Study On Ultrasonic Vibration Grinding Mechanism Of Nano-composite Ceramics Based On The Non-local Theory

Nano-composite ceramics has broad application prospects, but the surface micro-defect sensitivity and high processing costs limit their wide application in high-tech. At present, the trend of ceramics processing is a variety of processing methods for integrated complex process, ultrasonic grinding is recognized as an effective processing.In order to better studied ultrasonic grinding mechanism of nano-composite ceramics materials, based on linear non-local elasticity theory, we considered of the long-range interactions of micro-particles, the relation of microstructure and its macroscopic mechanical properties was established. The test method of ZTA nano -composite ceramics fracture under the conditions of ultrasonic vibration was proposed. Based on this method we investigated the fatigue life and crack expansion method of ZTA nano-composite ceramics materials which has a pre-crack under the common condition and the condition of ultrasonic vibration. Through the fatigue test the conclusion that ultrasonic vibration has the attenuation role of the cyclic stress was obtained, about 80 percents of common cyclic stress. Ultrasonic vibration also can change the fracture model of ZTA specimen. The role of high-frequency ultrasound to the material micro-structure of macro-mechanics was revealed in the test. These conclusions proved that high-frequency ultrasound is conducive to the ductile removal of ceramics .Based on indentation fracture mechanics and ultrasonic vibration theory we analysed the trajectories characteristics of single diamond grain and ductile removal mechanism of nano-composite ceramics in ultrasonic grinding process. The theoretical formula of grinding force and surface roughness under the ultrasonic vibration grinding was established. The effect laws of grinding depth, ultrasound frequency and power on the grinding force, grinding force ratio and surface quality were investigated. The test proved that the normal force of ultrasonic grinding is about 65 to 80 percents of common grinding force. The SEM photos of ZTA nano-composite material at different grinding modes were analysed and we found that in the surface properties, ultrasonic grinding critical grinding depth is twice of normal grinding critical grinding depth and as the frequency increases, this trend is more pronounced. The characteristic scales of the external and internal ultrasound characteristic scales of the impact grinding force ratio is an important factor in attenuation, through the study of non-local constitutive model, we analysed of causing the differences from the micro-mechanical in combination the macro point of view.