Deposition of lamellae well bonded dense ceramic coatings by plasma spraying through materials design

It is usually difficult to deposit dense ceramic coatings with splats well bonded by plasma spraying at ambient atmosphere. Following the recent research progress on the splat interface bonding formation, it was found that there is a well-defined relationship between the critical bonding temperature and materials melting point. Thus, it was proposed to control the lamellae bonding through the deposition temperature. In this study, to examine the feasibility of the bonding theory, a novel approach for the development of coating microstructure through materials design is proposed. Accordingly typical ceramic materials were selected of relative low melting point for plasma spraying of dense coating with well bonded splats. The experiment was conducted by using Mg3B2O6 and K2Ti6O13 for splat deposition at about 110¡æ cooling down from a higher temperature to avoid substrate adsorbates and coating deposition at ambient temperature. Results show that the splat is bonded perfectly with the substrate of the same chemistry, while the coatings present dense microstructure with the similar fracture morphology to sintered bulk ceramics. Moreover, the mechanical properties of the coatings will be presented and their relations to microstructural features will be discussed.