JP2004122181A - Metal-coated cast iron molding, metal cast steel molding and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cast iron molding and a cast steel molding each coated with an alloy layer which is not easily peeled to scratching, rubbing, impact or the like over a long period, and has excellent corrosion preventability or the like, and to provide a method of satisfactorily, easily and inexpensively producing them. <P>SOLUTION: In the cast iron molding in which casting temperature is 1,300 to 1,400°C, the surface is coated with a metal having a solidification starting temperature of ≤1,200°C, on the boundary between the coating metal 3 and the cast iron molding 1a, an alloy layer 2 is formed of the coating metal 3 and various elements composing the cast iron molding 1a, and the coating metal 3 is integrated with the cast iron molding 1a. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、鋳鉄鋳物と鋳鋼鋳物及びその製造方法に関するものである。更に詳しくは、表面に合金層と被覆金属の皮膜を形成した鋳鉄鋳物と鋳鋼鋳物及びその製造方法に関するものである。
【０００２】
【従来の技術】
鋳鉄鋳物及び鋳鋼鋳物は、自動車、船舶、機械等の部品、公共建造物の部材等の工業製品や工芸品、芸術品にいたるまで幅広い分野に使用されているが、錆びやすいという特性があるために、用途に応じて、塗装や金属メッキ、金属溶射等の処理を施すことが広く行われている。
【０００３】
塗装は、合成樹脂塗料を中心に、前処理も含めて様々な塗装系が用途に応じて提案実施されているが、塗膜の機械的強度、接着性、耐候性等の問題で長期耐久性は十分とは言えない。特に、引っ掻きや、擦れ、落下物による衝撃等にたいしては、塗膜が破壊、剥離しやすく、初期の性能を発揮できない場合も多い。
【０００４】
それに対して、金属メッキや金属溶射は、塗装系に比べて、皮膜の強度が高く、長期耐久性の点で優れた処理方法であるが、いずれも鋳物表面に物理的に密着した皮膜であるため、十分な接着強度が得られないという弱点がある。このような弱点を改善するために、ブラスト処理やプライマー処理等が提案されている（例えば特許文献１参照）。
【０００５】
【特許文献１】
特許第２７５２３３７号明細書
【０００６】
しかし、特許文献１では、近年の鋳鉄、鋳鋼材料の長寿命化要求にたいしては、さらなる耐食性の向上、皮膜の機械的性能の向上等が必要である。
特に溶融メッキ、電気メッキは、専用の設備を必要とするため簡単には実施できないし、溶融メッキ法では高温の溶融金属中に被塗物を浸積するため、熱歪みや水素ガスの吸着などの問題等が起こって使えない場合もある。
またいづれの処理も鋳造工程とは別の工程となるので、その分コスト高の要因となる。
【０００７】
【発明が解決しようとする課題】
そこで、本発明は鋳鉄鋳物及び鋳鋼鋳物の上記のような問題点を克服し、長期間の防食性を発揮でき、引っ掻きや擦れ、衝撃等に対して容易に剥離しない合金層を被覆した鋳鉄鋳物及び鋳鋼鋳物並びにそれらを良好、容易かつ安価に製造する方法を提供することを目的する。
【０００８】
【課題を解決するための手段】
本発明者らは、上記課題を解決するために鋭意検討を重ねた結果、鋳鉄鋳物及び鋳鋼鋳物を製造する時に使用する従来の塗型剤に替えて、鋳鉄及び鋳鋼の鋳込み温度より５０〜１００℃低い凝固開始温度を有する金属粉末、粘結剤、水等からなる塗型剤を消失模型表面あるいは鋳型表面に塗布した後に、溶融した鋳鉄あるは鋳鋼を該鋳型に注湯し、固化後に鋳型を除去することで、鋳物表面に被覆金属が形成され、その被覆金属が鋳物との界面で被覆金属と鋳物を構成する各種元素からなる合金層を形成して一体となっていることを特徴とする鋳鉄鋳物及び鋳鋼鋳物が出来、従来の金属メッキや金属溶射被覆に比べて、皮膜が容易に剥離せず、耐食性等を一層向上させることができることを見い出し、本発明に至った。
以下本発明を詳細に説明する。
【０００９】
請求項１に記載の発明に係る金属被覆鋳鉄鋳物は、鋳込み温度が１３００℃〜１４００℃である鋳鉄鋳物（１ａ）において、その表面が１２００℃以下の凝固開始温度を有する金属で被覆されており、その被覆金属（３）と鋳鉄鋳物（１ａ）との界面に、被覆金属（３）と鋳鉄鋳物（１ａ）を構成する各種元素とによって合金層（２）が形成され、被覆金属３（が）鋳鉄鋳物（１ａ）と一体となっていることを特徴とする。
