The Performance of Cubic Boron Nitride
The performance of cubic boron nitride (referred to as CBN) is similar to the performance of diamonds, and some performance (such as thermal stability) is better than diamond. Therefore, it has the same application as diamond.
The hardness of the substance is related to the atomic spacing of the composition lattice, and as the atomic spacing decreases, the crystal hardness increases. The CBN is 1.57, and the shortest distance between diamond atoms is 1.5. Therefore, the hardness of CBN (microscopic hardness 71.54GPa) is slightly lower than diamond, but it is compared to the other two major abrasive silicon carbide (micro hardness 25.48 ~ 35.28 GPA) and alumina (micro-hardness 17.64 ~ 27.44GPa) are much higher.
The hardness of CBN single crystal in the direction of  is used to use Nu’s hardness meter to be 4600kg/mm2, while diamonds are 10000kg/mm2; CBN single crystals are 3200kg/mm2 in the  direction, while diamonds are 7000kg/mm2, and diamonds are 7000kg/mm2. This shows that the hardness of CBN is the opposite sex, and its hardness is slightly lower than diamond.
- Heat conductivity
Cube boron nitride has a good thermal conductivity. Its thermal conductivity (79.54W/m﹒k). Although it can’t keep up with diamond (146.5 W/m﹒k), it is much higher than high -speed steel (16.7 ~ 25.1W/m﹒kk ) And hard alloy (20. 33 ~ 80.77 w/m﹒k). As the cutting speed increases, the thermal conductivity of the CBN has also gradually increased, which is conducive to reducing the temperature of the cutting area and reducing diffusion and wear.
At the same time, due to the good thermal conductivity of the CBN, it is used as a radiator second only to diamond.
- Thermal stability and antioxidantability
Cube boron nitride has high thermal stability and can withstand the cutting temperature above 1200 ° C. This is better than diamond. Cube boron nitride has high hardness and high thermal stability (referred to as high thermal hardness), which can be used as high temperature-resistant materials to reduce thermal damage to materials (tools).
The heat resistance of cube boron nitride is mainly determined by its composition and structure. Although cubic boron nitride has a similar structure to diamond, the carbon atom keys on the surface of diamond on the surface are unsaturated. Under the conditions of high temperature (above 720 ° C), these unsaturated surface carbon atoms are easy to combine with oxygen atoms to generate carbon oxides and generate carbon oxides. Remove the crystal, which gradually peels the crystal and disintegrate. The surface of the cubic nitrogen -nitride crystal is covered with nitrogen and boron atoms. The electron layer structure of the boron atom is 1S22S22P1, which can provide three key electrons, so that the price bond of the boron atom on the surface of the crystal surface is in the saturation state without empty suspension keys, so It is still relatively hot and stable at the oxidation temperature of diamond.
Therefore, CBN has a high antioxidant capacity and does not occur at 1000 °C. In the vacuum, the temperature from the temperature to 1550°C occurs from CBN to HBN.
- Chemical inertia
Cube boron nitride has a great chemistry, and has high chemical stability to acid and alkali in the neutral and reducing gas medium.
CBN is also chemically sentimental for iron, steel and oxidation environment. A thin layer of boron oxide is formed during oxidation. This oxide provides chemical stability for the coating, so it is particularly suitable for processing black metal materials. And diamonds are not the same. The affinity of steel and iron to carbon is large, so it is easy to stick dandruff during grinding, which will cause the grinding effect to become disadvantaged.
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