BUILD-UP METHOD

PROBLEM TO BE SOLVED: To avoid deterioration of thermal conductivity and deterioration of economical efficiency due to interposition of an intermediate layer by building-up an iron based alloy, in particular, wear-resistant iron based alloy directly and perfectly without interposing the intermediate layer of pure nickel, nickel based alloy or the like on copper base material.SOLUTION: When an iron-based alloy is built-up by welding on the surface of copper base material made of pure copper or copper alloy, a welding rod including high-melting point and large-specific gravity metal particles which have higher melting point than a weld build-up metal and have larger specific gravity than the weld build-up metal is manufactured. The high-melting point and large-specific gravity metal particles are projected into weld molten metal during welding, are precipitated to the neighborhood of a boundary surface with the copper base material in the weld molten metal and form a particle layer. The formed particle layer gets to a barrier layer and, thereby, prevents copper elements from being dissolved into the weld molten metal from the copper base material. Further, the particle layer attributes to wear suppression of the copper base material. Preferably, Ni material made of pure nickel or Ni alloy is applied on the surface of the high-melting point and large-specific gravity metal particles.SELECTED DRAWING: Figure 4 【課題】 銅母材の上に純ニッケルやニッケル基合金等の中間層を介在させることなく鉄基合金、特に耐磨耗性鉄基合金を直接に且つ健全に肉盛りして、中間層の介在による熱電導性の悪化及び経済性の悪化を回避する。【解決手段】 純銅又は銅合金からなる銅母材の表面に鉄基合金を溶接肉盛りする際に、溶接肉盛り金属より融点が高く溶接溶融金属より比重が大きい高融点大比重金属粒子を内包する溶接棒を作製する。溶接中に高融点大比重金属粒子が溶接溶融金属中に投入され、溶接溶融金属中の銅母材との境界面近傍に沈降して粒子層を形成する。形成された粒子層はバリア層となることにより、銅母材から溶接溶融金属中への銅元素の溶け込みを防止する。また、溶接溶融金属から銅母材への鉄元素の溶け込みを防止する。更に、銅母材の磨耗抑制に寄与する。好ましくは、高融点大比重金属粒子の表面に純Ｎｉ又はＮｉ合金からなるＮｉ材を被覆しておく。【選択図】 図４