制动复合材料的界面力学行为及其对摩擦学性能的影响

Most of the research on the new braking composite friction material has focused on macroscopic friction and wear behavior of the material, but there remains a lack of study on its micromechanical properties. The research on interface mechanics of composite material has great scientific significance for understanding fiber-reinforced mechanism, failure mechanism of interface, and establishing the relationship between micromechanical properties and macroscopic tribological properties. Nanoindentation, atomic force microscopy, and finite element methods will be used to characterize micromechanical properties and microstructures of the interface in the braking friction material. The gradual variation of the mechanical properties of the interface will be considered. The cohesive zone model will be used to simulate the interaction between interfaces. The coupling effects of size effects of both interface and nanoindentation with the anisotropy and the property gradient of the interface on indentation testing results will be investigated. The applicable conditions for characterizing interface properties by indentation testing under various types of indenters such as Berkovich indenter and spherical indenter will be obtained as well as the mechanical properties (e.g. elastic modulus and hardness) of the interface. The correction model for experimental results will be established, and the variation of mechanical properties with location across the interface will be quantitatively characterized. The results will reveal the effect of preparation parameters on interfacial bonding strength, the effect of interface mechanics on macroscopic tribological properties, and the relationship between micromechanical properties and microstructure of the interface, and provide scientific guidance for further improving tribological properties of the braking composite material.

新型制动复合摩擦材料的研究大都集中在宏观摩擦磨损性能上，而对材料微观力学性能的研究还较缺乏。研究复合材料的界面力学行为对理解纤维增强机理、界面失效机制、建立微观力学性质与宏观摩擦学性能之间的联系有重要的科学意义。利用纳米压痕、原子力显微镜、有限元模拟等方法对制动摩擦材料的微观界面进行力学性能和微观组织结构的表征，考虑界面处渐变的力学性能，采用内聚力模型模拟界面之间的相互作用，研究界面和纳米压痕的尺寸效应、界面各向异性以及性能的梯度变化等对压痕测试结果的耦合影响。获得棱锥、球形等压头下测量界面力学性能时，压痕测试的适用条件以及界面处弹性模量和硬度等力学性能，建立分析实验结果的修正模型，定量表征界面处力学性能随位置的变化。揭示制备参数对界面结合强度的影响、界面力学对宏观摩擦学性能的影响、以及增强相与基体之间界面的力学性能和微观组织之间的关联性，为进一步提升制动复合材料的摩檫学性能提供科学指导。

分别从四个途径制备了新型酚醛树脂基复合材料：（1）利用稀土溶液改性竹纤维，研究不同浓度和浸泡时间的影响；（2）利用剑麻纤维与硅酸铝纤维混杂增强酚醛树脂基复合材料，研究混杂纤维含量和比例的影响；（3）采用铸造废树脂砂填充树脂基制动材料，研究了不同含量的铸造废树脂砂对复合材料力学和摩擦学性能的影响；（4）采用粉煤灰空心微珠填充树脂基制动复合材料，研究了不同含量的粉煤灰空心微珠对复合材料摩擦学性能的影响。用铸造废树脂砂或粉煤灰空心微珠成功替代了传统汽车刹车片中的铜粉成分，实现制动复合材料的无铜化。利用扫描电镜、X射线衍射、傅里叶变换红外光谱、热重分析、真密度测试、硬度测试、冲击试验、摩擦磨损试验等对复合材料微观组织、力学及摩擦学性能进行了研究，揭示了纤维对基体的增强机制，获得了最佳的含量配比和工艺参数，为制备绿色环保、低成本的高性能无铜树脂基制动材料提供科学指导。