Experiment study of influences of gradient structure on the bonding strength and impact resistance of Al(2)O(3) ceramic coatings

Theory analysis results show gradient structure can reduce the stress mutation in the joint surface between the coating and the substrate comparing with the nongraded interface, the maximum Mises stress of the coatings is significantly reduced, reasonable graded structure can effectively improve the Mises stress distribution of the coatings and change the characteristics of stress distribution. Optimization of the microstructure is required to achieve reductions in certain critical stress components believed to be important for controlling interface failure, and an adopting gradient structure of 0.25 power exponent is proposed, which can effectively reduce impact loads and Mises stress mutations. Supersonic air plasma spraying is used to produce gradient coatings, coatings with designed exponential graded structure and 6 interlayers are prepared, the coatings specimen are analyzed and tested using for microstructure, bonding strength and impact resistance separately. The XRD analysis results of coatings cross