A Novel Si3N4–SiC Ceramic Used for Volumetric Receivers

Abstract

Si3N4–SiC composite ceramics used for volumetric receivers were fabricated by pressureless sintering of micrometer SiC, Si3N4, andalusite, and other minor additions powders. Mechanical, thermal expansion, thermal conductivity, and thermal shock resistance properties were tested at different sintering temperatures. The best sintering temperature of optimum formula A2 is 1360°C, and the bending strength reaches 79.60 Mpa. And moreover, its thermal expansion coefficient is 6.401 × 10−6/°C, thermal conductivity is 7.83 W/(m K), and no crack occurs even subjected to 30 cycles thermal shock with a bending strength increase rate of 4.72%. X‐ray diffraction results show that the phase constituents of the sintered products mainly consist of SiC, Si3N4, mullite, and quartz. Microstructure that is most appropriate and exhibits maximal thermal shock resistance was detected using SEM. The porosity of Si3N4–SiC ceramic foam prepared from formula A2 is 95%, which provides a rapid and steady action for the receiver. The evaluation of the present foam shows that Si3N4–SiC ceramic composite is a good candidate for volumetric receivers.