Effect of ultrasonic nanocrystal surface modification temperature: Microstructural evolution, mechanical properties and tribological behavior of silicon carbide manufactured by additive manufacturing

This study deals with the improvement in mechanical and tribological properties of silicon carbide (SiC) manufactured by additive manufacturing (AM) through ultrasonic nanocrystal surface modification (UNSM) at 23 °C (room temperature - RT) and 900 °C (high temperature - HT). It was demonstrated that the UNSM treatment temperature had a great effect on the mechanical and tribological properties of the as-printed SiC. The Ra and Rz surface roughness values of the as-printed SiC sample were reduced from 10.5 μm down to 6.5 μm and from 47.0 μm down to 25.9 μm after UNSM treatment at RT, respectively. Furthermore, it was further reduced down to 5.5 μm and 21.2 μm with increasing the UNSM treatment temperature. UNSM treatment at RT and HT was able to increase the surface hardness of the as-printed SiC sample from 2100 HV up to 2500 HV and 2700 HV, respectively. The coefficient of friction (COF) of the as-printed SiC sample was approximately 0.187, which reduced down to 0.172 and 0.141 after UNSM treatment at RT and HT, respectively. The specific wear rate (SWR) of the as-printed sample was 2.61 × 10−12 mm3/N × m, and decreased to 1.58 × 10−12 mm3/N × m and 6.46 × 10−13 mm3/N × m after UNSM treatment at RT and HT, respectively. The results of this investigation help improve the performance of AM-based SiC that is the potential candidate for many high-temperature applications such as nuclear, aerospace, optical, etc. instead of SiC manufactured by sintering method.