以聚氨酯(PU)为粘合剂, 某片状金属粉为颜料, 采用刮涂法制备了PU/片状金属复合涂层。 对不同颜料含量条件下涂层的红外发射率进行了测试, 并采用扫描电镜对涂层的微结构进行了观察。 发射率测试结果表明, 涂层发射率随金属粉含量增加呈“∪”型变化。 微结构观察结果表明, PU/片状金属复合涂层由PU和片状金属粉交错堆叠而成, 具有类似一维光子结构特征。 基于涂层的微结构特征, 对具有转折变化特征的4个金属粉含量点状态下涂层中一维光子结构的反射光谱进行了模拟计算, 结果表明: PU/片状金属复合涂层的发射率随金属粉含量变化呈“∪”型变化关系特征主要是由涂层中一维光子结构的主反射峰中心波长随颜料含量增加所产生的蓝移现象引起的。

Polyurethane (PU)/flaky metal composite coatings were prepared by using PU and flaky metal powders as adhesives and pigments, respectively. The infrared emissivity of coatings with different metal content was measured by infrared emissometer, and the microstructure of PU/flaky metal composite coatings was observed by scanning electron microscopy. The results of infrared emissivity measurement indicate that the emissivity changes significantly with increasing metal content and presents a “U” type. The results of microstructure observation indicate that PU/flaky metal composite coatings have one-dimensional photonic structural characteristics. According to the microstructure characteristics, the optical reflection spectra of one-dimensional photonic structure in PU/flaky metal composite coatings with different metal content were simulated, and the results show that “U” type variation of emissivity with increasing metal content is derived from the blue-shift of reflection peak wavelength with increasing metal content of one-dimensional photonic structure in coatings.