The Produce Process And The Performance Research Of The β/α Silicon Carbide Composite

Silicon carbide ceramics is one of the research focus in the field of materials science by its high hardness, high temperature resistance, corrosion resistance, oxidation resistance high thermal shock resistance, thermal stability, low thermal expansion coefficient, and the advantages of excellent heat transfer performance.In order to produce high performance the β/α composite silicon carbide ceramicas the goal,the issue based on the previous research work, to optimize and confirm the best formula process, by the densitytest of the green bodies, which is the solid content was 50%, with using 0.3um α-SiC, the 9%content of water-soluble phenolic resin, under the same forming process, thus green dvensity is the largest, and to the most benefit of sintering densification. Experiment confirmed the sieving time should be 20 min for pelletizing powder, thus screening efficiency was highest by the high-tech ceramic forming process optimization and finalizing; when forming pressure was 100 MPa, dwell time is 60 s, sintering performance was best. When particle diameter ratio was Dbig: Dmiddle: Dsmall(96μm:80μm:23μm)=4:3:1 and mass ratio was Mbig: Mmiddle: Msmall=17:7:1, the green density was 1.748 g/cm3.Withthe various property testingof silicon carbide ceramic sintered density, bending strength, vickers hardness and fracture toughness, and observationof microstructure and phase transformation, the paper optimize and determine the pressless sintering process that the sintering temperature was 2010℃, soaking time was 75 min, thus β/αcomposite silicon carbide ceramics had optimal performance after sintering that sintered density was 3.129g/cm3, hardness was 27.35 GPa, the fracture toughness was 4.64MPa·m1/2, the flexural strength was 401.62 MPa. Due to a small amount of β-SiC addtion in α-SiC, hencethere were long axis crystal appeared after sintering, makes the fracture mechanism was the original transgranular fracture into that the transgranular fracture was priority. Experiments time after time had shown that β-SiC addition amount was 10%, silicon carbide ceramics had the best performance.The article had carried on the preliminary exploratory research for slip casting process, with a low viscosity slurry into slip casting process, then carried out in accordance with the appropriate drying curve after drying, by proper process into silicon carbide ceramic sintering process.