聚合物自清洁表面微热压成型的机理研究

发布时间：2018-03-22 11:29

本文选题：自清洁　切入点：微热压成型　出处：《南昌大学》2017年硕士论文　论文类型：学位论文

【摘要】：换热设备结垢会导致换热器传热效率降低和能耗增加,为此,换热设备结垢的自清洁技术是实现其节能减排急需解决的关键技术问题。荷叶出污泥而不染的自清洁仿生机理研究表明解决表面结垢问题的的技术关键是通过在高能表面形成纳米微观结构粗糙表面,这可以获得类似的仿生自清洁功能,而实现这一仿生自清洁目标的技术关键是纳米微观结构粗糙自清洁功能表面的加工成型技术。基于这一工程背景,本文研究了纳米微观结构粗糙自清洁功能表面微热压成型技术,通过数值模拟研究了成型工艺参数、基片材料性能参数和纳米微观结构粗糙自清洁功能表面形貌对微热压成型过程的影响规律,揭示了纳米微观结构粗糙自清洁功能表面微热压成型机理,明晰了关键调控参数,为纳米微观结构粗糙自清洁功能表面微热压成型技术向以科学求质量、以技术保成功的全流程综合控制的工业化科学制造转化奠定了科学的理论基础和技术支撑。主要取得如下成果:基于纳米微观结构粗糙自清洁功能表面微热压成型的黏弹性、屈服、软化、硬化四个本质力学变形特性和连续固相相变演化特点,结合大温度变化范围大变形应力应变关系曲线实验结果,筛选出能预测相变演化影响的热机械大变形黏弹性-塑性应力应变本构模型;通过数值模拟,系统研究了工艺参数、基片材料特性和自清洁功能表面形貌对纳米微观结构粗糙自清洁功能表面微热压成型过程的影响规律,研究表明基片弹性模量、热压成型温度和压力是影响制品品质的关键调控参数,热压成型压力和成型变形应力与热压成型温度和模腔流道直径呈负关联关系,提高其热压成型温度至跨越基片材料玻璃化转变温度,使基片材料处于黏弹性高弹态,可使热压成型压力和成型变形应力趋于最小值,有利于成型制品脱模和避免基片热压成型断裂损伤和变形失效;研究发现基片材料改变对热压成型充填过程影响主要体现在反映基片材料抗变形能力的机械性能指标弹性模量,而基片材料固相连续相变演化是造成弹性模量急剧突降的主控因素;圆柱模型和圆锥台模型热压成型过程对比分析研究表明,圆锥台模型微热压成型压力和变形应力明显大于圆柱模型微热压成型压力和变形应力,且随着模型直径增大而下降。
[Abstract]:Scaling in heat exchangers can reduce heat transfer efficiency and increase energy consumption. Self-cleaning technology of heat exchanger is the key technology to realize energy saving and emission reduction. The research on bionic mechanism of self-cleaning and non-dyeing of lotus leaf sludge shows that the key technology to solve the problem of surface scaling is to solve the problem of scaling on the surface. High energy surfaces form nano-microstructure rough surfaces, This can obtain similar bionic self-cleaning function, and the key technology to achieve this bionic self-cleaning goal is the processing and molding technology of nano-microstructure rough self-cleaning functional surface. In this paper, the micro-hot pressing technology of nano-microstructure rough self-cleaning functional surface was studied, and the process parameters were studied by numerical simulation. The influence of the properties of substrate material and the surface morphology of nano-structure rough self-cleaning function on the micro-hot pressing process was studied. The mechanism of micro-hot-pressing forming of nano-microstructure rough self-cleaning functional surface was revealed, and the key control parameters were clarified. In order to obtain the quality scientifically, the micro-hot pressing technology of nano-microstructure and self-cleaning function surface can be obtained. The scientific theory foundation and technical support have been established by the industrialized scientific manufacturing transformation controlled by the technology guarantee. The main achievements are as follows: the viscoelasticity of micro-hot pressing molding based on the nano-microstructure rough self-cleaning functional surface, The four essential mechanical deformation characteristics of yield, softening and hardening and the evolution characteristics of continuous solid phase transformation are combined with the experimental results of the stress-strain relation curve of large temperature range and large deformation. A viscoelastic-plastic stress-strain constitutive model for large deformation of thermal machinery was selected to predict the effect of phase transition evolution, and the process parameters were systematically studied by numerical simulation. The effect of substrate material characteristics and self-cleaning function surface morphology on the micro-hot pressing process of nano-structure rough self-cleaning functional surface was studied. The results showed that the elastic modulus of the substrate was improved. The temperature and pressure of hot pressing are the key control parameters that affect the quality of products. The forming pressure and deformation stress have a negative correlation with the temperature of hot pressing and the diameter of die cavity. By increasing the hot pressing temperature to the glass transition temperature across the substrate material and making the substrate material in a viscoelastic high elastic state, the forming pressure and deformation stress of the substrate can be minimized. It is found that the influence of the change of substrate material on the filling process is mainly reflected in the elastic modulus, which reflects the deformation resistance of the substrate material. The continuous phase transition evolution of substrate material is the main controlling factor for the sharp drop of elastic modulus, and the comparative analysis of hot pressing process between cylindrical model and conical table model shows that, The micro-hot pressing pressure and deformation stress of the cone model are obviously higher than those of the cylindrical model, and the pressure and deformation stress decrease with the increase of the diameter of the model.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O631.11

【参考文献】