Nanoindentation-Based Mechanical Properties Evaluation of Nano-Structure and Composite Plasma Spray Formed Ceramic Nozzles

Ceramic nozzles are unique options in aerospace industry due to their ability to operate at high temperatures. However, their brittleness, structural defects, poor formability, and need for complex methods for measuring their mechanical properties are among the main obstacles to their development. In this study, four different conical nozzles were produced through Plasma Spray Forming (PSF). Given that Yttria-Stabilized Zirconia (YSZ) is one of the most common materials in high-temperature applications, it is considered as the base material. Throughout the research, three YSZ alternatives were investigated by changing the chemical composition (Ceria-Yttria co-Stabilized Zirconia (CYSZ)), by changing the particle size (nanostructured YSZ), and by double layer architecture design. The mechanical properties of the conical nozzles were then evaluated by the nanoindentation test using Oliver and Pharr method. This method can be quick and applicable for evaluation of the mechanical properties of ceramic parts based on the load-depth curve. X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were performed for the phase analysis and coating microstructure and porosities investigation. The results highlighted the promising features of nano-structured YSZ that are strongly based on the presence of nano-zones inside the coating structure.