Zinc-containing Coatings Research Articles

Biofunctionalization of dental abutments by a zinc/chitosan/gelatin coating to optimize fibroblast behavior and antibacterial properties.

Tightly sealed peri-implant gingival tissue provides a barrier against oral bacterial invasion, protecting the alveolar bone and maintaining long-term implant survival. To investigate if zinc can enhance the integration between peri-implant gingival tissue and abutment surface, we herein present novel zinc/chitosan/gelatin (Zn/CS/Gel) coatings prepared using the electrophoretic deposition (EPD) technique. The effect of these coatings on human gingival fibroblasts (hGFs) was investigated by culturing these cells on top of the EPD coatings. Surface characterization demonstrated that Zn2+ were released in a sustained and pH-responsive manner. The preclinical cell culture evaluation of these coatings indicated that the zinc-containing coatings enhanced cell migration, adhesion and collagen secretion of hGFs. Moreover, the zinc-containing coatings exhibited antibacterial efficacy by inhibiting the growth of Porphyromonas gingivalis and reducing attachment of Staphylococcus aureus. Notably, zinc-free CS/Gel coatings prevented attachment of P. gingivalis as well. The coatings were also shown to be cytocompatible with epithelial cells and osteoblasts, which are other relevant cell types which surround dental implants after clinical placement. Based on our findings, it can be concluded that Zn-containing coatings hold promise to enhance the adhesion of gingival tissue to the implant surface, which may potentially contribute to the formation of a robust peri-implant soft sealing counteracting bacterial invasion.

Investigation of In Vitro Cytocompatibility of Zinc-Containing Coatings Developed on Medical Magnesium Alloys.

In a neutral solution, we investigated the effects of Na2[ZnEDTA] concentrations at 0, 6, 12, 18, and 24 g/L on surface morphology, chemical composition, degradation resistance, and in vitro cytocompatibility of micro-arc oxidation (MAO) coatings developed on WE43 (Mg-Y-Nd-Zr) magnesium alloys. The results show that the enhanced Na2[ZnEDTA] concentration increased the Zn amount but slightly decreased the degradation resistance of MAO-treated coatings. Among the zinc-containing MAO samples, the fabricated sample in the base solution added 6 g/L Na2[ZnEDTA] exhibits the smallest corrosion current density (6.84 × 10-7 A·cm-2), while the sample developed in the solution added 24 g/L Na2[ZnEDTA] and contains the highest Zn content (3.64 wt.%) but exhibits the largest corrosion current density (1.39 × 10-6 A·cm-2). Compared to untreated WE43 magnesium alloys, zinc-containing MAO samples promote initial cell adhesion and spreading and reveal enhanced cell viability. Coating degradation resistance plays a more important role in osseogenic ability than Zn content. Among the untreated WE43 magnesium alloys and the treated MAO samples, the sample developed in the base solution with 6 g/L Na2[ZnEDTA] reveals the highest ALP expression at 14 d. Our results indicate that the MAO samples formed in the solution with Na2[ZnEDTA] promoted degradation resistance and osseogenesis differentiation of the WE43 magnesium alloys, suggesting potential clinic applications.

Antibacterial Calcium Phosphate Coatings for Biomedical Applications Fabricated via Micro-Arc Oxidation.

A promising method for improving the functional properties of calcium-phosphate coatings is the incorporation of various antibacterial additives into their structure. The microbial contamination of a superficial wound is inevitable, even if the rules of asepsis and antisepsis are optimally applied. One of the main problems is that bacteria often become resistant to antibiotics over time. However, this does not apply to certain elements, chemical compounds and drugs with antimicrobial properties. In this study, the fabrication and properties of zinc-containing calcium-phosphate coatings that were formed via micro-arc oxidation from three different electrolyte solutions are investigated. The first electrolyte is based on calcium oxide, the second on hydroxyapatite and the third on calcium acetate. By adding zinc oxide to the three electrolyte solutions, antibacterial properties of the coatings are achieved. Although the same amount of zinc oxide has been added to each electrolyte solution, the zinc concentration in the coatings obtained vary greatly. Furthermore, this study investigates the morphology, structure and chemical composition of the coatings. The antibacterial properties of the zinc-containing coatings were tested toward three strains of bacteria-Staphylococcus aureus, methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa. Coatings of calcium acetate and zinc oxide contained the highest amount of zinc and displayed the highest zinc release. Moreover, coatings containing hydroxyapatite and zinc oxide show the highest antibacterial activity toward Pseudomonas aeruginosa, and coatings containing calcium acetate and zinc oxide show the highest antibacterial activities toward Staphylococcus aureus and methicillin-resistant Staphylococcus aureus.

