仿生减阻涂层的制备及性能研究

发布时间：2018-02-02 18:02

本文关键词： 减阻超疏水涂层粘附力水凝胶表面摩擦系数　出处：《哈尔滨工程大学》2016年博士论文　论文类型：学位论文

【摘要】：水面及水下的航行器运行时遇到巨大的阻力,不仅会降低运动速度,导致机动性降低,还会增加能量消耗。因此,有效降低航行器运行时的阻力具有重大的意义。本文通过向自然学习,仿生荷叶及鱼体表粘液,制备超疏水涂层和水凝胶缓释涂层,分别考察其减阻的可能性并对减阻机理进行分析。通过化学沉积法在铜箔表面制备得到疏水性优异的超疏水涂层,经此涂层修饰的模型在水面运动速度得到提升,但涂层的机械稳定性差,在轻微的外界摩擦力作用下即可被破坏,从而失去超疏水性。利用高分子树脂固定疏水颗粒的方法(PDMS/铜粉)结合了基体树脂的韧性和疏水颗粒的粗糙结构可以实现稳定超疏水涂层的制备,不仅能够抵抗外界机械摩擦,还能够承受较高的温度及静水压力。通过对涂层的形貌及表面浸润性等性能进行分析,发现表面粗糙度对疏水性具有重要的影响。将PDMS/铜粉超疏水涂层修饰潜艇模型后,模型在水中完全被一层空气膜包围,通过速度测试,超疏水修饰后模型的运动速度可以提高10-15%,从而彻底排除超疏水使水面运动物体浸润面积减小从而降低摩擦阻力的说法,进一步说明是气液界面处摩擦力的降低而使模型的运动速度增加。利用碱性溶液腐蚀金属的方法制备得到具有减阻功能且耐溶剂的超疏水涂层。腐蚀时间对涂层的微观结构及组成有明显的影响,通过调控腐蚀时间可以调控涂层的表面形貌进而调节涂层表面的疏水性能。不同亲疏水性(超亲水、亲水、疏水、超疏水)表面的阻力系数差别巨大;低速运动时,物体表面由疏水状态转变为超疏水后阻力系数可降低80%。利用喷涂疏水纳米二氧化硅的方法在打磨的模型表面制备得到超疏水涂层,涂层具有明显的减阻效果;这种普适性的方法,不仅降低了超疏水涂层的制备难度,同时为低成本、大面积超疏水涂层的制备提供了思路。通过化学法得到具有高机械强度的高分子水凝胶,长直链分子减阻剂的加入不仅增加水凝胶的机械性能,其渗出后还能够降低水凝胶表面的摩擦系数,提高水凝胶表面的减阻效果。模具的亲疏水性对水凝胶表面有明显影响,亲水模具制备得到水凝胶表面摩擦系数高,会增加模型在水中运动的阻力;疏水模具制备得到水凝胶具有极低的表面摩擦系数,能够降低模型在水中的运动阻力。
[Abstract]:When the surface and underwater vehicle run into great resistance, it will not only reduce the speed of motion, resulting in lower mobility, but also increase energy consumption. It is of great significance to effectively reduce the resistance when the vehicle is running. In this paper, superhydrophobic coatings and hydrogel sustained-release coatings are prepared by learning from nature, bionic lotus leaves and fish surface mucus. The possibility of drag reduction was investigated and the mechanism of drag reduction was analyzed. Excellent hydrophobic superhydrophobic coatings were prepared on copper foil by chemical deposition. The model modified by this coating can improve the velocity of motion on the surface of water, but the mechanical stability of the coating is poor, and it can be destroyed under the action of slight external friction. Thus the super hydrophobicity was lost. PDMS / copper powder was used to fix the hydrophobic particles of polymer resin) the toughness of the matrix resin and the rough structure of the hydrophobic particles could be combined to achieve the preparation of stable superhydrophobic coatings. Not only can resist external mechanical friction, but also can withstand higher temperature and hydrostatic pressure. The morphology and surface wettability of the coating were analyzed. It is found that the surface roughness has an important effect on hydrophobicity. PDMS / Cu powder superhydrophobic coating is used to modify the submarine model, and the model is completely surrounded by an air film in the water and passed the velocity test. After superhydrophobic modification, the velocity of the model can be increased by 10-15, thus completely eliminating the theory that super-hydrophobic can reduce the area of water surface moving object and thus reduce the friction resistance. It is further explained that the reduction of friction at the gas-liquid interface increases the speed of movement of the model. A drag reducing and solvent resistant superhydrophobic coating is prepared by corrosion of the metal in alkaline solution. The corrosion time of the coating is related to the effect of corrosion time on the coating. The microstructure and composition of these compounds have obvious influence. The surface morphology and hydrophobic properties of the coating can be adjusted by adjusting the corrosion time. The resistance coefficients of different hydrophobic surfaces (superhydrophilic, hydrophilic, hydrophobic and superhydrophobic) are greatly different. When moving at low speed, the surface resistance coefficient can be reduced by 80% from hydrophobic state to superhydrophobic state. The superhydrophobic coating is prepared on the surface of the model by spraying hydrophobic nano-silica. The coating has obvious drag reduction effect. This universal method not only reduces the difficulty of preparing superhydrophobic coatings, but also reduces the cost. High molecular hydrogel with high mechanical strength was obtained by chemical method. The addition of long chain molecular drag reducer not only increased the mechanical properties of hydrogel. After exudation, the friction coefficient of hydrogel surface can be reduced, and the drag reduction effect of hydrogel surface can be improved. The hydrophobicity of mould has obvious influence on hydrogel surface. The surface friction coefficient of hydrogel is high when the hydrophilic mould is made, which will increase the resistance of the hydrophilic mold in water. Hydrophobic mold made hydrogel has a very low surface friction coefficient, which can reduce the movement resistance of the model in water.
【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：U661.311;TG174.4

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