Effect of alkaline earth metal oxide addition on flexural strength of porous mullite-bonded silicon carbide ceramics

The impact of alkaline earth metal oxide addition on flexural strength of porous mullite-bonded silicon carbide ceramics is analyzed. All batches were milled separately in a polypropylene jar for 24 h using distilled water and SiC grinding balls. Polyethylene glycol and polyvinyl alcohol were added as binders. The bulk density of each sample was calculated from its weight-to-volume ratio. The porosity was determined from the bulk density to true density ratio. The true density was calculated using the method reported elsewhere. A mullite bonding phase was synthesized at temperatures as low as 1350°C and was accelerated by adding alkaline earth metal oxides as a sintering additive. The addition of alkaline earth metal oxides resulted in a denser strut and reduced porosity. The porosities of the MBSC specimens with no additives and with the alkaline earth metal oxides ranged from 48.8 to 50.4% and 44.3 to 49.8%, respectively.