Prediction and fabrication of textured Si3N4 ceramics via grain rotation model
Yunwei Shi, Jinghan Wang, Yichao Ren, Aiyang Wang, Qianglong He, Yanbo He, Hao Wang, Weimin Wang, Zhengyi Fu
Abstract
• A grain rotation model was created to predict the texture evolution mechanism during hot pressing of Si 3 N 4 ceramics. • A new pseudo-hot isostatic pressing process with the large deformation was guided to fabricate the strongly textured ceramics. • This model could be applied to guide the design and fabrication of other isotropic and anisotropic ceramic materials. The grain preferential orientation has a significant influence on the mechanical properties of silicon nitride (Si 3 N 4 ) ceramics. Based on the Jeffery’s theory, a grain rotation model under uniaxial compression is created to predict the texture evolution mechanism during sintering of Si 3 N 4 ceramics. With deformation, the grain orientation was predicted to rotate towards the plane perpendicular to the pressure direction, and large strain was favorable for the formation of strong texture. According to guidance of the model, the weakly textured microstructure prepared by normal hot pressing is attributed to the limited strain, due to the constrains of graphite die. Therefore, a new PHIP (pseudo-hot isostatic pressing) process with the large deformation is guided to fabricate the strongly textured ceramics by promoting the grain rotation and dynamic grain growth. Generally, the experimental results are well accordance with the model prediction. Furthermore, this model could be applied to guide the design and fabrication of other isotropic and anisotropic ceramic materials.