Corrosion and erosion wear characteristics of HVOF sprayed Cr_3C_2-NiCr coating

The corrosion and erosion wear performance of HVOF sprayed Cr3C2-NiCr coatings deposited in three propane flow rate was studied by corrosion and erosion test,in which the mixture of 5 % H2SO4 solution and 15 wt.% brown alumina was used as erodent medium.The variation of accumulated weight loss of per square centimeter coating with the duration and different erosion jet angles were measured,and the microstructure and the worn morphology of the corrosion-erosion coatings were examined by SEM.It was found that the correlation between weight loss of per square centimeter coating and duration is basically shown linear relation,and the corrosion-erosion rate of this coating in low jet angle is much lower than that of in high jet angle.Moreover,the corrosion-erosion rate of this coating is lower than that of carbon steel.The coating deposited under the condition of moderate propane flow exhibits relatively lower corrosion-erosion wear rate.It is revealed that the corrosion-erosion wear of HVOF sprayed Cr3C2-NiCr coating mainly occurs in the spalling of splats and then the carbide particles peer off.The corrosion and erosion are liable to occur at the micro-crack and porosity.The preferential corrosion-erosion of NiCr binder phase during early stage results in the carbide peeling off subsequently.The initiation,propagation and interconnection of crack result in the spalling of splats finally.