen to be processed is determined. It is preferable to adjust the kind and amount of the thermosetting resin used for the slurry based on the following formula according to the firing step.
37 <X × Y <126 (1)
[0037]
Here, X is a residual carbon ratio (mass%) of the resin component, and is a ratio of the carbon amount after carbonization to the total amount of the resin component such as the skeleton resin and the thermosetting resin used in the slurry. Y is a mass ratio with respect to oxygen contained in the oxide of the metal added as the third component, such as Fe or Cr as the main component of all resin components. When the third component is used as a metal powder, it is not counted. Moreover, a resin component is the sum total of all resin containing frame | skeleton resin and a thermosetting resin.
In addition, as already stated, the value obtained by multiplying the residual carbon ratio (a) of the thermosetting resin by the mass ratio (b) to oxygen contained in the oxide of the thermosetting resin is expressed by the above formula (2). Thus, if the range is larger than 17 and smaller than 37, the amount of carbon remaining in the skeleton of the finished porous metal body is finally adjusted to a range of 0.1% by mass to 3.5% by mass. Can do.
[0038]
As described above, by considering the quantitative relationship between the resin component in the slurry and the metal oxide as in the above formulas (1) and (2), a small amount of carbon remains in the metal porous body. Therefore, it has excellent mechanical strength, heat resistance, and corrosion resistance. Further, the metal structure in the skeleton becomes dense, and the pore area in the cross section of the skeleton is suppressed to 30% or less. Moreover, the volume ratio of the porous body can be freely controlled within a range of 3% or more by controlling the amount of slurry and the like.
[0039]
The slurry is applied to the resin core using the slurry prepared as described above. In the present invention, as described above, in order to make the pore diameter of the metal porous body 500 μm or less, a resin core having a pore diameter of 625 μm or less is prepared, and slurry is applied thereto. A desirable pore diameter range is 100 to 350 μm. As a result, as described above, the seizure resistance when the composite material of the porous body and the light metal is formed is remarkably improved.
[0040]
The coating method is preferably such that after spraying the slurry or dipping the core into the slurry, the core is squeezed with a roll or the like to a predetermined coating amount. In that case, it is important to apply evenly to the inside of the skeleton of the core. In order to control the coating amount, it is also important to control the viscosity of the slurry. For example, it is easy to control by using a liquid thermosetting resin or a liquid made with a solvent. As the diluent, water is used when the resin is water-soluble, and an organic solvent is used when the resin is water-insoluble. In the drying after the coating, the treatment is performed at a temperature lower than the temperature at which the resin core is deformed.
[0041]
The resin core body coated with the slurry and dried is fired in a non-oxidizing atmosphere to form a porous metal body having a structure in which carbides are uniformly dispersed on the skeleton surface containing Fe and Cr as main components as described above. . As a preferred embodiment of the firing step, the two-stage heat treatment conditions are changed as described above. The resin core is removed under the conditions of the first heat treatment, and at the same time, the thermosetting resin is carbonized, the metal oxide is reduced with this carbon content, and a part of the metal component is converted into a carbide. Thereafter, the conditions are changed to a high temperature, and a strong foam metal structure is obtained together with sintering. By this treatment, metal carbide is formed in the skeleton of the metal porous body, and a metal porous body in which the carbide is uniformly distributed is obtained.
[0042]
In the firing step, the temperature of the first heat treatment step is preferably lower than the conditions for producing a uniform metal composition, and is preferably around 800 ° C. A temperature in the range of 750 ° C. to 1100 ° C. is preferable. The temperature of the second heat treatment step for sintering is in the range of 950 to 1350 ° C. suitable for forming an alloy of Fe and Cr as described above, and preferably 1100 ° C. Above 1250 ° C., particularly around 1200 ° C. is desirable.
[0043]
Alternatively, the firing can be performed in the following two heat treatment steps. That is, in the first heat treatment step, first, simultaneously with carbonization of the resin component, an FeCr composite oxide is formed by the reaction of Fe oxide and metal Cr, Cr alloy or Cr oxide. By forming this FeCr composite oxide, the reduction sintering operation in the next step is facilitated. Accordingly, in the first heat treatment step, carbonization of the resin is necessary, and therefore, it is preferable to set the ambient temperature to 400 ° C. or higher and 900 ° C. or lower in a non-oxidizing atmosphere. If the temperature is lower than 400 ° C., the carbonization of the resin takes time, which is uneconomical, and sufficient carbonization does not proceed, so that tar is easily formed in the next step, which may cause inconvenience in sintering. Further, when the temperature exceeds 900 ° C., the reduction reaction of the composite oxide proceeds, and it may be difficult to obtain a dense metal structure in the next second heat treatment step.
