Functional Microtextured Superhydrophobic Surface with Excellent Anti-Wear Resistance and Friction Reduction Properties

Abstract

The wear-resistant superhydrophobic (SHB) surfaces with excellent water-repellency ability were prepared by constructing a microtextured armor on an aluminum surface. With the assistance of laser-induced microtextures, the SHB surface could keep a longer water-repellency ability and a lower friction coefficient even after repeated friction tests under different loads and at different speeds. The mechanism of microtexture-protecting SHB coating is revealed based on both theoretical and elemental analysis. Additionally, we explore the relationship between the three-dimensional topography parameters (ISO 25178) and variation of water contact angles under different test recycles. The results show that the rough surface with appropriate S a and higher S ku exhibits a better wear resistance, which is mainly related to the storing ability of SHB coating inside the microtextures. Moreover, the surface with appropriate S tr exhibits excellent wear resistance, which is mainly associated with better chip-removal ability. Finally, the tribological properties of the microtextured SHB surface are researched. It is worth noting that compared with the microtextured surface without SHB coating and the SHB-coated surface without microtextures, the microtextured SHB surface has the lowest friction coefficient under dry friction because the SHB coating would largely decrease the surface energy of the interface, so the adhesion friction decreases. The microtexture armor on the surfaces would protect the wear of SHB coating, so the SHB coating inside the microtexture could continuously play the role of a particle lubricant at the sliding interface and decrease the friction force of the sliding interface. We believe that the present study would contribute to the further understanding of the constructing mechanism of anti-wear SHB surfaces and provide a new strategy for topography design of engineering surfaces with friction reduction properties.

Delayed Leidenfrost Effect of a Cutting Droplet on a Microgrooved Tool Surface

“…Line-by-line laser scanning is used to ablate the sample to create a microgrooved surface with varying levels of roughness (scanning speed ∼10 mm/s, frequency ∼300 kHz, the distance between adjacent grooves ∼80 m). Laser processing technology has the advantages of high machinable accuracy, good repeatability, and high processing efficiency; − the microgroove height of each sample is changed by controlling the processing power and the number of scans, and the three-dimensional topography results (Figure b) show that the prepared samples have great processing quality with uniform microgroove height. It should be noted that we formally control the depth of the microgrooves to obtain various roughness surfaces, which are labeled as follows: sample I ( Sa ∼ 0.01 μm, original smooth surface), sample II ( Sa ∼ 3 μm), sample III ( Sa ∼ 6 μm), sample IV ( Sa ∼ 9 μm), and sample V ( Sa ∼ 12 μm).…”

A Single-Step Route to Robust and Fluorine-Free Superhydrophobic Coatings via Aerosol-Assisted Chemical Vapor Deposition

“…Superhydrophobicity is a crucial property of materials for many large and small applications in which water adsorption can negatively influence functional performance. Examples include anti-icing coatings on airplanes, tuning the hydrophilicity of materials (e.g., cotton), and creating water resistant fabrics. , Superhydrophobicity was first observed in lotus leaves where water droplets roll off of the leaf surface rather than wet it, taking dirt particles with them to improve their functional performance, i.e., light harvesting or leaf health. , Superhydrophobicity is induced by the microscopic bumps and air spaces across the leaf, while the waxy cuticle provides the low surface energy required. , However, the widespread application of superhydrophobic coatings has been hindered due to their typically poor durability or robustness. , …”

“…Examples include anti-icing coatings on airplanes, tuning the hydrophilicity of materials (e.g., cotton), and creating water resistant fabrics. 1,2 Superhydrophobicity was first observed in lotus leaves where water droplets roll off of the leaf surface rather than wet it, taking dirt particles with them to improve their functional performance, i.e., light harvesting or leaf health. 3,4 Superhydrophobicity is induced by the microscopic bumps and air spaces across the leaf, while the waxy cuticle provides the low surface energy required.…”

Unusual Increasing Viscoelasticity of Wormlike Micelles Composed of Imidazolium Gemini Surfactants with Temperature

“…Gemini surfactants have two hydrophilic hydrophobic tails and two headgroups connected by rigid or flexible spacers on the head group. , Compared to the conventional gemini surfactants, the imidazolium gemini surfactants have special properties and bigger rigid imidazolium headgroups, which have potential applications in many fields. , For example, they show a stronger self-aggregation performance, better solubility, and thermal stability. − They are used to regulate different types of chemical reactions . Therefore, it is of practical interest to study the surface activity of imidazolium gemini surfactants.…”