| 摘要 |
PURPOSE:To improve remarkably corrosion resistance by coating a mixture composed of a granular material of a metal having the m.p. lower than the m.p. of a pipe material and a liquid or paste flux on the inside surface of the pipe and subjecting the coating to a heating treatment thereby forming the layer of the different metal or alloy on the inside surface. CONSTITUTION:A mixture composed of a granular material of a metal having the m.p. lower than the m.p. of a pipe material which is substantially Sn, Zn, Pb, Al, Ni, Ag or an alloy consisting essentially of said metals and a liquid or paste flux is coated on the inside surface of a copper pipe by using a plug or mandrel. The coating is then subjected to a heat treatment, by which a diffused layer is formed between the coating layer of the above-mentioned low melting metal and the pipe material and the inside surface can be easily alloyed. The inside surface of the copper pipe formed with the layer of the different metal or alloy exhibits excellent corrosion resistance. The formation of such layer is easy with a long- sized pipe as well. |
