Research on the anti-frost performance of hydrophobic TiN-polymer composite coating on aluminum alloy surface

It is well known that the heat exchanger of refrigerator or air conditioner is prone to freezing or condensation, which will affect the cooling effect inside the refrigerator or air conditioner, leading to extra power consumption and bacteria growth. In this study, we developed a multi-step method to prepare hydrophobic surfaces. In the first step, a needle-like structure is made on the surface of the aluminum alloy (AA) by alkali etching. To improve the durability and stability of coatings, different polymers, such as thermoplastic polyurethanes (TPU) or epoxy resin (EP), was mixed with titanium nitride (TiN) particles. Subsequently, the titanium nitride composite coating was applied to the substrate by spraying process or physical brushing technology which could be scaled up in the industry directly. After the final fluorination step, the aluminum substrate was covered with a hydrophobic surface. The results of the contact angle test assumed the hydrophobicity of the EP/TiN/FAS-17 and TPU/TiN/FAS-17 composite coatings. Additionally, compared to the pure TiN coating, the light conversion rate of the composite coatings maintained similar levels while better mechanical strength was achieved. Last but not least, both composite coatings demonstrated excellent ability to hinder icing in frosting and facilitate ice melting in defrosting experiments, further demonstrating their potential for use in anti-icing applications.