Boron carbide ceramics

Boron carbide was first prepared by Joly [156] and labeled as BgC by Moisson [157]. In 1934, Ridgeway [158] suggested the composition B4C, which is still under controversial discussion. As discussed in Section 7.2.2.2 in connection with the crystal structure, the composition as assessed today ranges from B4 3C to B10.4C. Due to the fabrication process where carbon is used to reduce boron oxide, the composition of the commercially available boron carbide is close to B4C. 

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Another factor is breaking up the projectile. This is again done using polymeric materials—here composites such as boron carbide ceramics in combination with aramids, UHMWPE, or fibrous glass. 

W. B. Johnson, T. D. Claar, and G. H. Schiroky, Preparation and processing of platelet reinforced ceramics by the directed reaction by zirconium with boron carbide. Ceram. Eng. Sci. Proc. KK7-8), 588-598 (1989). 

Organic precursors can be used both polycarbosilane and a small amount of phenolic resin, giving CSi and carbon by in situ pyrolysis the resulting boron-carbide ceramics have high density (> 92 %) and contain no free carbon and a small amount of SiC( 5wt%) . 

Some routes for the preparation of boron carbide ceramics were investigated recently. 

All the above primarily refers to materials containing relatively small amounts of impurities. However, boron carbide ceramics usually contain 7-20% A1 or AI2O3 to increase hardness and 6-13% silicon to improve mechanical characteristics [98]. Aluminum- and silicon-doped materials often exhibit structural nonuniformity. They have areas of pure boron carbide, and silicon- and aluminum-doped areas [107]. 

Table 4.9 Physical properties of boron carbide ceramics used in armor applications. After Karandikar et al. [576]. 

Table 11.2 Mechanical properties of self-bonded boron carbide ceramics.

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