Numerical and Experimental Analysis for Laser Surface Densification of Plasma Sprayed Coatings

Abstract

Advanced ceramics, suitable to fabricate ultra-high temperature ceramic components for structural applications and thermal protection systems, are not easily prepared by the plasma spray technique due to their extremely high melting temperature. How to prepare the materials with high density is a challenging research task. In this study, applying a laser surface treatment technique for the densification of zirconium diboride, the influence of laser power and beam diameter on the microstructure and mechanical properties of the coatings are examined both numerically and experimentally. Using a two dimensional mathematical model, which was developed incorporating melting, solidification, and evaporation phenomena, the microstructural characteristics during solidification are predicted via tracking the solid-liquid interface. For the mathematical model, volume-of-fluid technique is incorporated to track the free surface, while the surface force as a body force instead of a boundary condition. Typical laser processing parameters have been obtained for the desired both porosity reduction and microstructure from the model and the predicted results are compared with the experimental results.