The performance requirements of high alumina ceramic balls used as grinding media are mainly bulk density, wear resistance and compressive strength. Wear resistance is an important indicator to measure the quality of ceramic balls. This performance not only depends on the production process parameters, but also on the production formula of high alumina ceramic balls.
At present, the high alumina ceramic ball is Al2O3-Na2O-SiO2, with a small amount of CaO and MgO added, the firing temperature is lower and the abrasion is better. The wear resistance of the high alumina ceramic ball has a close relationship with the mechanical properties and microstructure of its own material, as well as its internal factors.
This article mainly talks about the influence of each composition on the performance and production process of high alumina ceramic balls:
In the high alumina ceramic ball, the Al2O3 component is the source of the corundum crystal phase. The higher the Al2O3 content, the stronger the porcelain body’s resistance to stress and corrosion damage, but the corresponding increase in the firing temperature, resulting in process conditions and economy Because of the unfavorable factors brought about by the performance, this product is based on the Al2O3 requirements of the chemical manufacturers, and tries to improve the material performance and make the production technical and economical.
The TiO2, BaO and other components in the high alumina ceramic ball together with SiO2 have a strong dissolving power for Al2O3 at an appropriate high temperature, and can form a certain amount of aluminosilicate melt, thereby promoting sintering and strengthening the glass network structure. Experiments have shown that adding CaO, BaO, etc. to the high-alumina porcelain can reduce the firing temperature, but the chemical stability is slightly reduced.
SiO2 can form a low-melting eutectic with Al2O3, CaO, BaO, etc. during firing. The formation of these liquid phases has the function of 1. It effectively promotes mass transfer and is beneficial to sintering 2. It produces secondary crystallization and reduces corundum crystals. The surface defects of the grains and the liquid phase can also inhibit the abnormal growth of the grains. Third, relying on the moisturizing force and surface tension of the solid phase to pull the fastener particles and fill the pores, so that the eroded surface area of the product is reduced, so the use performance such as corrosion resistance is improved, and the firing temperature is reduced. When the amount of Al2O3 is constant, if the content of SiO2 is increased too much, although the amount of mullite will increase, there will be less colloidal crystal grain glass phase. At the same time, the firing temperature will increase, the degree of sintering will not be good, and the corrosion resistance will also decrease, so SiO2 needs to be maintained Within a certain dosage range, a proper amount of liquid phase can be ensured, and aluminosilicate glass can be formed.
The main function of TiO2 is to dissolve with Al2O3 and activate the crystal grains to promote sintering. 2. Increase the defects of Al2O3 lattice and make the CaO-BaO-Al2O3-SiO2 system easy to melt.
The role of MgO is to inhibit the growth of Al2O3 crystals due to the formation of magnesium aluminum spinel on the surface of the corundum crystals, increase the density of the porcelain body, and promote the reaction of residual SiO2 with Al2O3 to form mullite. However, its fluxing effect is not good, and the change of MgO content has little effect on the corrosion resistance of the porcelain body and the firing temperature.
In addition, in order to ensure the performance of high alumina ceramic balls and the feasibility and economy of production, attention should be paid to the mutual restriction of composition changes; 1. High Al2O3 content, the amount of TiO2 needs to be increased 2. High SiO2 content, then CaO, BaO, etc. The content must be increased.
