Corrosion rate of thermal sprayed WC cermet coating
Takatani Yasuyuki; Tomita Tomoki; Tani Kazumi; Harada Yoshio
Abstract:The corrosion rates of thermal sprayed WC cermet coatings in 0.05 mol/dm3 sodium sulfate solutions at pH 1.0, 6.5 and 12.0 have been measured using AC impedance method and quantitative analysis of the solutions. The cermet coating films were made of WC-Co, WC-Co-Cr and WC-Cr-Ni powder materials by the high velocity oxygen-fuel spraying method. The WC-Co coating film has shown the lowest corrosion rate in the acidic solution. The WC-Co-Cr and WC-Cr-Ni coating films have shown better corrosion resistance in the neutral and the basic solutions. It was found that corrosion current measured by AC impedance corresponds to that calculated by the quantitative yield of dissolved metal ions. Key Words:cermet, WC-Co-Cr, WC-Cr-Ni, thermal spray coating, sodium sulfate, AC impedance, corrosion rate