[0044]
In this method, if the second heat treatment step is performed without passing through the first heat treatment step, the resin is not sufficiently carbonized, so that the skeleton structure is not sufficiently retained, and the skeleton is cracked or broken. May be likely to occur. Furthermore, since the FeCr composite oxide may be sintered without being sufficiently formed, defects due to the oxide may occur in the skeleton after firing.
[0045]
In the second heat treatment step, a redox reaction occurs between the carbon component from the resin component formed in the previous step and the FeCr composite oxide. At the same time, sintering of metal particles in the metal skeleton proceeds. The firing atmosphere may be a reducing atmosphere, but may be in a vacuum. Typical examples of the atmospheric gas that forms the reducing atmosphere include hydrogen gas, ammonia decomposition gas, or a mixed gas of hydrogen and nitrogen. When sintering in vacuum, the oxygen partial pressure is 0.5 Torr or less. The ambient temperature should be 950 ° C. or higher and 1350 ° C. or lower. Under these conditions, the FeCr composite oxide is easily reduced with the help of activated carbon generated by the carbonization of the resin component to form a skeleton and simultaneously with the FeCr alloy. become. If it is less than 950 ° C., reduction sintering takes time and is uneconomical. If it exceeds 1350 ° C., a liquid phase appears at the time of sintering, and the metal skeleton cannot be retained. A more preferable temperature is 1100 ° C. or higher and 1250 ° C. or lower.
[0046]
The skeleton of the metal porous body produced in this way is formed of a uniform FeCr alloy and becomes dense with a low porosity, so that the mechanical strength is improved.
The pore diameter of the metal porous body produced as described above is 500 μm or less. As already described, if the pore diameter of the foamed resin as the core is reduced, a smaller metal porous body can be obtained. The porous body of the present invention is excellent in mechanical strength, particularly bending strength toughness because it has a low porosity skeleton based on Fe and Cr in which carbides as described above are uniformly and finely dispersed. . For this reason, even if the hole diameter is as small as 500 μm or less, the moldability to the preform is not impaired as compared with the hole diameter exceeding that. Moreover, the bending strength is improved by reducing the hole diameter as compared with those having a large hole diameter. For example, the same material and the hole diameter of 790 μm are 0.17 MPa, whereas when the hole diameter is 500 μm or less, excellent bending strength exceeding 0.45 MPa is obtained. For this reason, the expansion of the use as a structural member which was not considered in the conventional one can be greatly expected.
[0047]
Furthermore, since the composite material of the present invention is filled with a light alloy to which mechanical strength excellent in heat resistance and corrosion resistance is imparted in the pores of the porous body by the impregnation method as described above, In particular, when combined with a porous body having a volume ratio of 3% or more and 30% or less, it is basically excellent as a structural member that is lightweight and excellent in durability. In particular, as described above, the composite material provided by the present invention is controlled to have a particularly small area occupied by a light alloy in an arbitrary cross section, so that it has excellent wear resistance and is particularly resistant to seizure during sliding. Because of its excellent properties, it can sufficiently meet the weight reduction of various sliding parts. Further, the solid lubricant added to the skeleton surface shows excellent seizure resistance even under severe conditions such as lack of lubricating oil in the sliding portion.
[0048]
【Example】
  Hereinafter, the present invention will be described specifically by way of examples.
  In addition, Examples 11, 15, 16, 21, 27, 31, 32, 37, 43, 47, 48, and 53 are missing numbers.
Example 1
  Fe with an average particle size of 0.7μm₂O_Three50% by mass of powder, 23% by mass of FeCr (Cr60%) alloy powder having an average particle size of 4 μm, 17% by mass of 65% aqueous phenol resin as a thermosetting resin, 2% by mass of CMC (carboxymethylcellulose) as a dispersant, and 8% by mass of water % To obtain a slurry. After impregnating the slurry with a polyurethane foam having a thickness of 10 mm and a pore diameter of 600 μm, the excessively adhered slurry was squeezed out and removed with a metal roll, and dried at 120 ° C. in the atmosphere for 10 minutes. This sheet was processed under the heat treatment conditions shown in Table 1 to prepare a porous metal body. Table 2 shows the results of examining the density of the finished porous metal body, the average porosity of the skeleton, the three-point bending strength, and the oxidation increment indicating heat resistance. The pore diameter of the produced metal porous body was 480 μm.
[0049]
[Table 1]

