Preparation And Properties Of Two-Layer Bulletproof Composite Based On B₄C

Bulletproof materials mainly consist of three kinds of materials which are metal,synthetic fiber and ceramics composites.Due to the excellent properties of high strength,high hardness and low density,ceramic materials have great development potential in manufacturing bulletproof materials.Owing to the low density and the high hardness which is second only to diamond and cubic boron nitride,B4C has more advantages than SiC and Al2O3 in manufacturing bulletproof materials.But the toughness of B4C is low.The toughness of B4C has to be improved if it is going to be used in preparing bulletproof materials.The toughing method of the combination of manufacturing two-layer composites and adding second phase particles is used to improve the toughness of B4C in this study.The two-layer B4C-B4C/Al composite is prepared by the process of hot pressed sintering and aluminizing in vacuum.The two-layer B4C-B4C/Ti3SiC2 and B4C-B4C/W2B5 composites are prepared by the process of hot pressed sintering.The compositions,microstructures,mechanical properties and bulletproof performance of the composites are studied in detail.The experimental results are shown as follows.(1)The densities of the three kinds of two-layer composites which are all less than 3 g/cm3 can satisfy the low-density requirement of the bulletproof materials.(2)The B4C-B4C/40%Ti3SiC2 composite shows the optimum properties among the system of adding Ti3SiC2into the ductile layer,and the property of the B4C-B4C/52%W2B5 composite is the best one among the specimens of adding W2B5 into the ductile layer.(3)Compared with pure B4C,the fracture toughness of the B4C-B4C/Al,B4C-B4C/30%Ti3SiC2 and B4C-B4C/52%W2B5 composites have been significantly improved.It is demonstrated that the fracture toughness of the two-layer materials is modified due to the second phase Al,Ti3SiC2 and W2B5 accompanied with the two-layer structure.(4)The protection factor for 12.7 mm API of three kinds of two-layer composites which are B4C-B4C/Al、B4C-B4C/30%Ti3SiC2 and B4C-B4C/52%W2B5 are in the ranges of 6.43-6.66,6.73-7.01 and 6.50-6.67,respectively.The bulletproof performance of three kinds of composites is better than the bulletproof materials had been reported elsewhere such as titanium alloy,3DMC composite based on B4C and Al2O3-based composite and so on.It shows that the new composites studied in this paper have great application potential in the field of bulletproof armor.