Abstract: Two kinds of WC-10Co-4Cr coating with different particle-density are deposited on 300M steel by high velocity oxygen fuel (HVOF) technology. The microstructure and properties are analyzed by scanning electron microscope, X-ray diffraction and micro-hardness tester. The depositing process of WC particles is focused on. And the corrosion resistance of each coating is analyzed by experiment in erosive electrochemistry. The results indicate that, during the course of spraying of high particle-density powder, the decomposing rate of WC is 15.47%, which is 1.34 times of that of low particle-density powder. The decomposing rate of WC during spraying is determined by both the energy absorbed from the flame and the capsulation of WC particles. The porosity of high particle-density coating is 1.52% and micro-hardness is 1 218 HV, which are 1.95 times and 1.04 times of that of low particle-density coating respectively. The spreading ability of WC particle is the key factor which affecting the porosity and the micro-hardness of the coating. The result of experiment in erosive electrochemistry shows that the corrosion resistance of low particle-density coating is better than that of high particle-density coating.

Key words: Corrosion resistance, High velocity oxygen fuel(HVOF), Particle-density, Spreading ability, WC-10Co-4Cr