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Densification and characterization of SiC-AlN composites for solar energy applications

Besisa, Dina H.A., Ewais, Emad M.M., Ahmed, Yasser M.Z., Elhosiny, Fouad I., Kuznetsov, Denis V., Fend, Thomas
Renewable energy 2018 v.129 pp. 201-213
X-ray diffraction, additives, air, argon (noble gases), ceramics, diffusivity, electricity, energy, foams, microstructure, nitrides, silicon carbide, solar collectors, solar energy, temperature, thermal conductivity, thermal expansion, Europe, Middle East
In an attempt to solve one of the most critical global concerns of energy resources depletion, the present work is focused on tailoring and processing of a new volumetric receiver material for solar energy and high temperature applications. This in turn support producing a highly qualified solar receiver material for the future energy and electricity supply of Middle East and Europe. Herein, the processing and studying of the different parameters affecting on the preparation of near fully dense SiC/AlN structures and investigation of their different characteristics were achieved. These ceramic composites will constitute the final foam struts of the pores of the volumetric air receiver. Various SiC/AlN composites were designed with different ratio of AlN content (0–40%) and produced via pressureless sintering. Influence of different parameters on sintering and densification of SiC/AlN composites such as sintering atmosphere, additives and temperature were investigated in order to achieve the required and qualified properties of the final product of proposed SiC/AlN solar receiver. The quality and performance of the produced composites were evaluated and analyzed through different investigations, including XRD, densification parameters, microstructure examination and thermal properties. The results show that the best sintering conditions for producing a highly dense and qualified carbide/nitride receiver was attained at a temperature of 2080 °C in argon/vacuum with 2.5%Y + A addition. The characteristics of the investigated composites were mainly dependent on their densification behavior and AlN content. Thermal conductivity, diffusivity and coefficient of thermal expansion gave enhanced values at high temperatures. The inspected SiC/AlN composites can be strongly nominated to be used in solar energy applications.