Anti-rust method of welded part, rust preventive sheet

摘要

PROBLEM TO BE SOLVED: To provide a rust-proofing method for a welded part, which can cover the welded part with a rust-proofing film having an excellent heat resistance and an excellent rust-proofing property, and a rust-proofing sheet.SOLUTION: A ferrous joined body 10 is prepared, which is composed of two ferrous members jointed together by welding. The ferrous joined body 10 has a coated part 12 of which surface is covered with a rust-proofing film 20, and a welded part 11 of which surface is not covered with the rust-proofing film 20. Then, a rust-proofing sheet 110 is adhered to the ferrous joined body 10 so as to cover the welded part 11. Next, the welded part 11 and its vicinity area are heated. This causes a reaction of a CuNi alloy powder 31 included in a Sn+Cu-Ni thick film joint material 141 and a Sn powder 32 by accompanying a liquid phase diffusion bonding to form a rust-proofing protective film 137 of which main phase is an intermetallic compound. The intermetallic compound is a CuNiSn alloy having a high melting point (for example, 400°C or more).SELECTED DRAWING: Figure 7