Cu-纳米TiB₂原位复合材料的微结构与性能

【作者】 荣伟；

【导师】 涂江平；

【作者基本信息】 浙江大学 ， 材料学， 2003， 硕士

【摘要】 本文以高强度、高导电和高耐磨性金属基复合材料为应用背景，对Cu-纳米TiB₂原位复合材料的制备工艺、组织结构及性能进行了研究。论文主要探讨了不同的材料制备工艺和TiB₂含量对Cu-纳米TiB₂原位复合材料微观结构和性能、特别是摩擦学性能的影响规律，以寻求最佳的材料制备工艺，满足Cu基复合材料高强度、高导电性以及优良摩擦磨损性能的要求。 从热力学的角度出发，探讨了TiB₂陶瓷相颗粒在Cu基体中原位生成的热力学条件。采用液相／液相原位反应法和固相／固相原位反应法，通过控制工艺流程和实验参数，制备出了Cu-纳米TiB₂原位复合材料。 采用金相光学显微镜、透射电子显微镜（TEM）、X射线衍射（XRD）和能谱仪（EDS）等对液相／液相和固相／固相原位反应法制备的Cu-纳米TiB₂原位复合材料的微结构进行了系统的观察，对原位生成的TiB₂纳米陶瓷相颗粒的形貌特征、形成机理做了较为详细的分析，并对冷加工变形的Cu基复合材料中TiB₂的分布情况进行了分析。结果表明，通过液相／液相和固相／固相原位反应法生成的TiB₂颗粒大小为10～20nm，在基体中均匀弥散分布，并且和基体之间的界面清洁，无界面生成物出现；形变加工工艺使TiB₂颗粒在Cu基体中呈方向性排布。 在Cu-纳米TiB₂原位复合材料微结构分析的基础上，研究了不同原位加工方法制备的Cu基复合材料的机械性能和电学性能，探讨了TiB₂含量及热处理工艺对Cu基复合材料的机械性能和电学性能的影响规律和作用机理。在实验范围内，Cu基复合材料的硬度随TiB₂含量的增加而逐渐增大；Cu基复合材料的强度随TiB₂含量的增加而不断增大，存在峰值强度。Cu-纳米TiB₂原位复合材料的电导率随TiB₂含量的增加而逐渐减小。 利用MMW-1型销—盘式磨损试验机研究了Cu-纳米TiB₂原位复合材料的干滑动摩擦磨损行为。探讨了施加载荷和滑动速度的改变对Cu基复合材料摩擦系数和磨损率的影响，并用扫描电子显微镜（SEM）对其磨损表面形貌进行了观察分析。研究表明，Cu-纳米TiB₂原位复合材料的摩擦系数和磨损率随TiB₂含量增加而减小。浙江大学硕士学位论文摘要载荷和滑动速度影响Cu一纳米TIB:原位复合材料的摩擦系数和磨损率，其磨损机制主要为粘着磨损和磨粒磨损。 在电接触滑动磨损试验机上进行了Cu一纳米TIB:原位复合材料的电接触滑动磨损实验。探讨了电流条件对Cu基复合材料滑动磨损性能的影响规律，并对其在电流作用下的磨损行为和机理进行了分析。结果表明，液相/液相法制备的Cu一纳米TIBZ原位复合材料的磨损率随电流的增加而增大:在相同电流条件下，Cu基复合材料的磨损率和基体中TIBZ含量近似成线性递减关系，TIB:的存在改善了Cu基复合材料的电接触滑动磨损性能;其磨损机制主要有粘着磨损、磨粒磨损和电侵蚀磨损。 综上所述，采用原位反应法生成的纳米TIBZ陶瓷相颗粒使Cu基复合材料的机械性能获得很大的提高。同时，纳米TIBZ颗粒存在有效改善了Cu基复合材料的摩擦学性能。更多还原

【Abstract】 Upon the application background of high strength, high conductivity and good wear resistance of metal matrix composites, the fabricated process, microstructures and properties of copper matrix composites reinforced by diboride titanium (TiB2) nanoparticles were investigated. In this paper, the effects of fabricated process and various TiB2 contents on the microstructure, mechanical property, electrical property, and tribological property of in-situ Cu-TiB2 nanocomposites was discussed, in order to meet with the demand of copper matrix composites with high strength, high conductivity and good wear resistance as well.The thermodynamic data for the reactions between B and Ti in copper matrix were analyzed. By the liquid-liquid in-situ reaction process and solid-solid in-situ reaction process, copper matrix composites reinforced by TiB2 nanoparticles were fabricated through controlling the process parameters.The microstructures of specimens fabricated by the liquid-liquid in-situ reaction process and solid-solid in-situ reaction process were systematically investigated by means of optical microscope, TEM, XRD and EDS. The morphological and structural characteristic of TiB2 nanoparticles and their formation mechanism were analyzed in detail, and the distributing of TiB2 nanoparticles in the copper matrix was observed. It was found that TiB2 globe-shaped particles have a size of about 10-20 nm and uniformly disperse in the copper matrix, and the interface between TiB2 nanoparticle and copper matrix was clear and clean. The TiB2 particles were oriented arrange in the as-drawn copper matrix composites.On the basis of the analysis of the microstructrue of copper matrix nanocomposites, the mechanical and electrical properties of the nanocomposites fabricated by different in-situ reaction processes were investigated. The effects and mechanisms of various TiB2 contents and heat treatment on mechanical and electrical properties of in-situ copper matrix nanocomposites were discussed. The results showed the hardness and strength of the in-situ nanocomposites increased with increasing the TiB2 content, and there was maximum strength value. The electrical conductivity decreases with increasing the TiB2 nanoparticles in the copper matrix.Dry sliding wear behavior of in situ Cu-TiB2 nanocomposites at different sliding speeds and loads was investigated on the MMW-1 pin-on-disk wear tester. The worn surfaces of the copper matrix nanocomposites were examined using scanning electron microscope (SEM). The friction coefficients and wear rate of in situ Cu-TiB2 nanocomposites decreased with increasing the TiB2 content, and were affected by different loads and sliding speeds. Adhesive wear and abrasive wear were the dominant wear mechanisms under dry sliding conditions.The electrical sliding wear behavior of in situ Cu-TiB2 nanocomposites was investigated on a pin-on-disk wear tester under electric current conditions. The worn surfaces of the copper matrix composites were examined by SEM. The results indicated that the wear rate of in situ Cu-TiB2 nanocomposites fabricated by liquid-liquid reaction process increased with increasing electric current. And under the same test conditions, the wear rate of the copper matrix composites decreased with increasing electric current. Adhesive wear, abrasive wear and arc erosion were the dominant wear mechanisms under electric current conditions.In conclusion, TiB2 nanoparticles fabricated by in-situ reaction can increase greatly mechanical property of the copper matrix composites, and improve obviously tribological property of Cu matrix composites.更多还原