Fabrication of silicon preforms of high green density (>1·2 g/cm3) by slip casting of silicon (in aqueous medium) has been studied. The nitridation product consists of 59–85% α-Si3N4, 7–22%β-Si3N4 and 7–23% Si2N2O phase. The amounts of un-nitrided silicon were negligible. The microstructure is either granular or consists of needle-like grains (α-Si3N4) and whiskers deposited in the large pores. MOR values of the specimens are almost constant up to 1000°C or 1400°C or show slight increase up to 1000°C or 1200°C. In some cases a little dip around 1200°C, then a sharp increase in MOR up to 1400°C was observed.Kic values are almost constant up to 1000°C, and thereafter increase sharply.
Pore size distribution, existence of Si2N2O phase and oxidation of RBSN at high temperatures have been considered for the explanation of the observed behaviour.
Volume 44, 2021
Continuous Article Publishing mode
Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020
Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
Physical Sciences 2020
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