【００１０】
また、請求項２に記載の発明に係る金属被覆鋳鋼鋳物は、鋳込み温度が１５００℃〜１６００℃である鋳鋼鋳物（１ｂ）において、その表面が１４００℃以下の凝固開始温度を有する金属で被覆されており、その被覆金属（３）と鋳鋼鋳物（１ｂ）との界面に、被覆金属（３）と鋳鋼鋳物（１ｂ）を構成する各種元素とによって合金層（２）が形成され、被覆金属（３）が鋳鋼鋳物（１ｂ）と一体となっていることを特徴とする。
【００１１】
本発明で使用する金属粉末は、凝固開始温度が鋳鉄鋳物の場合は１２００℃以下、鋳鋼鋳物の場合は１４００℃以下であり、鋳型への注湯時に鋳鉄あるいは鋳鋼の熱により完全に溶融し鋳物表面を被覆する被覆金属の皮膜を形成すると同時に溶融した被覆金属と鋳物の溶湯との界面を通して、それらを構成する各種元素が相互に拡散して、鋳物表面には合金層皮膜を形成する。この合金層皮膜は鋳物と一体化して容易には剥離しない強固な被膜であり、鋳物表面を保護する機能を付与することができる。
【００１２】
一例として本発明の方法で得られた試験片の断面における合金層及び被覆金属の皮膜部について、電子顕微鏡（ＳＥＭ）及びＸ線マイクロアナライザー（ＥＰＭＡ）で観察した結果を図１と図２に示した。この例からも分かる通り、鋳物表面には、鋳物構成元素であるＦｅを含む合金層皮膜が形成される。
【００１３】
さらに請求項３に記載の発明は、請求項１に記載の金属被覆鋳鉄鋳物又は請求項２に記載の金属被覆鋳鋼鋳物における被覆金属（３）が、Ｃｕ、Ｓｎ、Ｚｎ、Ｐｂ、Ａｌ、Ｍｎ、Ｎｉ、Ｐ、Ｃｒ、Ｓｉ、Ｍｇ、Ｆｅの１種または２種以上を含有し、かつ前記凝固開始温度の条件を満たす単体金属及び合金であることを特徴とする。
【００１４】
被覆金属としては、請求項１及び２に記載した凝固開始温度の条件を満たす単体金属あるいは合金の粉末が使用できるが、耐食性の付与を主目的とする場合は、上記金属のうちの１種または２種以上を含有するものが望ましい。
これらの単体金属及び合金は、鋳鉄及び鋳鋼にたいして、それらを溶解するあるいはそれらに溶解される性質があるのでこれらの単体金属及び合金と鋳物を構成する各種元素からなる合金層被膜を容易に形成することができる上に、鋳鉄及び鋳鋼に比べて耐食性が優れるという性質を有しているため、鋳物表面に前記合金層皮膜が形成されれると高い耐食性を有する鋳鉄鋳物及び鋳鋼鋳物となる。当然のことながら鋳鉄や鋳鋼鋳物の鋳肌と異なる色合いや、その合金層がもつ耐摩耗性や硬度特性等の目的に応じた機能も付与できる。
【００１５】
本発明で使用する金属粉末の平均粒子径としては、大きすぎると塗型剤中で沈降しやすく、また均一な合金層被膜を形成することが困難となるため、１ｍｍ以下、好ましくは５００μｍ以下、更に好ましくは２５０μｍ以下が望ましい。
【００１６】
請求項４に記載の発明は、請求項１に記載の金属被覆鋳鉄鋳物又は請求項２に記載の金属被覆鋳鋼鋳物を製造する方法であって、前記被覆金属（３）の粉末を含む塗型剤（４）を、消失模型鋳造法及びフルモールド法では鋳型（５）に装着した消失模型表面に塗布した後、前記鋳型（５）に溶融した鋳鉄あるいは鋳鋼を注湯し、鋳鉄鋳物（１ａ）又は鋳鋼鋳物（１ｂ）の表面に金属を被覆し、また、消失模型法及びフルモールド法以外の造型法では鋳型（５）表面に塗布した後、前記鋳型（５）に溶融した鋳鉄あるいは鋳鋼を注湯し、鋳鉄鋳物（１ａ）又は鋳鋼鋳物（１ｂ）の表面に金属を被覆することを特徴とする。
【００１７】
なお、消失模型鋳造法及びフルモールド法以外の造型法では、従来の塗型剤を塗布乾燥後、本発明の塗型剤（４）を重ね塗りしてもよい。
【００１８】
また、請求項５に記載の発明は、前記被覆金属（３）の粉末を含む塗型剤（４）が、ベントナイト等の無機粘結剤及び水を必須の成分として含有することを特徴とする。
【００１９】
組成は金属粉末１００部に対して、ベントナイト等無機系粘結剤が５〜２０部、水６０〜２００部の範囲が好ましい。水の量が多すぎると粘度が低すぎて、金属粉末が短時間で沈降分離をおこし、少なすぎると粘度が高くなりすぎて、均一な塗布が難しくなる。また粘結剤の量が多すぎると均一な合金皮膜ができにくくなり、少なすぎると塗膜の強度が弱くなる。従って、必須成分の組成としては前記の範囲が好ましい。塗型剤の適正組成は、使用する金属粉末の種類によって異なる。例えばＣｕ系の金属粉末の一例を示せば、ＣｕとＣｕ−Ｓｎ及びＣｕ−Ｍｎでは下記表１の通り適正組成は変わる。下記表１の例のように粘結剤にベントナイトを使用する場合は、ベントナイトに所定の水を加え、ベントナイトを水に十分膨潤させながら撹拌して、所望の金属粉末を所定量加えて撹拌混合することで塗型剤を調整することができる。このように金属粉末の種類に応じて前記の範囲内で組成を調整すれば良好な塗型剤となる。
【００２０】
【表１】

【００２１】
塗型剤には、黒鉛等の耐火骨材を加えてもよい。それによって、焼き付き等が抑制できる場合もある。フルモールド法等の有機消失模型に使用する塗型剤の場合は、塗布時の濡れ性をよくするために少量の界面活性剤を添加してもよい。また、塗型剤の乾燥を速くするために、水に対して０〜２０Ｗｔ％程度の範囲でメタノール等のアルコールを加えても良い。
【００２２】
無機系の粘結剤は有機系の粘結剤に比べて、ガスの発生が殆どなく、良好な鋳肌になる。このような無機系の粘結剤としては、カオリンを主成分とする木節粘土やモンモリロナイトを主成分とするベントナイト等の粘土系粘結剤あるいはまた水ガラス等が使用できる。また、補助粘結剤として、水溶性の有機粘結剤を無機系主粘結剤に対して０〜３０Ｗｔ％の範囲内で加えてもよい。
