The effect of the amount and size of alumina sintering aid particles on some mechanical properties and microstructure of silicon carbide bulky pieces via spark plasma sintering

Abstract

Abstract In this paper, for sintering silicon carbide nanopowders via the spark plasma sintering method, nano-and micro-sized alumina sintering aids were used separately at 3 vol.%, 5 vol.%, and 7 vol.%. The sintering process was undertaken at 1900 °C for 10 min. To investigate some mechanical and physical properties of the resulting samples, density was obtained via the Archimedean method, and hardness was taken by the Vickers indenter method. The microstructure of the samples was examined through scanning electron microscopy. The results indicated that in the samples containing nano-alumina, the largest percentage of density and hardness was related to the sample containing 5 vol.% nano-alumina as a sintering aid and were obtained as 99% of theoretical density and 31.3 GPa, respectively. For the samples containing micro-alumina, the highest percentage of density and hardness was related to the sample containing 7 vol.% micro-alumina and obtained 93% of theoretical density and 20.1 GPa, respectively. By investigating the fractured surfaces of the samples and via the linear intercept method, the largest mean grain size was associated with the densest sample at 3.7 µm.