A Study on the Effect of Ultrafine SiC Additions on Corrosion and Wear Performance of Alumina-Silicon Carbide Composite Material Produced by SPS Sintering

• Main Authors: Ntebogeng F. Mogale, Wallace R. Matizamhuka
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Metals
• Subjects: SPS; corrosion; wear; alumina-silicon carbide; composite
• Online Access: https://www.mdpi.com/2075-4701/10/10/1337

Alumina-silicon carbide (Al₂O₃–SiC) composites of varying compositions (15, 20, 25 and 30 vol.%)–SiC were produced by the ball milling of Al₂O₃ and SiC powders, followed by spark plasma sintering. The samples were sintered at a temperature and pressure of 1600 °C and 50 MPa, respectively, thermally etched at 1400 °C and mechanically fractured by hammer impact. The effect of SiC additions to monolithic Al₂O₃ on the densification response, microstructural and phase evolutions, and fracture morphologies were evaluated. The wear performance of the composites using a ball-on-sample configuration was evaluated and compared to that of monolithic Al₂O₃. In addition, the corrosion performance of the composites in a 3.5% NaCl solution was examined using open circuit potential and potentiodynamic polarization assessments. SiC additions to monolithic Al₂O₃ delayed densification due to the powder agglomeration resulting from the powder processing. SiC particles were observed to be located inside Al₂O₃ grains and some at grain boundaries. Intergranular and transgranular fracture modes were observed on the fractured composite surfaces. The study has shown that the Al₂O₃–SiC composite is a promising material for improved wear resistance with SiC content increments higher than 15 vol.%. Moreover, the increase in SiC content displayed no improvement in corrosion performance.