Influence of microstructure and crystallographic phases on the tribological properties of SiC obtained by spark plasma sintering

SiC ceramics with different crystalline phases (α, β and α+β) were fabricated by spark plasma sintering without the use of sintering additives to study the influence of grain morphology on their tribological behavior. Hardness and fracture toughness were measured by Vickers indentations. The values of hardness varied from 14 GPa to 29 GPa depending mainly on density of the samples. Fracture toughness values ranged from 2.6 to 4.3 MPa m1/2. The room-temperature unlubricated tribological behavior of the samples was studied using a modified pin-on-disc tribometer. Similar friction coefficient values (~0.7) and wear rates (10−6 mm3/N m) were obtained for all samples. Worn surface observations revealed that plowing and polishing were the main wear mechanisms.