PURPOSE: To obtain a duplex-coated steel material excellent in heat resistance, corrosion resistance, and adhesive strength, by applying vapor deposition coating to the cleaned surface of a steel material under vacuum so as to form an Al-Si alloy plating layer and an Al (alloy) plating layer of respectively prescribed thicknesses in succession.
CONSTITUTION: Si and Al heated and evaporated from individual vessels are vapor-deposited onto a surface-cleaned steel material under a vacuum atmosphere of ≤10-3Torr, by which an Al-Si alloy plating layer in which Si content and thickness are regulated to 10W90wt.% and ≥0.1μm thickness is formed as a primary layer. Subsequently, without exposure to air, a vapor deposition plating layer composed of Al or Al alloy (excluding Al-Si alloy) and having ≥1μm thickness is formed as a secondary layer on the primary layer, by which a duplex-coated steel material excellent in resistance to heat and corrosion can be obtained. Further, as the Al alloy constituting the secondary layer, an alloy containing metals selected from Cr, Mg, Ti, and Sn by 1W50wt.% is suitably used.
SATO HIROSHI
TOYAMA MASAO
NISHIMOTO HIDETOSHI
IKEDA TSUGUMOTO
KAWAFUKU JIYUNJI