【００２３】
請求項４に記載の製造方法は、前記のように調合した塗型剤をフルモールド法及び消失模型造型法では鋳型に装着した消失模型表面に塗布し、消失模型法及びフルモールド法以外の造型法では鋳型表面に前記塗型材を塗布し、塗型剤を十分乾燥した後に、当該鋳型に溶融した鋳鉄あるいは鋳鋼を注湯し、固化後に鋳型を除去することで、鋳物表面に被膜金属層が形成される鋳造方法であって、その被覆金属が鋳物との界面で被覆金属と鋳物を構成する各種元素からなる合金層を形成して一体となっていることを特徴とする鋳鉄鋳物及び鋳鋼鋳物を鋳造することができる。
【００２４】
一般に鋳造においては、鋳込みは鋳鉄では１３００℃〜１４００℃、鋳鋼では１５００℃〜１６００℃の温度で行われる。鋳型に流入した溶湯（溶鉄）は、注湯時より５０℃〜１００℃程度温度が一気に低下するので、鋳型に流入した溶湯は鋳鉄で１２００℃〜１３００℃、鋳鋼で１４００℃〜１５００℃程度となる。従って、前記塗型剤中に含まれている凝固開始点の条件を満たす単体金属もしくは合金粉末は、鋳型に流入した鋳鉄あるいは鋳鋼の溶湯の熱により完全に溶融する。詳細は未だ不明ではあるが、溶融した金属粉末は鋳物の溶湯の表面で被膜を形成し、被膜と鋳物との界面でそれらを構成する各種元素が相互に拡散して、鋳物表面に合金層皮膜を形成するものと考えられる。この相互拡散が界面の近傍に留まり、溶融した金属粉末が鋳物の中心部まで均一拡散しないのは、鋳型中の溶湯は比較的短時間で凝固終了温度に達するためと考えられる。
【００２５】
なお、括弧内の記号は、図面及び後述する発明の実施例に記載された対応要素または対応事項を示す。
【００２６】
【発明の実施の形態】
以下本発明の詳細を実施例により説明する。尚、本発明はこれらの実施例に特に限定されるものではない。
以下の実施例及び比較例で作成した試験片はすべて表２にまとめて示した。
【００２７】
＜実施例１＞
ベントナイト１０重量部に水７０重量部を添加し、十分撹拌混合させて、均一な粘調な水溶液になったところで平均粒径が４０μｍのＣｕの粉末１００重量部を添加して撹拌混合し、塗型剤スラリー▲１▼を調整した。以下同様な方法でベントナイト１０重量部、水１００重量部、平均粒径４０μｍのＣｕ−Ｓｎ（１０）粉末１００重量部の組成で塗型剤スラリー▲２▼を、ベントナイト１０重量部、水１００重量部、平均粒径４０μｍのＣｕ−Ｓｎ（２０）粉末１００重量部の組成で塗型剤スラリー▲３▼を、ベントナイト１０重量部、水１５０重量部、平均粒径１５０μｍのＣｕ−Ｍｎ（３０）粉末１００重量部の組成で塗型剤スラリー▲４▼を、ベントナイト１０重量部、水１００重量部、平均粒径７４μｍのＣｕ−Ｆｅ（４）−Ｍｎ（５）粉末１００重量部の組成で塗型剤スラリー▲５▼を、ベントナイト１０重量部、水１００重量部、平均粒径６３μｍのＦｅ−Ｐ（２０）粉末１００重量部の組成で塗型剤スラリー▲６▼を、ベントナイト１０重量部、水１００重量部、平均粒径６３μｍの　Ｃｕ−Ａｌ（１０）−Ｎｉ（３）粉末１００重量部の組成で塗型剤スラリー▲７▼を、ベントナイト１０重量部、水６０重量部、平均粒径１５０μｍのＡｌ−Ｍｇ（４）粉末１００重量部の組成で塗型剤スラリー▲８▼を、ベントナイト１０重量部、水１００重量部、平均粒径５００μｍのＣｕ−Ｓｎ（１０）粉末１００重量部の組成で塗型剤スラリー▲９▼を、ベントナイト１０重量部、水１００重量部、平均粒径１１００μｍのＣｕ−Ｓｎ（１０）粉末１００重量部の組成で塗型剤スラリーＺを、それぞれ調合した。
【００２８】
これら塗型剤スラリー▲１▼〜▲９▼、およびＺを鋳型５の上型５ａと下型５ｂの鋳物形成部６にそれぞれ刷毛で平滑に全面塗布し、十分乾燥させた。尚、ここでは自硬性フラン鋳型を使用し、底面２００ｍｍ×５０ｍｍとして高さを１０ｍｍ、３０ｍｍ、５０ｍｍ、１００ｍｍに変えた試験片を鋳込めるように図３に示した鋳型５を塗型剤スラリーの数だけ作成した。
【００２９】
このように準備した鋳型５にダクタイル鋳鉄の溶湯を１３２０℃で鋳込み、表面が合金層２及び被覆金属３の皮膜に覆われたダクタイル鋳鉄鋳物を作成した。尚、鋳込み終了の後、型をばらし、取り出した鋳物１の表面に付着している型砂はショットブラスト法で除去した。
【００３０】
得られた鋳物１は、鋳物１表面の皮膜（合金層２及び被覆金属３）の均一性、剥離強度（接着性）、耐食性、鋳肌の平滑性について評価した。その結果を表３に示した。尚、ここで行った評価は、以下の方法で実施した。
【００３１】
皮膜（合金層２及び被覆金属３）の均一性については、目視で３段階評価（○：均一、△：ほぼ均一だが局所的にわずかに未被覆部あり、×：被覆がまだら）を行った。剥離強度はショットブラストでφ２ｍｍの鋼球を投射して剥離の有無を判定した。耐食性につては３％食塩水中に２４時間浸積した後に大気中で３日放置した時点の錆びの発生状況を３段階（Ａ：錆び発生まったくなし、Ｂ：局所的にごくわずか錆び発生、Ｃ：全面に錆び発生）で評価した。鋳肌の平滑性は比較例１の通常の方法により鋳造した鋳物１の鋳肌に対して、同等か、同等以上かあるいは同等以下かを目視で相対評価した。
【００３２】
＜実施例２＞
実施例１と全く同様に塗型剤スラリー▲１▼〜▲３▼を調合し、発泡ポリスリレン模型に塗型剤スラリーをそれぞれ塗布して十分乾燥させた。発泡ポリスチレン模型は、底面が２００ｍｍ×５０ｍｍとして高さが１０ｍｍのものを使用した。この塗型剤４を塗布し乾燥させた発泡ポリスチレン模型を砂込めして造形し、鋳型５を作成した。この鋳型５にねずみ鋳鉄の溶湯を１３６０℃で鋳込み、実施例１と同様に表面が合金層２に覆われたねずみ鋳鉄鋳物を作成した。
