Optimization of Microhardness in Nanostructured Thermal Barrier Coatings Using Spark Plasma Sintering (SPS) and Taguchi Design

In this study, nanostructured thermal barrier coatings (TBCs) were fabricated using the Spark Plasma Sintering (SPS) method on an Inconel 713 LC superalloy substrate. These coatings were compared to those produced by Atmospheric Plasma Spray (APS) in terms of mechanical properties. The aim of this study was to investigate and optimize the process parameters to improve the microhardness of these coatings. Key parameters, such as temperature, pressure, and holding time, were optimized using the Taguchi design of experiments (L9). The results showed that SPS coatings exhibited significantly higher hardness compared to APS coatings, due to a notable reduction in porosity and increased density. The highest microhardness achieved for SPS coatings was 700 HV at a temperature of 1080°C, a pressure of 25 MPa, and a holding time of 6 minutes. In contrast, APS coatings demonstrated lower hardness, primarily due to higher porosity and lower density. This study highlights that precise control of process parameters in the SPS method can produce coatings with enhanced mechanical properties, making them suitable for high-temperature applications in aerospace and power generation industries. Furthermore, the Taguchi method effectively reduced the number of experiments and improved process efficiency.