The usability and preliminary effectiveness of ultrasonic nanocrystalline surface modification technique on surface properties of silicon carbide

- Sintered SiC was treated by UNSM technique.
- UNSM technique increased density and reduced surface roughness.
- UNSM technique improved the mechanical and tribological properties.
- UNSM technique had no effect on chemical composition.
- The results of this study are expected to make SiC a more attractive ceramic.

This study reports the change in microstructural, mechanical and tribological characteristics of sintered silicon carbide (SiC) ceramic subjected to ultrasonic nanocrystalline surface modification (UNSM) technique. The surface microstructure of the untreated and UNSM-treated specimens was examined by SEM, EDS and XRD. The mechanical properties of the specimens were measured by nanoindentation. The tribological properties of the specimens were assessed using a ball-on-disk tribometer against a bearing steel (SAE52100) ball at two different temperatures under dry reciprocating conditions. It was confirmed by SEM that the UNSM-treated specimens had much denser microstructure than those of the untreated specimens. The EDS results revealed that the UNSM technique has no effect on the chemical composition of sintered SiC ceramic. The average surface roughness obtained by AFM was found to be about 83.6 nm and 60.1 nm for the untreated and UNSM-treated specimens, respectively. The tribological results showed that the UNSM-treated specimens exhibited a lower friction coefficient and higher wear resistance compared to those of the untreated specimens. In addition, it was found that the UNSM technique was able to decrease the quantity of pores. The results of this study are expected to make sintered SiC ceramic more attractive for numerous applications in various industries.