During plasma spray process, metallurgical bonding between the impinging particles and the substrate surface can provide substantial contribution for the improvement in the adhesion strength of the coatings. In this work, a one-dimension heat transfer model was used to investigate the integrated effect of cast iron droplet solidification, cooling, and melting and resolidification of aluminum substrate during spraying. The results indicated that the substrate surface temperature could be higher than its melting point during the splat deposition. This indicates that the substrate melting will take place under present condition. On the other hand, it is also found that initial substrate temperature has a profound effect on the development of melt undercooling in a splat, the splat bottom temperature, and the substrate surface temperature. A high initial temperature of the substrate promotes a deeper melting of substrate surface, which may lead to the metallurgical bonding formation between the cast iron splat and the aluminum substrate.
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