Theory of chip formation in grinding of fiber reinforced ceramics with porous matrix

对轻量化建筑的需求导致了创新材料的应用，以及建筑材料的不断发展。由于金属高温合金在耐热性方面的发展潜力有限，纤维增强陶瓷成为材料发展的焦点。纤维增强陶瓷（陶瓷基复合材料）由于其高机械稳定性、高损伤容限和耐热性以及低密度而具有很高的应用潜力和未来的重要性。多孔基纤维增强陶瓷代表了一种现代设计理念，与致密基纤维增强陶瓷相比，多孔基纤维增强陶瓷的生产成本更低。然而，多孔基纤维增强陶瓷的加工特性尚未得到深入研究。因此，尚不清楚磨削过程对这些材料外围区域的影响程度。该项目的目标是为具有多孔基体的纤维增强氧化物陶瓷的磨削机制开发一个解释性模型，从而实现基于知识的优化磨削工艺设计。以基体和纤维均由氧化物陶瓷组成的whpox陶瓷为例，定性和定量地描述了纤维取向和纤维材料对加工特性的影响。此外，还将解释磨削参数与得到的表面完整区之间存在哪些因果关系，以及磨削过程的效果在多大程度上受到纤维取向和纤维材料的影响。将开发一个经验模型，该模型将切屑形成描述为材料特性和磨削工艺参数的函数。在此基础上，推导出基于材料特性的启发式模型，该模型解释了磨削后工件的切削机理和表面完整区特性。

The demand for lightweight construction leads to innovative material applications, as well as a constant development of construction materials. Due to a limited development potential in terms of thermal resistance of metallic superalloys, fiber-reinforced ceramics came into the focus of material developments. Fiber-reinforced ceramics (ceramic matrix composites (CMCs)) represent a group of materials with high application potential and future importance due to their high mechanical stability, high damage tolerance and thermal resistance a well as low density. Fiber-reinforced ceramics with porous matrix represent a modern design concept, which can be produced at lower costs in comparison to conventional fiber-reinforced ceramics with dense matrix. However, the machining characteristics of fiber-reinforced ceramics with porous matrix are not investigated yet. Thus, it is not known to what extent a grinding process affects the peripheral zone of these materials.The goal of the project is to develop an explanatory model for the cutting mechanisms in grinding fiber-reinforced oxide ceramics with porous matrix and thereby enable an optimized knowledge-based grinding process design. Using the example of WHIPOX ceramics, in which both the matrix and the fibers consist of an oxide ceramic, the influence of the fiber orientation and the fiber material on the machining characteristics will be described both, qualitatively and quantitatively. Furthermore, it will be explained, which cause-effect relationships between the grinding parameters and the resulting surface integrity zone exist and to what extent the effects of a grinding process can be influenced by the fiber orientation and fiber material. An empirical model will be developed, which describes the chip formation as a function of the material properties and the grinding process parameters. Based on the findings, a heuristic model will be derived, which explains the cutting mechanisms and the surface integrity zone properties of the workpiece after grinding on basis of the material properties.