Depositing thin SiC shells to weld chopped SiC fibers as ultralight highly preamble porous combustion media

Abstract

This article reports an ultralight highly permeable combustion medium for many gas-fired applications where more combustion efficiency, smaller thermal inertia and less structural size are urgently required. Chopped SiC fiber papers were prepared and then formed into mat structures. Then they were coated with SiC shells to weld the fibers at points of contact, resulting in rigid fiber porous media (FPM) with light and thin characteristics. Different SiC shell thicknesses were deposited to optimize the overall performance influenced by permeability, thermal physical properties and combustion performance. It was found that two types of pore structures existed in the FPM, the smaller pores near the lap joints and the larger pores away from the lap joints, leading to high permeability. The FPM with 3.0 µm SiC shell thickness, can achieve the relatively ideal combustion effect, with less CO and only 13 ppm NOx in the flue gas. The increase of SiC shell thickness will slightly decrease the porosity and permeability, but it is conducive to improve the structural stability under gas blowing environment at high temperature. The thin SiC shell welded FPM are of great potential to improve the combustion efficiency and prolong service life due to their exceptional ultralight highly preamble characteristics.