Mechanism of compound fracture and removal in grinding process for low-expansion glass ceramics

The mechanism of fracture and its removal for low-expansion glass ceramics processing was studied through grinding experiments. A dynamic coefficient Kd was proposed to characterise the brittle material processing property. Using surface roughness as the evaluation index, the limitations of the empirical model and the brittle fracture model were analysed. On the basis of simple single-factor tests, two-step changes on the processing surface of brittle materials were observed for the first time, which could be described in terms of the critical depth of ductile and ductile–brittletransition (hc1) and the critical depth of ductile–brittle and brittle transition (hc2). The brittle material fracture processing and removal could be divided into three phases: ductile fracture, ductile–brittle fracture and brittle fracture. Furthermore, a compound grinding factor Q and a model of compound regime were proposed in this study, in order to comprehensively test the variation tendency of surface roughness and improve the model accuracy. A multi-factor cross-validation test also was conducted, and the results of the three models were compared with the test results. The model of compound regime (Ra3) showed the highest precision.