[0050]
No. No. 1 has a low temperature in the second heat treatment step. No. 7 was inferior in the above characteristics compared to other porous metal bodies because the temperature of the second heat treatment step was high.
[0051]
[Table 2]

[0052]
From the above results, when the temperature of the second heat treatment step is low, the average porosity of the skeleton increases and the three-point bending strength decreases. Moreover, since the surface area also increases, the heat resistance due to oxidation decreases. Conversely, if the temperature is too high, the metal skeleton cannot be maintained and the density increases, but the three-point bending strength decreases. The density of the metal porous body depends on the amount of slurry applied. As described above, the second heat treatment temperature is preferably 950 to 1350 ° C., and it is more preferable to perform the heat treatment in a two-stage process.
[0053]
Example 2
Fe having the average particle size shown in Table 3₂O_Three50% by mass of powder, 23% by mass of FeCr (Cr 60%) alloy powder having an average particle size of 8 μm, 17% by mass of 65% aqueous phenol resin solution as thermosetting resin, 2% by mass of CMC as dispersant, and 8% by mass of water A slurry was prepared. This slurry was impregnated and applied to a polyurethane foam having a thickness of 10 mm and a pore diameter of 340 μm, and excess slurry was squeezed out and removed with a metal roll. Then, it dried for 10 minutes at 120 degreeC in air | atmosphere. Then N₂After carbonizing polyurethane and phenolic resin by heat treatment at 800 ° C for 20 minutes, H₂The medium was reduced and sintered at 1200 ° C. for 30 minutes to obtain a porous metal body of FeCr alloy. Table 4 shows the results of examining the density of the finished porous metal body, the average porosity of the skeleton, the three-point bending strength, and the oxidation increment rate.
The prepared porous metal body had a pore size of 270 μm.
[0054]
[Table 3]

[0055]
[Table 4]

[0056]
From Tables 3 and 4, when the average particle size of the Fe oxide is large, the average porosity of the skeleton exceeds 30%, and the tensile strength decreases. As the average particle size of the Fe oxide increases, the surface area of the skeleton of the resulting porous metal body increases, and the density and tensile strength of the metal decrease. As a result, the oxidation increment, which is a measure of heat resistance, increases. Therefore, the average particle diameter of the Fe oxide is preferably 5 μm or less, and more preferably 1 μm or less.
[0057]
Example 3
Fe having an average particle size of 0.7 μm in the same production procedure as in Example 2₂O_ThreeUsing the powder, a metal porous body was produced under the conditions in which the amount of residual carbon was changed by changing the amount of phenol resin which is a thermosetting resin in the slurry. When this state is expressed by the residual carbon ratio X of the resin component and the mass ratio Y with respect to oxygen contained in the oxide of the resin component, it is as shown in Table 5. The resin component is phenol resin, urethane foam, and CMC.
[0058]
[Table 5]

[0059]
Table 6 shows the results of investigating the density of the metal porous body formed under the slurry preparation conditions shown in Table 5, the average porosity of the skeleton, the three-point bending strength, and the oxidation increment rate.
[0060]
[Table 6]

[0061]
From the results of Table 6, it can be seen that a difference occurs in the characteristics of the manufactured porous metal body depending on the value of X × Y. From the comparison between Table 6 and Table 5, the value of X × Y is smaller than 37 (the product of the residual carbon ratio of the resin component and the mass ratio of the resin component to the oxygen contained in the oxide is smaller than 37), and metal It turns out that the characteristic of a porous body deteriorates. In particular, the porosity of the skeleton cross section becomes larger, and as a result, the increment of oxidation tends to increase due to a decrease in tensile strength and a decrease in heat resistance. On the contrary, the same tendency exists even when the value of X × Y is larger than 126 (the product of the residual carbon ratio of the resin component and the mass ratio of the resin component to the oxygen contained in the oxide is larger than 126). Therefore, it can be seen from the results of this example that a more preferable porous metal body can be obtained by setting the value of X × Y to be more than 37 and less than 126.
[0062]
Example 4
Fe with an average particle size of 0.8μm_ThreeO_Four50% by mass of powder, 7.9% by mass of Cr powder having an average particle size of 5 μm, and a powder added with the third metal powder of the type and amount shown in Table 7, 12% by mass of 65% aqueous phenol resin solution, dispersant (CMC) 2% by mass of water was added to prepare a slurry with a blending ratio of 100% by mass. Using this slurry, a polyurethane foam having a thickness of 15 mm and a pore diameter of 500 μm was impregnated and applied, and excess slurry was squeezed out and removed with a metal roll. Then, it dried for 10 minutes at 120 degreeC in air | atmosphere. Then N₂Heating at 700 ° C. for 25 minutes in an atmosphere forms a carbonized resin and a FeCr composite oxide, and further heats at 1180 ° C. for 30 minutes in a vacuum with an oxygen partial pressure of 0.5 Torr for reduction sintering. A porous metal body of FeCr alloy containing the components was obtained. The finished metal porous body was evaluated in the same manner as in the previous examples. The results are shown in Table 8.
The pore diameter of the produced metal porous body was 400 μm.
[0063]
[Table 7]

