Yixing Zhu

Superamphiphobic and Electroactive Nanocomposite toward Self-Cleaning, Antiwear, and Anticorrosion Coatings

Multifunctional coatings are in urgent demand in emerging fields. In this work, nanocomposite coatings with extraordinary self-cleaning, antiwear, and anticorrosion properties were prepared on aluminum substrate by a facile spraying technique. Core-shell structured polyaniline/functionalized carbon nanotubes (PANI/fCNTs) composite and nanosized silica were synergistically integrated into ethylene tetrafluoroethylene (ETFE) matrix to construct lotus-leaf-like structures, and 1H,1H,2H,2H- perfluorooctyltriethoxysilane (POTS) was used to decrease the surface energy. The composite coating with 6 wt % PANI/fCNTs possesses superamphiphobic property, with contact angles of 167°, 163°, and 159° toward water, glycerol, and ethylene glycol, respectively. This coating demonstrates stable nonwetting performance over a wide temperature range (<400 °C), as well as outstanding self-cleaning ability to prevent contamination by sludge, concentrated H2SO4, and ethylene glycol. Superamphiphobic surface property could be maintained even after 45 000 times abrasion or bending test for 30 times. The coating displayed strong adhesive ability (grade 1 according to the GB/T9286) on the etched aluminum plate. The superamphiphobic surface could be retained after immersion in 1 mol/L HCl and 3.5 wt % NaCl solutions for 60 and 90 d, respectively. It should be noted that this coating reveals significantly improved anticorrosion performance as compared to the bare ETFE coating and ETFE composite coating without PANI/fCNTs. Such coatings with integrated functionalities offer promising self-cleaning and anticorrosion applications under erosive/abrasive environment.

Mechanical and tribological characteristics of carbon nanotube-reinforced polyvinylidene fluoride (PVDF)/epoxy composites

In this study, epoxy (EP) composites filled with different contents of polyvinylidene fluoride (PVDF) and carbon nanotubes (CNTs) were fabricated by the solvent evaporation and curing method. FT-IR and XRD analysis were performed to explore the discolorment mechanism of the PVDF/EP composites before and after curing. The effects of the PVDF and CNT content on the mechanical and tribological properties of the composites were investigated. Results revealed that 1.0% CNT/30% PVDF/EP composites exhibited a 36.2% and 10.1% increase in flexural strength and hardness, as compared to those of the 30% PVDF/EP composites. The wear rates of 1.0% CNT/30% PVDF/EP composites and 30% PVDF/EP composites were 92.1% and 86.8% lower than that of pristine EP under 1.0 MPa and 0.76 m s−1, respectively. Meanwhile, the fractured and worn surfaces of specimens were both analyzed by the observations of SEM. In addition, wear tests under various applied loads were conducted for pristine EP, 30% PVDF/EP and 1.0% CNT/30% PVDF/EP composites. The results showed that the wear properties of the two composites were both superior to those of pristine EP due to the formation of a transfer film as revealed by SEM-EDS analysis, which could effectively protect the worn surface from direct abrasion during the wear testing.

A superrobust superhydrophobic PSU composite coating with self-cleaning properties, wear resistance and corrosion resistance

In this study, a superhydrophobic polysulfone (PSU) composite coating with a high water contact angle (WCA) of 159° and a low slide angle (SA) of only 3.5° has been fabricated through a simple thermal spraying method. The ductility and mechanical properties of the PSU composite coating were improved effectively through the combination of the cross-linking ability of PVDF and the special multilayer structure of MMT. The wear resistance of the prepared coating is approximately 14.3 times longer than that of commercial fluorocarbon coating. Simultaneously, the prepared superhydrophobic coating also possesses outstanding corrosion resistance; the corrosion current and corrosion potential decreased from 10−0.9 to 10−3.6 μA cm−2 and from −803 to −218 mV, respectively. Furthermore, the prepared coating demonstrated superb self-cleaning, anti-fouling and durability properties. It is believed that this robust superhydrophobic PSU/PVDF/MMT–PDMS composite coating may provide the possibility to realize large-scale fabrication and applications in industry.

Fabrication of superhydrophobic fiber fabric/epoxy composites coating on aluminum substrate with long-lived wear resistance

A superhydrophobic coating with long-lived wear resistance was successfully prepared by integrating the hydrophobization of cotton fiber fabric and the curing of epoxy composites consisting of polyurethane (PU), polyfluoroalkoxy (PFA) and hydrophobic SiO2 nanoparticles. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were employed to investigate the chemical compositions and morphologies of the modified cotton fiber fabric and the prepared coating. When the epoxy solution containing 35 wt% PFA and 25 wt% PU, the obtained coating exhibited superhydrophobic behavior with a water contact angle (WCA) of 153.5 ± 1°. Tribological tests indicated that this fiber fabric/epoxy composites coating had stable friction coefficient and excellent wear-resistance under the harsh conditions with the applied load of 2.8 MPa and the sliding velocity of 0.51 m s−1. After 240000 cycles of abrasion, the coating just showed the decrease in thickness of 80 μm without apparent damage and could retain high hydrophobicity with the WCA of 142°. Simultaneously, the coating was resistant to the acid or alkali solution. This wear-resistant superhydrophobic fiber fabric/epoxy composites coating may be a good candidate for the practical industrial applications under harsh working conditions.