Abstract Advanced ceramics exhibit excellent mechanical properties at elevated temperatures suggesting them as plausible cutting tool materials for machining of heat-resistant superalloys. However, despite numerous efforts to date, relative brittleness of ceramic tools can result in chipping or catastrophic failure, especially during an intermittent process where excessive thermo-mechanical alteration occurs, like high-speed face milling. Previous studies by the authors revealed that in high-speed milling of inconel with SiAlON tools, after surpassing a certain cutting speed where extreme levels of strain rates and temperatures exist, the IN718 machinability transforms drastically, showing a significant reduction in cutting force, chipping and tool wear. Following this observation, in the current paper, an attempt has been made to further investigate the phenomena acting at the shear deformation zones through analysis of chip formation mechanisms and tool-workpiece tribosystem. Numerous characterization techniques have been used in this research, such as cutting force measurements, chip cross-section studies, SEM/EDS, TEM, and nanoindentation. Results suggest that a reduction in material flow strength occurs at the extreme conditions of the cut, showing similarities to fluid flow in TEM images of the tool face. Increasing the cutting speed generally facilitates chip formation; However, a rise in cutting force by further increasing the speed, and excessive generation of unstable built-up layers practically limits the cutting speed. Additional XPS studies show that variation in cutting speed also changes the frictional response of the tool-workpiece tribosystem by forming lubricious and thermal-barrier tribofilms.

中文翻译：

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IN718陶瓷刀具高速铣削切屑形成及摩擦学行为

摘要 先进陶瓷在高温下表现出优异的机械性能，表明它们是用于加工耐热高温合金的合理切削工具材料。然而，尽管迄今为止做出了很多努力，但陶瓷刀具的相对脆性会导致崩刃或灾难性故障，尤其是在发生过度热机械变化的间歇过程中，如高速面铣。作者之前的研究表明，在使用 SiAlON 刀具高速铣削铬镍铁合金时，在超过一定的切削速度（存在极端应变率和温度）后，IN718 的可加工性发生了巨大变化，显示出切削力、崩刃和切削力的显着降低。工具磨损。根据这一观察，在目前的论文中，已尝试通过分析切屑形成机制和刀具-工件摩擦系统来进一步研究剪切变形区的现象。本研究中使用了许多表征技术，例如切削力测量、芯片横截面研究、SEM/EDS、TEM 和纳米压痕。结果表明，材料流动强度在切割的极端条件下会降低，这与工具面的 TEM 图像中的流体流动相似。提高切削速度一般有利于切屑的形成；然而，通过进一步提高速度而增加切削力，以及过度产生不稳定的堆积层实际上限制了切削速度。