INSERT-CASTING METHOD OF COPPER OR COPPER ALLOY PIPE TO ALUMINUM ALLOY CASTING

PURPOSE:To improve the heat transmission characteristic of an Al alloy casting by forming preliminarily a coating layer which has the m.p. higher than the m.p. of an Al alloy and is hardly diffusible into the melt of the Al alloy on the outside surface of a copper or copper alloy pipe. CONSTITUTION:An Al wire or the like having the m.p. higher than the m.p. of the Al alloy is heated and melted and is thermally sprayed by a thermal spraying gun to the outside surface of the copper or copper alloy pipe 2. The coating layer 3 which is hardly diffusible into the melt of the Al alloy is formed on the outside surface of the pipe 2. The thickness of the layer 3 is made at least >=250mum and to the extent at which the penetration to the inside of the molten Al alloy is prevented. The copper or copper alloy pipe 2 formed with the layer 3 is insert-cast into a cooling plate 1 made of the Al alloy. Since the pipe 2 having the good heat transmission characteristic can be insert-cast to the Al alloy casting by the above-mentioned method, the heat transmission characteristic of the casting is improved.