Spark plasma sintering of Al-SiC composites with high SiC content: study of microstructure and tribological properties

The article presents the results of the microstructure and tribological properties of Al-xSiC composites (x = 70 and 90 wt% SiC) produced in spark plasma sintering (SPS). Due to their attractive thermal, physical, and mechanical properties, aluminum matrix composites with high-volume fractions of silicon carbide (> 50%) have become a major area of interest as a potential material for multifunctional electronic packaging and cryogenic applications. The SPS process was carried out in a vacuum atmosphere under various conditions. Composites with a density close to theoretical (96-98%) were obtained. X-ray diffraction and scanning electron microscopy with EDS analysis were used to characterize the microstructure. Mechanical properties were determined by hardness measurements and a three-point bending test. The tribological properties of the composites were determined utilizing a block-on-ring tribotester. As a criterion for wear resistance, weight loss measured under specific friction conditions, that is, depending on the type of material and the applied load, was adopted. The researched materials were characterized by an even distribution of the carbide phase in the matrix. Composites with the highest SiC phase content (90 wt%) had higher hardness (2537 HV1) and flexural strength (242 +/- 15 MPa) with worse wear resistance at the same time. The weight loss of this composite was 0.43 and 0.76% for friction under loads of 100 and 200 N, respectively, and was 360 and 270% higher than that determined for the composites with the lower content of the SiC phase (70 wt%). The wear rate was three times higher for the Al-90wt%SiC composites.