碳化硼陶瓷材料是时下比较热门的超硬结构陶瓷材料，由于出色的力学性能而具有广泛的应用前景。这种材料具有很高的硬度、弹性模量、抗弯强度，在恶劣条件下有较好的稳定性，广泛应用于耐磨材料，防弹材料和核工程的控制材料领域。本研究主要内容是如何对防弹用碳化硼陶瓷材料进行工艺优化，得到防护性能更好的碳化硼陶瓷。碳化硼陶瓷在具有很好力学性能的同时，由于密度较小对于防护装备的减重具有很大的作用。但是这种材料也有一些必须克服且亟待优化的缺陷，主要表现在断裂韧性比较低，低温致密烧结困难、高温抗氧化性有待提高。本研究内容主要是利用工业上广泛应用的制备技术手段，尽量在保证其他力学性能优势的前提下，提高碳化硼陶瓷的断裂韧性。为制备具有较高致密度和较好力学性能的热压烧结碳化硼,并且为下一步工业化批量生产做准备，本次研究使用了球磨混料、喷雾造粒、冷等静压成型、热压烧结等已经工业化的陶瓷制备技术。并且对各个工艺的参数都进行了大量基础性探索实验，最终确定了碳化硅、酚醛树脂和PEG为添加剂，通过和乙醇溶剂混合，长时间高强度球磨之后进行喷雾造粒的前期工艺。并且通过冷等静压成型、脱脂、热压烧结等后续工艺制备出了力学性能优异的碳化硼陶瓷。实验得到了适合工业化大批量生产的工艺参数，并且探究了碳化硅和碳的添加剂对于热压烧结碳化硼的显微结构和力学性能的影响。最终笔者得到了致密度达99.08%，维氏硬度32.9GPa ，断裂韧性6.27 MPa?m1/2的碳化硼样品。显微照片显示适量碳的添加（约6 wt.%相对含量的酚醛树脂添加）有利于陶瓷的致密，碳化硅添加剂有利于阻碍晶粒长大，并对力学性能造成影响。随着碳化硅添加剂的增加，陶瓷的硬度降低但是断裂韧性增强，因为碳化硅的添加改变了原来碳化硼陶瓷的断裂模式。按照研究得到的各种工艺参数生产的陶瓷防弹板按某工艺复合成成品防弹插板，进行防弹实验，测试结果均满足NIJ0101.04的IV等级，具有很好的防护效果。
Boron carbide is a structural material with high hardness attracting many attention. The ceramic is used widely for the outstanding mechanical properties. Boron carbide is a ceramic with high elasticity modulus, high hardness and elasticity modulus. Boron carbide maintains stability even in extreme circumstance and can be used as wear parts, rollers, mechanical seals, nozzles, cutting tools and even personal armors. Boron carbide can also be served as control rod and shield material in nuclear reactors for good chemical stability and high neutron absorption cross-section.The density of boron carbide is low which benefits the use as personal armor. While there are two drawbacks inhibiting the wider use of B4C ceramic. First, pure B4C with high relative density is very difficult to be sintered because of its low self-diffusion coefficient because of the high covalent bonds between carbon and boron atoms. The second drawback is the low fracture toughness which is common for ceramics material. Our research aims to improve the fracture toughness and keep other superior mechanical properties by methods and technique widely used in commercial industry. In order to obtain the hot-pressedB4C ceramics with high relative density and excellent mechanical properties, ball-milling, atomization drying method were conducted in the present study. We obtained technological parameters of every procedures and selected silicon carbide, phenolic resin and PEG as additives. Then we got composite ceramics with outstanding mechanical properties by cold isostatic pressure and hot-pressed method.The author got technological parameters for the volume-produce of B4C-SiC composite ceramics. The effects of silicon carbide and carbon additives on densification, microstructure and mechanical properties were investigated, and the author obtained B4C ceramics with a relative density of 99.08%, a Vickers hardness of 31.9 GPa, and a fracture toughness of 6.27 MPa?m1/2. It is proved by micrographs that moderate carbide additive (~relative phenolic resin content 6 wt.%) benefits the densification. The SiC additive hinders grain growth and influents the mechanical properties. With increasing the SiC addition, the hardness decreases and the fracture toughness rises, as the fracture mode of B4C has been changed by SiC additive.The bullet proof composite plating produced by the obtained technological parameters were inspect by the standard NIJ0101.04 and reached IV degree, which means superior ballistic property.
