Preparation Technology Research Of Greate Size Heterogeneous Type Al₂O₃

Large-size special 99Al₂O₃ bullet-proof panels is a very practical protective material for the human body. But the existing preparation technology has already restricted the large scale production, such as low productivity, preparation of the cost of high, poor product quality. So its highly effective preparation technology became the domestic and foreign research hot spot in recent years. Semi-water based gelcasting possesses the characteristics such as the production equipment to be simple, the investment is small, the formation body density is high, the intensity is high, shrinkage is small, drying method is relatively simple merit and suitable for forming of complex shape products.The large-size special 99Al₂O₃ bullet proof plate suited the human body shape were prepared with high pure Al₂O₃ powder as a raw material in semi-water based gelcasting. Preparation of the high performance slurry, solidification and drying of the body and the sintering technology were studied. Effects of the pH value, the solids content, the dispersing agent, the ball grinding time, the organic monomer content and the plasticizer to the slurry performance were discussed. The drying process of the body were examined by controlling the drying temperature and time and a reasonable drying curve was developed. Furthermore, the effects of different sintering aids and sintering system were discussed via the mechanical properties testing, scanning electron microscopy and X-ray diffraction analysis on the product.The study comes to conclusions as follows: When the pH value of 10, dispersant PMAA-NH4 adding the quality of the 0.6% powder, organic powder accounted for the quality of AM monomer of 3.0%, glycerol added to the quality of water 12% , that can be obtained solid volume fraction of 58% of low-viscosity slurry. When initiator content 0.3～0.6vol% and catalyst content 0.024～0.05vol%, slurry can be obtained for curing high-quality body at 40℃. The dry environment of body need transfer the high temperature and the low temperature humidity to be low and damp gradually. The approximate drying period is 70h. The green body density may reaches 2.6g/cm3, the line contraction is 1.5% and distorts not obviously under the conditions of 58 solid-phase content. The magnesite and CeO₂ best content is 0.2%, 0.6%, respectively. Best firing temperature 1670℃, holding time for 4 hour. Under the above condition, preparing high performance 99Al₂O₃ bullet proof plate that the bulk density reach 3.89g/cm³, the bending strength reaches 432MPa, the fracture toughness property reaches 4.06MPa·m , HRA achieves 90.