换热器表面疏水涂层的制备及性能测试

Preparation and Performance Test of Hydrophobic Coating on Heat Exchanger Surface

摘要:

在可溶性聚四氟乙烯（PFA）、聚四氟乙烯（PTFE）及环氧树脂（EP）中添加纳米二氧化硅等材料，制备了应用于冷凝式换热器表面的超疏水自清洁性复合涂层。对复合涂层进行接触角、导热系数、耐磨性、结合强度及自清洁性测试，研究其综合性能。测试结果表明，含7.5 %~9.4 %纳米SiO₂的PFA涂层与含1.4 %~2.3 %纳米SiO₂的PTFE涂层接触角均在150°以上，其表面自清洁性优异。添加0.8 %~1.7 %的石墨可将涂层的导热系数由0.2 W·m^-1·K^-1提升至2 W·m^-1·K^-1以上。涂层的耐磨性随SiC含量的增加而提升，对于PFA超疏水涂层，添加SiC能使涂层被砂纸打磨后仍能保持良好的疏水性。EP涂层的结合强度达ASTM（美国材料与试验协会）等级5B，PFA涂层为4B，PTFE涂层为3B。

Abstract:

A superhydrophobic self-cleaning composite coating applied to the surface of a condensing heat exchanger was prepared by adding nano-silica and other materials to polyfluoroalkoxy（PFA）， polytetrafluoroethylene（PTFE） and epoxy resin（EP）. The composite coatings were tested for contact angle， thermal conductivity， wear resistance， bonding strength and self-cleaning properties to study its comprehensive properties. The test results show that the contact angles of the PFA coating containing 7.5 %–9.4 % nano-SiO₂ and the PTFE coating containing 1.4 %–2.3 % nano-SiO₂ are both above 150°， and its surface self-cleaning is excellent. The thermal conductivity of coatings can be increased from 0.2 W·m^-1·K^-1 to more than 2 W·m^-1·K^-1 by adding 0.8 %–1.7 % of graphite. The wear resistance of the coating increases with the increase in the SiC content. For the PFA superhydrophobic coating， the addition of SiC enables the coating to maintain good hydrophobicity after grinding. The bonding strength of the epoxy resin coating reaches ASTM （American Society of Testing Materials)grade 5B， while that of the PFA coating and PTFE coating is 4B and 3B， respectively.