Ceramics (Boron carbide powder)

Boron carbide ceramic powder (B4C) is the core raw material for preparing high-performance boron carbide ceramics, with characteristics such as high hardness, wear resistance, and neutron absorption capacity. It is widely used in military, nuclear, and wear-resistant fields. The following is a summary of key information:

1. Basic characteristics Physical properties: Microhardness of about 50GPa, coefficient of thermal expansion of 4.5 × 10 ⁻⁶/℃, acid and alkali corrosion resistance but high brittleness. Crystal structure: Hexagonal diamond lattice, with a unit cell containing 12 boron atoms and 3 carbon atoms.

2. Preparation process Traditional method: Carbon reduction boron anhydride method (indirect heating at 2200 ℃) is used to prepare powders, which are then hot pressed and sintered (at 2100 ℃ and 80-100MPa pressure) to form a density of up to 98% of theoretical value. Improved process: Zhengzhou Songshan Boron Industry's patent uses a mixture of titanium carbide and nickel yttrium oxide composite balls, which are hot pressed and sintered at 2150-2200 ℃ to enhance density and toughness; Another patent improves uniformity and fracture toughness through gel casting and carbon fiber reinforcement, combined with vacuum siliconizing reaction sintering.

3. Application Fields Nuclear industry: The high neutron absorption cross-section makes it suitable for use as a control agent in nuclear reactors. Wear resistant components: used for high-temperature heat exchangers, corrosion-resistant vessels, and ceramic nozzles.