Corrosion and abrasive wear behaviour of laser consolidated plasma sprayed sic coating on Fe–15Cr–25Ni alloy

Abstract

Silicon carbide powders (75 μm) were plasma sprayed on austenitic Fe–15Cr–25Ni alloy. A continuous wave CO₂ laser was used to consolidate the plasma sprayed layer and to decompose SiC particles during glazing. Optical and scanning electron microscopic techniques revealed that the structure of the laser consolidated layer consisted of cellular dendrites with M₇ C₃ carbides dispersed mainly at the dendritic boundaries. Consequently, the surface hardness of the Fe–15Cr–25Ni alloy improved considerably. Abrasive wear tests showed that the laser modified specimen exhibited lower wear mass loss and a lower coefficient of friction than the raw Fe–15Cr–25Ni alloy. Potentiodynamic and cyclic polarisation behaviour of the laser modified and raw Fe–15Cr–25Ni alloy specimens in 0·5M H₂ SO₄ and 0·5M NaCl solutions was also investigated.