Experimental approach to probe into mechanisms of high-temperature erosion of NbB2-ZrO2

In the backdrop of potential applications of boride-based materials in high-speed supersonic aircrafts, the present investigation probes in comprehending the mechanisms of high-temperature erosive wear of spark plasma sintered NbB2-ZrO2 composite. The solid particle erosion experiments were performed at different temperatures starting from room temperature (25 degrees C) to 800 degrees C using Al2O3 particles (50 mu m). The air-erodent particle mixture was impinged toward the target surface at normal impact with a velocity of 50 m/s. The detailed microstructural analysis using HRTEM reveals the generation and accumulation of a large number of dislocations within NbB2 and ZrO2 grains of the eroded surfaces. Such observations indicate the activation of dislocation plasticity during erosion at 800 degrees C. XRD-based analyses provided residual stress-based interpretation for the enhancement of erosion resistance at high temperatures. In contrast, substantial material loss via brittle failure, involving the generation and intersection of the lateral/radial cracks, was recorded after room temperature erosion. In case of erosion at 400 degrees C and 800 degrees C, the residual stress relaxes as a consequence of high-temperature exposure prior to erosion. The accumulation of dislocations near the crater region and shot peening phenomena play a dominant role in decreasing erosion rate with increasing erosion test temperature.

Automated summary

This study investigates the high-temperature erosive wear mechanisms of spark plasma sintered NbB2-ZrO2 composite under different temperatures through experiments and microstructural analysis. The activation of dislocation plasticity during erosion at high temperatures plays a key role in erosion resistance, while substantial material loss occurs during erosion at room temperature.