Pulsed laser mixing has been used as surface modification technique for the improvement in the mechanical properties of ceramics. Thin metallic layers of nickel were deposited on structural silicon nitride and were irradiated with Xenon Chloride (XeCl) laser pulses. The laser parameters were optimized to lead to the formation of mixed layers. The mixed interfacial layers were analyzed using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Rutherford Backscattering (RBS) techniques. Detailed heat flow calculations were performed to simulate the effects of intense laser irradiation on metal coated ceramic structures. The melt lifetimes and the interfacial temperatures obtained using these calculations, were applied to understand the laser mixing phenomena occuring in these layered structures. Thermodynamics of chemical reactions between the metal overlayers and the substrate were done to predict the formation of mixed interfacial layers during laser irradiation.