[0064]
[Table 8]

[0065]
From the results of Table 7 and Table 8, it is possible to modify the FeCr alloy porous metal body by including a third metal, and if the amount does not greatly affect the composition, the third metal may be included. It can be seen that the physical properties, mechanical strength, and heat resistance are not adversely affected, and the properties such as heat resistance and three-point bending strength can be improved by increasing the third component.
[0066]
Example 5
No. 1 used in Example 4 above. About 24, the slurry which changed the quantity of a metal oxide and a resin component was produced. Of the resin components, only the amount of phenol resin in the slurry was changed. The other component compositions are No. 24.
The blending ratio is shown in Table 9 as X and Y.
[0067]
[Table 9]

[0068]
Using these slurries, a porous metal body was produced under the same conditions as those in Example 4. The resulting porous metal body was evaluated in the same manner as in the previous examples. The results are shown in Table 10. The pore diameter of the produced metal porous body was 400 μm.
[0069]
[Table 10]

[0070]
From the results of Table 9 and Table 10, it can be seen that a more excellent porous metal body is formed when a blending ratio in a range where the value of X × Y exceeds 37 and is less than 126 is used.
[0071]
Examples 6-10
Fe with an average particle size of 0.6μm₂O_Three52% by mass of powder, 23% by mass of FeCr alloy (Cr63%) powder having an average particle size of 7 μm, 13% by mass of 65% aqueous phenol resin as thermosetting resin, 1.5% by mass of dispersant (CMC), and 10% of water The slurry was mixed with a composition of 5% by mass.
This slurry was impregnated into a polyurethane foam sheet having a thickness of 10 mm and a pore diameter of 340 μm. Slurry adhering excessively with a metal roll during lifting was squeezed out and dried at 120 ° C. in the atmosphere for 10 minutes. This sheet was heat-treated under the conditions shown in Table 11 to obtain a porous metal body. Table 12 shows the characteristics of the finished metal porous body.
In addition, evaluation about the "minimum curvature radius" in Table 12 fixed the one end of a plate-shaped metal porous body (140 mm x 90 mm x 3 mmt), bent the other end and brought it closer to the fixed end, and fractured. When the radius of curvature was measured, this was defined as the “minimum radius of curvature”. A product having a large radius of curvature can be used even if it is about 9th embodiment, but if it is processed into a cylinder with a diameter of 80 mm, the product of about 9th embodiment cannot be used.
[0072]
[Table 11]

[0073]
[Table 12]

[0074]
From the results shown in Table 12, the density of the porous metal body does not change depending on the carbon content. However, in bending, when the carbon content increases, the minimum radius of curvature exceeds 10 cm and the workability decreases. I understand. About hardness, it turns out that it becomes hard as the amount of residual carbons increases. Here, “carbon content” and “remaining carbon ratio” will be described as follows.
Residual carbon ratio: In the process of heat treatment divided into two stages, the urethane foam and heat carbonized in the first heat treatment with respect to the total amount of resin components such as the skeleton resin and the thermosetting resin used in the slurry The mass ratio of the remaining amount of the curable resin.
Carbon content: When the second stage heat treatment is carried out at the above-mentioned residual carbon ratio, most of the carbon is used for oxide reduction, but the final product of the carbon amount remaining after this second stage heat treatment is used. The mass ratio with respect to a certain metal porous body.
[0075]
Since the metal porous body according to the present invention has good processability and the hardness of the metal porous body is required, it is necessary that the carbon content is appropriate.
[0076]
Examples 12-14, Comparative Examples 1-3
  Based on the slurry of the components / compositions used in Example 6, the various amounts of the thermosetting resin were changed to prepare various slurries with different mass ratios with the metal oxide (the amount of the thermosetting resin) Is shown in the second column of Table 13.). Using this slurry, a metal porous body was produced under the same conditions as in Example 6 after slurry impregnation. The resin residual carbon ratio (a) of these porous metal bodies and the mass ratio (b) to oxygen contained in the oxide of the thermosetting resin were confirmed and are also shown in Table 13.
  Table 14 shows the properties of the obtained porous body.
[0077]
[Table 13]

