Herein, microwave thermal crack method is innovatively employed in cutting Al2O3 ceramics.Different from the conventional cutting technology, thermal controlled fracture method is progressive and environmentally friendly, which adopts tensile stress to peel off the brittle material into two parts. The heat source induces tensile stress as thermal stress. Additionally, based on Fourier heat transfer equation and thermo-elasticity, the physical model of microwave thermal crack cutting Al2O3 ceramics is established and calculated. The thickness of the graphite coating, the width of the graphite coating and the prefabricated crack in the process of microwave thermal crack cutting Al2O3 were studied. The effect of graphite coating width on crack trajectory was also investigated by simulation combined with test. From the result, it can be seen that the narrower the width of graphite coating, the weaker the processing ability and the better the trajectory control ability. The microscope is adopted to evaluate the surface and cross section morphologies detailly.This study elaborates briefly the interaction mechanism of microwave thermal crack cutting Al2O3 ceramic surface and provides practical guidance for aerospace industries applications.

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The thermal-controlled fracture method has been increasingly focused upon in the high-quality splitting of advanced brittle materials due to its excellent characteristics related to the fact that it does not remove material. For opaque, brittle materials, their poor fracture quality and low machining capacity resulting from their single-sided heat mode is a bottleneck problem at present. This work proposed the use of dual-sided thermal stress induced by microwave to split opaque, brittle materials. The experimental results indicate that the machining capacity of this method is more than twice that of the single-sided heat mode, and the fracture quality in splitting opaque, brittle materials was significantly improved by dual-sided thermal stress. A microwave cutting experiment was carried out to investigate the distribution characteristic of fracture quality by using different workpiece thicknesses and processing parameters. A dual-sided thermal stress cutting model was established to calculate the temperature field and thermal stress field and was used to simulate the crack propagation behaviors. The accuracy of the simulation model was verified using temperature measurement experiments. The improvement mechanism of the machining capacity and fracture quality of this method was revealed using the fracture mechanics theory based on calculation results from a simulation. This study provides an innovative and feasible method for cutting opaque, brittle materials with promising fracture quality and machining capacity for industrial application.

Herein, microwave thermal crack method is innovatively employed in cutting Al2O3 ceramics. Different from the conventional cutting technology, thermal controlled fracture method is progressive and environmentally friendly, which adopts tensile stress to peel off the brittle material into two parts. The heat source induces tensile stress as thermal stress. Additionally, based on Fourier heat transfer equation and thermo-elasticity, the physical model of microwave thermal crack cutting Al2O3 ceramics is established and calculated. The thickness of the graphite coating, the width of the graphite coating and the prefabricated crack in the process of microwave thermal crack cutting Al2O3 were studied. The effect of graphite coating width on crack trajectory was also investigated by simulation combined with test. From the result, it can be seen that the narrower the width of graphite coating, the weaker the processing ability and the better the trajectory control ability. The microscope is adopted to evaluate the surface and cross section morphologies detailly. This study elaborates briefly the interaction mechanism of microwave thermal crack cutting Al2O3 ceramic surface and provides practical guidance for aerospace industries applications.