Magnesium oxide is a material that no one is unfamiliar with, it is a fairly common basic oxide and is the main raw material for the production of magnesium hydroxide and magnesium metal. Hebei Messi Biology Co., Ltd. said that in the field of electronic ceramics, magnesium oxide has some special excellent properties due to its high melting point of 2800℃. The specific applications can be divided into two ways: direct sintering into ceramics and use as sintering aid for other ceramics.
① Direct sintering into ceramics
Magnesium oxide nano is a good ceramic raw material, because of its good heat resistance and its own strong resistance to erosion of alkaline metal solutions (and magnesium, nickel, uranium, aluminum, molybdenum, etc. do not interact), so it is decided that the application of magnesium oxide ceramics are often always related to high temperature environment.
In terms of preparation, magnesium oxide is difficult to sinter due to the tight density of ion packing in the lattice, the high symmetry of ion arrangement and the low number of lattice defects. Therefore, in order to promote sintering as well as to make the grains slightly larger, and to reduce the hydration tendency of the preparation, some additives can be added, such as TiO2, Al2O3, V2O3, etc. If the requirement of high purity of magnesium oxide ceramics, you can not use the method of adding additives to promote sintering and grain growth, but the method of activation sintering, that is, magnesium hydroxide calcined at the appropriate temperature, to get a lot of lattice defects of active magnesium oxide, used to manufacture sintered magnesium oxide ceramics.
Applications, magnesium oxide ceramics can be used as a crucible for smelting metal, in the atomic energy industry is also suitable for smelting high purity uranium and thorium; can also be used as a thermocouple protection casing. Use it can make the electromagnetic wave through the nature of the radome and infrared radiation projection window material, etc., smelting metal, alloy, such as nickel alloy, radioactive metal uranium, thorium alloy, iron and its alloy crucible. Piezoelectric, superconducting materials and other raw materials, and non-polluting, lead corrosion resistance, etc.; can also do ceramic sintering carrier, especially β-Al2O3 and other high temperature corrosive, volatile substances in the sintering protection of ceramic products.
②Used as a sintering aid for other ceramics
Adding nano magnesium oxide in the preparation process of other ceramics can lower the glass transition temperature, lower the sintering temperature, improve the optical and mechanical properties of ceramics, so as to obtain high quality ceramic materials.
For example, silicon nitride ceramics are one of the most promising high-temperature structural materials for their excellent high-temperature strength, thermal shock resistance and chemical stability, but its strong covalent bonding and low diffusion coefficient make it difficult to sinter densification. However, if metal oxides such as magnesium oxide are added, they can react with the silica on the surface of the silicon nitride powder during the sintering process to produce a silicate liquid phase which can effectively promote the sintering of silicon nitride ceramics. At present, MgO-Y2O3 composite sintering additives are generally used to achieve atmospheric pressure sintering of silicon nitride ceramics.