Why can silicon carbide and boron carbide ceramics be bulletproof

In everyone's impression, ceramics is fragile, but after modern technology processing, ceramics "suddenly changed", has become a hard, high strength new material, since the 21st century, bullet-proof ceramics developed rapidly, there are many kinds, including alumina, silicon carbide, boron carbide, silicon nitride, titanium boride, etc.  Among them, alumina ceramics (Al2O3), silicon carbide ceramics (SiC), boron carbide ceramics (B4C) are widely used.  

Silicon carbide bulletproof ceramics

Silicon carbide strong covalent bond, it still has the high strength at high temperature bonding, silicon carbide ceramics are relatively low density, high hardness, wear resistance, corrosion resistance, high heat conductivity, good thermal shock resistance, belongs to the high cost performance of structural ceramics, silicon carbide ceramic moderately priced at the same time, the performance-to-price ratio is high, is one of the most potential for development of high-performance armor materials.  It is also widely used bulletproof ceramics in China.  

Boron carbide bulletproof ceramics

Boron carbide is the superhard material whose hardness is second only to diamond and cubic boron nitride in the known materials. Its thermal expansion coefficient is low, thermal conductivity is high, it has good chemical stability, acid and alkali corrosion resistance, and most molten metal is not wet and does not act.  B4C has the lowest density and higher elastic modulus among several commonly used armor ceramics, making it a good choice for military armor and space materials.  However, boron carbide ceramics have high requirements for processing technology, requiring high temperature and high pressure sintering, so the cost is the highest among the three kinds of ceramics.

Alumina bulletproof ceramics

The cost of alumina bulletproof ceramics is the lowest, but the bulletproof performance is far less than silicon carbide and boron carbide, so at present, the production unit of domestic bulletproof ceramics in silicon carbide and boron carbide bulletproof, and alumina ceramics is very rare.  Alumina bulletproof ceramics are widely used in transparent materials with optical function, such as single soldier bulletproof mask, missile detection window, submarine periscope and other military equipment.