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

Ntebogeng F Mogale,Wallace R Matizamhuka

doi:10.3390/met10101337

Abstract

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.

Highlights

There has been increasing attention for ‘ceramic nanocomposites’ [1]
This paper offers the primary results of an investigation on the behavior of Al2 O3 –silicon carbide (SiC) ultrafine grained composites under a NaCl corrosive environment
A characterization study was conducted on pure Al2 O3 and Al2 O3 –SiC powders obtained by milling, as well as the composites consolidated by spark plasma sintering (SPS)

Summary

Introduction

There has been increasing attention for ‘ceramic nanocomposites’ [1] These consist of a ceramic matrix such as alumina (Al2 O3 ) reinforced by dispersing nanoparticles of another ceramic material like silicon carbide (SiC). Besides SiC, mechanical properties can be improved by introducing other secondary hardened phases to the Al2 O3 matrix, including TiB2 , TiC, Ti(C,N) and ZrO2 particles. A study conducted by Kim and Lee showed that adding TiC particles to the Al2 O3 matrix improved flexural strength and fracture toughness [2]. Properties such as flexural strength, fracture toughness, and hardness were later reported to be improved with an increment in TiB2 [3]. Literature reported that SiC addition to Al2 O3 as reinforcement enhances the mechanical properties significantly as related to other reinforcing additives [5,6,7,8,9]

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