ZrB2 Zirconium Boride Powder
EINECS No.: 234-963-5
Molecular formula: ZrB2
Molecular weight 112.84
The density 4.52g/cm3
Melting point (3040 ℃)
It has high hardness and is a quasi metal compound with hexagonal structure
1. Aerospace Industry
ZrB2 series composites are very suitable for the application of ultra-high temperature zero ablation materials for supersonic spacecraft and missile shells due to their high melting point, high hardness, good conductivity and good neutron control ability. Especially with the rapid development of rocket and missile technology, the demand for high temperature structural materials of zirconium borate based ceramics is more urgent. With the deepening of research and development work and the continuous improvement of production technology, it is certain that the research, production and application of ZrB2 series composites will leap forward at a new pace.
Zirconium diboride (ZrB2) has high melting point, high modulus, high hardness, high thermal conductivity and electrical conductivity, and good thermal shock resistance due to its strong chemical bond. It has become the most potential candidate material for ultra-high temperature ceramics. ZrB2 ceramic products have been widely used as high-temperature structural and functional materials, such as turbine blades and MHD power generation electrodes in aviation industry. In addition, compared with many ceramic materials, it has better electrical conductivity, and can produce parts with complex shapes by wire cutting technology. However, ZrB2 has high melting point, difficult when sintering and relatively low strength and toughness, which limits its application in harsh working environment. For this reason, scholars at home and abroad have done a lot of research work on ZrB2 composites with other components by using various advanced sintering processes, so as to improve the comprehensive properties of the materials. In this paper, ZrB2 composites and their densification are reviewed.
ZrB2 ceramic is an excellent, special refractory material, which can be used as high temperature thermocouple protection sleeve, casting mold, metallurgical metal crucible, etc. because of its airtightness and conductivity, it is necessary to work with the aluminum oxide inner tube to carry out effective temperature measurement when working as the thermocouple . The thermowell made of this material can be used continuously for a long time in molten iron and brass. ZrB2 ceramics can also be used as antioxidants in refractories. LV Chunyan et al. reported that by adding ZrB2 to MgO-C refractory or directly using ZrB2 as aggregate or fine powder. It makes refractory brick and castable and shows very good oxidation resistance and fire resistance performance. The oxidation resistance mechanism can be analyzed as follows: B2O3 generated by ZrB2 oxidation at medium temperature forms mgo-b2o3 molten phase in MgO-C, thus protecting the brick.
3 electrode material
Low conductivity, electricity transition system is electron transition. suitable for contact material and electrode material because of its low resistivity and electronic conduction mechanism. It can be used in electrode and high temperature heating element of metal thermocouple. In 1994, Feng Dagan developed a kind of thermoelectric couple material of ZrB2 and graphite, which can work in oxidation atmosphere at 1200 ~ 1600 ℃
When the temperature is 1 600 ℃, it can reach about 70 MV and the thermoelectric power rate is about 55 μ V / ℃. The results show that the thermoelectric potential is a single value function with good linearity. The repeatability of the thermoelectric potential is 1% ~ 1.5% of the measured temperature after several tests in the oxidation atmosphere. The maximum change of the thermoelectric potential is 0.5% ~ 1% of the measured temperature in a short time for more than 3 h. It can be used for successive detection in some special occasions where metal thermocouple and radiation thermometer are not suitable. As a good thermocouple material.