Plasma Spraying Cr₂O₃ Particle Deposition Behavior And Mechanism Study

Plasma spraying is the most widely used spraying method in thermal spraying applications,and it is excellent in enhancing the surface wear resistance,corrosion resistance and high temperature oxidation resistance of parts,which can effectively improve the overall performance of the parts.The stress distribution during particle deposition has a direct effect on the coating performance,but there is no means to monitor the process,so numerical simulation has become an important method to explore the particle deposition process.In this paper,the multi-particle deposition process of Cr₂O₃ and Ni20Cr particles on 7075-aluminum alloy substrate and the changes of temperature and stress fields during the deposition of Cr₂O₃ particles on Ni20Cr substrate were simulated using ABAQUS software.To investigate the effect of substrate temperature on the coating morphology and stress distribution during the multi-particle deposition process.The microscopic morphology and porosity of the Cr₂O₃ and Ni20Cr coatings were investigated by characterization means to verify the rationality of the multi-particle simulation model.The following conclusions are drawn using the coupled Euler-Lagrange(CEL)method:(1)The particles rapidly change into a flattened shape after impacting the substrate at different substrate temperatures.When the substrate temperature reaches300K,the particles are prone to sputtering during deposition,and the increase in surface temperature affects the surface morphology of the coating.Sputtering basically no longer occurs when the substrate temperature reaches 600K,and the stress inside the coating also decreases with the increase in substrate temperature,and there is a large stress concentration at the edge where the particles are combined with the substrate.(2)Cr₂O₃ and Ni20Cr particles in the deposition process of 7075 aluminum alloy substrate,Ni20Cr particles produce higher thermal effect on the substrate,and its stress affected area range is larger.(3)During the deposition of Cr₂O₃ particles in 7075 aluminum alloy and Ni20Cr substrate,the maximum stress on 7075 aluminum alloy substrate is 127MPa higher than that of Ni20Cr substrate,and the surface of 7075 aluminum alloy substrate is thermally affected more quickly,but the temperature of thermally affected area is lower after the end of particle deposition.(4)The reliability of the multi-particle deposition model is verified by metallographic organization and SEM scanned images;preliminary predictions of coating porosity can also be made by the multi-particle simulation model,and the results match the pore results measured by microscopic characterization.