Morphology characteristics and mechanical properties of hot-pressed micron/sub-micron boron carbide ceramics

Boron carbide (B₄C), an important armored ceramic material with poor sinterability, is regarded as a potential bulletproof material for personnel and vehicles. Introducing sub-micron B₄C powder into composite ceramics could be one approach to achieve promising high mechanical properties instead of micron and nano-grained B₄C powders. Herein, sub-micron B₄C powder was introduced into micron B₄C powder as a “toughened phase” to construct additive-free sub-micron/micron mixed B₄C ceramic via a hot-pressing process. The influence of sub-micron powder content on the relative density, microstructure and mechanical properties of the ceramics was investigated. For instance, the specimen containing 20% sub-micron B₄C powder possessed enhanced mechanical properties with flexure strength of 488 MPa and fracture toughness of 3.48 MPa m^1/2. Furthermore, transmission electron microscopy (TEM) analysis reveals that the pores of the obtained sub-micron/micron B₄C specimens were round instead of triangular and smaller compared with no sub-micron powder added specimens, which guarantee the high relative density and enhanced mechanical properties. These findings clarify the importance of sub-micron B₄C powder in increased mechanical properties and may pave a new way to design of armored protective ceramics.