原位生成Ni颗粒增韧纳米ZrB2基陶瓷的制备方法与微观结构研究

目的提高Zr B2基防热陶瓷材料的韧性,以满足其高抗热冲击性能的需求。方法采用沉淀-共沉积法在纳米Zr B2粉体中原位生成Ni颗粒作为增韧相,经放电等离子烧结后获得分布均匀的Ni-Zr B2纳米复合材料,通过三点弯曲实验、断裂韧性实验以及硬度测试,分别评价不同Ni含量对Ni-Zr B2纳米复合材料力学性能的影响,并通过SEM,XRD对材料微观组织进行分析。结果 Ni颗粒的引入,可有效提高Zr B2的相对密度,增加韧性,同时强度和硬度有所提高。通过不同Ni含量的对比发现,Zr B2-15%Ni力学性能最优,断裂韧性达到7.8±0.3 MPa·m1/2,相对于原始Zr B2材料提升1倍。从微观组织的电子扫描照片也可以看出,Ni颗粒在Zr B2表面均匀分布,断口表现为穿晶断裂和延晶断裂的复合断裂模式,不同于原始Zr B2材料的穿晶断裂。这也是断裂韧性显著提升的主要原因。结论原位生成Ni颗粒的引入,可有效提高Zr B2材料相对密度、强度、硬度以及断裂韧性。对比不同Ni含量的力学性能,Zr B2-15%Ni组分的力学性能最优,这一方法可有效提高Zr B2材料的断裂韧性,进一步满足其高抗热冲击性能的需求。

Preparation Method and Microstructure of In-situ Ni Particle Reinforced ZrB2 Based Ceramics

Objective To improve the toughness of ZrB2 based thermal protective ceramics to meet their high thermal shock resistance requirements.Methods The in-situ Ni particles were produced as reinforced phase through precipitation-codeposition on nano ZrB2 powder. Ni-ZrB2 nano composites with uniform distribution were obtained by spark plasma sintering. Effects of Ni content on mechanical properties of Ni-ZrB2 nano composite materials were evaluated through three-point bending test, frac-ture toughness test and hardness test. And the microstructures of the material were characterized by SEM and XRD.Results In-troduction of Ni particles, could effectively improve the relative density of ZrB2, and increase its toughness, strength and hard-ness. By comparing the different content of Ni, it was suggested that ZrB2-15％ Ni had excellent mechanical properties. Its frac-ture toughness reached to 7.8±0.3 Mpa·m1/2, increased by 1 times compared with the original ZrB2 material. From the micro-structure obtained through SEM, it can be seen that the Ni particles are uniformly distributed on the surface of ZrB2, and the fracture was characterized by transgranular fracture and intergranular fracture, which was different from the transgranular frac-ture of the original ZrB2 material. This was also the main reason for the remarkable increase of fracture toughness.Conclusion Introduction of in-situ Ni particles, can effectively improve the ZrB2 material relative density, strength, hardness and fracture toughness. Compared with mechanical properties between different Ni contents, the ZrB2-15％ Ni components have the best mechanical properties. This method can effectively improve the fracture toughness of ZrB2 materials and further meet the de-mand of the high thermal shock resistance.