FLORENTINA MARILENA CLICINSCHI, CRISTINA ANTONELA BANCIU, DORINEL TĂLPEANU, MAGDALENA VALENTINA LUNGU, CRISTINA CORNELIA COSTEA, GABRIELA BEATRICE SBÂRCEA, DELIA PĂTROI, VIRGIL EMANUEL MARINESCU

Abstract

The aim of this research was to obtain composite ceramic materials based on a silicon carbide (SiC) matrix modified with sintering additives (Al₂O₃ and Y₂O₃) and reinforced with 1 wt.% or 5 wt.% milled carbon fibers (Cf) using the spark plasma sintering (SPS) technique. SPS processing was carried out under vacuum at an applied axial pressure of 50 MPa and a sintering temperature of 1850°C, with a holding time of 10 minutes. The structural and morphological characteristics of the silicon carbide-based composites were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Physical and mechanical properties, including bulk density, apparent porosity, Vickers hardness, elastic modulus, friction coefficient, and specific wear rate, were evaluated for all sintered specimens. XRD analysis indicated the predominance of the β-SiC phase in the composite materials. The results showed that all samples sintered at 1850°C achieved bulk densities above 3 g/cm³ and apparent porosities below 1.72%, corresponding to a densification degree of at least 98.28%. Furthermore, all analysed specimens exhibited Vickers hardness values exceeding 1568 HV, modulus of elasticity in the range of 240-299 GPa, and an average friction coefficient between 0.41 and 0.93 in dry sliding conditions.