得られたねずみ鋳鉄鋳物を実施例１と全く同様に評価した。その結果を表３に示した。
【００３３】
＜実施例３＞
実施例１と全く同様な方法で塗型剤スラリー▲１▼〜▲３▼について、１５５０℃の鋳鋼の溶湯で合金層２及び被覆金属３に覆われた鋳鋼鋳物を得た。
得られた鋳鋼鋳物を実施例１と全く同様に評価した。その結果を表３に示した。
【００３４】
＜比較例１＞
実施例１で使用した塗型剤スラリーに替えて、現在、通常に使用されている黒鉛骨材系の塗型剤スラリーを使用する以外は、実施例１と全く同様にしてダクタイル鋳鉄の鋳物を作成した。
得られたダクタイル鋳鉄鋳物を実施例１と全く同様に評価した。その結果を表３に示した。
【００３５】
＜比較例２＞
比較例１と全く同様にダクタイル鋳鉄の鋳物を作成し、表面を溶融亜鉛メッキした試験片を作成した。
得られた亜鉛メッキダクタイル鋳鉄を実施例１と全く同様に評価した。その結果を表３に示した。
【００３６】
【表２】

【００３７】
【表３】

【００３８】
表３に示す結果から明らかなように、本発明方法によって製造した鋳物は、皮膜の均一性、剥離強度、耐食性及び鋳肌平滑性のいずれにおいても、比較例のものと比べて、優れている。
【００３９】
【発明の効果】
本発明の請求項１に記載の金属被覆鋳鉄鋳物は、強固に鋳鉄鋳物の表面を保護する合金層及び被覆金属の皮膜を有するため、従来の塗装や金属メッキあるいは金属溶射により表面処理した鋳物に比べ、長期耐食性を始め、その合金層及び被覆金属の皮膜が持つ耐摩耗性や表面硬度特性等の機能、及び鋳鉄にない色合いの鋳肌を付与することが可能となる。
【００４０】
本発明の請求項２に記載の金属被覆鋳鋼鋳物は、強固に鋳鋼鋳物の表面を保護する合金層及び被覆金属の皮膜を有するため、従来の塗装や金属メッキあるいは金属溶射により表面処理した鋳物に比べ、長期耐食性を始め、その合金層及び被覆金属の皮膜が持つ耐摩耗性や表面硬度特性等の機能、及び鋳鋼にない色合いの鋳肌を付与することが可能となる。
【００４１】
また、請求項３に記載の発明は、被覆金属が、Ｃｕ、Ｓｎ、Ｚｎ、Ｐｂ、Ａｌ、Ｍｎ、Ｎｉ、Ｐ、Ｃｒ、Ｓｉ、Ｍｇ、Ｆｅの１種または２種以上を含有し、かつ凝固開始温度の条件を満たす単体金属及び合金であるので、請求項１に記載の鋳鉄鋳物及び請求項２に記載の鋳鋼鋳物の耐食性、耐摩耗性、表面硬度特性等の機能、及び鋳鉄や鋳鋼にない色合いの鋳肌を、より効果的に付与することができる。
【００４２】
さらに、請求項４に記載の発明は、被覆金属の粉末を含む塗型剤を、消失模型鋳造法及びフルモールド法では鋳型に装着した消失模型表面に塗布し、消失模型法及びフルモールド法以外の造型法では鋳型表面に塗布し、鋳型に溶融した鋳鉄あるいは鋳鋼を注湯し、鋳鉄鋳物又は鋳鋼鋳物の表面に金属を被覆するので、請求項１に記載の金属被覆鋳鉄鋳物又は請求項２に記載の金属被覆鋳鋼鋳物を良好、容易かつ安価に製造することができる。
【００４３】
またさらに、請求項５に記載の発明は、被覆金属の粉末を含む塗型剤が、ベントナイト等の無機粘結剤及び水を必須の成分として含有するので、請求項１に記載の金属被覆鋳鉄鋳物又は請求項２に記載の金属被覆鋳鋼鋳物を良好、容易かつ安価に製造することが可能である。
【図面の簡単な説明】
【図１】本発明の実施例におけるねずみ鋳鉄鋳物のＳＥＭ−ＥＰＭＡ分析結果に基づく断面図である。
【図２】本発明の実施例におけるねずみ鋳鉄鋳物断面のＥＰＭＡ線分析結果を示すグラフである。
【図３】本発明の実施例１において作成した自硬性フラン型であり、（ａ）は正面概略図、（ｂ）は平面概略図である。
【符号の説明】
１　　鋳物
１ａ　鋳鉄鋳物
１ｂ　鋳鋼鋳物
２　　合金層
３　　被覆金属
４　　塗型剤
５　　鋳型
５ａ　上型
５ｂ　下型
６　　鋳物形成部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cast iron casting and a cast steel casting and a method for producing the same. More particularly, the present invention relates to a cast iron casting and a cast steel casting having an alloy layer and a coating film of a coating metal formed on a surface thereof, and a method for producing the same.
[0002]
[Prior art]
Cast iron castings and cast steel castings are used in a wide range of fields from automobiles, ships, parts of machinery, industrial products such as members of public buildings, crafts, arts, etc. In addition, depending on the application, treatments such as painting, metal plating, and metal spraying are widely performed.
