| 摘要 |
PURPOSE:To develop an iron or steel material having the coating which is highly resistant to heat and corrosion by electroplating Ni on the surface of the iron or steel material then depositing and superposing an Al hot dipped layer thereon and further forming a dense film consisting of chromic oxide thereon. CONSTITUTION:The surface of an iron or steel material is subjected to pretreatments such as degreasing, descaling, etc. to a clean surface 1', on which an electroplating film 2 of Ni is formed and further a hot-dipped film 3 of Al is deposited and superposed thereon. A chromic acid soln. of a chromic acid or a mixture of the chromic acid and chromate or the like is impregnated on the surface of the layer 3 and is heated for >=20min at 200-700 deg.C, whereby a dense film 4 consisting of the thin film of chromium oxide and having the resistance to heat and corrosion is formed. |
