Characteristics of Cubic Boron Nitride (CBN)

July 18, 2022

The properties of cubic boron nitride (CBN for short) are similar to those of diamond, and some properties, such as thermal stability, are better than diamond. Therefore, it has as wide a range of applications as diamond.

Properties of cubic boron nitride

1. Hardness The hardness of a substance is related to the atomic spacing of the constituent lattice, and as the atomic spacing decreases, the crystal hardness increases. CBN is 1.57 angstroms, and the shortest distance between diamond atoms is 1.5 angstroms. Therefore, the hardness of CBN (microhardness 71.54GPa) is slightly lower than that of diamond, but higher than that of the other two main abrasives, silicon carbide (microhardness 25.48~35.28 GPa) and alumina (microhardness 17.64~27.44GPa) are much higher.

Cubic Boron Nitride (CBN)

2. Thermal conductivity Cubic boron nitride has good thermal conductivity, its thermal conductivity (79.54w/m.k), although not as good as diamond (146.5w/m.k), but much higher than high-speed steel (16.7~25.1w/m.k) ) and cemented carbide (20. 33 ~80.77 w/m.k). With the increase of cutting speed, the thermal conductivity of CBN gradually increases, which is beneficial to reduce the temperature of the cutting zone and reduce the diffusion wear. At the same time, due to the good thermal conductivity of CBN, it is second only to diamond as a heat sink.

3. Thermal stability and oxidation resistance Cubic boron nitride has high thermal stability and can withstand cutting temperatures above 1200℃, which is better than diamond. Cubic boron nitride has high hardness and high thermal stability (referred to as high thermal hardness), and can be used as a high temperature resistant material to reduce thermal damage to materials (tools).

4. Chemically inert CBN is chemically inert, and has high chemical stability to acids and bases in neutral and reducing gas media.

CBN is also chemically inert to iron, steel and oxidizing environments, forming a thin layer of boron oxide when oxidized. This oxide provides chemical stability to the coating and is therefore particularly suitable for processing ferrous materials. On the other hand, diamond is not the case. Steel and iron have a large affinity for carbon, so it is easy to stick chips during grinding, resulting in poor grinding effect. Contact us for free inquiry now!

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