[0078]
[Table 14]

[0079]
When the value of a × b is 17 or less, the carbon content in the metal porous body becomes smaller than 0.1% by mass, and the workability decreases. When produced under the condition satisfying the formula (2), the carbon content in the metal porous body can be controlled to 0.1 mass% or more and 3.5 mass% or less, and the minimum curvature radius of the metal porous body in that range Becomes smaller and various bending processes become easier. In the case of 37 or more, the carbon content exceeds 3.5% by mass and the minimum radius of curvature becomes large, and the molding restrictions become large. Furthermore, the hardness of the metal skeleton tends to increase. From the above results, it can be seen that controlling the preferred carbon content to 0.1 mass% or more and 3.5 mass% or less can be achieved by controlling the value of a × b.
[0080]
Example 17-20, Comparative Example 4
  Fe with an average particle size of 0.5 μm₂O_Three54% by mass of powder, 16% by mass of FeCr alloy (Cr63%) powder having an average particle size of 5 μm, 1.5% by mass of dispersant (CMC) and 65% aqueous phenol resin solution as thermosetting resin are added in the amounts shown in Table 15. Water was added to this to prepare a slurry having a blending ratio of 100% by mass.
  This slurry was impregnated into a polyurethane foam sheet having a thickness of 12 mm and a pore diameter of 420 μm, and then excess slurry was squeezed out and removed with a metal roll, followed by drying at 120 ° C. in the atmosphere for 10 minutes. This sheet was heat-treated under the conditions of Example 9 in Table 11 to produce a porous metal body. Table 16 shows the characteristics of the produced porous metal body.
  The pore diameter of the metal porous body was 340 μm.
[0081]
[Table 15]

[0082]
[Table 16]

[0083]
  Examples 17 to 16 shown in Table 1620The density of the porous metal bodies of Examples 6 to 6 shown in Tables 12 and 1410, 12-14The difference in the density of the metal porous body is due to the difference in the porosity and the like of the urethane foam sheet used for the material. The relationship between carbon content, minimum radius of curvature (indicating workability) and hardness is similar to the results in Table 14. When the carbon content exceeds 3.5% by mass, the workability deteriorates as apparent from the data on the minimum radius of curvature in Table 16. However, the metal porous body having a relatively high residual carbon as described above has no problem even if the degree of processing is low, and is suitable for applications in which wear resistance is important. Further, in the case of Example 17 with a low carbon content, since the hardness is low, there is a possibility that a good result will not be brought about to make a metal composite material combined with a light alloy.
[0084]
Example 22-26, 28-30, 33-36 (Metal Composite Production Example 1) and Comparative Examples 5-9
  Example 6-10, 12-14, 17-20, Comparative Examples 5-8A part of the metal porous body obtained in the above was put into a mold, and an aluminum alloy (AC8C) melt heated to 750 ° C. was impregnated into the porous body under a pressure of 39.2 MPa to prepare an aluminum composite material. The resulting aluminum composite was cut into a rectangular sample (15 mm × 15 mm × 10 mm) shown in FIG. 5 (a) and subjected to a roller pin wear test using the test apparatus shown in FIG. 5 (c). Specifically, as shown in the figure, the sample to be evaluated is processed into the shape shown in Fig. (A), and the roller processed in the shape of the roller shown in Fig. (B) is rotated under predetermined conditions. Thus, the wear performance was evaluated.
[0085]
The conditions of the roller pin wear test are as follows.
Opposite material: Nitride steel with hardness of Hv1000, rotating roller with diameter of 80mm and width of 10mm
Rotation speed: 200rpm
Pressing load: 60kg
Time: 20 minutes
Lubricating oil: SAE10W30
Drop rate: 5 ml / min
[0086]
In this test, the produced aluminum composite material specimen generates heat because it is pressed against the mating material rotating vertically from the upper part with a pressing load applied. Therefore, the roller and the composite material sample were prevented from welding by dripping the lubricating oil onto both contact portions. After loading, after 20 minutes had elapsed, the rotation of the mating member was stopped, the wear depth of the sample was measured, and the results shown in Table 17 were obtained. Here, as Comparative Example 1, an aluminum alloy (AC8C) was cut into a rectangle and used.
[0087]
In this roller pin wear test, the combination with the roller material to be combined also affects the test results. As shown in Table 17, it can be seen that the wear resistance is remarkably improved in the composite material of the present invention. When the carbon content is extremely low, the composite effect is reduced, and the wear resistance is improved as the carbon content is increased. In this test, the process of processing the porous metal body of the example was not performed, but if it is processed in a complicated manner, the workability also becomes a problem. Therefore, either wear resistance or workability is within the range where the carbon content is high. It is necessary to adjust and select the carbon content depending on whether it is important.
[0088]

