Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
11011441 | Materials Chemistry and Physics | 2019 | 23 Pages |
Abstract
Present work reports the effects of multiwalled carbon nanotube (MWCNT) reinforcement on sintering and mechanical properties of additive free, dense (>96%) 15R-SiAlON polytype. Laboratory made precursor polytype powder, prepared through carbothermal-reduction-nitridation technique and devoid of any external sintering additive, were dispersed with MWCNT and were consolidated using spark plasma sintering at 2000â¯Â°C for 10â¯min under 40â¯MPa. Differential electrical conductivity causing localized heating resulted in improved sintering behaviour in the composites. Apart from formation of both equiaxed and elongated SiAlON grains, various CNT/SiAlON interactions were noticed in the composites. Depending on test load, the 0.5â¯wt% MWCNT/15R-SiAlON composite offered 9.6-17% and 12-13% higher hardness and indentation fracture toughness, respectively, over the monolith. Indentation size effect and load dependence of indentation toughness of the studied specimens have been reported. Under 20N, >30% reduction in specific wear rate was observed at only 0.5â¯wt% MWCNT loading. Self-reinforcement offered by elongated matrix grains, reinforcement by structurally survived CNTs, matrix grain refinement by the dispersed nanotubes and solid lubrication offered by the pulled-out CNTs were the key factors behind obtaining improved tribo-mechanical performance of the composites over pure 15R-SiAlON polytype.
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Authors
Mita Biswas, Soumya Sarkar, Siddhartha Bandyopadhyay,