【作者】 刘燕；

【导师】 任露泉；

【作者基本信息】 吉林大学 ， 农业机械化工程， 2006， 博士

【摘要】 灰铸铁与粉末冶金材料是两种在工业中广泛使用的材料,由于加工工艺限制,表面硬度低、耐磨性差,降低了零件寿命,增大了损耗,运用表面改性技术改善表面性能是工业界急待解决的问题。本文针对灰铸铁与粉末冶金材料基体,借鉴天然生物材料例如骨骼、竹材、木材等分级梯度结构特征,采用了两种表面改性技术-激光熔覆法和复合电沉积法,进行仿生梯度纳米复合涂层的设计与制备。运用试验优化设计的方法,优化了工艺参数。深入探讨了两种表面改性技术的工艺参数对涂层组织与性能的影响,揭示了激光熔覆层中不同部分组织的形成机理,系统分析了复合电沉积工艺参数对涂层中纳米颗粒含量、组织、形貌、性能的影响,其中工艺参数对复合涂层组织、形貌的影响规律和机理,目前在文献中少见报道。比较了仿生梯度复合涂层与基体或未增加纳米材料涂层的组织与性能,激光熔覆法中比较了仿生梯度复合涂层与基体的耐磨性,并分析了耐磨机理;复合电沉积法中比较了仿生梯度复合涂层与纯镍钴层组织及耐磨性,并分析了组织形成机理及耐磨机理。系统分析了两种涂层结构、成分及性能的变化特征,激光熔覆法制备的仿生梯度复合涂层从熔覆区到基体区结构呈现梯度变化,硬度也呈现梯度变化;电沉积法制备的仿生梯度复合涂层由表层到里层纳米颗粒含量呈现梯度变化,硬度也呈现梯度变化。特别地,复合电沉积法制备的仿生梯度复合涂层具有疏水性,运用仿生非光滑理论对其疏水原理进行了分析。在定性分析电沉积法仿生梯度复合涂层微观形貌的基础上,采用分形分析定量分析表面微观形貌,分析表明复合涂层具有分形特征。上述的研究工作为新型的梯度涂层的设计、制备及研究提供了一定的理论依据,也为材料的仿生涂层技术拓宽了应用领域。更多还原

【Abstract】 The gray iron and the powder metallurgy parts are two kinds the widely used materials in the industry. Due to limitation of processing technology, the surface property of materials is poor. Therefore, it is essential to improve surface properties by surface modification technology.The hierarchical gradient character of nature materials such as skeleton ,bamboo and wood are designed on the gray iron surface and the powder metallurgy parts surface in the paper.The two kinds of methods are used both laser cladding and composite electrodeposition.The biomimetic gradient nano-composite coating are prepared.The experiment optimization design method are used to the craft parameters optimal.The results are concluded the craft parameters are best when power of laser cladding is 3.0kw and the scanning speed is 90mm/min on gray iron surface. Similar to the craft parameters are best when power of laser cladding is 2.5kw and the scanning speed is 90mm/min on powder metallurgy materials surface.The results are concluded in composite electrodeposition that the crafe parameters are best when current density is 40mAcm-2,pH value is 3～4,stiring style is supersonic vibration mix mechanical stiring, content of nano-particulates is 20g/l.The influence of craft parameters are discussed on gray iron and powder metallurgy surface modification coating during laser cladding.The microstrcture are effected by content, the craft parameters, shape control factor G/υ(Gradient of temperature/coagulation speed) but the shape control factor is decided by craft parameters.The microstructure of coating on gray iron surface and powder metallurgy更多还原