【作者】 夏卫生；

【导师】 张海鸥；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2008， 博士

【摘要】 等离子熔射工艺具有短流程、快速成形等独特优势,已被广泛应用于诸多高新技术领域,如快速模具、功能涂层和固体氧化物燃料电池(SOFC)等。然而,等离子熔射是一种多个子过程相互依赖和参数相互关联的复杂工艺,如何选择合理的工艺参数,制备高性能的满足实际需求的涂层是控制制造过程的技术关键,从而对等离子熔射成形工艺的稳定性以及可再现性提出了新的高层次要求。因此,本文从成形系统设计、成形过程监控、工艺参数与射流形态和皮膜性能关系以及皮膜质量智能预测等方面开展了系统的研究,并将研究结果应用于固体氧化物燃料电池这一新能源领域。主要研究内容如下:(1)基于以太网开发了针对等离子熔射工艺需求的MOTOMAN UP20型机器人控制软件,采用PC+PLC开发等离子熔射控制系统,最终建立了熔射成形过程监控、机器人熔射路径在线调整和机器人实时监控等多功能集成的开放式机器人等离子熔射平台,从而实现了等离子熔射与机器人运动两工作单元自动协调的一体化控制,提高了成形系统柔性,为专用等离子熔射机器人系统的研制提供了技术基础。应用OPC(OLE for Process Control)协议与COM(Component Object Model)技术开发了机器人等离子熔射成形过程监控SprayMonitor软件。(2)提出了一种熔射皮膜温度在线检测方法,实现了对大范围皮膜温度分布的实时可视化监测与动态分析。通过实验研究了机器人路径对皮膜温度分布的影响,分析了皮膜破坏的温度突变信息,分析了不同熔射距离与射流长度条件下的热传递特点等。相关研究结论为等离子熔射成形性与质量控制提供了依据。(3)率先开展熔射工艺参数与射流形态和皮膜性能之间关系的研究。提出了采用射流狭长度对射流形态进行表征,并对工艺参数与狭长度特征值进行聚类分析。根据皮膜性能参数以及微观组织结构对分类结果进行质量评判,生成由工艺参数到最佳分类的推理规则集,据此提出一种等离子射流产生子系统的智能化控制方案。(4)为将等离子熔射拓展到制备高性能SOFC核心部件的领域,自主设计了液料输送系统,采用液料等离子熔射制备出高致密度的SOFC电解质层(孔隙率1.61%)。皮膜微观组织分析表明,粉末颗粒熔化比较充分,层间结合紧密,因此不仅有利于提高电解质层的机械强度和致密性,而且有助于提高其导电性能。在上述研究的基础上,对大气与液料等离子熔射制备SOFC核心部件过程进行射流诊断以及温度监控等,改进了成形工艺、提高了工艺稳定性与可再现性。本文研究内容为机器人等离子熔射成形过程中等离子电源参数、机器人熔射路径以及送粉、送液等多工艺条件的合理匹配提供了依据,为一次熔射成形包含孔隙电极和致密电解质层的SOFC三合一电极提供了关键技术基础。更多还原

【Abstract】 Plasma spray has been applied widely in the high and new technology industries, such as rapid mould, functional coating, solid oxide fuel cell (SOFC) and so on, in view of its short-circuit, rapid and other unique characteristics. However, as a complicated process with the multiple sub-process correlations and the parameter interdependencies, it is a key issue to select the appropriate spraying parameters to fabricate the high-quality coatings meeting with the actual requirements in the control of the manufacturing process. Furthermore, high grade and new demands for the process stability and reproducibility of plasma spray arise. Therefore, systematic researches ranging from developing the control system, monitoring the spraying process, investigating relationships between processing parameter, plasma jet and coating quality, and predicting the resultant coating quality are carried out in this thesis. Relevant results are applied in the SOFC, a new energy resource field, and major research contents are listed as follows.(1) Specially designed MOTOMAN UP20 robot control software was presented based on Ethernet to meet with the requirements of plasma spray. Plasma spray control system was developed based on PC+PLC. Finally, the Open architecture robotic plasma spray forming system was established accompanied with forming process monitoring, on-line adjustment of robot spraying trajectories, real-time control of robot and other functions. The flexibility of the resultant forming system is promoted integrating the two working units, the plasma spray forming and the robot motion control. They are the technical foundation for the development of the professional robotic plasma spray system. A monitoring software SprayMonitor was developed on the basis of OPC (OLE for Process Control) protocol and COM (Component Object Model).(2) An on-line temperature measurement approach for sprayed coatings is presented in this dissertation, which realizes the real-time visual monitoring and dynamic analysis. The influence of robot spray trajectory parameters on coating temperature was experimentally investigated. The analysis of heating effect on substrate by plasma jet and particle flux were carried out under different spray distances and lengths of plasma jet to analyze their characteristics. These conclusions can be used in the formability and quality control of plasma spray.(3) Investigations on the relationship between processing parameter, plasma jet and coating quality were carried out. The morphological feature of plasma jet was first characterized by the aspect ratio, and the clustering analysis was done based on experimental results. The quality of clusters was evaluated by the properties and microstructure of coatings, so the inference rule sets from processing parameters to the optimal quality cluster were produced. Hence, an intelligent control approach of plasma power source was presented.(4) To shift plasma spray to the new field, manufacturing core compontents of SOFC, the liquid feedstock system was designed, and suspension plasma spray (SPS) was used to prepare the dense electrolyte of SOFCs. The porosity of the resultant electrolyte is 1.61%. SEM of the electrolyte coating show that melting state of spray particles was sufficiently promoted during the process of SPS and the tight bonding among the flat layers was also observed. Both the factors are not only favorable to enhance the mechanical strength and density, but also helpful to effectively improve the electrical conductivity of electrolyte.Based on the studies above, the quality diagnosis of plasma jet and the temperature control of sprayed coating were carried out during fabricating core components of SOFC by APS and SPS. Both the spray forming processes were improved and their stability and reproducibility were also upgraded.The contents of this thesis provide a reference for optimal matching of plasma spraying parameters, including plasma power source, robot spray trajectories, powder and suspension feeding and so on. Furthermore, they are also the key technique foundation for the fabrication of the core component of SOFC during the integral spray process by APS and SPS, which contains the porous electrodes but density electrolyte.更多还原