Plasma spray deposition, characterization and production of strontium zirconate coating powder used for thermal barrier coatings

The objective of the present work is to produce strontium zirconate (SrZrO3) coating powder and coatings which are used for application as materials for thermal barrier coatings (TBC) at operating temperatures >1300°C. In this study, strontium zirconate was coated by atmospheric plasma spraying technique on stainless steel (SS304) substrates. Strontium zirconate is produced by solid phase synthesis from zirconium dioxide and strontium carbonate. Starting powders were a high grade ZrO2, and commercial SrCO3 (Aldrich,>98%, Munich, Germany). Powders calcined at 1250°C and 1350°C for 24 h, 1600°C for 4 h and 6 h with a heating rate of 5 K/min. The powders were calibrated the correct particle size for plasma spraying. Atmospheric plasma spraying (APS) technique is generally used for depositing ceramic materials due to the high enthalpy and temperature available in the plasma jet. Depending on the process parameters, the temperature at the core of plasma jet can be as high as 10.000–15.000 K and any metal or ceramic powder injected into the plasma jet can be melted and spray coated. The injected spray grade powder particles are rapidly melted, accelerated and propelled at high velocity to the substrate surface. By virtue of its low thermal conductivity, high melting point SrZrO3 ceramic has potential applications for thermal barrier coatings (TBC). The resulting powders and coatings were characterized using SEM-EDS and XRD techniques. It was also measured on the physical properties such as density, velocity and particle size distribution of the coating powder. Keywords: SrZrO3, Atmospheric plasma spraying, Thermal cycling