Research On The Control Method Of The Zirconia Ceramics Crack Growth Induced By Microwave

With excellent mechanical properties,the application of engineering ceramics in aerospace,national defense and daily life is becoming increasingly widespread.Because of its brittleness,high hardness,high temperature resistance and poor thermal conductivity,it is difficult to process most ceramic materials,and it is difficult to guarantee the processing efficiency,accuracy and processing quality with the existing processing methods.Microwave thermal cracking ceramics use the characteristics of the materials hardness and brittleness to ensure high cutting quality while ensuring the cutting efficiency.Therefore,this paper has carried out research work on microwave thermal cracking cutting technology of zirconia ceramic materials.First,based on the characteristics of microwaves and ceramics,the interaction between microwaves and ceramic materials was studied.Based on the relevant theories of heat transfer,elastoplastic mechanics,and brittle material fracture mechanics,the microwave energy processing of ceramic materials was analyzed.The transfer process and microwave energy-induced thermal stress cause the ceramic material to produce cracks and the conditions of cracks further expanding with microwave energy.Secondly,based on the above theoretical analysis,according to the boundary conditions and initial conditions of the actual experiment,the thermomechanical coupling model of microwave thermal cracking zirconia ceramics was established,and the distribution of temperature field and stress field in the workpiece under the heat source model was simulated and analyzed.The simulated temperature field is compared with the measured temperature field to verify the rationality of the simulation model.On this basis,further analysis of the effect of microwave absorber width,microwave power,scanning speed,and double-sided heat source on the temperature field and thermal stress changes in the process of microwave thermal cracking ceramics provides a basis for the subsequent study of the mechanical mechanism of crack propagation.Finally,according to the characteristics of crack propagation in brittle materials,under the theoretical framework of elastoplastic mechanics,based on the material continuum assumption,the ideal mechanical conditions for microwave thermal cracking ceramic crack growth conditions are given,including crack cracking conditions and cracking directions.Through the expansion finite element method,the crack propagation law under different stress fields is analyzed and simulated,and the mechanical mechanism of the crack propagation trajectory migration during microwave thermal cracking is obtained.Based on the above mechanism,a processing technology combining a double-sided heat source and a prefabricated initial crack is proposed.The simulation analysis results show that the processing technology has a significant control effect on controlling the crack propagation trajectory deviation.Using the above simulation conditions,a zirconia ceramic microwave cutting verification test was carried out.The experiment proved that the double-sided heat source and prefabricated edge cracks can control the crack propagation trajectory well.