Mechanical Properties and Thermal Conductivity of Ytterbium-Silicate-Mullite Composites.

Author(s) Xiao, J.; Chen, W.; Wei, L.; He, W.; Guo, H.
Journal Materials (Basel)
Date Published 2020 Feb 03

Various Ytterbium-Silicate-Mullite composites were successfully fabricated by adding YbSiO into mullite ceramics and then using pressureless sintering at 1550 °C. The influence of YbSiO addition on the microstructure, mechanical properties, and thermal conductivity of ytterbium-silicate-mullite composites was investigated. Results show that the composites mainly consisted of a mullite matrix and some in situ formed YbSiO and AlO phases. By the addition of YbSiO, the Vickers hardness of composites reached ~9.0 at an additive concentration of 5 mol %. Fracture toughness increased to ~2.7 MPa·m at the additive concentration of 15 mol %, owing to the trans-granular fracture and crack deflection of the pinning effect of the AlO phase in the composites. With the increase of the AlO phase in the composite, the thermal conductivity for the 15YbAM reached around 4.0 W/(m·K) at 1200 °C. Although the thermal conductivity increased, it is still acceptable for such composites to be used as environmental barrier coatings.

DOI 10.3390/ma13030671
ISSN 1996-1944
Citation Materials (Basel). 2020;13(3).

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