Nacre-mimetic Strategy to Fabricate Waterborne FrGO/Zn/Epoxy Coatings with Dual Corrosion Protection.

The service life of metal and other infrastructure requires extending through eco-friendly, low-carbon technology. Here, a nacre-mimetic γ-Fe2O3/reduced graphene oxide (FrGO)/zinc-containing epoxy coating (FrGO/Zn/epoxy coating) was fabricated by spraying a mixture of waterborne epoxy resin, zinc flakes, and magnetic conductive FrGO under a magnetic field. The FrGO, which was synthesized by in situ redox and precipitation, was aligned in the zinc-containing coatings (ZCC), and it oriented the zinc flakes in the direction of the magnetic field to mimic the lamellar structure of nacre. The obtained anti-corrosion coating showed enhanced barrier protection and cathodic protection, which was confirmed by the electrochemical tests and salt spray test results. The waterborne coatings less than 50 μm thick with parallelly aligned FrGO and 30 wt % zinc flakes exhibited a long cathodic period lasting more than 99 days and excellent barrier performance with a high initial coating resistance of 5.31 × 109 Ω·cm2, which was superior to that of the conventional zinc-rich coating containing 80 wt % zinc (80 days, 3.74 × 103 Ω·cm2). The dual anti-corrosion mechanism of the waterborne FrGO/Zn/epoxy coating was investigated. The integrity and long-term cathodic protection of the coatings were derived from the compactness achieved by the nacre-mimetic structure and the interface chemical and hydrogen bonding crosslinking interactions and the high, uniform zinc utilization achieved by the aligned FrGO-Zn charge transmission network. This work provides a feasible nacre-inspired strategy to fabricate a lightweight anti-corrosion waterborne ZCC that is resource-efficient and promising in creating compact materials with other functional properties, such as electromagnetic shielding and conductive networks.

Analysis of methods for obtaining zinc-containing coatings using hot-dip galvanizing production waste

The article presents the waste generated during the production of hot-dip galvanizing. The analysis of the proposed methods of using these wastes in the production of zinc-containing coatings is carried out. It is shown that hard zinc can be successfully used in the compositions of saturating mixtures during thermal diffusion galvanizing of steel products and obtain high-quality coatings. The disadvantages include the need for grinding hard zinc.The dispersed waste of hot-dip galvanizing production, which is formed as a result of blowing pipes with superheated steam, can be used as a cheap substitute for expensive zinc powder in the compositions of zinc-filled paints. For paints, a fraction of 2–15 microns is used, which is 27 % of the total fractional composition. Therefore, in order to use a wider range of values of the fractional composition of dispersed waste to obtain zinc coatings and thus ensure the recycling of zinc into industrial circulation, the authors of this article plan to optimize and develop the compositions of powder compositions and the technology of thermal diffusion saturation of steel products based on zinc-containing waste.

Analysis of corrosive properties of zinc-containing coatings based on dispersed waste hot zinc plating

A comparative analysis of the corrosion properties of zinc-containing coatings obtained on the basis of metallic powder zinc and dispersed hot-dip galvanized waste has been carried out. The results of a study of the corrosion resistance of zinc-containing coatings by the electrochemical method and in a salt spray chamber have shown that coatings obtained on the basis of dispersed hot-dip galvanized waste are not inferior in protective properties to coatings based on powder standard zinc.

Significant Improvement of Anticorrosion Properties of Zinc-Containing Coating Using Sodium Polystyrene Sulfonate Noncovalent Modified Graphene Dispersions

High-quality graphene zinc-containing anticorrosive coatings are highly and urgently desirable for effective, economical anticorrosion of metals and alloys in industrial products. The realization of such coatings is, however, hindered by the dispersibility and compatibility of the graphene in them. This work reports a novel direct modification of graphene using sodium polystyrene sulfonate (PSS) without reduction of graphene oxide, leading to homogeneous dispersion of graphene in water. The agglomeration of graphene is prevented thanks to the formation of π−π interaction between PSS and graphene sheets. Such graphene dispersion can effectively improve the anticorrosion performance of the zinc-containing epoxy coatings. With the addition of graphene modified by PSS into the 20% zinc-containing epoxy coating (graphene is 0.05% by weight of the coating), its anticorrosion properties revealed by both electrochemical characterization and the neutral salt spray tolerance analysis are rather close to those of 60% zinc-containing epoxy coating. These results demonstrate that direct PSS modification is an effective method for graphene dispersion and thus open a pathway to achieve graphene zinc-containing anticorrosive coatings with high performance.

