石墨烯对聚氨酯/Al复合涂层耐盐水性能的影响

目的提高聚氨酯(PU)/Al复合涂层的耐盐水性能。方法以石墨烯为改性剂、PU为粘合剂、Al粉为颜料,采用刮涂法制备石墨烯改性PU/Al复合涂层,分析探讨改性前后涂层经盐水腐蚀不同时间后,微结构、红外发射率、光泽度及力学性能的变化规律及成因。结果石墨烯改性涂层的发射率对盐水腐蚀的稳定性改善明显,经盐水腐蚀21 d后,发射率仅从腐蚀前的0.335上升为腐蚀后的0.355。经长时间盐水腐蚀后,改性后涂层比改性前涂层具有更低的发射率。在不同的盐水腐蚀时间内,改性后涂层比改性前涂层均具有更低的光泽度,且稳定性较高,经盐水腐蚀21d后,改性后涂层的光泽度仍然可保持在16.1,这有利于实现涂层的低发射率与低光泽兼容。改性前后涂层的硬度、附着力对盐水腐蚀均具有较高的稳定性,说明石墨烯改性对改善涂层耐冲击强度及盐水腐蚀的稳定性作用有限,后续仍需进一步研究改进。结论石墨烯改性可明显提高PU/Al复合涂层的红外发射率及光泽度对盐水腐蚀的稳定性。

Effect of Graphene on the Salt Water Resistance of Polyurethane/Al Composite Coating

The work aims to improve the salt water resistance of polyurethane(PU)/Al composite coating. Graphene modified PU/Al composite coating was prepared by scratch coating method with graphene, PU and Al powders as modification agent, adhesives and pigments, respectively. The variation and causes of microstructure, infrared emissivity, glossiness and mechanical properties of the coating before and after modification by salt water corrosion for different times were discussed. The emissivity stability to salt water corrosion of the graphene modified coating was significantly improved. After salt water corrosion for 21 days, the emissivity was only increased from 0.335 before corrosion to 0.355 after corrosion. After a long period of salt water corrosion, the modified coating had a lower emissivity than the unmodified coating. The modified coating had lower glossiness than the unmodified coating for different salt water corrosion times, and had high stability. After salt water corrosion for 21 days, the glossiness of the modified coating could still be kept at a lower value of 16.1, which was beneficial to achieve compatibility of low emissivity and low glossiness of the coating. The hardness and adhesion strength of the coatings before and after modification had high stability to salt water corrosion. Graphene modification had limited effect on improving the stability of impact strength of the coating to salt water corrosion, and further research and improvement were needed. Graphene modification can significantly improve the stability of infrared emissivity and glossiness to the salt water corrosion of PU/Al composite coating.