表面特性对冰粘附强度影响的研究

发布时间：2018-03-07 06:38

本文选题：粘附强度　切入点：化学刻蚀　出处：《广州大学》2014年硕士论文　论文类型：学位论文

【摘要】：表面结冰不但降低了制冷系统的运行效率，而且给航天航空、电力传输、网络通讯等领域的正常运行带来了潜在的危险，甚至会造成严重的经济损失。因此，研究材料表面冰层粘附特性，特别是研究不同表面冰粘附强度的变化规律对抑冰除冰、保证系统安全高效运行有着重要意义。采用NaOH溶液化学刻蚀、氟硅烷修饰裸铝表面等方法制备了实验所需的具有不同表面特性的试片，并对其表面特性进行了实验表征，将各试片置于低温条件下结冰，利用构建的冰粘附强度实验装置，测试浸润性、表面微观结构和表面能等对试片表面冰粘附强度的影响规律，，进而探索抑冰减粘的材料表面，从而指导低粘附表面结构的优化设计。结果显示，疏水表面粘附强度均小于亲水表面的粘附强度，其中刻蚀时间为8min，氟硅烷修饰24h的S8#试片，表面接触角值最大（154.9°），其冰粘附强度最小，仅为22.8kPa，相比裸铝试片，冰粘附减小系数达3.3。进一步的研究表明冰粘附强度与接触角两者之间关系并不明确，不能单纯用表面接触角来评价材料表面抑冰减粘性能。通过对冰粘附强度与表面粗糙度、分形维数关系的分析，发现亲水表面冰粘附强度随着粗糙度的增加而增加，疏水表面上冰粘附强度随着粗糙度的增加而减小，这主要是由于表面粗糙度对浸润性的不同影响造成的。进一步分析表明，表面粗糙度与其粘附强度存在下列关系y=1.0726x+52.509（亲水）， y-0.6736x+74.483（疏水）；此外，亲水表面冰粘附强度随分形维数的增加而减小，疏水表面冰粘附强度随分形维数的增加而增加。相应的线性关系式分别为： y=-146.6x+493.5（亲水）， y=95.45x-209.9（疏水）。表面能也对冰粘附强度有较大影响。表面能较小的试片，冰粘附强度也较小；表面能较大的试片，冰粘附强度也较大。从经典异质核化理论分析，经氟硅烷修饰后表面能较低的铝表面，临界冰晶核半径较大，冰晶较难形成，导致冰粘附强度较小。
[Abstract]:Surface icing not only reduces the operational efficiency of the refrigeration system, but also brings potential danger to the normal operation of aerospace, electric power transmission, network communication and other fields, and even causes serious economic losses. It is of great significance to study the adhesion characteristics of ice layer on the surface of materials, especially to study the change of ice adhesion strength on different surfaces to suppress ice and deicing, and to ensure the safe and efficient operation of the system. Samples with different surface properties were prepared by chemical etching of NaOH solution and modification of bare aluminum surface by fluorosilane. The surface properties of the specimens were characterized by experiments, and each specimen was frozen at low temperature. The effects of wettability, surface microstructure and surface energy on the ice adhesion strength on the surface of the test piece were tested by using the ice adhesion strength experimental device, and then the surface of the material which inhibited the ice adhesion was explored. Therefore, the optimum design of low adhesion surface structure can be guided. The results showed that the adhesion strength of hydrophobic surface was lower than that of hydrophilic surface. The surface contact angle of S8# specimen modified with fluorosilane for 24 hours was 154.9 掳/ m, and the adhesion strength of ice was the smallest, only 22.8kPa. compared with bare aluminum specimen, the adhesive strength of hydrophobic surface was lower than that of hydrophilic surface. Further research shows that the relationship between the ice adhesion strength and the contact angle is not clear, and the surface contact angle can not be used to evaluate the surface ice antiadhesion performance of the materials. Through the analysis of the relationship between ice adhesion strength and surface roughness and fractal dimension, it is found that the ice adhesion strength of hydrophilic surface increases with the increase of roughness, and the ice adhesion strength on hydrophobic surface decreases with the increase of roughness. This is mainly due to the different effects of surface roughness on wettability. Further analysis shows that the relationship between surface roughness and its adhesion strength is as follows: y = 1.0726x 52.509 (hydrophilic, y-0.6736x 74.483) (hydrophobic; The adhesion strength of hydrophilic surface ice decreases with the increase of fractal dimension, and the adhesion strength of hydrophobic surface ice increases with the increase of fractal dimension. The corresponding linear relations are as follows: Y-146.6x 493.5 (hydrophilic, 95.45x-209.9). The surface energy also has a great influence on the ice adhesion strength. The ice adhesion strength is also smaller for the specimen with lower surface energy, and the ice adhesion strength is larger for the specimen with higher surface energy. When the surface energy of aluminum modified by fluorosilane is lower, the critical ice core radius is larger, and the ice crystal is difficult to form, which leads to the smaller adhesion strength of ice.
【学位授予单位】：广州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB657

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