Effects of ZrC content on the microstructure and mechanical property of ZrC/ZTA composites consolidated by hot pressing
Shufen Li, Yabin Zhu, Jianlong Chai, Yi‐Wen Liu, Lijuan Niu, Xing Gao, Peng Jin, Tielong Shen, Minghuan Cui, Zhiguang Wang, Erqing Xie
Abstract
In the present work, effects of ZrC addition (10, 15, 20, 25 vol%) on microstructure and mechanical properties of ZTA 20 mol% (Zirconia-20 mol% Toughened Alumina) ceramic composites were investigated. Samples were prepared by Hot Pressing Sintering (HP) at 1600 ℃ and 30 MPa for a soaking time of 2 h. Microstructures were characterized by XRD, Raman, SEM and TEM. XRD and Raman spectra results revealed that only ZrC, α-Al2O3 and ZrO2 were detected for all composites, indicating that these ceramic composites had excellent chemical compatibilities. SEM images showed refined microstructure was obtained, and the fracture surfaces exhibited a mixed process of transgranular and intergranular fracture. According to the TEM observations, some nano-sized ZrC particles dispersed inside Al2O3 grains and formed an intra/inter-type nanostructure. The relative densities and Vickers hardness were inversely proportional to ZrC content, which gradually decreased from 98.24% to 94.89%, from 1 847-1691 HV1, respectively. Flexural strength and fracture toughness were tested by three-point bending method and single-edge notched beam method, respectively. The fracture toughness increased at first and then decreased with ZrC content increased from 0 to 25 vol%. The maximum value was 11.23 MPa m1/2 with 20 vol% ZrC addition, with an enhancement of 51% compared to the undoped ZTA mixture. The flexural strength, with a maximum of 1121 MPa without ZrC addition and decreased to 645 MPa with ZrC-10(vol%) addition, then increased monotonously to 1084 MPa as the ZrC content increased from 10 to 25 vol%.