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- Barick, Prasenjit, et al.
(författare)
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Effect of pressure and temperature on densification, microstructure and mechanical properties of spark plasma sintered silicon carbide processed with β-silicon carbide nanopowder and sintering additives
- 2016
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 42:3, s. 3836-3848
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Tidskriftsartikel (refereegranskat)abstract
- The effects of applied pressure and temperature during spark plasma sintering (SPS) of additive-containing nanocrystalline silicon carbide on its densification, microstructure, and mechanical properties have been investigated. Both relative density and grain size are found to increase with temperature. Furthermore, with increase in pressure at constant temperature, the relative density improves significantly, whereas the grain size decreases. Reasonably high relative density (~96%) is achieved on carrying out SPS at 1300 °C under applied pressure of 75 MPa for 5 min, with a maximum of ~97.7% at 1500 °C under 50 MPa for 5 min. TEM studies have shown the presence of an amorphous phase at grain boundaries and triple points, which confirms the formation of liquid phase during sintering and its significant contribution to densification of SiC at relatively lower temperatures (≤1400 °C). The relative density decreases on raising the SPS temperature beyond 1500 °C, probably due to pores caused by vaporization of the liquid phase. Whereas β-SiC is observed in the microstructures for SPS carried out at temperatures ≤1500 °C, α-SiC evolves and its volume fraction increases with further increase in SPS temperatures. Both hardness and Young׳s modulus increase with increase in relative density, whereas indentation fracture toughness appears to be higher in case of two-phase microstructure containing α and β-SiC.
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2. |
- Barick, Prasenjit, et al.
(författare)
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Spray-freeze-dried nanosized silicon carbide containing granules : Properties, compaction behaviour and sintering
- 2016
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Ingår i: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 36:16, s. 3863-3877
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Tidskriftsartikel (refereegranskat)abstract
- Spherical granules comprising silicon carbide nanoparticles have been produced with the help of sprayfreeze-drying (SFD) technique. The effect of solid loading of slurries on rheological properties, flowability and morphology of the resulting SFD granules has been studied. Further, a systematic study has been performed to investigate the effect of applied pressures and granule density on the relative densities and microstructures of the green compacts. A marginal increase in viscosity is noted as the solid content of slurries increases from 5 to 15 vol% with significant increase in viscosity being observed in case of 18 vol% slurry. The granules prepared from SiC slurries are spherical in shape with their mean size, density, gravimetric flow rate, and yield strength increasing with the increase in solid content. The mechanical properties of sintered SiC produced from SFD granules are found relatively superior to that made from commercially available spray-dried (SD) granules.
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