Determination of the microscopic wear mechanisms and operational suitability of diamond and cBN for the precision machining of hardened steel under variation of the thermomechanical load using multiscale measurement methods

立方氮化硼（cBN）具有较高的耐热化学性能，是一种常用的超磨料。与cBN相比，金刚石具有优越的机械性能，并且在低工艺温度下具有更长的刀具寿命；然而，它的耐温性较差。金刚石和cBN刀具用于加工钢的磨损机制尚不清楚，从而限制了它们的应用，从而表明了研究空白。此外，如何使用金刚石和cBN来提高精密磨削结果的可预测性和磨料颗粒功能的可靠性是一个特别有趣的问题。了解金刚石和cBN与钢表面的相互作用，从而了解纳米尺度上的磨粒磨损，也是一个开放的摩擦学方面。这可以通过晶粒表面的磨损相关特性及其对温度和压力的依赖的微观描述来澄清。该项目旨在描述金刚石和cBN磨料颗粒以及由淬火轴承钢100Cr6制成的工件在中观和纳米尺度上的化学、结构和物理表面特性；随着磨削过程条件的变化，热机械载荷也会发生变化。这些相互关联的特性表征了精密磨削的磨粒磨损机理，以及磨粒的适用性和效率，以实现工件的高表面质量。一方面，声子应描述在磨削过程中耗散到碳或氮化硼原子晶格中的能量，并应与磨损和摩擦的宏观和微观分析联系起来。另一方面，推导了cBN和金刚石磨具精密加工的特定应用工艺参数空间，以及与cBN相比，使用金刚石磨具的潜在局限性和优势。最后阐明cBN和金刚石作为磨削介质在精密磨削中的定向和经济应用的耐磨性和材料磨损性能。在这种情况下，将使用包括宏观和微观结构地形特征研究的互补和多尺度方法，并通过拉曼和布里渊激光散射分析与化学和物理特性相关的原子间相互作用。金刚石和cBN磨料颗粒与工件表面接触时的热机械负荷将通过测量压力和温度的量子传感器在现场记录和操作。

Cubic boron nitride (cBN) is the superabrasive material frequently used for machining steels due to its high thermochemical resistance. In comparison to cBN, diamond possesses superior mechanical properties and allows for longer tool lifetimes at low process temperatures; however, it is less temperature-resistant. The wear mechanisms of the diamond and cBN tools for machining steels are not understood yet, thus limiting their applications and, in turn, indicating a research gap. Moreover, it is of particular interest how the predictability of the precision-grinding result and the reliability of the abrasive grain functionality using diamond and cBN could be enhanced. The understanding of the interaction of diamond and cBN with a steel surface and, hence, of the abrasive grain wear at the nanoscale is moreover an open tribological aspect. It could be clarified by a microscopic description of the wear-relevant properties of the grain surface and their dependences on the temperature and pressure.The project aims at describing chemical, structural, and physical surface properties of diamond and cBN abrasive grains as well as of the workpiece made from hardened bearing steel 100Cr6 at the meso- and nanoscale; following the conditions of grinding processes, the thermomechanical load is varied. The mutually correlated properties shall characterize the grain wear mechanisms for the precision grinding as well as the suitability and efficiency of the abrasive grains for realizing a high surface quality of the workpiece. On the one hand, acoustic phonons shall describe the energy which is dissipated into the carbon or boron-nitride atomic lattice during the grinding process and shall be linked with macro- and microscopic analyses of the wear and friction. On the other hand, application-specific process-parameter spaces for the precise machining with cBN and diamond grinding tools and potential limits and advantages of using diamond in comparison to cBN will be deduced. The wear resistance and the material abrasion performance will finally be elucidated for the target-oriented and economical application of cBN and diamond as grinding medium in precision grinding.In that context, complementary and multiscale methods, which embrace macro- and microscopic studies of structural-topographic features will be used and interatomic interactions which are relevant to chemical and physical properties will be analyzed by means of Raman and Brillouin laser-light scattering. The thermomechanical load of diamond and cBN abrasive grains being in contact with the workpiece surface will be recorded in situ and operando by a quantum sensor measurement of pressure and temperature.