金属層挿入酸化物被覆ステンレス鋼の腐食挙動

抄録

The Corrosion behavior of sputter-deposited ceramic coatings, part of which contained various pure metals in intermediate layers, was investigated. In films coated by RF sputtering, defects such as pinholes inevitably occurred. These defects play a significant role in corrosion. In this study, various oxide films were coated on stainless steel by RF sputtering and pinhole defects in coating films were evaluated using electrochemical measurement. Electrochemical measurement was to evaluate the total defect area of the film using the value of the critical passivation current density during anodic polarization in a 0.5kmol/m³ H₂SO₄+0.01kmol/m³ KSCN solution, which restricts substrate steel passivation. The results obtained are summarized as follows
(1) Ceramic coatings containing pure Al in intermediate layers showed better corrosion resisitance than other coatings.
(2) In single- and multilayer coatings, the value of the critical passivation current density decreased in the following sequence: single-layer>double-layer>multilayer containing pure metal in the intermediate layer.
(3) Coatings made in the suquence of oxide/metal/oxide had much better corrosion resistance than those in the sequence of oxide/oxide/metal.