【作者】 方学锋；

【导师】 王泽华；

【作者基本信息】 河海大学 ， 材料加工工程， 2006， 硕士

【摘要】 铝合金是交通运输工具尤其是汽车实现轻量化的首选材料,但受其硬度低和耐磨性差的缘故,使用范围受到很大的限制。通过应用等离子喷涂技术,在铝合金零部件表面形成一层硬度高、耐磨性好的材料,解决铝合金硬度低和耐磨性差的缺点。涂层与铝合金基体结合强度低是当前影响等离子喷涂应用的核心问题,本文从涂层与铝合金基体的结合机理和喷涂工艺上研究了等离子喷涂Al₂O₃-45TiO₂的结合性能。 本文概述了等离子喷涂技术原理及工艺流程,分析了涂层结构、喷涂工艺、熔融粒子受热及运动对涂层结合强度的影响。探讨了涂层结合过程和结合机理。 在确定主要影响参数的基础上,对粘结底层NiCrAlCo—Y₂O₃和工作层Al₂O₃-45TiO₂进行了结合强度正交试验,得到了影响结合强度的主次因素,优化了粘结底层和工作层的喷涂工艺,提出了等离子喷涂NiCrAlCo—Y₂O₃粘结底层和Al₂O₃-45TiO₂工作层的最佳工艺参数。 对Al₂O₃-45TiO₂和WC-10Co4Cr两种陶瓷涂层进行了比较,氧化物系陶瓷无高温烧损和分解现象,性能更好;考虑铝合金高温氧化问题,设计了氩气保护环境下喷涂,减少了表面氧化铝对涂层与基体结合界面的不良影响,Al₂O₃-45TiO₂与铝合金基体的结合强度由原来的28.0MPa提高到31.6MPa。 设计并喷涂了梯度涂层和非梯度涂层,对梯度涂层和非梯度涂层的性能进行了比较试验。梯度涂层减少了涂层的内应力,结合强度提高到37.4MPa。采用线扫描对涂层成分进行分析,检测结果表明,涂层的实际成分分布与设计要求一致。 通过金相显微镜、扫描电镜和能谱分析仪对涂层进行微观检测,从本质上对试验的结果进行分析,为提高铝基体与涂层的结合强度提出了可靠的依据。更多还原

【Abstract】 Aluminum alloy is an optimum material for light weighting of vehicles, especially for automobiles. But, the low hardness and bad wear-resistance limited its application. Using plasma spraying technology to spray a hard coating on aluminum substrate can solve the shortages. Low bonding strength is a critical problem restricting its application of plasma spraying on aluminum. Bonding performance of plasma spraying Al₂O₃-45TiO₉ coating on aluminum substrate was researched from the respects of bonding mechanism and spraying processing.The principle of plasma spraying technology and its process were summarized. The influence of coatings structure, spraying parameters, heat transfer and movement of melt particles to the bonding strength was investigated. And the bonding mechanism was discussed.Orthogonal experiments were carried out on the spraying parameters of the process with NiCrAICo—Y₂O₃ bonding coatings and Al₂O₃-45TiO₂working coatings,which selected the primary influence factors and secondary influence factors. The optimized spraying processes for NiCrAICo — Y₂O₃ bonding coatings and Al₂O₃-45TiO₂ working coatings were determined.Al₂O₃-45TiO₂ coating was compared with WC-10Co4Cr coating. It showed that oxide ceramic coating was better than carbide coating as no burning loss of elements and no decomposition of compounds at high temperature. Considering the easy oxidation of aluminum at high temperature, it was designed to spray coating with the argon atmosphere to decrease the oxidation of aluminum substrate and reduce the forming of alumina on interface. Compared with the coating sprayed at atmosphere, the bonding strength of Al₂O₃-45TiO₂ coating sprayed at argon atmosphere was increased from 28.0MPa to 31.6MPa.Gradient and non-gradient of Al₂O₃-45TiO₂ coatings were designed and manufactured. The bonding strength was studied. The results showed that the gradient coating reduced the inner stress of coating and increased the bonding strength. The bonding strength of gradient coatings was high up to 37.4MPa. The chemical elementdistribution of the coating was measured with lining scan of the probe. The testing result was consistent with the design.The coatings were inspected by using equipment of metallurgical microscope, stereoscan and energy spectrometer, managing to find out the microstructure and the reason effecting on the bonding strength of Al-,O3-45TiO, coating on aluminum substrate.更多还原