PREPARATION AND CHARACTERIZATION OF CERAMIC THERMAL BARRIER COATINGS BY SOLVENT BASED SLURRY METHOD

Abstract

The use of thermal barrier coatings (TBCs) to increase the combustion temperature in diesel engines has received considerable attention where one of the most promising of coating materials is mullite. The objective of this study is to characterize and assess the mechanical properties of various compositions of titanium and mullite mixtures for application as thermal barrier coating materials in diesel engines piston crown. In the present study, functionally graded coatings (FGTBC) were deposited by solvent based slurry method using a simple surface coating machine. The microstructure, phase composition, adhesion strength and micro-hardness were found to change gradually through the three-layer functionally graded coatings which was beneficial for the improvement of mechanical properties of the coatings. The microstructure formed in the functionally graded coating is attributable to the degree of firing of the feedstock powder. With an increase in the percentage of titanium (increment by 10wt.%) in the intermediate composite layer, the adhesion strength and hardness of the coatings increased. Both micro-hardness and adhesion strength values were in correlation with the microstructural analysis, proportional to the presence of unmelted particles and pores in these coatings.