Article ID Journal Published Year Pages File Type
5438607 Ceramics International 2017 22 Pages PDF
Abstract
Si-B-C-N monoliths with 5 wt% LaB6 additives were prepared by spark plasma sintering at 1250-2000 °C and 50 MPa using a mechanically alloyed mixture of graphite, c-Si, h-BN and LaB6 powders as the starting materials. Microstructural evolution, mechanical and thermal properties of the as-prepared La/Si-B-C-N monoliths were investigated. The densification of the ceramics starts at 1160° and ends at 1800 °C with the formation of La-containing compounds coupled with SiC and BN(C) phases. La-containing BN(C) grains develop into a lamellar structure at 1900 °C offering improved fracture toughness and decreased Vickers hardness, flexural strength and elastic modulus. The formation of lamellar BN(C) is also responsible for a high thermal expansion coefficient of 4.2×10−6 /°C.
Related Topics
Physical Sciences and Engineering Materials Science Ceramics and Composites
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