纳米TiC加入量对TiC高温陶瓷烧结和力学性能的影响

Effect of nano-TiC addition on sinterability and mechanical properties of TiC high temperature ceramics

为研究纳米TiC在烧结过程中对TiC基体烧结和力学性能的影响,在粒径约3μm的TiC微粉中分别添加质量分数为0、10%、20%、50%、90%的纳米TiC,采用放电等离子体烧结工艺(于1 600℃烧结5 min,烧结压力50 MPa)制备出了TiC高温陶瓷。利用阿基米德排水法、SEM、压痕法等测试手段表征烧结后陶瓷的烧结性、显微结构及力学性能,并从致密度和显微结构的变化讨论了纳米TiC加入量对TiC陶瓷烧结的影响,从硬度和断裂韧性的变化探讨了纳米TiC量对其力学性能的影响。结果表明:纳米TiC在基体中的分散性是影响TiC陶瓷烧结性和力学性能的主要原因,加入少量(10%质量分数)纳米TiC时,分散性较好,有助于提高TiC陶瓷的烧结性和力学性能;添加纳米TiC可以明显细化TiC陶瓷的显微结构组织;当纳米TiC质量分数为10%时,TiC陶瓷的断裂韧性最大,呈现明显的裂纹偏转、桥接等增韧机制。

TiC high temperature ceramics were prepare0 by spark plasma sintering method （firing at 1 600 ~C for 5 min,50 UPai ,adding nano-Tic（o,iO%,20%,50% and 90% ,in mass,the same hereinafter） into TiC micropowders （about 3 iJm） in order to research the effect of nano-TiC on the sinterability and me- chanical properties of TiC matrix. The sinterability, microstructure and mechanical properties were charac- terized by Archimedes method,SEM and indentation method, respectively, Effect of nano-TiC addition on the sinterability of TiC ceramics was discussed according to the changes on densification and microstruc- ture,and its influence on mechanical properties was discussed according to the hardness and fracture toughness. The results show that the dispersity of nano-TiC in the matrix mainly impacts the sinterability and mechanical properties of TiC ceramics; a low nano-TiC addition （ 10% ） leads to an excellent dispersity,im- proving the sinterability and mechanical properties of TiC ceramics; fine microstructures can be obtained by adding nano-TiC ;with 10% nano-TiC,TiC ceramics have the highest fracture toughness, performing ob- vious toughening mechanisms such as crack deflection and bridging.