Cu-纳米TiB₂原位复合材料的制备及摩擦磨损性能

【作者】 王耐艳；

【导师】 刘茂森； 涂江平；

【作者基本信息】 浙江大学 ， 材料学， 2002， 硕士

【摘要】 本文采用原位反应法制备了Cu-纳米TiB₂原位复合材料，在此基础上分析了原位复合材料的微结构，进行了干滑动摩擦磨损和电接触滑动磨损实验，完成的主要工作如下： 从热力学的角度出发，分析了陶瓷TiB₂颗粒在铜基体中原位生成的热力学条件，并用电解铜、工业纯钛、B₂O₃、C（还原剂）以及Cu-Ti、Cu-B等合金为原料，通过控制适当的反应温度、反应时间和快速凝固等工艺手段，制备了Cu-纳米TiB2原位复合材料。 通过光学显微镜、TEM、XRD等对Cu-TiB2原位复合材料进行了金相组织、微结构分析，原位复合材料的铸态金相组织中弥散分布着团簇状的TiB2颗粒；形变态金相组织中TiB2颗粒呈纤维状排列；TEM观察表明：在基体内存在着尺寸约为50nm、弥散分布的TiB2颗粒，且TiB2颗粒与基体之间界面清晰，但由于TiB2结构与铜晶体结构的差别较大，TiB2颗粒与基体之间无固定的位向关系；纳米TiB对铜基体有良好的增强作用。 利用销-盘式摩擦磨损试验机研究了Cu-纳米TiB2原位复合材料/Cu-C（石墨）复合材料的干滑动磨损和电接触磨损行为。纳米TiB2颗粒增强了Cu基体的抗磨损性能。随着载荷的增加，Cu-纳米TiB2原位复合材料的磨损率和摩擦系数增加；由于在较高载荷下发生表面开裂，高含量的TiB2相增强原位复合材料发生了由轻度磨损向严重磨损形式的转化。在中等载荷下由于表面保护性氧化膜的形成和基体中纳米TiB2相的存在使复合材料具有良好的抗软化能力，Cu-纳米TiB2原位复合材料的磨损率和摩擦系数随着滑动速度的增加而下降。在较高滑动速度下，塑性流变和氧化磨损为其主要磨损机制。 在一定载荷和滑动速度下，随电流的增加，Cu-纳米TiB2原位复合材料的磨损率增加，Cu-纳米TiB2原位复合材料的电接触滑动磨损机制主要为磨粒磨损和电侵蚀磨损。更多还原

【Abstract】 Copper-nanosized TiBi composites were prepared by in-situ process. The microstructure, mechanical and electrical properties, and dry sliding wear behavior and electric sliding wear of Cu-nanosized TiB₂ in-situ composites was investigated; mostly task as follows:The thermodynamic data for the reactions between B and Ti in the molten liquid of copper were analyzed, the copper matrix composites reinforced by in-situ TiBi nanoparticles were prepared by reactions of 8263, carbon and titanium in copper-titanium melt, and copper-titanium, copper-boron in alloy melt, respectively, which controlled the reaction temperature, reaction time and solidification process.The rnicrostructure and mechanical and electrical properties of the in-situ composites were investigated by using optics microscope, TEM and XRD. The results showed that the in-situ formed TiBi particles which had a size of about 50nm, exhibited a homogenous dispersion in the copper matrix. Moreover, the interface between the nanoscale particles and the copper matrix was clean, and there was no certain location relationship. Due to their reinforcement, the tensile strength and hardness of the in-situ Cu-TiB₂ nanocomposite significantly improved.Dry sliding wear behavior and electric sliding wear of Cu-nanosized TiB2 in-situ composites were investigated using a pin-on-disk test rig. It has been found that TiB₂ nanoparticles improved the wear of resistance the in-situ composites. The wear rate and friction coefficient of the in-situ composites increased with increasing the applied load. Owing to the interfacial cracking which occurs under higher applied load conditions, the composite with high content of TiB₂ phase exhibited a transition from mild wear to severe wear over the applied load range from 10 N to 80 N. Under moderate applied load, Increasing the sliding speed caused a decrease in wear rate and friction coefficient of the in-situ composites because the formation of a protective oxide film occurred on the sliding surface and the hardness of the subsurface layer was maintained due toreinforcement of TiB2 nanoparticles in the Cu matrix. The predominant wear mechanisms of Cu-nanosized TiB2 in-situ composites are plastic flow and oxidational wear at higher sliding speed.Under a constant applied load and sliding speed, the wear rate of Cu-nanosized TiB2 in-situ composites was increased with increasing the electric current. The predominant electric wear mechanisms of the Cu-nanosized TiB2 in-situ composites are abrasive wear and arc erosion.更多还原