[0003]
Various coating systems, including pre-treatment, have been proposed and implemented, mainly for synthetic resin coatings, depending on the application.However, due to problems such as the mechanical strength, adhesion, and weather resistance of the coating, long-term durability is required. Is not enough. In particular, with respect to scratching, rubbing, impact from falling objects, and the like, the coating film is easily broken or peeled, and often fails to exhibit the initial performance.
[0004]
Metal plating and metal spraying, on the other hand, are high-strength coatings and superior in long-term durability, compared to coating systems, but all are physically adhered to the casting surface. Therefore, there is a disadvantage that sufficient adhesive strength cannot be obtained. In order to improve such weaknesses, blast treatment, primer treatment, and the like have been proposed (for example, see Patent Document 1).
[0005]
[Patent Document 1]
Patent No. 2752337 Specification [0006]
However, in Patent Literature 1, in order to extend the life of cast iron and cast steel materials in recent years, it is necessary to further improve corrosion resistance and mechanical properties of the coating.
In particular, hot-dip plating and electroplating cannot be easily performed because special equipment is required, and hot-dip plating immerses the object in high-temperature molten metal, causing thermal distortion and adsorption of hydrogen gas. In some cases, it can not be used due to the problems described above.
In addition, each of these processes is a separate process from the casting process, and therefore causes a cost increase.
[0007]
[Problems to be solved by the invention]
Therefore, the present invention overcomes the above-described problems of cast iron castings and cast steel castings, can exhibit long-term corrosion protection, and is coated with an alloy layer that is not easily peeled off by scratching, rubbing, or impact. And a method for producing cast steel castings and good, easy and inexpensive products.
[0008]
[Means for Solving the Problems]
The present inventors have conducted intensive studies in order to solve the above problems, and found that the casting temperature of the cast iron and the cast steel was changed to 50 to 100 in place of the conventional mold wash used when manufacturing cast iron castings and cast steel castings. After applying a coating agent comprising a metal powder having a low solidification onset temperature, a binder, and water to the disappearing model surface or the mold surface, the molten cast iron or cast steel is poured into the mold, and the mold is solidified. By removing, the coating metal is formed on the surface of the casting, and the coating metal forms an alloy layer made of various elements constituting the casting and the coating metal at the interface with the casting, and is integrally formed. It has been found that a cast iron casting and a cast steel casting can be produced, and the coating is not easily peeled off as compared with conventional metal plating and metal spray coating, and the corrosion resistance and the like can be further improved, and the present invention has been achieved.
Hereinafter, the present invention will be described in detail.
[0009]
The metal-coated cast iron casting according to the first aspect of the present invention is a cast iron casting (1a) having a casting temperature of 1300 ° C to 1400 ° C, the surface of which is coated with a metal having a solidification starting temperature of 1200 ° C or less. At the interface between the coating metal (3) and the cast iron casting (1a), an alloy layer (2) is formed by the coating metal (3) and various elements constituting the casting iron casting (1a). ) It is characterized by being integral with the cast iron casting (1a).
[0010]
The metal-coated cast steel casting according to the second aspect of the invention is a cast steel casting (1b) having a casting temperature of 1500 ° C. to 1600 ° C., the surface of which is coated with a metal having a solidification start temperature of 1400 ° C. or less. An alloy layer (2) is formed at the interface between the coating metal (3) and the cast steel casting (1b) by the coating metal (3) and various elements constituting the casting steel casting (1b). 3) is characterized in that it is integrated with the cast steel casting (1b).
[0011]
The metal powder used in the present invention has a solidification start temperature of 1200 ° C. or less for cast iron castings and 1400 ° C. or less for cast steel castings, and is completely melted by the heat of cast iron or cast steel when pouring into a mold. At the same time as forming a coating of the coating metal covering the surface, various elements constituting the molten coating metal and the molten metal of the casting are mutually diffused through the interface between the molten coating metal and the molten metal of the casting to form an alloy layer coating on the casting surface. This alloy layer film is a strong film which is integrated with the casting and is not easily peeled off, and can impart a function of protecting the casting surface.
[0012]
As an example, FIGS. 1 and 2 show the results of observing the alloy layer and the coating portion of the coated metal on the cross section of the test piece obtained by the method of the present invention using an electron microscope (SEM) and an X-ray microanalyzer (EPMA). Was. As can be seen from this example, an alloy layer film containing Fe which is a casting constituent element is formed on the casting surface.
[0013]
Further, in the invention according to claim 3, the coated metal (3) in the metal-coated cast iron casting according to claim 1 or the metal-coated cast steel casting according to claim 2 is Cu, Sn, Zn, Pb, Al, Mn. , Ni, P, Cr, Si, Mg, and Fe, and is a simple metal or alloy that satisfies the solidification initiation temperature.
[0014]
As the coating metal, a powder of a single metal or an alloy satisfying the condition of the solidification starting temperature described in claims 1 and 2 can be used. However, when the main purpose is to impart corrosion resistance, one of the above metals or Those containing two or more are desirable.
Since these simple metals and alloys have the property of dissolving or dissolving in cast iron and cast steel, they easily form an alloy layer coating composed of these simple metals and alloys and various elements constituting the casting. In addition to the fact that the alloy layer film has excellent corrosion resistance as compared with cast iron and cast steel, when the alloy layer film is formed on the surface of the casting, the cast iron casting and the cast steel casting have high corrosion resistance. As a matter of course, it is also possible to provide a function different from the cast surface of the cast iron or cast steel casting, or a function according to the purpose such as wear resistance and hardness characteristics of the alloy layer.
[0015]
As the average particle diameter of the metal powder used in the present invention, if it is too large, it tends to settle in the coating agent, and it is difficult to form a uniform alloy layer coating, so that the average particle diameter is 1 mm or less, preferably 500 μm or less, More preferably, it is 250 μm or less.
