The improvement of mechanical and combustion properties of SiC reticulated porous ceramics with multi-layer strut containing Ca/Cr co-doped LaAlO3 coating

SiC reticulated porous ceramics (SRPC) was the critical part of porous media burners. During the ignition and shutdown process of porous burner, SRPC have to subject the large thermal stress caused by sharp temperature gradients. Meanwhile, most of the heat exchange in the burner is achieved through the high-temperature radiation heat transfer of the medium material. The strength and infrared emissivity of SRPC directly determined their service life and heating efficiency. In this work, a multi-layer strut in SRPC was constructed to improve the strength and infrared radiation properties via vacuum infiltration and spraying, including SiC skeleton, dense alumina transition layer and Ca/Cr co-doped LaAlO3 coating. The results indicated that the multi-layer strut significantly increased the strength of SRPC, and the Ca/Cr co-doped LaAlO3 coating increased the boiling rate of porous burner from 25.5 °C/min to 31.2 °C/min. Furthermore, the Ca/Cr co-doped LaAlO3 coating with its high infrared emissivity (0.80) increased the surface temperature of porous burner, also reduce the pollutant emission (CO and NOx) of SRPC. In addition, Ca/Cr co-doped LaAlO3 promoted the combustion of low concentration methane, the lean-burn limit of methane stable combustion for porous burner had been enlarged, even the mixed gas containing 4 vol% methane could achieve stable combustion.