超疏水低红外发射率复合涂层的制备及性能表征

目的制备得到具有超疏水特性的低红外发射率涂层。方法以纳米SiO_2为微纳结构改性剂,聚二甲基硅氧烷(PDMS)为树脂基体,Al粉为功能颜料,采用刮涂法制备得到了多种类型的改性和非改性PDMS/Al复合涂层。分析探讨了PDMS和Al粉配比、纳米SiO_2添加量及表面微纳结构层对涂层性能的影响规律及成因。结果 PDMS和Al粉配比对涂层发射率和光泽度影响明显,当PDMS和Al粉配比为6∶4时,涂层的发射率和光泽度可分别低至0.265和10.3,涂层的水接触角可达到109.5°,要明显高于传统树脂基低发射率涂层。添加纳米SiO_2可使涂层的粗糙度上升明显,从而使涂层的疏水性显著增强。当纳米SiO_2质量分数为8%时,涂层的水接触角可增大到130°,涂层的发射率和光泽度仍可低至0.330和9.8。PDMS/SiO_2微纳结构层可在PDMS/Al复合涂层表面形成明显的乳突状微纳结构,从而使涂层实现超疏水特性。当PDMS和纳米SiO_2配比为7∶3时,改性后的涂层水接触角可高达156°,同时具有相对较低的发射率(0.661)和极低的光泽度(2.1)。结论在PDMS/Al复合涂层表面构筑一定厚度的微纳结构层,可实现该涂层超疏水、低发射率和低光泽的兼容。

Preparation and Performance Characterization of Superhydrophobic Low Infrared Emissivity Composite Coating

The work aims to prepare a low infrared emissivity coating with superhydrophobic property.Various types of modified and unmodified polydimethylsiloxane(PDMS)/Al composite coatings were prepared by scratch coating method with nano-SiO2 as micro-nano structural modifier,PDMS as resin matrix and Al powders as functional pigments,respectively.The effects and causes of the ratio of PDMS to Al powders,the addition amount of nano-SiO2 and the surface micro-nano structural layer on the coating properties were discussed.The ratio of PDMS and Al powder had a significant effect on the emissivity and glossiness of the coating.When the ratio of PDMS to Al powders was 6∶4,the emissivity and glossiness of the coating could be as low as 0.265 and 10.3,respectively.The water contact angle could reach 109.5°,which was significantly higher than that of conventional resin-based low emissivity coating.Adding nano-SiO2 could significantly increase the roughness of the coating,thereby significantly enhancing the hydrophobicity of the coating.When the amount of nano-SiO2 was 8%,the water contact angle of the coating increased to 130°and the emissivity and glossiness of the coating could still be as low as 0.330 and 9.8.The PDMS/SiO2 micro-nano structural layer formed a distinct papillary micro-nano structure on the surface of the PDMS/Al composite coating,so that the coating achieved superhydrophobic property.When the ratio of PDMS to nano-SiO2 was 7∶3,the water contact angle of the modified coating could be as high as 156°,and the coating had a relatively low emissivity(0.661)and extremely low glossiness(2.1)performance.The compatibility of superhydrophobic property,low emissivity and low glossiness of the PDMS/Al composite coating can be achieved by constructing a micro-nano structural layer with a certain thickness on the surface of the coating.