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热阻方面的发展潜力有限，纤维增强陶瓷成为材料发展的重点。纤维增强陶瓷(陶瓷基复合材料)由于具有高机械稳定性、高损伤容限和耐热性以及低密度等优点，是一类具有很高应用潜力和发展前景的材料。多孔纤维增强陶瓷代表了一种现代的设计理念，与传统的致密基体纤维增强陶瓷相比，可以以更低的成本生产出来。然而，纤维增强多孔陶瓷的加工特性还没有得到研究。因此，磨削工艺对这些材料的周边区域的影响程度尚不清楚。该项目的目标是开发一种用于磨削多孔基质纤维增强氧化物陶瓷的切割机理的解释模型，从而实现基于知识的优化磨削工艺设计。以WHIPOX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，其中基质和纤维均由氧化物陶瓷组成。此外，还将解释磨削参数和由此产生的表面完整性区域之间存在哪些因果关系，以及磨削过程的效果受纤维取向和纤维材料影响的程度。建立了切屑形成的经验模型，该模型描述了切屑形成与材料性能和磨削工艺参数的函数关系。在此基础上，建立了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割机理和表面完整性区域的特性。

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.