Effect Of Plains And Twills Laminated Structure On Filtration Properties Of SiC_f/SiC Composites

Coal combustion is the main cause of haze,and high-temperature flue gas and coal gas filtration produced by burning coal are imminent.The development of high-temperature high-temperature flue gas filter materials has become a research focus for researchers.In this project,high-strength and low-resistance SiC_f/SiC high-efficiency filter ceramic matrix composites are prepared by CVI process,which can effectively compensate for the shortcomings of the existing high-temperature ceramic filter materials such as poor thermal shock resistance,poor high temperature stability,poor toughness,and short service life.This subject has important research and application for improving the comprehensive performance of SiC_f/SiC composites and broadening the application range of SiC_f/SiC composites,especially in the field of high-temperature flue gas filtration.The filtration performance and mechanical properties of SiCf/SiC composites depend not only on the woven and laminated structure of the SiC fiber,but also on the porosity and pore size distribution.In this project,SiCf/SiC composites for high-temperature flue gas filtration were tested using filter media performance testing system,digital air permeability meter and universal material testing machine,combined with scanning electron microscope and optical microscope for SiCf/SiC composites.Characterization of micro-morphology provides experimental guidance and theoretical support for the design,development and practical application of SiCf/SiC composite filters for high-temperature flue gas filtration.The main findings of this paper are as follows:1.Fabricating SiC fiber preforms by using two-dimensional biaxially woven SiC fiber cloth and then laminating and sewing.The SiC_f/SiC composites were prepared by CVI,and the porosity of the composites of plains,plains/twills fabrics and twills were 35.23%,35.91%and 33.47%,respectively.2.The flexural strengths of the composites of plains,plains/twills fabrics,and twills were43.01 MPa,40.8 MPa,and 37.9 MPa,respectively.3.The average pore sizes of the composites of plains,plains/twills fabrics,and twills were50.76?m,61.02?m,and 69.48?m,respectively.4.The air permeability of the composites of plains,plains/twills fabrics,and twills were 99.60mm/s,189.60 mm/s,and 283.10 mm/s,respectively,at 250 Pa;The filtration resistance were 228Pa,128Pa,50Pa,respectively,when the wind speed was 1.0m/min.The air permeability of the plains composite was the lowest and the filtration resistance was the highest.5.The filtration efficiency of the plains,plains/twills fabrics,and twills composites were 99.56%,99.33%,and 99.19%,respectively;the filtration efficiency is 99.99%for particles size larger than10?m,and above 98%for 1.0?m,which meets the requirements of industrial applications.6.Considering the comprehensive performance of the plains,plains/twills fabrics,and twills composites,the filtration performance of the three structural composites meets the GB/T 6719-2009national testing standard.