Thermal conductivity study of SiC nanoparticle beds for thermal insulation applications

Abstract

Applications of oxide nanoparticles in thermal insulation materials can be limited by their low thermal reliabilities at high temperature, in this work, silicon carbide (SiC) nanoparticle beds were probed to prepare thermal insulation materials due to the good corrosion resistance of SiC in high temperatures, which can retain its initial morphology even at a temperature as high as 1800 °C, and also the superior high-temperature phase reliability up to 2000 °C without phase transformation. We firstly prepared SiC nanoparticle beds, and then measured thermal conductivity. To understand the heat transfer in SiC nanoparticle beds, a theoretical model was also proposed by considering influences of both thermal contact resistances between nanoparticles and that between nanoparticles and air. Results show that SiC nanoparticle beds have excellent thermal insulation performance with a thermal conductivity even lower than 0.07 W/(m·K), which is attributed to the large thermal contact resistances between nanoparticles. There is a large size effect of SiC on thermal conductivity, and the thermal conductivity of a bed prepared with small nanoparticles is much lower than that prepared with large nanoparticles. Sintering treatments could reduce the number of grains in a bed thus reinforce thermal stability for high temperature applications, but also enhance thermal conductivity. Considering the high thermal stability and still low thermal conductivity, the SiC nanoparticle bed is a better choice for an application in high temperature thermal insulation. This work is expected to supply some information for high-temperature thermal insulation material preparation.