Abstract
The Cr3+-modified α-cordierite ceramics Mg2Al4-xCrxSi5O18 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1, named MAS, MASCr0.2, MASCr0.4, MASCr0.6, MASCr0.8, and MASCr1, respectively) have been synthesized via the sol-gel process followed by cold isostatic pressing and sintering. The effects of trivalent chromium ion content in α-cordierite ceramic on microstructure and thermophysical properties were investigated. The MASCr0.2 ceramic exhibits the highest average emissivity value of 0.87 across the whole infrared range of 3–20 μm at 500 °C, especially at the vital infrared wavelength of 3–5 μm, the value can reach 0.92. The emissivity will decrease with the increase of doping amount owing to the growing precipitation of cristobalite and MgAl2O4 spinel phases. The lowest thermal conductivity 2.077 W/m K is discovered in MASCr0.2, a decrease of 23% compared to MAS. The MASCr0.4 ceramic with a close emissivity value compared to MASCr0.2 exhibits the TEC of 7.8 × 10?6 K?1 due to the multiphase structure.
NSTL
Elsevier