Study On The Fabrication Of Porous SiC Ceramic And Its Composite With Epoxy Resin

The experiment studied the preparation of porous SiC compound ceramic, the epoxy resin pouring material and their composite material, and had made a new kind of high strength and low density composite material which can be used as solid buoyancy material.Liquid phase sintered porous SiC ceramic was prepared at a relative low temperature with Al₂O₃-Y₂O₃ as sintering additives. With the help of starch consolidation, adding pore former and surfactant foaming methods were used to form pore. By studying the sinter temperature, the use level of sintering additives, the porosity, the microstructure and the strength of the ceramic, it was found:in the starch consolidation process, drying temperature was 50℃⁹0℃, and it became faster when the temperature rise; the green body of the ceramic is absolutely even and uniform. The best sinter temperature is 1550℃, and the best Al₂O₃-Y₂O₃ content is 10wt%. In the adding pore former experiment, the porousity and strength is determined by the content of starch. When the starch content is 10wt% to 60wt%, the density of the ceramic is 1.46g/cm³ to 0.94g/cm³, and compressive strength 31.5MPa ⁴MPa. In the surfactant foaming experiment, the ceramic has a tri-modal pores structure and the solid loading of the slurry was the principal factor which influenced the density and strength most. When the total solid loading was varied from 60 wt% to 72.0 wt%, the density was 0.43 g/cm³¹.22 g/cm³ and the compressive strength was 5¹9MPa.We studied the optimum curing agent content respectively using ethylenediamine, polyamide and modified amine T31 as epoxy resin curing agent, and compared their mechanical properties to choose the best one. It was found that the epoxy resin cured by polyamide had the best mechanical property; the optimum curing agent content was 1:0.9(wt); at this proportion, the compressive strength was 81.7MPa, density was 1.08g/cm³ and water absorbing capacity was less than 0.25%。Using silane coupling agent to modify the porous ceramic, It was compounded with epoxy resin in the shape of block and ball in vacuum condition. Its density and strength was compared with HGM/epoxy resin composite. Compared with porous ceramic, the density of composite slightly increased, but the strength increased significantly:density was 0.57g/cm³¹.3g/cm³ and the strength was 6.4MPa²1.2MPa; Epoxy resin/HGM material has a density of 0.97g/cm³⁰.68 g/cm³,strength 75 MPa⁵8 MPa,when porous ceramic ball was added in, the strength of the composite rise obviously, And the content of porous ceramic ball has an optimum amount. The composite which HGM content is 25wt% and porous ceramic ball content is15wt% has a density of 0.73g/cm³ and compressive strength 71MPa, which is close to the"6000m"buoyancy material made in Russia...