基于界面细观力学行为的纤维增韧陶瓷基复合材料磨削机理

The fiber-reinforced ceramic matrix composites have higher anti-impact toughness and bending strength than the traditional ceramics, and are important defense equipment materials. Due to fiber enhancement, fracture of the fiber-reinforced ceramic matrix composites are similar with that of metals and they have thick skin to crack, and the fiber-reinforced ceramic matrix composites are typical difficult-to-machine materials which has high hardness and obdurability. Although grinding is the leading way of machining the fiber-reinforced ceramic matrix composites, it is still in initial stage at home and abroad at present. Since continuous fiber takes on the role of toughening and the influence mechanism between the continuous fiber and the material removal mechanism is not distinct, there are two problems needed to be solved, which seriously restricts the development of defense equipment capabilities. One is the low machining efficiency of the fiber-reinforced ceramic matrix composites, and the other is that it is difficult to control machining damage. The project chooses carbon fiber-reinforced silicon carbide ceramic matrix composites as the experimental object, studying the failure mechanism between toughening fiber/ ceramic interface micromechanics and interface, establishing the constitutive models of the fiber-reinforced ceramic matrix composites. At the same time, the project studies the mechanism that continuous fiber affects the micro crack initiation and growth under the action of a grit by a single particle grinding experimental and numerical simulation, reveals the mechanism of material removal and surface generation during grinding process, optimizes grinding process and process parameters, improves grinding efficiency and decreases machining damage.

与传统结构陶瓷相比纤维增韧陶瓷基复合材料具有更高的抗冲击韧性和抗弯强度，是重要的国防装备新材料。由于纤维的增强作用，纤维增韧陶瓷基复合材料具有类似金属的断裂行为，对裂纹不敏感，是典型的高硬度、强韧性难加工新材料。磨削加工是纤维增韧陶瓷基复合材料的主导加工方法，目前国内外在此方面的研究还处于初期阶段，作为增韧相存在的连续纤维对材料去除的作用机制尚不明晰，导致磨削效率低下、加工损伤不易控制等问题亟待解决，严重制约国防装备能力的发展。本项目拟以碳纤维增韧碳化硅陶瓷基复合材料为研究对象，研究增韧纤维/陶瓷界面细观力学行为与界面失效机制，建立纤维增韧陶瓷基复合材料本构模型，通过单颗粒磨削实验与数值模拟研究在磨粒干预条件下连续纤维对复合材料微观裂纹萌生、扩展及材料去除的作用机制，揭示纤维增韧陶瓷基复合材料磨削过程材料去除与新表面创成机理，优化磨削工艺与工艺参数，提高磨削效率、降低加工损伤。

与传统结构陶瓷相比纤维增韧陶瓷基复合材料具有更高的抗冲击韧性和抗弯强度，是重要的国防装备新材料。由于纤维的增强作用，纤维增韧陶瓷基复合材料具有类似金属的断裂行为，对裂纹不敏感，是典型的高硬度、强韧性难加工新材料。. 本课题研究了增韧纤维/陶瓷界面细观力学行为与界面失效机制。建立纤维增韧陶瓷基复合材料本构模型，通过单颗粒刻划实验与磨削实验研究在磨粒干预条件下连续纤维对复合材料微观裂纹萌生、扩展及材料去除的作用机制，揭示纤维增韧陶瓷基复合材料磨削过程材料去除与新表面创成机理，优化磨削工艺与工艺参数，提高磨削效率、降低加工损伤。. 本课题分析了陶瓷基复合材料制备过程中纤维/基体界面的物理、化学作用，研究了纤维/基体界面本构关系以及界面在载荷作用下的失效机制，同时建立了“纤维—界面—基体”的单胞物理分析模型。此外，通过陶瓷基复合材料单胞理论模型的分析，设计并制备了单向C/SiC模型复合材料并以此研究陶瓷基复合材料的磨削加工机理。上述工作为编织陶瓷基复合材料力学性能的研究提供了理论基础。通过试验揭示了单颗磨粒作用下的界面失效机制及微观材料去除机理。该研究为陶瓷基复合材料磨削机理及复合材料细观力学研究提供了理论基础。. 在陶瓷基复合材料磨削机理方面，利用金刚石砂轮，对复合材料进行磨削试验。试验揭示了纤维方向、磨削参数（磨削深度、进给速度、砂轮转速）对磨削过程中磨削力、表面粗糙度、表面微观特征的影响规律，探明了C/SiC的磨削加工材料去除机理。该机理的探明对陶瓷基复合材料优化磨削工艺与工艺参数，提高磨削效率、降低加工损伤具有重要意义。. 本课题的研究成果不仅对完善磨削加工理论具有重要的科学价值，更对提升陶瓷基复合材料的加工性能，扩大陶瓷基复合材料的应用范围，增强国防装备能力具有重要的社会意义和经济价值。