陶瓷基复合材料的磨料水射流高效低损伤钻削机理研究

Due to excellent properties such as light weight, high strength and high temperature resistance, ceramic matrix composites materials are the ideal materials for the key structural components of the extreme environment for aerospace applications. Drilling is a typical process in the machining of composite components. In order to solve the problems that the traditional mechanical process of drilling ceramic matrix composites is extremely difficult, expensive and easily damaged, many non-traditional machining technologies (e.g. abrasive waterjet machining) have emerged and have been successfully applied in the machining of ceramic matrix composites. The project will study on high efficiency and low damage machining mechanism of ceramic matrix composite drilled by abrasive waterjet , and will intend to carry out four aspects of research: experimental study of machining performance drilled by abrasive waterjet for ceramic matrix composites; dynamic simulation study of abrasive waterjet based on computational fluid dynamics theory; To reduce delamination damage, conducting mechanism analysis of delamination formation during low damage drilling of ceramic matrix composite by abrasive waterjet; process optimization of abrasive waterjet drilling of ceramic matrix composites and establishing a multi-objective optimization model of the robust system. The research results of this project will be of great importance in realizing the low damage drilling of ceramic matrix composites and broadening the application fields of abrasive water jet technology. It is of great importance to break the monopoly of key components of foreign countries and China will achieve the dream of becoming a strong country in aerospace. The research results of this project will play an important role in theoretical significance and broad application prospects.

陶瓷基复合材料具有轻质、高强、耐高温等优异性能，是航空航天用极端环境关键结构部件的理想材料。为解决传统机械工艺钻削陶瓷基复合材料极其困难、成本昂贵和损伤较多等问题，涌现出了磨料水射流加工等特种加工技术，并成功应用于陶瓷基复合材料的加工领域。本项目将主要研究陶瓷基复合材料高效低损伤钻削机理研究，拟开展四个方面的研究: 磨料水射流钻削陶瓷基复合材料的加工性能实验研究；基于计算流体力学理论的磨料水射流动态特性模拟研究；磨料水射流低损伤钻削陶瓷基复合材料时的机理研究，分析分层的形成和控制机理，从而减少分层损伤；磨料水射流钻削陶瓷基复合材料时的工艺优化研究，建立工艺系统鲁棒性约束多目标优化模型。本项目的研究成果将为实现陶瓷基复合材料高效低损伤钻孔加工，扩宽磨料水射流技术的应用领域，打破国外对我国航空航天关键部件垄断，实现我国航空航天强国梦，具有重要的理论研究意义和广阔的应用前景。

本课题针对传统方式钻削加工陶瓷基复合材料和单晶晶片等难加工材料及其困难、成本昂贵和损伤较多等问题，使用磨料水射流技术来钻削陶瓷基复合材料和单晶晶片。主要研究了如下内容：(1) 磨料水射流加工Cf/SiC复合材料时的孔特征及表面损伤形成机理。研究了孔特征和表面损伤的形成机理。结果表明，在一定的参数范围内，孔入口和孔出口直径随喷嘴移动速度、射流压力、靶距和磨料流量的变化而变化。过加工现象对孔尺寸精度的影响最大。通过改善射流轨迹可以有效提高孔尺寸精度，并得到了各种损伤的形成机理；(2) 磨料水射流加工Cf/SiC复合材料时的切孔形状精度优化。通过响应曲面法实验分析得到了各因素交互作用下孔锥度的变化规律。选择进给速度0.1mm/s，压强150MPa，靶距3mm，磨料流量190g/min作为最佳工艺参数，该工艺参数下获得的孔入出口直径差为0.010mm，为实际孔径的0.4%。通过单因素实验分析，得出刀补值随实际孔径的变化规律及作用机理。加工过程中的甩尾效应能够在其他工艺参数不变的前提下随实际孔径变化引起刀补值的变化，甩尾效应导致射流在工件处的运动轨迹半径大于刀头的运动轨迹半径，进而造成刀补值的变化。通过刀具值优化，刀补值近似为一个与实际孔径无关的常数（1.508mm），得出的入出口直径差和孔径偏差均小于实际孔径的1%，从而证明本研究提供的形状精度优化方法切实有效；(3) 超声振动辅助磨料水射流钻削SiC晶片的加工性能提高机理。超声辅助磨料水射流加工技术能提高材料去除率和表面质量等加工性能。加工性能的提高可归结于加工过程中的两种行为。一方面，源于磨粒从振动表面回弹时的动力学变化的清除效应。另一方面，振动表面上产生的剪切应力能促进工件表面出现延性模式的材料去除。上述研究成果为实现磨料水射流高效、低损伤钻削陶瓷基复合材料和单晶晶片等难加工材料提供重要的理论基础和技术保障。