Cavitation Erosion of Cobalt Alloy Coatings Containing Tungsten Carbide Particles in Hydrochloric and Sulphuric Corrosive Media

Abstract

Cavitation erosion tests of composite coatings based on vacuum fusion sintered cobalt alloy containing tungsten carbide particles were carried out in 30 percent HCl and 50 percent H2 SO4 solutions. The technique used included an ultrasonic vibratory apparatus at 30°C, 25μm amplitude and 30 kHz frequency. Weight loss was measured with an analytical balance and the microstructure was observed with SEM. The test results showed that the cavitation erosion resistance of the composite coatings was increased by increasing the tungsten carbide content. The cavitation erosion is mainly caused by removal of the matrix material. The steady-state erosion rates have a linear relationship with the volume fraction of the tungsten carbide phase.