[0089]
From the above results, the porous body of the present invention has Fe carbide or FeCr carbide as a homogeneous dispersed phase in an alloy composed of Fe and Cr, so that the skeleton itself has high hardness, and itself has wear resistance. It turns out that it is excellent in mechanical strength. Therefore, the composite material of the present example combined with an Al alloy using this as a skeleton is excellent in wear resistance.
[0090]
Example 38-42, 44-46, 49-52 (Metal Composite Production Example 2) and Comparative Example 2
  Example 6 similar to Metal Composite Production Example 1-10, 12-14, 17-20, Comparative Examples 5-8Using the metal porous body obtained in the above, a composite using a magnesium alloy was performed. A part of each porous metal body of the example was put in a mold, and a molten magnesium alloy (AZ91A) heated to 750 ° C. was injected under a pressure of 24.5 MPa to prepare a magnesium composite material. The resulting composite material was cut into a rectangular shape, and the wear resistance was measured using a roller pin abrasion tester.
[0091]
The conditions of the roller pin wear test are as follows.
Counterpart material: Nitride steel with hardness of Hv1000, rotating roller nitrided steel with diameter of 80 mm and width of 10 mm (same as Production Example 1)
Rotation speed: 300rpm
Pressing load: 50kg
Time: 15 minutes
Lubricating oil: SAE10W30
Drop rate: 5 ml / min
[0092]
This test method was also performed in the same manner as in Metal Composite Production Example 1, and the results are shown in Table 18. The comparative example 2 used here cuts out a magnesium alloy (AZ91A) into the rectangle. As shown in Table 18, when the carbon content is small, the value approaches the wear depth of Comparative Example 2 that was not combined. However, wear resistance improves as the carbon content increases.
As for the correlation between the amount of residual carbon and the amount of wear, the hardness increases and the wear resistance tends to improve as the carbon content increases, as in the case of the aluminum composite.
[0093]
[Table 18]

[0094]
In the metal porous body of the present invention, Fe carbide or FeCr carbide exists in an alloy composed of Fe and Cr as a uniform dispersed phase, so that the skeleton itself has high hardness, and itself has wear resistance and mechanical strength. Is excellent. Therefore, the composite material of the present example combined with the Mg alloy using this as a skeleton is excellent in wear resistance.
[0095]
Examples 54-58
Fe with an average particle size of 0.4 μm₂O_Three50% by mass of powder, 14.5% by mass of FeCr (Cr63%) alloy powder having an average particle size of 5 μm, a powder added with a metal powder of the type and amount shown in Table 19, and 12% by mass of 65% aqueous phenol resin solution, dispersant (CMC) A slurry having a blending ratio of 100% by mass with water added to 1.5% by mass was prepared. This slurry was impregnated into a polyurethane foam having a thickness of 10 mm and a pore diameter of 340 μm, and then the excessively adhered slurry was removed with a metal roll and dried at 120 ° C. for 10 minutes. This sheet was processed under the heat treatment conditions shown in Example 9 in Table 11 to prepare a metal porous body. Table 20 shows the density, carbon content, and Vickers hardness of the finished porous metal body.
[0096]
[Table 19]

[0097]
[Table 20]

[0098]
Examples 59-63 (Metal Composite Material Production Example 3) and Comparative Example 3
The metal porous body produced in the above Examples 54 to 58 was set in a mold, and a molten aluminum alloy (AC8A) heated to 760 ° C. was 20 kg / cm.²An aluminum composite material was produced by pressure injection at. The obtained composite material was subjected to a roller pin wear test. Moreover, the same abrasion test was done using the thing which cut out the aluminum alloy (AC8A) into the rectangle as the comparative example 3. The results are shown in Table 21.
The wear test conditions are as follows.
Opposite material: Nitride steel with a hardness of Hv1000, a rotating roller with a diameter of 80 mm and a width of 10 mm (same as Production Example 1)
Rotation speed: 50rpm
Pressing load: 100kg
Time: 20 minutes
Lubricating oil: SAE10W30
Drop rate: 1 ml / min
[0099]
[Table 21]

