纳米SiC颗粒增强反应结合碳化硼陶瓷复合材料的研究

Silicon Carbide Nano-Particulates Reinforced Reaction Bonded Boron Carbide Composites

采用真空熔渗法,通过对B_4C-C素坯于1550℃渗Si,得到了较致密的反应结合碳化硼陶瓷复合材料。通过生成Si C纳米颗粒对材料进行强化,并探讨了纳米Si C颗粒对材料组织与性能的影响及其强韧化机理。实验表明,材料包括B_4C、Si、Si C和B_(12)(C,Si,B)_3四相。结果表明,选取酚醛树脂作为外加碳源,可在材料中成功引入细小的Si C纳米颗粒,使复合材料的抗折强度、断裂韧性和维氏硬度较以炭黑为外加碳源的材料,分别增加了35%、36%和15%,分别高达442 MPa、4.9 MPa·m^(1/2)和23 GPa。

Reaction bonded boron carbide(RBBC) composites were fabricated based on a molten Si infiltration method. The mechanical properties of the composites were improved by the reaction formed silicon carbide(SiC) nano-particulates. The role of SiC nano-particulates in the microstructure, density and mechanical properties of RBBC composites, and the strengthening mechanism were researched. The XRD results show that the composites consist of four phases, namely, B_4 C, Si, reaction formed SiC and ternary phase B_(12)(C, Si, B)_3. The SiC nano-particulates were introduced into the RBBC composites using phenolic resin as carbon sources. The bending strength, fracture toughness and Vickers-hardness of the RBBC composites fabricated with phenolic resin as carbon sources are 442 MPa, 4.9 MPa·m^(1/2) and 23 GPa, which increase by 35%, 36% and 15%, respectively, compared with those of RBBC composites fabricated with black carbon as carbon sources. Clearly, an introduction of the nano-sized SiC particles to RBBC composites is responsible for the increase in the mechanical properties of the composites.