二维超声磨削微纳米复相陶瓷表面变质层特性研究

Characteristics of Surface Deterioration Layer of Micro-Nanocomposited Ceramics under Two Dimensional Ultrasonic Vibration Grinding

利用二维超声振动磨削,对微纳米复相陶瓷磨削表面变质层的结构、晶粒度和晶格畸变等进行研究。在一定的磨削条件下,微纳米复相陶瓷二维超声振动磨削表层是以晶粒碎化的材料粉末化以及少量的材料压碎和晶粒脱落等方式为主的塑性变质层,亚表层是以晶格畸变、晶界滑移为主的塑性变形层,材料脆性碎裂去除方式极少,以塑性变形去除机理为主。为此提出了微纳米复相陶瓷二维超声振动磨削表面变质层结构模型。通过TEM,SEM观察发现:纳米材料微观变形机理为内晶型结构增强相的晶粒内位错,基体晶粒的晶界滑移、晶间第二相的变形为其变形协调机制。由于纳米粒子分散在晶界间,阻碍了裂纹的扩展,使得材料表现为穿晶断裂行为,从而获得良好的加工表面。

The surface deterioration layer of the micro-nanocomposited ceramics grinding under two dimensional ultrasonic vibration grinding （TDUVG） was studied, including the crystal grain size and crystal lattice distortion in the layers. The grinding superficial coat of TDUVG displayed plastic deformation under a certain grinding condition. They occurred mainly in material powdering and crystal grain fragmentation. The subsurface layer deformed also plastically operated by crystal lattice distortion and the crystal boundary slipping. The material removal via brittleness disruption occurred little. Based on these results, we suggested the structural model for the grinding surface deterioration layer. TEM and SEM observation revealed that the microscopic distortion was operated by the coordinated mechanism, including intragranular dislocation in crystal strengthened structures. The nanoparticles along the grain boundaries reduced expanding of cracks, and this led the failure of the materials in transcrystalline fractures. This fracture behavior provided the materials favorable finished surface.