[0016]
The invention according to claim 4 is a method for producing a metal-coated cast iron casting according to claim 1 or a metal-coated cast steel casting according to claim 2, wherein the coating die includes powder of the coated metal (3). In the vanishing model casting method and the full mold method, the agent (4) is applied to the surface of the vanishing model mounted on the mold (5), and then the molten cast iron or cast steel is poured into the mold (5) to form a cast iron casting (1a). ) Or the surface of a cast steel casting (1b) is coated with metal, and applied to the surface of a mold (5) by a molding method other than the vanishing model method and the full molding method, and then cast iron or cast steel melted in the mold (5). Is poured, and the surface of the cast iron casting (1a) or the cast steel casting (1b) is coated with a metal.
[0017]
In a molding method other than the vanishing model casting method and the full molding method, a conventional coating agent may be applied and dried, and then the coating agent (4) of the present invention may be overcoated.
[0018]
The invention according to claim 5 is characterized in that the coating agent (4) containing the powder of the coated metal (3) contains an inorganic binder such as bentonite and water as essential components. .
[0019]
The composition is preferably in the range of 5 to 20 parts of inorganic binder such as bentonite and 60 to 200 parts of water with respect to 100 parts of metal powder. If the amount of water is too large, the viscosity is too low, and the metal powder undergoes sedimentation in a short time. If the amount is too small, the viscosity becomes too high, and uniform coating becomes difficult. If the amount of the binder is too large, it is difficult to form a uniform alloy film, and if the amount is too small, the strength of the coating film becomes weak. Therefore, the above range is preferable as the composition of the essential components. The appropriate composition of the coating composition depends on the type of metal powder used. For example, if an example of a Cu-based metal powder is shown, the appropriate composition of Cu, Cu-Sn, and Cu-Mn changes as shown in Table 1 below. When bentonite is used as a binder as in the example of Table 1 below, predetermined water is added to bentonite, and the bentonite is stirred while sufficiently swelling in water, and a predetermined amount of a desired metal powder is added and stirred and mixed. By doing so, the coating agent can be adjusted. Thus, if the composition is adjusted within the above range according to the type of the metal powder, a good mold-coating agent can be obtained.
[0020]
[Table 1]

[0021]
A refractory aggregate such as graphite may be added to the coating composition. Thereby, burn-in and the like may be suppressed in some cases. In the case of a coating agent used for an organic disappearance model such as a full mold method, a small amount of a surfactant may be added to improve wettability at the time of application. In order to speed up drying of the coating composition, alcohol such as methanol may be added in the range of about 0 to 20 Wt% with respect to water.
[0022]
Inorganic binders generate less gas and have better casting surface than organic binders. As such an inorganic binder, a clay binder such as Kibushi clay containing kaolin as a main component or bentonite containing montmorillonite as a main component, or water glass can be used. Further, as an auxiliary binder, a water-soluble organic binder may be added within a range of 0 to 30 Wt% based on the inorganic main binder.
[0023]
The manufacturing method according to claim 4, wherein the coating agent prepared as described above is applied to the surface of the disappearing model attached to the mold in the full molding method and the disappearing model molding method, and the molding is performed by a method other than the disappearing model method and the full molding method. In the method, the mold material is applied to the surface of the mold, and after the mold agent is sufficiently dried, molten cast iron or cast steel is poured into the mold, and the mold is removed after solidification. A casting method to be formed, wherein the coating metal forms an alloy layer made of various elements constituting the casting with the coating metal at an interface with the casting, and is integrated with the casting metal and the casting steel casting. Can be cast.
[0024]
Generally, in casting, casting is performed at a temperature of 1300 ° C. to 1400 ° C. for cast iron and 1500 ° C. to 1600 ° C. for cast steel. Since the temperature of the molten metal (molten iron) that has flowed into the mold drops by about 50 ° C. to 100 ° C. at a stretch from the time of pouring, the molten metal that has flowed into the mold is 1200 ° C. to 1300 ° C. for cast iron and about 1400 ° C. to 1500 ° C. for cast steel Become. Therefore, the single metal or alloy powder that satisfies the condition of the solidification start point contained in the mold wash is completely melted by the heat of the molten cast iron or cast steel that has flowed into the mold. Although the details are still unknown, the molten metal powder forms a coating on the surface of the molten metal of the casting, and at the interface between the coating and the casting, the various elements constituting them diffuse into each other, forming an alloy layer coating on the casting surface. Is considered to form. The reason that the mutual diffusion remains near the interface and the molten metal powder does not diffuse uniformly to the center of the casting is considered that the molten metal in the mold reaches the solidification end temperature in a relatively short time.
[0025]
The symbols in parentheses indicate corresponding elements or matters described in the drawings and embodiments of the invention described later.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, details of the present invention will be described with reference to examples. The present invention is not particularly limited to these examples.
The test pieces prepared in the following Examples and Comparative Examples are all shown in Table 2.
