Basic Properties, Synthesis and Typical Properties of Boron Carbide

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What is Boron Carbide?

Boron Carbide Powder belongs to the trigonal system. The unit cell contains 12 B and 3 C. The unit cell’s stereo diagonally connected C atoms are in an active configuration. They can be substituted by B atoms, forming a replacement solid and leaving the crystal lattice in order to form high-boron compounds.

B4C’s molecular weight is 52.25 with C21.74% (and B78.25%), is usually gray or black and has the following characteristics: density 2.519g/cm3, hardness Mohs 9.35, microhardness 49GPa. This powder is very efficient in grinding and can achieve 60%-70% the efficiency of diamond.

B4C Powder has a melting temperature of 2450°C (decomposition). The coefficient for expansion at 1000degC (4.5×10-6degC-1) is 4.5×10-6degC-1. Thermal conductivity is 62.79W/m*k for 100degC, and 121.4W/m*k for 700degC. B4C powder can be used primarily as an abrasive. B4C hot-pressed products are suitable for wear-resistant or heat-resistant parts. B4C has a wide range of applications in the refractory and refractory industries. It is often used as an anti-oxidant additive to carbon-bonded refractories. Unshaped materials enhance the body’s strength and resistance to corrosion.

The properties and synthesis of Boron Carbide

B4C powder is commonly synthesized by reducing boron anhydride and excess carbon.


The synthesis reaction may be carried out either in an electric arc or a muffle oven. In a resistance-type furnace, the synthesis of B4C is better achieved by heating boron anhydride B2O3 with carbon C to a lower decomposition temperature than B4C. B4C is broken down into boron and carbon rich phase in the electric-arc furnace because of the high temperature. The reaction product may contain a lot of free C (20%-30%). As a result, the B4C obtained is of slightly inferior quality.

In order to synthesize B4C using an electric arc, boric acids (with a content greater than 92%), artificial graphite with a fixed carbon of greater than 95%, and petroleum coke with 85% fixed carbon are used. The theoretical dosage is calculated based on the reaction formula. The theoretical amount is approximately 2% higher. Each of artificial graphite and petroleum coke accounts for 50% of total carbon addition, which is then 3%-4% more than the theoretical amount. Add the three prepared raw materials to the arc and mix them in a ball-mill. B4C can then be obtained by carbonizing the furnace and reducing it between 1700 and 2300. Finaly, the frit will be sorted and cleaned, then crushed and ground. It will also go through a pickling process, sedimentation, classification and other processes to get B4C with different particle sizes.

(aka. Technology Co. Ltd., a trusted global chemical materials supplier & manufacturer has over 12 years experience in providing high-quality nanomaterials and chemicals. The B4C powder that we produce is of high purity with a fine particle size. If you need lower, please call us.