Among many compounds, metal boride has better high temperature performance than metal carbide. For example, diboride (TiB2) cermet products are more suitable than titanium carbide (TiC) and tungsten carbide (WC) cermet products. Use under high temperature and high erosion working conditions. Titanium diboride powder is gray (or gray-black), ranking sixth in the world’s top ten highest melting point materials (the melting point ranking table is shown in Table 1). The anti-oxidation temperature in air can reach 1100 ℃, as a new type of ceramic material, it has very excellent physical and chemical properties, in addition to the extremely high melting point, the hardness is also large, the chemical stability, electrical and thermal conductivity, mechanical properties at high temperatures Are all excellent.
The characteristics of titanium boride as structural materials and functional materials:
①In terms of structural materials. The high strength and hardness of titanium boride make it possible to make tools, wire drawing films, sand blasting nozzles and hard tool materials. At the same time, it can also become an additive for composite materials.
②Functional materials. The resistivity of titanium boride and pure iron is very similar, so its application in functional materials is very “act”. Through the characteristics of the electrical properties of titanium boride, flexible PTC materials can be made.
Method for preparing titanium diboride raw material
At present, the methods for preparing titanium diboride raw materials mainly include carbothermal reduction method, self-propagating high temperature and synthesis method, mechanochemical reaction method, vapor deposition method, ball milling method, etc.
①Carbothermal reduction method
Using titanium and boron oxide as raw materials and carbon black as a reducing agent, a high-temperature carbon reduction treatment is carried out in a carbon tube furnace for a long time. The purity of the synthesized titanium diboride powder depends on the purity of the raw material powder. This method is a process that is widely used in industrial production. The disadvantage is that the obtained titanium diboride powder particles have a large volume and a high impurity content.
②Self-propagating high temperature synthesis method (SHS)
In this method, the raw material mixture to be reacted is first pressed into a block, and then ignited at one end of the block to ignite the reaction. The huge heat released by the reaction causes the adjacent materials to react, and finally a combustion wave spreading at a speed v is formed. Finally, as the combustion wave advances, the raw material mixture is converted into the final product. Due to the self-purification effect of the self-propagating high-temperature synthesis process, the product has high purity, so the obtained powder is easy to be further sintered, and the external energy consumption is low. When combined with other special technical means, dense titanium diboride can be directly prepared material.
③ Mechanochemical reaction method (MR)
In this method, the reactant powder is placed in a high-energy ball mill, and the powder undergoes repeated changes from deformation to crushing under the action of squeezing and shearing of the ball. The intense frictional collision of the ball milling medium causes the mechanical energy to be converted into chemical energy, thereby synthesizing the required reactants. Compared with the first two methods to prepare titanium diboride, the mechanochemical reaction method has the advantages of low synthesis temperature, wide source of raw materials and low cost.
Application direction of titanium diboride
Titanium diboride and its composite materials can be combined with other metals and ceramic-based polymers to form a series of new materials with commercial application value.
① Titanium diboride can be used as grain refinement and particle strengthening additive. It can be incorporated into aluminum-based, copper-based titanium aluminum alloy and iron-based materials, which can greatly improve the mechanical mechanics and physical and chemical properties of the material. This grain refinement and particle strengthening effect will increase as the purity and fineness of the titanium diboride powder increase.
② Titanium diboride can be compounded with non-oxide ceramics such as silicon carbide, aluminum nitride, boron nitride, titanium carbide, etc., or oxide ceramic materials such as aluminum oxide. After extensive experimental research, it has been shown that the The new composite material has more excellent mechanical strength and fracture toughness, and can be one of the high-quality materials for armor protection materials.
③ Titanium diboride particles mixed with high-performance resin can be made into PTC heating ceramics and head-type PTC materials, which has the characteristics of safety, energy saving, reliability, easy processing and molding. A key high-tech for the replacement of household appliances such as hot air heating rooms.
④ Titanium diboride’s excellent electrical conductivity and excellent corrosion resistance to molten metal can be used to make evaporators, molten metal crucibles, aluminum electrolytic cell cathodes, spark plugs and other electrode and contact opening materials.
⑤Due to the good wettability of titanium diboride and metal aluminum liquid, using titanium diboride as the cathode coating material of aluminum electrolytic cell can reduce the power consumption of aluminum electrolytic cell and prolong the life of electrolytic cell.
⑥ Titanium diboride can be used to make ceramic cutting tools and molds. It can manufacture finishing tools, wire drawing dies, extrusion dies, sandblasting nozzles, sealing elements, etc.