Transient thermal and mechanical analysis of NiCrBSi coatings manufactured by hybrid plasma spray process with in-situ laser remelting.

A 3D multi-layer model was established to simulate the hybrid plasma spray process with in-situ laser remelting. Effective properties of as-sprayed and remelted NiCrBSi coatings versus temperature were used during the thermal and mechanical analysis. Considering the surface roughness of plasma sprayed NiCrBSi coatings, an absorption coefficient of 0.5 was estimated from the comparison of the predicted and measured remelted thickness. The heat accumulation during the deposition process of multiple layers affects the temperature level, as well as the stress magnitude. The predicted results also indicate that the longitudinal component of the residual stresses is the highest. During final cooling, the stresses generated in the remelted coating are more sensitive to the variation of the elastic modulus rather than the mismatch of the expansion coefficient between the coating and the substrate, which thus induces tensile stresses within the remelted coating. Finally, the influence of the cooling rate was limited while the substrate preheating seems a good method to decrease the stress level within the remelted coating. [ABSTRACT FROM AUTHOR]