Chromium Oxycarbide Thin Films Prepared by Inductively Coupled Radio-Frequency Plasma-Assisted Magnetron Sputtering

Abstract

Chromium oxycarbide films were prepared on SUS 304 stainless steel at temperatures of ∼673 K using the inductively coupled radio-frequency plasma-assisted magnetron-sputtering technique. An inductively coupled 13.56 MHz electromagnetic field with a power of 40 W was supplied to excite the glow discharge, and a direct-current power of 700 W was supplied to sputter a 99.9% chromium target in an Ar/CO2/CH4 mixture and in Ar/CO mixture. Electron probe microanalysis revealed that the film contained chromium, oxygen, and carbon. Vickers microhardness of the film was determined to be >1.96 × 1010 Pa. X-ray diffractometry measurements revealed that the film structure was cubic, and the lattice constant was a0= 0.42 nm. This structure was almost the same as that of chromium oxycarbide, Cr2CO, (rock-salt structure, lattice constant of 0.413 nm). The corrosion resistance of the SUS 304 stainless steel to 1 kmol/m3 H2SO4 at 293 K was improved by coating it with a Cr(C,O) film to a thickness of 5.92 μm.