| 摘要 |
PROBLEM TO BE SOLVED: To prevent corrosion of copper or copper alloy in a hot water supply apparatus by forming a water repellent silicon coating at least on the surface of the copper or copper alloy basic material of a water touching part for the hot water supply apparatus thereby forming a coating superior in adhesion and durability. SOLUTION: When the water touching surface of a water touching part 1 is treated with a silane based compound (RSiX: R is a hydrophobic group such as an alkyl group or a fluoroalkyl group, X is s substituent such as halogen or alkoxyl group), the silane based compound is bonded to a silanol group existing on the surface of the water touching part in a hot water supply apparatus composed of a copper or copper alloy basic material and condensed to form a polysiloxane layer. Consequently, the surface of the copper or copper alloy basic material 1 is covered with a hydrophobic group, e.g. an alkyl group or a fluoroalkyl group, and a water repellent layer 2 is formed. Since the water repellent layer 2 is integrated with metallic atoms composing the copper or copper alloy of the basic material 1 through covalent bond, a thin film extremely superior in adhesion and durability is formed.
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