Preparation And Performance Research Of Composite Silicon Carbide Honeycomb Porous Ceramic

Diesel vehicle exhaust mainly includes NO_x,HC,SO_x,soot particles and CO,and the particles are usually less than 2.5μm in diameter,which has a huge impact on human health.For the particulate emission problem,in addition to the development of relevant emission regulations,the most effective device to purify exhaust gas is the wall-flow diesel particulate trap,the carrier material is currently mainly cordierite and silicon carbide-based ceramics.Compared to other materials,silicon carbide has excellent high-temperature performance,high thermal conductivity,as well as better resistance to acid corrosion,and relatively strong carbon soot loading capacity.However,there are relatively obvious disadvantages of silicon carbide:the sintering temperature of silicon carbide ceramics is very high,generally around 2200℃.How to achieve low-temperature sintering is currently the main issue explored.This paper focuses on several aspects of low-temperature sintering of silicon carbide ceramics,using corn starch as the porogenic agent and silicon carbide as the main raw material to achieve low-temperature sintering of silicon carbide by bonding phase.The raw honeycomb porous ceramic blanks are obtained by extrusion molding process using homemade molds.Strontium feldspar or barium feldspar-silicon carbide ceramic blanks are sintered at 1320℃,1350℃ and 1380℃ to achieve better performance by bonding silicon carbide through the feldspar phase.When the sintering temperature is 1350℃,the properties are better.The compressive strength of the silicon carbide honeycomb ceramic perpendicular to the pore channel and the pore wall in the direction of 45°can be as high as about 1 MPa,with a porosity well over 45%and a low coefficient of thermal expansion.By sintering silicon carbide at 1320℃ or 1350℃ through strontium or barium feldspar phases,the energy consumption generated by sintering is much lower than other methods,so low-temperature sintering of silicon carbide is beneficial to industrial production.In addition,when sintering strontium or barium feldspar-silicon carbide ceramics in Ar gas-protected atmosphere,the conversion of the feldspar phase was found to be significantly higher.While exploring different protective atmospheres for sintering aluminosilicate titanate-silicon carbide ceramics,the results obtained experimentally for mullite or celluar ceramic composite silicon carbide ceramics are of some reference significance to researchers,although they did not produce the expected results.The coefficient of thermal expansion of the protective atmosphere sintered silicon carbide composite ceramics can be as low as 4.3×10^-6/℃.The porosity of the ceramics can be as high as 55%with a median pore size between 9-12μm,and is therefore sufficient to meet the basic parameters of the particle trap.This study is of significance for the industrial production and application of silicon carbide particle traps by a simple process production route such as extrusion molding and low temperature sintering of silicon carbide ceramics.