六硼化硅(SiB_6)添加剂对B_4C陶瓷致密化与力学性能的影响

Densification and Mechanical Properties of Boron Carbide Ceramics with Addition of Silicon Hexaboride

采用热压烧结(2000℃保温1h)制备了添加2wt%和5wt%SiB_6的B_4C陶瓷,研究了SiB_6不同添加量对B_4C陶瓷致密化和力学性能的影响.结果表明:SiB_6能有效地促进B4C的烧结,并有助于提高材料的力学性能.SiB_6的添加量为2wt%时,B4C陶瓷的块体密度为2.515g/cm^3,是理论密度的99.5%,抗折强度和硬度分别达到426.6MPa和31.2GPa.SiB_6添加量增加为5wt%时,材料的密度为2.500g/cm^3,强度和硬度分别下降为387MPa和29.7GPa.不同添加量对B4C陶瓷的断裂韧性的影响不明显,添加2wt%和5wt%SiB_6的B_4C陶瓷的K_(?)分别为3.20和3.28MPa·m^(1/2).文中还对烧结样品的物相和影响力学性能的原因进行了讨论.

Boron carbide（B4C）ceramics were fabricated by hot-pressing at 2000℃for 1h with 2wt% and 5wt% SiB6 additives respectively.The effect of addition of SiB6 on sinterability and mechanical properties of B4C ceramics was studied.The results show that B4C ceramics can be fully densified by the addition of SiB6 and thus the mechanical properties of the sintered samples are effectively improved. When 2wt% SiB6 is added,the bulk density of B4C ceramics reaches 2.515g/cm3 which is about 99.5% of the theoretical density,while hardness and flexural strength of the sintered sample are 31.2GPa and 426.6MPa respectively.With the amount of SiB6 increase to 5wt%,the density,hardness and flexural strength of B4C ceramics are reduced to 2.500g/cm3,29.7GPa and 387MPa respectively.On the other hand,the adding amount of SiB6 does not make a remarkable effect on fracture toughness of B4C samples since the K（1c）values in both cases are around 3.2MPa.m（1/2）.The phase assemblages and the reasons induced the changes in mechanical properties of the sintered samples with addtion of SiB6 are also discussed.