Preparation and thermal shock resistance of sialon/SiC composite ceramics used for solar absorber
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RESEARCH
Preparation and thermal shock resistance of sialon/SiC composite ceramics used for solar absorber Xiaohong Xu 1 & Dongbin Wang 1,2 & Zhenggang Rao 1 & Jianfeng Wu 1 & Xing Liu 1 & Chen Zhang 1 Received: 8 July 2020 / Revised: 26 October 2020 / Accepted: 18 November 2020 # Australian Ceramic Society 2020
Abstract In this paper, sialon/SiC composite ceramics were synthesized in situ from SiC, α-Si3N4, AlN, calcined bauxite, quartz, and Y2O3 via layered buried sintering at different temperatures (1540–1640 °C). The sialon/SiC composite ceramics designed in this study are expected to be used as thermal absorb materials in solar thermal power generation based on the good mechanical character and thermal shock resistance. The results showed that the β-sialon/SiC sample with 60 wt% silicon carbide sintered at 1600 °C exhibited the optimal performances with dense microstructure, high bending strength, and good thermal shock resistance. After 30 thermal shock cycles, the bending strength of β-sialon/SiC sample with 60 wt% silicon carbide was 66.68 MPa with a decrease of 4.79%. In thermal shock tests, SiC and Si3N4 in the sample were oxidized into amorphous SiO2, and small amount of sialon was decomposed into mullite, which resulted in good thermal shock resistance. It was believed that in situ sialon/SiC composite ceramics can be a promising candidate for solar absorber owing to good thermal shock resistance. Keywords Sialon/SiC composite ceramics . Thermal shock resistance . Solar absorber
Introduction As one of the most important components of a solar thermal tower plant (STTP) system, solar absorber materials are designed to receive concentrated solar energy, which determine the power generation efficiency of the system. The hightemperature resistance (instantaneous temperature up to 1000 °C) is essential for the solar thermal power generation [1]. Hoffschmidt [2, 3] reported that candidate materials for solar absorber were usually metal fiber mesh, siliconized silicon carbide (SSiC) foam, clay bound silicon carbide (CBSiC) foam, and cordierite foam. The current solar absorber materials still have some disadvantages in working temperature, thermal shock resistance, high-temperature oxidation resistance, thermal conductivity, and solar absorptance.
* Dongbin Wang [email protected] 1
State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070, People’s Republic of China
2
School of Material Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China
In order to solve the above problems, a series of researches have been conducted on the factors of thermal shock resistance, oxidation resistance, thermal conductivity, and solar absorptance [4–7]. The thermal shock resistance of cordierite/SiC composites [4] and mullite-bonded SiC ceramics [5] was studied. The thermal shock resistance and oxidation resistance of β-sialon/Si3N4 composites were investigated [6]. Mullite-bonded Si3N4/SiC composite ceramics were fabricated and thermal shock resis
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