Thermal cycle behaviour of plasma sprayed thermal barrier coatings on cast iron substrate for the application of liner of internal combustion engine

Abstract

In the present scenario, research on Thermal Barrier Coatings (TBCs) is attracting significant attention in high-temperature applications due to the rising demand in industrial applications, such as gas turbine blades and internal combustion engine components. To meet these demands, it is essential to enhance the mechanical and oxidation properties of thermal barrier coatings. The atmospheric plasma spray methodology for producing these coatings has become a central focus in recent times. In this work, TBCs were prepared by blending pure alumina and Yttria-Stabilized Zirconia (YSZ) in equal proportions. Extensive study of TBCs carried out under high-temperature conditions through thermal cycle tests at elevated temperatures, around 850 °C. A total of 350 thermal cycles were conducted, and microstructures of the coating surface were examined at 150, 250, and 350 cycles. High-temperature stress, generated due to the sintering of the coating, also influences the life of the coatings. Specimen with a topcoat thickness of 300 μm, exhibited good thermal shock resistance compared to the specimens with topcoats of thickness of 100 μm and 200 μm. The effects of process parameters, porosity, and thermal shock resistance are presented in detail. The topcoat with a thickness of 300 μm demonstrated excellent thermal shock resistance and reduced formation of thermally grown oxide (TGO). The porosity of the coating, found to be between 2% and 3%, contributed to its dense nature, effectively reducing oxidation rates and enhancing the coating's lifespan under cyclic high-temperature conditions.

Keywords

• Thermal barrier coatings (TBCs
• Thermal cycle
• Thermally grown oxide (TGO)
• Oxidation
• Atmospheric plasma spray (APS)