Abstract
We studied corrosion wear of alloy tool steel (SKD 11) coated with VC and precipitation-hardened stainless steel (SUS 630) in NaCl aqueous solution. SUS 630 lost more weight than SKD 11 coated with VC, except where SUS 630 was used as a rotor at a load region below 9.8×10-1MPa. VC film appeared externally sound overall. Sample edges revealed galvanic corrosion of the substrate and partial disappearance of the VC film, and SUS 630 was plastically deformed under high load. The polarization curve indicated that VC film and SUS 630 form a galvanic couple with SKD 11 in NaCl solution, and that VC film and SUS 630 behave cathodic and SKD 11 anodic.
Pinhole defects were detected in VC-coated SKD 11 using optical and scanning electron microscopy by anodic polarization in deaerated 0.5kmol·m-3 H2SO4 solution. Pinhole defects averaged 2∼4 per cm2
