【作者】 金国；

【导师】 李庆芬； 徐滨士；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2006， 博士

【摘要】 磨损是材料失效的主要形式之一，因磨损造成的经济损失是非常惊人的，而且很多情况下是不可避免的。磨损一般发生在材料表面，因此普遍采用表面涂层的方法来减少材料的磨损。 本文采用新开发的电热爆炸定向喷涂技术制备了WC／Co金属陶瓷涂层和3Cr13不锈钢涂层；同时采用改进的高速电弧喷涂技术制备了3Cr13不锈钢涂层。利用SEM、TEM、EDAX、XRD及Nano-indentation等技术，研究了涂层的微观组织形貌、相结构、成分和纳米力学性能等；同时研究了涂层的滑动磨损性能和冲蚀磨损性能及其机理；借助数值计算和理论模拟分析了电热爆炸定向喷涂粒子沉积过程中的界面温度变化规律，得出了最大熔化深度和凝固速度等参数，并结合快速凝固理论分析了这些参数对涂层微观组织形成的影响，并对该结果进行了实验验证；在对某型重载车辆两种关键零件磨损机理分析的基础上，采取电热爆炸定向喷涂方法对其表面进行了修复和再制造，并装备到重载车辆上进行了实际应用研究。 组织结构分析结果表明：电热爆炸定向喷涂WC／Co和3Cr13涂层组织结构均由微纳米晶组成，涂层均匀致密，无层状结构，其与基体主要是冶金结合，硬度和弹性模量较高；而高速电弧喷涂3Cr13涂层较致密，具有明显的层状结构，与基体主要为机械结合。 耐磨性能研究结果表明：电热爆炸定向喷涂WC／Co金属陶瓷耐磨性能优异；电热爆炸定向喷涂3Cr13涂层的耐磨性比高速电弧喷涂3Cr13涂层的高。由磨损机理分析可知：电热爆炸定向喷涂WC／Co和3Cr13涂层优良的耐磨性是由其细晶强化效应、好的冶金结合以及“硬质耐磨相+软质基体相”特征决定的。 数值计算和理论模拟得出：电热爆炸定向喷涂粒子沉积过程中，沉积粒子的冷速很高，凝固速度很快；而高冷速有利于沉积粒子形成细晶组织，还可能形成非晶相；此外，快速凝固有利于形成柱状晶和等轴晶，且晶粒长大过程中易发生元素的偏析现象。这些结果均得到了实验验证。 重载车辆实车考核结果表明：电热爆炸定向喷涂层明显提高了关键零件更多还原

【Abstract】 Wear is one of the main materials failure forms. The economic loss resulting from wearing is enormous and unavoidable. The most adopted method to reduce wear is surface coating technology. And in hundreds of surface coating technologies, thermal spraying technology is used widely. But at the more and more rigor service conditions, the request for the coatings properties is more and more high. So the old spraying technologies are improved and new technologies are developed. Electro-thermal explosion directional spraying (EEDS) technology is one of such new developed technologies to prepare high properties coatings.In this paper, WC/Co cermet composites coatings and AISI 420 coatings were prepared by EEDS. AISI 420 coatings were also prepared by the improved high velocity arc spraying (HVAS) technology. The morphologies, compositions, phases and nano-mechanical properties of the coatings were determined by means of SEM, TEM, XRD, EDAX and nano-indentation test, respectively. Sliding wear and erosion wear properties and mechanisms were investigated. Numerical calculation and theory simulation were used to study the interface temperature, the largest melting depth, solidification speed. And experiments were operated to prove the results.The analyses of microstructures and properties of coatings show that the EEDS coatings are composed of nanometer/micrometer crystal and are characterized by uniform and compact microstructure, high hardness and elastic modulus, good bonding which mainly is a metallurgical one.The HVAS AISI 420 coatings are also compact but not as good as EEDS AISI 420 coatings. The coatings have obvious lamellar structure and the bonding is a mechanical one.The studies of wear resistances show that the EEDS WC/Co coatings have good wear resistance. The EEDS AISI 420 coatings have better wear resistance更多还原