Nano-silica – “panacea” to improve the performance of ceramics!

When it comes to the application of silica in ceramics, the first thing that comes to mind is quartz ceramics. Due to its many excellent properties, quartz ceramics have been widely used in metallurgy, electrical, glass, aviation, corrosion-resistant parts, photovoltaic and other industries since its inception. When preparing quartz ceramics, some additives are often added to improve performance, but the “SiO2” component is always the absolute protagonist. In fact, as a supporting role, SiO2 is often added to other ceramic materials in the form of auxiliary materials, which will significantly improve the performance of ceramic materials in all aspects.

1. The effect of nano-silica on the properties of alumina ceramics:

At home and abroad, in-depth research has been carried out on various additives doped alumina ceramics to improve their mechanical properties, among which nano-SiO2 is a commonly used sintering aid component. Chen Xi et al. studied the effect of adding MgO-SiO2 on the sintering properties of high-purity Al2O3 ceramics. SiO2 can obtain stable silicate liquid phases at high temperatures. They are binary or ternary low-melting compounds, and the liquid phase can promote sintering. , reduce the sintering temperature, refine the grains, and improve the mechanical properties of alumina ceramics. In addition, if nano-SiO2 (VK-SP30) is added to 95 ceramics instead of nano-Al2O3, it can not only play the role of nano-particle refinement, but also improve the strength, toughness, hardness and elastic modulus of ceramic materials. Its effect is more ideal than adding Al2O3. Ji Juncheng et al. added different amounts of nano-SiO2 to 95 alumina ceramics, prepared samples by dry pressing, and explored the effects of different sintering temperatures and nano-SiO2 additions on the sintering properties and mechanical properties of 95 alumina ceramics. The results show that: When the addition amount of nano-SiO2 is 2% and the sintering temperature is 1600℃, the grain size of the sample is uniform, the maximum bulk density is 3.70g/cm3, and the flexural strength and fracture toughness reach the maximum value of 342.89MPa and 5.34MPa·m1/ 2. Compared with the samples without nano-SiO2, the flexural strength and fracture toughness are increased by 34.28% and 4.5%, respectively.

2. The effect of nano-silica on the properties of aluminum titanate ceramics:

Aluminum titanate (Al2TiO5, AT for short) is a ceramic material with high melting point and low expansion characteristics. It is widely used in automobile engine components, non-ferrous metal casting and electronic ceramics and other industries. However, the aluminum titanate material will decompose into corundum and rutile at 800-1280 ℃, thus losing its low expansion characteristics. Therefore, exploring the stabilization method and stabilization mechanism of aluminum titanate is the key to the research of aluminum titanate material. Lu Hongbin et al. used the secondary firing process to study the effect and mechanism of additives MgO and nano-silica (VK-SP30) on inhibiting the thermal decomposition of aluminum titanate. The research results show that MgO and SiO2 composite additives can significantly improve the thermal stability and flexural strength of aluminum titanate.

3. Influence of Nano-Silica on Properties of BaTiO3 Ceramics

Through research, it was found that the SiO2-coated BaTiO3 powder material was sintered into ceramics at 1225 ℃, and the dielectric ceramics with perovskite structure could be obtained. The introduction of SiO2 formed the second phase Ba2TiSi2O8. After sintering, the leakage current of the ceramic dielectric material is relatively large, and the voltage resistance characteristics cannot show a certain rule, but the voltage resistance performance and energy storage density of the material are improved. The effect of doping on BeO ceramics Beryllium oxide ceramics have the characteristics of high thermal conductivity, high melting point, high strength, high insulation, high chemical and thermal stability, low dielectric constant, low dielectric loss and good process adaptability. It has been widely used in the fields of vacuum electronic technology, nuclear technology, microelectronics and optoelectronic technology, and has become an indispensable basic electronic functional material in the fields of military electronic information technology and aerospace applications. At present, beryllium oxide ceramics are developing in the direction of high purity and high performance. Generally, products containing more than 99% of BeO are required, but the higher the purity, the more difficult the material is to be sintered and dense.