工程陶瓷引弧微爆炸加工过程的高速摄像

摘要

为了研究工程陶瓷引弧微爆炸加工的工作原理,建立了高速摄像试验系统对微爆炸等离子体射流的产生过程、外观形态进行了观测,得到了微爆炸等离子体射流的产生原理.对氮化硅陶瓷和氧化铝陶瓷冲击蚀坑的形成过程进行了高速摄像观测,并利用扫描电镜观察了冲击蚀坑的截面形貌,得到了陶瓷加工的材料去除机理.实验结果表明,等离子体射流的形成过程可分为火花放电和稳定等离子体射流2个阶段,等离子体射流的直径随着电流值的增大而增大,冲击蚀坑直径随着加工时间逐渐扩展.氮化硅陶瓷加工时升华分解,蚀坑表面覆盖一层结构疏松的变质组织,在亚表面上有横向裂纹形成;氧化铝陶瓷加工时直接熔化,表面变质层成分为非晶体玻璃相.%In order to study the working principle of micro-detonation of striking arc machining(MDSAM) for engineering ceramics,a high-speed photography system was established,and used to observe the generating process and appearance morphology of micro-detonation plasma jet.And the generating principle of micro-detonation plasma jet was obtained.The formation process of the impact corrosion pits for both Si3N4 and Al2O3 ceramics was observed with the high-speed photography system,and the cross-section morphology of the impact corrosion pits was observed with scanning electron microscopy(SEM).Moreover,the material removal mechanism for ceramics processing was attained.The experimental results show that the generating process of plasma jet can be divided into two stages including the spark discharge and stable plasma jet.The diameter of plasma jet increases with increasing the current value,and the diameter of impact corrosion pits will expand with increasing the machining time.The sublimation decomposition occurs in the machining process of Si3N4 ceramics.The surfaces of the corrosion pits are covered with a layer of loose metamorphic microstructures,and some transverse cracks initiate on the subsurface.The Al2O3 ceramics will directly melt in the machining process,and the constituent of surface metamorphic layer is amorphous glass phase.