Rotary ultrasonic machining (RUM) has been considered as an effective approach in the manufacturing of advanced materials such as ceramic matrix composite (CMC). However, the distinct removal mechanisms in RUM with different vibration forms has not been elucidated, which hinders the adoption of RUM technology in the field of material processing. In this research, the ultrasonic-assisted scratching tests of CMC were conducted to reveal the fundamentals of material removal and surface formation. Based on the kinematics of RUM processes, the vibration effects exerted in cutting areas were clarified as impact-separation and reciprocating-polishing, thus two types of diamond indenters have been specially designed for the intermittent and continuous scratching tests, respectively. The scratching force, friction factor and grooves morphology have been analyzed and compared with that of the conventional scratching without vibration. For the intermittent scratching with vertical vibration, it was found that the high frequency impact-separation between indenter and workpiece increased the critical penetration depth of ductile-brittle transition, which can help restrain the cracking defects of CMC. For the continuous scratching with tangential vibration, the overlapping rate was firstly proposed to evaluate the effect of reciprocating polishing. It was shown that higher overlapping rate and larger dynamic shear angle can be achieved by matching the scratching velocity with vibration frequency, which is conducive to obtaining even fiber fracture and better surface integrity. Due to the minimal volume of material removed in each vibration cycle, the scratching resistance was significantly lowered with smaller fluctuation under both vibration forms. Moreover, the diminishing of vibration effectiveness at certain scratching parameters was also discussed. This research work brings in a better understanding on the material removal mechanisms under different effects of ultrasonic vibration, which can provide a guidance for the design and optimization of the vibration assisted processing of advanced materials.

旋转超声加工（RUM）被认为是制造先进材料（例如陶瓷基复合材料（CMC））的有效方法。然而，尚未阐明具有不同振动形式的RUM中不同的去除机理，这阻碍了RUM技术在材料加工领域的采用。在这项研究中，进行了CMC的超声辅助刮擦测试，以揭示材料去除和表面形成的基础。根据RUM加工的运动学，明确了在切削区域中施加的振动效应为冲击分离和往复抛光，因此专门设计了两种类型的金刚石压头分别用于间歇和连续刮擦测试。抓力 分析了摩擦系数和沟槽的形态，并将其与没有振动的常规刮擦进行了比较。对于垂直振动的间歇性刮擦，发现压头和工件之间的高频冲击分离增加了韧性-脆性转变的临界穿透深度，这有助于抑制CMC的裂纹缺陷。对于具有切向振动的连续刮擦，首先提出了重叠率以评估往复抛光的效果。结果表明，通过使刮擦速度与振动频率相匹配，可以获得更高的重叠率和更大的动态剪切角，有利于获得均匀的纤维断裂和更好的表面完整性。由于每个振动周期中去除的材料量最少，在两种振动形式下，抗划伤性均显着降低，且波动较小。此外，还讨论了在某些刮擦参数下振动效率的降低。这项研究工作使人们对超声振动不同作用下的材料去除机理有了更好的了解，可以为先进材料的振动辅助处理的设计和优化提供指导。