Under normal circumstances, conventional boron carbide powder can only achieve a relative density of 80%-87% through pressure-less sintering at 2250-2300°C.
Boron carbide (B4C) is considered an excellent ballistic ceramic material due to its lightweight, high specific modulus, and superior ballistic performance. However, its preparation is challenging because boron carbide has a highly covalent bond structure, with a covalent bond ratio reaching 93.94%, which is much higher than that of silicon carbide (88%) and silicon nitride (70%). This high covalent bond ratio means that the elimination of internal pores and the grain boundary and bulk diffusion in boron carbide require temperatures above 2200°C to occur adequately.
Under normal circumstances, conventional boron carbide powder can only achieve a relative density of 80%-87% through pressureless sintering at 2250-2300°C. At such high temperatures, the grains coarsen and grow rapidly, hindering pore elimination and resulting in many residual pores, which affects the material's density. To improve the sintering density and performance of boron carbide ceramics, hot-pressing sintering is more commonly used. However, this process is costly and expensive, limiting the application of hot-pressed boron carbide mainly to high-end protection markets such as protective systems for helicopters, submarines, patrol boats, and fighter jets.
With continuous technological advancements and innovations, the performance and application fields of boron carbide materials are expected to be further expanded and improved. In the future, improved preparation methods and the development of new materials will help reduce costs, enhance the sintering density of boron carbide, and expand its use in various protective applications.