[0100]
Examples 64-65 and Comparative Examples 4-5
Fe with an average particle size of 0.4 μm₂O_Three50% by mass of powder, 14.5% by mass of FeCr (Cr63%) alloy powder having an average particle size of 5 μm, 4.4% by mass of Ni powder having an average particle size of 2.8 μm, 12% by mass of 65% phenol resin solution, dispersant (CMC) A slurry having a blending ratio of 100% by mass with water added to 1.5% by mass was prepared. After impregnating this slurry in polyurethane foam shown in Table 22, the slurry excessively adhered with a metal roll was squeezed out and dried at 120 ° C. for 10 minutes. This sheet was processed under the heat treatment conditions shown in Example 9 in Table 11 to prepare a metal porous body. Table 23 shows the density, carbon content, pore diameter, and three-point bending strength of the resulting porous metal body. It can be seen that a sample having a hole diameter of 0.5 mm or less has a bending strength of 1.5 times or more compared to a hole diameter of 0.64 mm.
[0101]
[Table 22]

[0102]
[Table 23]

[0103]
Examples 66 to 68 (Metal Composite Material Production Example 4) and Comparative Examples 6 to 7
The porous metal body produced in Examples 54, 64 and 65 and Comparative Examples 4 and 5 was set in a mold, and a molten aluminum alloy (AC8A) heated to 760 ° C. was 20 kg / cm.²An aluminum composite material was produced by pressure injection at. Table 24 shows the result of the seizure test performed on the obtained composite material.
The seizure test conditions are as follows.
Mating material: nitrided steel, diameter 11.3 mm, tip R = 10 mm
Load: Start from 1 kgf and increase the weight by 1 kgf every minute
Stroke: 50mm
Test speed: 200 cpm
Atmosphere: Wipe off after applying oil (SAE10W-30)
[0104]
[Table 24]

[0105]
Examples 69-75 and Comparative Examples 8-11
The porous metal body of Example 54 was immersed in an aqueous solution containing a solid lubricant shown in Table 25, and after taking out, the porous metal body dried at 70 ° C. for 1 hour was set in a mold and heated to 760 ° C. 20kg / cm of molten alloy (AC8A)²An aluminum composite material was produced by pressure injection at. The obtained composite material was tested under the same conditions as the seizure test in Metal Composite Production Example 4.
As a comparative example, a composite material was produced and tested in the same manner as in Example 69 except that a porous metal body was produced in the same manner as in Example 18 using a polyurethane foam having a pore diameter of 700 μm. The results are shown in Table 26.
The solid lubricant concentration in the aqueous solution containing the solid lubricant is 50%, and the amount of solid lubricant added after immersion is 10-15% of the weight of the metal porous body.
[0106]
[Table 25]

[0107]
[Table 26]

[0108]
From the evaluation results, it is understood that the seizure resistance is further improved by adding the solid lubricant to the surface of the metal porous body. FIG. 6 shows a schematic diagram of the solid lubricant applied to the skeleton surface.
[0109]
Examples 76-84
Table 27 shows the porous metal body produced by changing the compounding ratio of Cr, Mo and Ni with respect to the porous metal body of Example 55. Table 28 shows the results of the sulfuric acid immersion test for these porous metal bodies. It can be seen that the corrosion resistance is dramatically improved by changing the compounding ratio.
[0110]
The corrosion test conditions are as follows.
Solution: Sulfuric acid (1N)
Temperature: Room temperature
Time: 24 hours
Evaluation method: Immerse the sample in 1N sulfuric acid, take out the sample after 24 hours, and measure the change in weight.
[0111]
[Table 27]

[0112]
[Table 28]

[0113]
As described above, the corrosion resistance level in strong acid can be designed by changing the alloy composition. These metal porous bodies can be applied as electrode materials in strong acid atmospheres such as solid polymer fuel cells.
Moreover, the Cr carbide phase of the present invention has an effect of reducing contact resistance when applied as these electrode materials.
[0114]
【The invention's effect】
As described above, according to the manufacturing method of the present invention, it is possible to obtain a porous metal body of FeCr alloy in which metal carbide is uniformly dispersed, and has excellent characteristics in terms of strength and heat resistance. I can do it. It is also possible to obtain a metal porous body obtained by alloying a third metal that improves the properties of the metal porous body.
In addition, since the metal porous body according to the present invention has appropriate workability and hardness by uniformly dispersing the metal carbide phase in the skeleton, an alloy mainly composed of light metals such as Al or Mg and It is also suitable as a skeleton for obtaining the composite material. By using the porous metal body of the present invention, the obtained composite material has improved wear resistance and can be appropriately processed. In particular, by suppressing the pore diameter of the metal porous body serving as a skeleton to 500 μm or less, seizure resistance is significantly improved when a light alloy and composite material is used as a sliding member.
[Brief description of the drawings]
FIG. 1 is an enlarged schematic view of a porous metal body according to the production method of the present invention.
FIG. 2 is a diagram illustrating a skeleton cross section of a metal porous body.
FIG. 3 is a view showing the presence of metal carbide dispersed in the skeleton cross section of the porous metal body of the present invention.
FIG. 4 is an enlarged view of a cross section of a metal composite material using the porous metal body of the present invention.
FIG. 5 is a view showing a roller pin wear test apparatus according to an embodiment of the present invention and a test piece thereof.
FIG. 6 is a schematic view of a solid lubricant applied to the skeleton surface of the porous metal body of the present invention.
[Explanation of symbols]
1 Metal skeleton
2 holes
3 Matrix
4 Carbide phase
5 Al alloy matrix
6 Metal porous body skeleton
7 Roller pin wear test piece
8 Mating material roller
9 Load application device

