How Abrasive Raw Materials Make or Break Heat-Resistant Solutions
The 2-5mm tabular alumina is dense, fully contracted, and the sintered α-Al2O3 consists of 50-400μm grains to form the aggregate structure. Ultrafine α-Al2O3 pellets are rapidly calcined at slightly below the melting temperature, and 18-20mm pellets are crushed or ground after heat treatment to obtain 2-5mm tabular alumina of various sizes.
Low content of silicon oxide, iron oxide and titanium oxide in corundum is very important for excellent high temperature performance. The biggest difference between sintered 2-5mm tabular alumina and other synthetic high-alumina aggregates, such as fused white corundum, is the impurity content with finer size. The higher impurity content introduced in finer size will greatly reduce the high temperature volume stability and creep resistance. Comparing the porosity of fused white corundum and 2-5mm tabular alumina, although the total porosity of the two aggregates is the same, the grain porosity is significantly different. The open porosity of fused grains is 2-3 times that of sintered grains. Most of the pores of fused alumina are composed of large open pores, while more than half of the pores of 2-5mm tabular alumina are closed pores. A high proportion of closed pores is necessary for high thermal shock resistance, which is a typical feature of 2-5mm tabular alumina, which exhibits high thermal shock resistance and high strength. The surface of 2-5mm tabular alumina grains is not as smooth as the surface of fused corundum grains, but is rougher with shallow hemispherical pores. This surface structure promotes its reaction and mechanical interlocking with the matrix, thereby improving the strength of the refractory.
The properties of 2-5mm tabular alumina have many applications in the field of refractory materials. Tabular corundum is an ideal material containing 90-100% alumina for high alumina bricks and amorphous linings. 2-5mm tabular alumina is suitable for ceramic, chemical and water-bound matrices. 2-5mm tabular alumina can be used alone and in bonding systems, or with calcined or activated alumina. Because 2-5mm tabular alumina exhibits extremely high purity even in fine powder, it can be used to enhance the performance of lower alumina aggregates. Because Tabular Alumina exhibits extremely high purity even in fine powder, it can be used to enhance the performance of lower alumina aggregates. For example, bauxite and fused brown corundum, use coarse particles of these aggregates and medium particles and fine powders of 2-5mm tabular alumina.
As an ultra-high temperature refractory material, 2-5mm plate-shaped corundum has the characteristics of high purity, low alkali, high density, high strength, high thermal conductivity, high shock resistance, corrosion resistance, high insulation, etc. It is mainly used as aggregate and powder of advanced refractory materials, and is used in shaped and unshaped refractory materials. As long as fused white corundum, sub-white corundum, and brown corundum are used, 2-5mm tabular alumina can be used instead, and the product performance is significantly improved.
