添加氮化硅对莫来石碳化硅材料性能的影响

Effects of Compound of Silicon Nitride and Silicon Carbideon on Properties of Mullite Refractories

以莫来石、红柱石为主要原料,加入不同含量的氮化硅、碳化硅细粉,探讨了添加氮化硅对莫来石碳化硅材料性能的影响。结果表明:在1 450℃下制备的材料的显气孔率基本维持在15%左右,体积密度在2.45 g/cm^3左右,烧后线变化率相差不大,高温抗折强度和荷重软化温度也分别能够达到29.8 MPa和1 560℃,都表现出了较高的水准,且基本不受氮化硅加入量的影响;添加氮化硅能够提高材料的抗热震性能,但材料的常温耐压强度随着氮化硅含量的增加呈降低趋势;材料在烧结过程中,氮化硅和碳化硅均发生了氧化并在材料表面形成一层黄褐色氧化产物,其主要为玻璃相;在材料的截面出现致密层,且致密层的厚度随着氮化硅含量的增加而减小。

Using mullite and andalusite as the main raw material, by adding different content of silicon nitride and silicon carbide powder, the effects of compound of silicon nitride and silicon carbide on the properties of mullite refractories were explored. The results showed that the apparent porosity of the materials remained at about 15%, and the volume density was about 2.45 g/cm^3, the liner change rate was similar. The high temperature flexural strength and softening temperature have reached a high level, they can reach 29.8 MPa and 1 560℃. That basically do not affected by the addition of silicon nitride. The silicon nitride can increase the thermal shock resistance of the materials, but the normal temperature compressive strength decreased with the increasing of silicon nitride content. The silicon nitride and silicon carbide in the materials were oxidized in the sintering process, and form a layer of brown oxidation products on the surface of the materials. The oxidation products was mainly glass phase. Dense layer was appeared in the cross section of the materials. The thickness of the dense layer of the materials decreased with the increasing of silicon nitride content.