Effects of graphene on the corrosion evolution of epoxy zinc-containing coatings

Effects of graphene on the corrosion evolution of epoxy zinc-containing coatings

Effects of graphene on the corrosion evolution of zinc particles in waterborne epoxy zinc-containing coatings

In this paper, graphene/ waterborne epoxy zinc-containing coatings with different graphene contents were prepared. The corrosion resistance properties of the graphene/ waterborne epoxy zinc-containing coatings were investigated by electrochemical impedance spectroscopy (EIS), immersion test and neutral salt spray test. The results showed that addition of 0.6 wt% graphene into the coating could remarkably improve its cathodic protection performance and barrier performance comparing with the coating without graphene. In addition, the effects of graphene on the corrosion evolution of zinc particles in the coating were observed by the field-emission scanning electron microscopy (FE-SEM) coupled with energy dispersive spectroscopy (EDS). The results showed that the zinc particles near the interface between steel substrate and the coating corroded firstly after the corrosive media diffused in the coating and reached the interface due to the cathodic protection to the steel, and then zinc particles continued to be corroded from the interface to upper part of the coating since they could provide the cathodic protection to the substrate thanks to the electrical connection of graphene. Meanwhile, X-ray diffraction (XRD) patterns confirmed the corrosion products of the zinc particles were mainly consisted of Zn5(OH)8Cl2·H2O.

Influences of Na2SiO3 and EDTA-ZnNa2 concentration on properties of zinc-containing coatings on WE43 magnesium alloys

There exists great interest in the development of coatings that can simultaneously improve corrosion resistance and contain essential trace elements on biomedical magnesium alloys. In an alkaline solution composed of NaF, phytic acid (H12Phy), Na2SiO3 and EDTA-ZnNa2, it was demonstrated that zinc-containing coatings with improved corrosion resistance were successfully fabricated on WE43 magnesium alloys using a one-step micro-arc oxidation (MAO) procedure. The influences of Na2SiO3 and EDTA-ZnNa2 concentrations on MAO coating properties were systematically evaluated using SEM, EDS, XRD, XPS, scratch test and potentiodynamic polarization. These results demonstrate that MAO coatings containing 1.67 wt% Zn exhibit superior corrosion resistance. Na2SiO3 is one type of passive agent of magnesium alloys, and has been shown to be favorable for the formation of coatings as it enhances corrosion resistance by improving surface uniformity, coating thickness and adhesion to the substrate. Raised EDTA-ZnNa2 in the range of 1 to 3 g/L is found to increase zinc content in MAO coatings but decrease their corrosion resistance. As an acidic substance, EDTA-ZnNa2 is a corrosive agent of magnesium alloys and has shown to be harmful for the formation of MAO coatings. Additionally, the corrosion mechanism of MAO coatings was discussed by measuring electrochemical impedance spectroscopy as a function of immersion time.

In Vivo Effect of Titanium Implants with Porous Zinc-Containing Coatings Prepared by Plasma Electrolytic Oxidation Method on Osseointegration in Rabbits.

The aim of this study was to confirm the in vivo effect of surface-modified titanium (Ti) implants with zinc (Zn) prepared by a plasma electrolytic oxidation (PEO) method on the process of osseointegration. Forty-five New Zealand white rabbits were used. Implants were divided into three groups due to different surface treatments (the PEO-Zn group, the PEO-calcium phosphorus [Ca/P] group, and the sandblasted [control] group) and were randomly inserted into rabbits' mandibles. The implant surface morphology and chemical state of the relevant elements were observed. The maximum push-out force, the bone-to-implant contact (BIC), and the mineral apposition ratio (MAR) were detected at 4, 8, and 12 weeks after implantation. A two-layer structure, with a dense inner layer and a porous outer layer, was found in the PEO samples. In the PEO-Zn group, CaHPO4·2H2O (dicalcium phosphate dihydrate) was the main calcium compound, and ZnO was identified as the predominant form of Zn. More bone deposition was found on the top of the PEO-Zn implant, which was also confirmed by scanning electron microscope (SEM) afterward, and the shear strength reached a maximum value of 1.57 ± 0.26 MPa at 12 weeks compared with the sandblasted group and the PEO-Ca/P group. The BIC values and the MARs of the PEO-Zn group were significantly higher than the control group, especially at the early weeks (P < .05), and first reached maximum values of 73.91% ± 9.01% and 4.89 ± 0.60 μm/d at 12 weeks, respectively. Implants with Zn coating by the PEO method could accelerate bone formation and bone remodeling, shorten the osseointegration period, and enhance bone-implant bonding force.