Preparation Of Porous Silicon Carbide Ceramics Bonded By Mullite

Porous silicon carbide ceramics which has excellent performances,such as high porosity,high specific surface area,thermal stability,good acid and base resistance,chemical stability and high mechanical strength can be applied to sewage treatment to purify industrial wastewater and domestic sewage.It can effectively protect the environment of water resources.Nowadays the porous silicon carbide ceramics is mainly fabricated by recrystallization which has high sintering temperature.As mullite has good chemical compatibility with SiC,it can be used as ceramic binder to fabricate porous silicon carbide ceramics that can effectively reduce sintering temperature.In our research,mullite bonded SiC porous ceramic was fabricated through both of powder compacting process and extruding molding process with adding pore forming materials in SiC as ceramic aggregate,mullite compounded by Al₂O₃ and Si O2 in high sintering temperature as ceramic binder and Y₂O₃ as sintering aids.Effects of sintering atmosphere,different contents of mullite,different kinds and contents of pore-forming agent and different contents of HPMC and water on the flexural strength,porosity,pore size and gas flow distribution of porous ceramic were discussed.Phase composition and fracture surface microtopography of porous ceramic were characterized by XRD and SEM.Through systematic research,principal results are as follows:?1?The research of sintering atmosphere.The porous ceramics were fabricated in four kinds of sintering atmosphere of air atmosphere,vacuum atmosphere,N2 atmosphere and immerged carbon powders atmosphere.The comparative test result indicate that sample which had high flexural strength and good acid and base resistance had the best overall performance in immerged carbon powders sintering atmosphere.?2?The research of fabricating porous ceramics by powder compacting process.The porous ceramics were fabricated by powder compacting process in immergedcarbon powders sintering atmosphere with different contents of mullite,different kinds and contents of pore-forming agent.The comparative test result indicate that porous ceramics which had flexural strength of 15 MPa,porosity of 43%,pore-size distribution of 1¹.5?m,gas flow concentration distribution of 1 1.5?m,less distribution of 1.5 5 ? m and closely contacted particles had the best overall performance when the content of mullite was 15wt% and the content of carbon black as pore-forming agent was 10wt%.?3?The research of fabricating porous ceramics by extruding molding process.The porous ceramics were fabricated by extruding molding process in immerged carbon powders sintering atmosphere with different contents of HPMC and water when the content of mullite was 15wt% and the content of carbon black as pore-forming agent was10wt%.The comparative test result indicate that porous ceramics which had flexural strength of 43.6MPa,porosity of 42.6%,pore-size distribution of 1 1.5?m,gas flow concentration distribution of 1 1.5?m,less distribution of 1.5 4 ? m and closely contacted particles had the best overall performance when the content of HPMC was 7wt%and the content of water was 10wt%.