Action mechanisms of nanoparticles with defined interfaces in cutting fluids

切削液是由不同组分（基础液和添加剂）组成的复杂系统，广泛用于金属加工过程，以提高工艺质量和生产率。然而，切削液的效果在很大程度上取决于其配方。一些研究已经揭示了纳米颗粒对切削液性能的积极影响。然而，颗粒性质和颗粒相互作用对纳米流体的所得性质的影响的理解尚未实现。此外，实际研磨过程中纳米流体的结构-性质关系以及它们对外围（例如萃取和进料单元）的影响也没有得到充分的研究。因此，目前的研究状况不允许预测纳米流体作为切削液的适用性，特别是最小量润滑（MQL），其中最少量的流体被供应到工件上。该项目旨在更好地理解纳米流体中纳米颗粒的过程-结构-性质关系，以应用于MQL。一个重要的部分是在水性和疏水性介质中使用不同的纳米颗粒和添加剂系统地制备纳米流体。通过纳米颗粒的化学表面改性，可以调节纳米流体的胶体稳定性。颗粒特性和流体稳定性的影响，首先在实验室水平，然后在机器水平的外圆磨削过程中的冷却和润滑效果进行了研究。研究结果应有助于预测基于纳米流体的切削液的稳定性和性能的模型的开发，以便能够将MQL用于磨削过程。

Cutting fluids are complex systems consisting of different components (base fluid and additives) which are widely used for metalworking processes to increase process quality and productivity. The effect of the cutting fluid, however, highly depends on its formulation. Several studies have already revealed a positive effect of nanoparticles on the performance of cutting fluids. However, an understanding of the impact of particle properties and particle interactions on the resulting properties of the nanofluids has not been achieved yet. Furthermore, the structure-property relationships of nanofluids for the actual grinding process as well as their effects on the periphery, e.g. extraction and feed unit, have not been sufficiently examined either. Hence, the current state of research does not allow the prediction of the applicability of nanofluids as cutting fluids and in particular for minimum quantity lubrication (MQL), where smallest quantities of the fluid are supplied onto the workpiece. This project aims for a better understanding of the process-structure-property relationships of nanoparticles in nanofluids for the application in MQL. An essential part is the systematic preparation of nanofluids using different nanoparticles and additives in aqueous and hydrophobic media. By chemical surface modifications of the nanoparticles, the colloidal stability of the nanofluids can be adjusted. The effects of particle properties and fluid stability are first investigated at laboratory level and then at machine level in a cylindrical grinding process with regard to the cooling and lubricating effect. The findings should contribute to the development of models for predicting the stability and performance of nanofluid-based cutting fluids in order to enable the use of MQL for grinding processes.