Investigation of microstructure,surface and tribological properties of mullite and SiC based ceramic matrix composite fabricated by powder metallurgy

Abstract

In the current research, a novel ceramic matrix composite with a high proportion of mullite matrix and SiC reinforcement was fabricated by the powder metallurgy process. The effects of material composition, hydraulic press load, and sintering temperature were investigated by characterizing fabricated composites by evaluating porosity, surface roughness, and tribological behaviour by dry sliding wear testing at room temperature using pin-on-disc apparatus. The multicriteria decision analysis optimization technique using grey relational analysis (GRA) was carried out, and the optimized fabrication parameters were determined. The results obtained from GRA suggested that 20 wt.% SiC reinforcement in 80 wt.% mullite in composite at 430 MPa hydraulic press load and 1400°C sintering temperature resulted in enhanced mechanical properties with porosity, wear, and surface roughness values of 44.80%, 666 µm, and 6.344 µm, respectively. Surface morphology using SEM and XRD/EDS mapping confirmed the presence of wear debris along with the formation of aluminium oxides, cristobalite, and intermetallic dense strengthening phases Al₂SiO₅, Al₄SiO₉, and Al₆Si₂O₁₃, which improve abrasion and thermal resistance. The fabricated composite, with its high porosity, low surface roughness, minimal wear, and high-temperature intermetallic strengthening phases, can be used in journal bearings and thermal protection layers in automobiles and aircrafts.