Supervisor: prof. D. Galusek, FunGlass, Slovakia
Co – supervisor: Dr. A. H. Pakseresht, FunGlass, Slovakia
Abstract: Most engineering products faced with high-temperature and harsh environment are susceptible to failure due to thermal shock problems leading to degradation and eventual failure of systems and components during thermal cycles. In industrial sectors, deposit different kind of coatings and surface modifications have been used to increase the efficiency of the systems. During recent years, thermal barrier coatings have become one of the priorities of the high temperature industries. This kind of coating usually deposited with EB-PVD or thermal spray methods. Among thermal spray method, plasma spray is used widely as a potential alternative to traditional coating methods to produce ceramic coatings. These kinds of coatings have been widely utilized in industrial sections to produce erosion resistance, thermal insulation and hot corrosion protection film on metallic substrates. It should be noted that the most frequently used of ceramic coating are ceramic oxide. Among them, ZrO2 as a structural ceramic material has a significant capability for engineering usages due to their inimitable properties. In the high temperature operating conditions, TBCs are exposed to face high-temperature oxidation, hot corrosion and thermal shock. Therefore, this kind of coating plays an important role in improving the efficiency and performance of metallic substrates in harsh environments.
Similar to the ceramic matrix the main problem for the continued evolution of TBCs, as well as increase their range of application, lies in their weakness in the cohesive strength and poor fracture toughness of the ceramic layer. It is worth mentioning that materials toughening have been done by fiber reinforcement for decades. Desirable properties have been shown by adding continuous fibers or whiskers to ceramic matrixes. In addition, reinforced materials have a higher thermal shock resistance, thermal insulation, and toughness in comparison to their conventional ones.
In this research, we will introduce ceramic fiber-reinforced TBC as another part of modern TBCs. We will try to improve the understanding of the thermal shock resistance of fiber-reinforced TBCs, by means of introducing YSZ fibers to top coat. In this regards the optimized coatings were sprayed onto superalloy substrate using both the conventional and composite YSZ. Moreover, microstructure, thermal shock and hot corrosion behavior of deposited coatings will be investigated and compared.