Numerical and experimental analysis of temperature field and mechanical analysis for the multi-layer Cr3C2-NiCr coating deposited by HVOF

Cr3C2-NiCr coating has been extensively applied on the surface of components to resist high temperature oxidation, hot corrosion and erosion. The service properties of multi-layer Cr3C2-NiCr coatings deposited by HVOF are highly correlated with cyclic heating and cooling effects and subsequent residual stress distribution during the coating deposition process. A finite element model of the HVOF spraying process was developed based the superposition of double Gauss heat sources to study the thermal and mechanical evolutions of the specimen. The stacking of the coating is accomplished by the activation of each layer by using the birth-death element method. The heat transferred from sprayed particles and flame flow to the substrate is considered by using the superposition of two heat fluxes with a Gaussian distribution. The results show that the model can be used to analyze the transient heating stress state and deflection of the specimen during coating deposition and cooling. The reduction of heat flux can reduce the temperature accumulation of the specimen from the initial stage. Also, different convection coefficients on the coating surface are adopted to simulate different heat dissipation conditions during the coating deposition. The increase of the convection coefficient can effectively reduce the final deflection of the specimens and the final residual stress of the coating. Finally, the surface temperature variation and the final deflection of the specimen predicted by the numerical model are consistent with the measured values. This work provides an effective computational approach to analyze and optimize the HVOF spraying process.