[0027]
<Example 1>
70 parts by weight of water is added to 10 parts by weight of bentonite, and the mixture is sufficiently stirred and mixed. When a uniform viscous aqueous solution is formed, 100 parts by weight of a Cu powder having an average particle size of 40 μm is added, mixed with stirring, and coated. The mold slurry (1) was prepared. In the same manner, a mold wash slurry (2) having a composition of 10 parts by weight of bentonite, 100 parts by weight of water, and 100 parts by weight of Cu-Sn (10) powder having an average particle size of 40 μm was prepared by adding 10 parts by weight of bentonite and 100 parts by weight of water. Parts, 100 parts by weight of a Cu—Sn (20) powder having an average particle diameter of 40 μm, a coating agent slurry (3), 10 parts by weight of bentonite, 150 parts by weight of water, and Cu—Mn (30) having an average particle diameter of 150 μm. A mold wash slurry (4) having a composition of 100 parts by weight of powder was applied with a composition of 10 parts by weight of bentonite, 100 parts by weight of water, and 100 parts by weight of Cu-Fe (4) -Mn (5) powder having an average particle size of 74 μm. 10 parts by weight of bentonite, 100 parts by weight of water, and 100 parts by weight of Fe-P (20) powder having an average particle diameter of 63 μm, and 10 parts by weight of bentonite, 100 parts by weight of water, 100 parts by weight of a Cu-Al (10) -Ni (3) powder having an average particle diameter of 63 μm, a coating agent slurry (7), 10 parts by weight of bentonite, 60 parts by weight of water, average particle diameter A coating agent slurry (8) having a composition of 100 parts by weight of Al-Mg (4) powder of 150 µm was mixed with 10 parts by weight of bentonite, 100 parts by weight of water, and 100 parts by weight of Cu-Sn (10) powder having an average particle diameter of 500 µm. A coating agent slurry (9) having a composition of 10 parts by weight of bentonite, 100 parts by weight of water, and 100 parts by weight of a Cu—Sn (10) powder having an average particle diameter of 1100 μm was prepared.
[0028]
These coating agent slurries (1) to (9) and Z were applied to the casting forming portions 6 of the upper die 5a and the lower die 5b of the mold 5, respectively, by using a brush, and were completely dried. In this case, a self-hardening furan mold was used, and the mold 5 shown in FIG. 3 was used to mold a mold slurry shown in FIG. 3 so that a test piece whose height was changed to 10 mm, 30 mm, 50 mm, and 100 mm with a base of 200 mm × 50 mm could be cast. Created only the number.
[0029]
A melt of ductile cast iron was cast into the thus prepared mold 5 at 1320 ° C. to prepare a ductile cast iron casting whose surface was covered with the coating of the alloy layer 2 and the coating metal 3. After completion of the casting, the mold was separated and the mold sand adhering to the surface of the casting 1 taken out was removed by a shot blast method.
[0030]
The casting 1 thus obtained was evaluated for the uniformity, the peel strength (adhesion), the corrosion resistance, and the smoothness of the casting surface on the surface of the casting 1 (the alloy layer 2 and the coating metal 3). Table 3 shows the results. In addition, the evaluation performed here was implemented by the following method.
[0031]
The uniformity of the film (alloy layer 2 and coated metal 3) was visually evaluated in three steps (評 価: uniform, Δ: almost uniform but slightly uncoated locally, ×: mottled coating). . Peeling strength was determined by projecting a steel ball of φ2 mm by shot blasting to determine the presence or absence of peeling. Regarding the corrosion resistance, the state of rust generation when immersed in 3% saline for 24 hours and then left in the air for 3 days was evaluated in three stages (A: no rust, B: very slight rust locally, C : Rust occurred on the entire surface). The smoothness of the casting surface was visually evaluated relative to the casting surface of the casting 1 cast by the ordinary method of Comparative Example 1 as to whether it was equal, equal to or more than, or equal to or less than.
[0032]
<Example 2>
Coating agent slurries (1) to (3) were prepared in exactly the same manner as in Example 1, and the coating agent slurries were applied to foamed polythylene models, respectively, and dried sufficiently. The expanded polystyrene model used had a bottom surface of 200 mm × 50 mm and a height of 10 mm. The foamed polystyrene model coated with the mold wash 4 and dried was filled with sand to form a mold 5. A molten cast of gray cast iron was cast into this mold 5 at 1360 ° C. to produce a gray cast iron casting whose surface was covered with an alloy layer 2 as in Example 1.
The obtained gray iron casting was evaluated in exactly the same manner as in Example 1. Table 3 shows the results.
[0033]
<Example 3>
A cast steel casting covered with the alloy layer 2 and the coating metal 3 with the molten cast steel at 1550 ° C. was obtained from the mold wash slurries (1) to (3) in exactly the same manner as in Example 1.
The obtained cast steel casting was evaluated exactly as in Example 1. Table 3 shows the results.
[0034]
<Comparative Example 1>
A ductile cast iron casting was prepared in exactly the same manner as in Example 1 except that a graphite-aggregate-based coating agent slurry, which is now commonly used, was used instead of the coating agent slurry used in Example 1. Created.
The obtained ductile iron casting was evaluated in exactly the same manner as in Example 1. Table 3 shows the results.
[0035]
<Comparative Example 2>
A ductile cast iron casting was prepared in exactly the same manner as in Comparative Example 1, and a test piece having a hot-dip galvanized surface was prepared.
The obtained galvanized ductile cast iron was evaluated exactly as in Example 1. Table 3 shows the results.
[0036]
[Table 2]

[0037]
[Table 3]

[0038]
As is clear from the results shown in Table 3, the castings produced by the method of the present invention are superior to those of the comparative examples in all of the uniformity of the coating, the peel strength, the corrosion resistance and the casting surface smoothness. .
[0039]
【The invention's effect】
Since the metal-coated cast iron according to claim 1 of the present invention has an alloy layer and a coating of a coated metal that strongly protects the surface of the cast iron casting, it can be applied to a casting that has been surface-treated by conventional painting, metal plating, or metal spraying. On the other hand, it is possible to provide functions such as long-term corrosion resistance, wear resistance and surface hardness characteristics of the alloy layer and the coating of the coating metal, and a cast surface having a color not found in cast iron.
[0040]
Since the metal-coated cast steel casting according to claim 2 of the present invention has an alloy layer and a coating of a coating metal that firmly protects the surface of the cast steel casting, it can be applied to a casting that has been surface-treated by conventional painting, metal plating, or metal spraying. On the other hand, it is possible to impart not only long-term corrosion resistance, but also functions such as wear resistance and surface hardness characteristics of the alloy layer and the coating of the coating metal, and a cast surface having a color not found in cast steel.
