The efficiency of gas turbine engines needs to be improved to reduce fuel consumption, emission of greenhouse gases and cost. Two of the methods to improve the efficiency are by reducing the weight of the engine and increasing the inlet temperatures. Conventional nickel-based alloys are already put to the limit with inlet temperature. Therefore, Silicon Carbide Ceramic Matrix Composites (SiC CMCs) are investigated to replace superalloys as they have superior mechanical properties such as high melting point and low weight of approximately 1/3rd of superalloys. However, there is a major disadvantage to using SiC CMCs. Under operating conditions of gas turbine engines, the mass recession of the SiC takes place due to the volatilization of Silicon Hydroxide caused due to oxidation and reaction with water vapor. Therefore, a protective layer of coating is introduced to prevent the SiC CMCs from oxidation. This protective layer is called Environmental Barrier Coating (EBC). EBC is deposited on SiC using the thermal spray technique suspension plasma spray which uses a liquid feedstock.

For effective performance of EBC, the coating needs to be highly dense, free from cracks and crystalline. EBC was deposited by varying the spray parameters to study its effect on microstructure. SEM images of the coating were taken and the images were analyzed to measure porosity and the level of cracks. XRD analysis was done to determine the percentage of crystalline and amorphous phases in the coating. Thermal cyclic fatigue test was carried out to study the formation of thermally grown oxide (TGO) in the coating and substrate.

It was observed that the percentage of porosity has a significant influence on the formation of cracks. The number of cracks was reduced when the porosity was higher. A layer of TGO was observed after TCF testing between the bond coat and top coat interface.