Thermo-Physical Properties of Plasma-Sprayed K2Ti6O13 Coatings for Diesel Engine Piston

A new challenge in the transport systems concerns with improving efficiency. Thermal swing coatings are interesting candidates for internal combustion engines due to their potential to reduce cooling requirements and increase efficiency. K2Ti6O13 (KTO) thermal barrier coatings (TBCs) were prepared by atmospheric plasma spraying through powder structure design and optimization of deposition conditions. The thermophysical properties of plasma-sprayed KTO deposits and their effect on the thermal swing have been investigated. Their thermal conductivities were tested by a laser flash method and the thermal performance of the coatings was further examined by thermal swing test. The phases, nominal chemical compositions and microstructure of KTO deposits were characterized by X-ray diffraction (XRD) and scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS). The results indicated that the chemical composition change occurs to the coatings resulting in a deviation from nominal stoichiometry due to chemical reactions between the plasma gas and particles. The thermal conductivity of the coating is very sensitive to the coating compositions, and the coating prepared using porous powder under pure argon presents a single K2Ti6O13 phase and high porosity, and the lowest thermal conductivity of 0.85 W/m·K.