[0041]
In the invention according to claim 3, the coating metal contains one or more of Cu, Sn, Zn, Pb, Al, Mn, Ni, P, Cr, Si, Mg, Fe, and Since it is a simple metal and alloy satisfying the condition of the solidification start temperature, the functions of the cast iron casting according to claim 1 and the cast steel casting according to claim 2 such as corrosion resistance, wear resistance, surface hardness characteristics, etc., and cast iron and cast steel A cast surface having a color that cannot be obtained can be provided more effectively.
[0042]
Further, in the invention according to claim 4, a mold wash containing powder of a coated metal is applied to the surface of a disappearing model attached to a mold in the disappearing model casting method and the full mold method, and the method is not applied to the disappearing model method and the full mold method. In the molding method of (1), the surface of a cast iron casting or a cast steel casting is coated with a metal by applying a molten cast iron or cast steel to the mold surface and pouring molten metal into the casting mold, so that the metal-coated cast iron casting according to claim 1 or claim 2. , A good, easy and inexpensive metal-coated cast steel casting.
[0043]
Furthermore, the invention according to claim 5 is the metal-coated cast iron according to claim 1, since the mold wash containing the powder of the coated metal contains an inorganic binder such as bentonite and water as essential components. It is possible to produce a casting or a metal-coated cast steel casting according to the present invention in a good, easy and inexpensive manner.
[Brief description of the drawings]
FIG. 1 is a sectional view based on a SEM-EPMA analysis result of a gray cast iron casting in an example of the present invention.
FIG. 2 is a graph showing an EPMA line analysis result of a cross section of a gray cast iron casting in an example of the present invention.
FIG. 3 is a self-hardening furan type prepared in Example 1 of the present invention, wherein (a) is a schematic front view and (b) is a schematic plan view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Casting 1a Cast iron casting 1b Cast steel casting 2 Alloy layer 3 Coating metal 4 Coating agent 5 Mold 5a Upper mold 5b Lower mold 6 Casting forming part

Claims (5)

鋳込み温度が１３００℃〜１４００℃である鋳鉄鋳物において、その表面が１２００℃以下の凝固開始温度を有する金属で被覆されており、その被覆金属と鋳鉄鋳物との界面に、被覆金属と鋳鉄鋳物を構成する各種元素とによって合金層が形成され、被覆金属が鋳鉄鋳物と一体となっていることを特徴とする金属被覆鋳鉄鋳物。In a cast iron casting having a casting temperature of 1300 ° C. to 1400 ° C., its surface is coated with a metal having a solidification starting temperature of 1200 ° C. or less, and the interface between the coated metal and the cast iron casting is coated with the coated metal and the cast iron casting. A metal-coated cast iron casting, wherein an alloy layer is formed by various constituent elements, and the coated metal is integrated with the cast iron casting. 鋳込み温度が１５００℃〜１６００℃である鋳鋼鋳物において、その表面が１４００℃以下の凝固開始温度を有する金属で被覆されており、その被覆金属と鋳鋼鋳物との界面に、被覆金属と鋳鋼鋳物を構成する各種元素とによって合金層が形成され、被覆金属が鋳鋼鋳物と一体となっていることを特徴とする金属被覆鋳鋼鋳物。In a cast steel casting having a casting temperature of 1500 ° C. to 1600 ° C., the surface thereof is coated with a metal having a solidification start temperature of 1400 ° C. or less, and the interface between the coated metal and the cast steel casting is coated with the coated metal and the cast steel casting. A metal-coated cast steel casting, wherein an alloy layer is formed by various constituent elements, and a coating metal is integrated with the cast steel casting. 前記被覆金属が、Ｃｕ、Ｓｎ、Ｚｎ、Ｐｂ、Ａｌ、Ｍｎ、Ｎｉ、Ｐ、Ｃｒ、Ｓｉ、Ｍｇ、Ｆｅの１種または２種以上を含有し、かつ前記凝固開始温度の条件を満たす単体金属及び合金であることを特徴とする請求項１に記載の金属被覆鋳鉄鋳物又は請求項２に記載の金属被覆鋳鋼鋳物。A simple metal in which the coating metal contains one or more of Cu, Sn, Zn, Pb, Al, Mn, Ni, P, Cr, Si, Mg, and Fe, and satisfies the condition of the solidification start temperature; And a metal-coated cast iron casting according to claim 1 or a metal-coated cast steel casting according to claim 2. 請求項１に記載の金属被覆鋳鉄鋳物又は請求項２に記載の金属被覆鋳鋼鋳物を製造する方法であって、
前記被覆金属の粉末を含む塗型剤を、消失模型鋳造法及びフルモールド法では鋳型に装着した消失模型表面に塗布し、
消失模型法及びフルモールド法以外の造型法では鋳型表面に塗布した後、
前記鋳型に溶融した鋳鉄あるいは鋳鋼を注湯し、鋳鉄鋳物又は鋳鋼鋳物の表面に金属を被覆することを特徴とする金属被覆鋳鉄鋳物又は金属被覆鋳鋼鋳物の製造方法。A method for producing a metal-coated cast iron casting according to claim 1 or a metal-coated cast steel casting according to claim 2,
In the vanishing model casting method and the full mold method, a mold wash containing the coated metal powder is applied to the vanishing model surface attached to the mold,
In the molding method other than the vanishing model method and the full molding method, after applying to the mold surface,
A method for producing a metal-coated cast iron or metal-coated cast steel casting, comprising pouring molten cast iron or cast steel into the mold and coating the surface of the cast iron or cast steel with metal. 前記被覆金属の粉末を含む塗型剤が、ベントナイト等の無機粘結剤及び水を必須の成分として含有することを特徴とする請求項４に記載の金属被覆鋳鉄鋳物又は金属被覆鋳鋼鋳物の製造方法。The production of the metal-coated cast iron casting or the metal-coated cast steel casting according to claim 4, wherein the mold wash containing the powder of the coated metal contains an inorganic binder such as bentonite and water as essential components. Method.

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