Fabrication Of Superhydrophobic Surfaces On Copper Substrates Via Flow Plating Technology

Superhydrophobic surface is the surface with a contact angle above150°. It is significant to construct superhydrophobic surfaces with comprehensive properties on copper substrates. However, the existing methods of preparing superhydrophobic surfaces on copper substrates have defects, such as the complex processes and the poor mechanical property. To solve the problems, using flow plating technology to prepare composite coating on copper substrates by adding nano-particle into the nickel plating solution is proposed. The main work includes the following.An improved experimental device for flow plating technology was designed for settling the problem that graphite electrode is perishable. Thanks to the improved experimental device, processing voltage can be greatly decreased with a simplified process and higher process efficience.Ni/SiO2composite coating and Ni/Al2O3composite coating with excellent superhydrophobicity are attained using this new equipment. The influence of main processing parameters on contact angle and sliding angle of water droplet is researched. Under the condition of12V plating voltage and4min plating time, the contact angle and the sliding angle on the obtained Ni/SiO2composite coating are165°and4.3°respectively while the contact angle and the sliding angle on the Ni/Al2O3composite coating are162°and5.5°respectively.Through analyzing the wettability model of superhydrophobic composite coating, it can be inferred that the contact between water droplets and the composite coating conforms to the Cassie state. Water droplets won’t sank in the micro/nano structures, so the sliding angles are small because of little sliding resistance.The influence of plating voltage and plating time on the morphology and wettability of the Ni/SiO2composite coatings and the Ni/Al2O3composite coatings is studied. It is found that cavities and micrometer scale papilla-like structures composed of clusters of grains are evenly distributed on the processed surfaces and nano-scale villiform structures are found embedded in the micrometer scale structures. These micro/nano structures with globular particles and nano-scale villiform structures are the basis for superhydrophobicity. After fluorination, the superhydrophobicity was obtained on the micro/nano coating. Comprehensive performance test shows that the microhardness of two composite coatings was greatly improved compared with copper substrates, which solves the problems of bad surface hardness of copper substrates. And nano Al2O3particle performs better in improving microhardness of composite coating. The acquired coatings with outstanding self-cleaning properties have excellent stability and wearability. The combination intensity of the copper substrates and the coatings are strong. The fabricated composite coatings have good comprehensive mechanical properties.