【作者】 刘朝晖；

【导师】 黄因慧；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2006， 硕士

【摘要】 传统陶瓷材料具有优异的耐磨、耐蚀、耐热和抗高温氧化性能,但其脆性较大且难以加工;而纳米陶瓷材料具有良好的韧性和优异的力学性能,并兼具有传统陶瓷材料的优点。本文将激光重熔的方法与纳米陶瓷材料复合电沉积技术结合起来,利用喷射电沉积的方法以提高材料所选定区域复合沉积的形成效率,再利用激光重熔复合镀层,使复合镀层与基体之间原有的机械结合变为冶金结合,以增强了结合力,并提高复合层的表面特性。主要工作有以下:1.分析了电沉积的阴极过程、金属电结晶过程、喷射电镀、激光重熔等的特点和相关基础理论,利用激光作用下热力学方程建立了激光扫描的热传导模型,并分析了与纳米喷射复合电镀和激光重熔相关的工艺。2.开展了Ni-纳米Al₂O₃复合电镀层工艺的试验研究,利用大功率CO2激光对复合镀层进行重熔,通过试验手段初探了Ni-纳米Al₂O₃复合镀层的制备及复合镀层激光重熔的工艺。3.分析复合电沉积激光重熔试验所得数据,研究纳米Al₂O₃颗粒的加入对镀层的微观组织、显微硬度、耐腐蚀性能的影响,以及激光重熔对复合镀层试件的性能影响。4.分析了试件激光重熔后熔池附近的金相组织,纳米Al₂O₃颗粒在镀层中的含量及分布形式,试件的断口形貌,探讨了导致试件抗拉性能和断后延伸率下降的原因;对腐蚀后的试件表面进行金相分析,探讨了腐蚀速度加快的原因;对添加纳米Al₂O₃颗粒复合镀层及重熔后的镀层进行XRD和SEM分析,得到Al₂O₃在复合镀层中含量和存在形式。更多还原

【Abstract】 Traditional ceramic materials have good performance in wear-resistant, corrosive-resistant, heat-resistant etc, but it’s hard to machine for its brittleness, however, nano-scale ceramic material has good toughness, novelty performance and good performance of the traditional. In this article, the technology combining laser remelting technology with nano ceramic co-depositing is used. Numerical control selective jet electro deposition is used to improve the shaping efficiency of selective region, then laser remelting is used to change the mechanical combination of codeposition to the alloyed combination to improve the surface performance. Main works completed and conclusions summarized are presented as follows:1. The cathode process of electro deposition, the process of crystal, characteristic and correlative theories of jet electro deposition and laser remelting are analyzed. The formula of heat transferring of scanning laser is built by referring the formula of thermodynamics of laser. The correlative technics of nano jet co-depositing and laser remelting is also analyzed.2. In the experimental research of nickel nano alumina composite depositing, high power carbon dioxide laser is used to remelt the codeposition coatings, and technics of preparation nickel nano alumina codeposition coatings and laser remelting is originally explored.3. By analyzing the data of experiment, the affect of the microstructure, micro-hardness and corrosive-resistant of the coating of codeposition after the insert of nano-scale alumina particles is expatiated. And the affect of the microstructure, tensile strength and corrosive-resistant of the samples after remelted is also expatiated.4. Metallograph of the nearby the melt pool is observed, and the content of alumina in coating and break appearance are analyzed. The cause of tensile strength and specific elongation getting worse is also probed. By analyzing the corrosion figure of the surface of samples, the cause of corrosion speed up is probed. By analyzing coating that remelted and unremelted by SEM and XRD, the content and state of alumina existing in coating is acknowledged.更多还原