B_(4)C-PrB_(6)/CeB_(6)汽车材料的制备及性能研究

Preparation and Properties of Automobile Material B_(4) C⁃PrB_(6)/CeB_(6)

分别以Pr_(6)O11和CeO_(2)为添加剂,采用无压烧结、热压烧结和放电等离子烧结法分别在2200℃、1900℃和1700℃制备了B_(4)C基复合材料,并对其微观结构和力学性能进行了研究。结果表明,通过原位反应形成的PrB_(6)和CeB_(6)可以填充B_(4)C晶粒之间的孔隙,提高复合材料的致密性;与无压烧结和热压烧结相比,放电等离子烧结制备的复合材料具有更高的致密性;B_(4)C-CeB_(6)复合材料断裂韧性得以提高的原因是实现了高致密以及裂纹沿着CeB_(6)发生了偏转、分枝和桥联,最终延长了裂纹的扩展路径,降低了应力集中。采用放电等离子烧结制备的B_(4)C-CeB_(6)复合材料综合力学性能较好,相对密度、维氏硬度、抗弯强度和断裂韧性分别达到了99.3%、34.7 GPa、451 MPa和4.38 MPa·m^(1/2)。

With Pr_(6)O11 and CeO_(2) as additives,B_(4)C matrix composite materials were prepared at 2200℃,1900℃,and 1700℃by adopting techniques of pressureless sintering,hot pressing sintering,and spark plasma sintering,respectively.The relative microstructure and mechanical properties were also studied.It is found that PrB_(6) and CeB_(6) formed in situ can fill the pores between B_(4)C grains,and improve the density of the composites.Compared with pressureless sintering and hot pressing sintering,the technique of spark plasma sintering can bring the prepared composites with higher density.The fracture toughness of B_(4)C-CeB_(6) composites can be improved due to its high relative density,as well as the deflection,branching and bridging of cracks occuring along CeB_(6),which extends the expansion path of cracks and reduces stress concentration.The B_(4)C-CeB_(6) composite prepared by spark plasma sintering has good comprehensive mechanical properties,with the relative density,vickers hardness,bending strength and fracture toughness reaching 99.3%,34.7 GPa,451 MPa and 4.38 MPa·m^(1/2),respectively.