| 摘要 |
PURPOSE:To raise the manufacturing yield of products by enabling good solar energy absorptive film to be formed by a method in which the surface of a steel plate is treated so that a metal element-enriched layer in a reduced state is formed and then subjected to a bright annealing, followed by rust-proofing treatment before a selective absorption film processing. CONSTITUTION:A metal element(in reduced state)-enriched layer is provided on the surface of a stainless steel plate in a thickness of 50Angstrom depth at most. In forming a selective absorption film for solar energy collection, the steel plate is subjected to a bright annealing process under conditions to meet the relationships, 800<=y<=1,100, -70<=x<=-30, and 10x+1,390<=y, where (x) is the temperature of dew point in deg.C and (y) is the temperature of annealing in deg.C, in an atmosphere of ammonia decomposed gas, hydrogen, etc. Then, the steel plate is dipped in a solution composed of 10-50wt% sulfuric acid and 0-30wt% sodium bichromate at 80 deg.C for 30min at maximum. |