Claims (7)

A slurry comprising an Fe oxide powder having an average particle size of 5 μm or less, one or more powders selected from metal Cr, Cr alloy, and Cr oxide, and a thermosetting resin and a diluent as a main component. The blending ratio with the oxide powder is such that the resin ratio is such that the residual carbon ratio of the resin component and the mass ratio of the resin component to the oxygen contained in the oxide satisfy the following formula (1). The slurry is prepared and applied to a foamed resin core having a pore size of 625 μm or less and then dried, followed by firing including a heat treatment step at 950 ° C. to 1350 ° C. in a non-oxidizing atmosphere. A method for producing a porous metal body.
37 <X × Y <126 (1)
X: Residual carbon ratio of resin component (mass%)
Y: Mass ratio to oxygen contained in oxide of resin component A slurry having an average particle size of 5 μm or less as a main component of Fe oxide powder, one or more powders selected from metal Cr, Cr alloy and Cr oxide, and thermosetting resin and diluent as main components . The blending ratio of the resin and the oxide powder is such that the residual carbon ratio of the solution containing the thermosetting resin and the mass ratio with respect to oxygen contained in the oxide of the solution containing the thermosetting resin satisfy the following formula (2). produced as a kind of resin weight, pore size and dried Nurigi the slurry to a resin core body of the following expanded structure 625 .mu.m, followed in a non-oxidizing atmosphere, heat treatment process at 950 ° C. or higher 1350 ° C. or less The manufacturing method of the metal porous body characterized by performing baking containing this.
17 <a × b <37 (2)
here,
a: Residual carbon ratio (mass%) of the solution containing the thermosetting resin
b: Mass ratio with respect to oxygen contained in the oxide of the solution containing the thermosetting resin
Solution containing thermosetting resin: Dissolved thermosetting resin in water or solvent Firing is performed by removing the resin core and simultaneously carbonizing the thermosetting resin, reducing the metal oxide with this carbon component, and carbonizing a part of the metal component, and then 1100. ° C. by heating to a high temperature of 1350 ° C. inclusive, to claim 1 or 2, characterized in that in a two-step process comprising more the second heat treatment step of forming a sintered body with strong foam metal structure The manufacturing method of the metal porous body of description. Firing is performed by a first heat treatment step for carbonizing a resin component in a non-oxidizing atmosphere, and a metal oxide is reduced by carbon generated in the first step at a temperature of 950 ° C. to 1350 ° C. in a reducing atmosphere. In addition, a part of the metal component is converted into a carbide, and then the reduced metal component is alloyed and sintered to form a strong foam metal structure, which is performed in a two-step process. The manufacturing method of the metal porous body of Claim 1 or 2 . Ni in the slurry to the kneading, Cu, Mo, Al, P , B, according to claim 1, wherein the Si, at least one powder selected from the group consisting of Ti, and further mixing the oxide powder The manufacturing method of the metal porous body in any one of -4 . The pores in the porous metal body obtained by the process according to any one of claims 1 to 5, metal composite, which comprises impregnating injecting a melt of Al alloy or Mg alloy in the above pressure 98KPa A method of manufacturing the material. The skeleton surface of the porous metal body obtained by the production method according to claim 1 is selected from the group consisting of graphite, molybdenum disulfide, tungsten disulfide, boron nitride, molybdenum trioxide, and iron oxide. A method for producing a metal composite material, comprising coating at least one kind of solid lubricant and impregnating and pouring a molten Al alloy or Mg alloy into the pores under a pressure of 98 KPa or more.

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