超声辅助螺旋磨削SiCf/SiC陶瓷基复合材料

针对SiC纤维增强SiC陶瓷基复合材料(SiC_f/SiC)存在加工质量差、材料去除困难等问题，开展金刚石砂轮超声辅助螺旋磨削SiC_f/SiC陶瓷基复合材料试验，研究其出口质量、孔壁形貌及孔壁表面粗糙度。结果表明：与传统制孔相比，超声辅助螺旋磨削制孔出口处材料无大面积崩边;砂轮磨削速度方向与纤维方向的夹角θ的周期性变化导致孔壁表面形貌呈现规律性变化。当θ在0°/180°时，纤维与基体多发生脱黏现象；当θ在45°时，纤维多发生剪切断裂；当θ在90°时，纤维多发生挤压断裂；当θ在135°时，纤维既发生剪切断裂又发生挤压断裂；孔壁表面粗糙度Sa在θ为90°时最低，在θ为135°时最高。在一定范围内，表面粗糙度Sa随着超声振幅的增大而降低，最大降幅为38.7%；随着进给速度的增大而升高，最大增幅为39.3%。

Ultrasonic assisted helical grinding of SiCf/SiC ceramic matrix composites

SiC fiber reinforced SiC ceramic matrix composites (SiC_f/SiC) have problems such as poor machining quality and difficult material removal. To study these problems, SiC_f/SiC composites were processed by ultrasonic-assisted helical grinding. The exit quality of hole, hole wall morphology and three-dimensional surface roughness of hole wall were explored. The results show that compared with traditional hole making, the material at the exit of the hole made by ultrasonic-assisted helical grinding has no large area chipping. The periodic change of the angle θ between the direction of the cutting speed of the grinding wheel and the fiber direction leads to regular changes in the surface morphology of the hole wall. When θ is 0°/180°, the fiber and the matrix are debonded. When θ is 45°, the fiber is sheared and fractured. When θ is 90°, the fiber is crushed and fractured. When θ is 135°, the fiber has both shear fracture and extrusion fracture. The hole wall surface roughness S_a is the lowest value when θ is 90°, and S_a is the highest value when θ is 135°. Within a certain range, the surface roughness value S_a decreases with the increase of the ultrasonic amplitude, with a maximum decrease of 38.7%, and increases with the increase of the feed rate, with a maximum increase of 39.3%.