Copper-based Coatings Research Articles

Fabrication and Characterization of Advanced Selective Plated Copper Coatings Incorporating Nanosized Particles of ZnO and TiO2

This study reports preliminary results on the fabrication and characterization of selective plated copper-based coatings with enhanced surface properties and durability through the incorporation of zinc oxide and titanium oxide particles. The coatings were produced using an electrolyte containing 3% wt. zinc oxide and 1% wt. titanium oxide particles, and their microstructures, phase compositions, and mechanical properties were investigated. The results show that the incorporation of ceramic particles leads to the formation of metal-matrix composite materials with finer grain structures, improved microhardness, and enhanced wear resistance. The coating incorporating ZnO particles exhibits superior wear resistance, maintaining stable roughness values and minimal material loss, while the coating with TiO2 particles also shows improved wear resistance with moderate roughness increases.

Phase Analysis, Microhardness and Wear Resistance of Selective Plated Copper-Based Coatings Containing Silver Particles

This study investigated the composition and properties of copper-based selective electrochemical coatings containing silver particles deposited on 316L stainless steel substrates. The method of formation of the coatings, using acid and alkaline electrolyte solutions, is described. A comparative analysis of the obtained coatings with selective copper coatings without added particles was carried out. An X-ray structural analysis was performed to determine the phase composition. Mechanical properties such as microhardness, surface roughness and wear resistance were investigated. The results show that the coatings are continuous, without visible defects, and the particles are deposited in depth as well. In both types of copper coatings with added silver particles, a dominant Cu phase and the presence of Ag were registered. It was established that the type of oxides formed in the deposition process is an important factor determining the microhardness and wear resistance of the coatings. The conclusions drawn confirm the effectiveness of the selective electrochemical deposition method for obtaining copper-based coatings containing silver particles and determine their characteristic mechanical properties.

Cu(II) complexes using acylhydrazones or cyclen for biocidal antifouling coatings

Abstract Copper and copper-based compounds have broad spectrum antimicrobial activity, but concerns about leaching into the environment and toxicity on non-target organisms is leading the use of copper-based coatings being restricted. Our objective was to develop coatings that used the biocidal activity of copper, but with low negative impacts by reducing its leaching into the environment. This study reports the synthesis and characterisation of copper coordinating ligands, their formulation into coatings and testing of their antibacterial activity. A polyacylhydrazone and a series of simple acylhydrazones were synthesised and coordinated to Cu(II), but were considered unsuitable due to either their poor water-solubility or high levels of copper leaching. In an alternative approach, copper was successfully chelated to the tetraazamacrocycle, cyclen, and used to synthesise Cu(II)-cyclen functionalised silica particles, which were successfully combined with commercial paint formulations. These functionalised products showed poor antibacterial activity when incorporated into epoxy coatings, probably due to the low copper content of the formulations. However, these ligands may have other applications, such as removal of heavy metals from contaminated effluent steams.

An Antimicrobial Marine Cage Surface Modified with Antibacterial Peptides

Long-term immersion in seawater easily causes surface fouling and affects the marine aquaculture industry. The commonly used method is to apply copper-based coatings on surfaces, however, the release of copper ions will harm marine organisms. Antimicrobial peptides (AMPs) are a substance extracted from organisms that possess environmental friendliness. This study extracted AMPs from traditional Chinese medicine, analyzed their amino acid sequences, and bound them to the surfaces of cage materials based on the strong adhesion of dopamine in weakly alkaline environments. The Fourier transform infrared spectrometer (FTIR) spectrum results showed that the antibacterial peptide was successfully bound to the substrate surface, and the contact angle results demonstrated a significant change in the wettability of the substrate surface. Antibacterial tests were conducted on the surface of the sample using Staphylococcus aureus (S. aureus). The results illustrated that 304 stainless steel (SS) and nylon (PA) surfaces modified by the antibacterial peptide exhibited significant biofilm resistance, with antibacterial adhesion properties reaching 88.68% and 82.61%, respectively, exhibiting the robustness of the antimicrobial efficiency. This study can provide theoretical support for the antifouling performance of the surfaces of marine aquaculture cages.

Ecological Effect of Differently Treated Wooden Materials on Microalgal Biofilm Formation in the Grado Lagoon (Northern Adriatic Sea).

Within the framework of the Interreg Italy-Slovenia programme, the project DuraSoft aimed at testing innovative technologies to improve the durability of traditional wooden structures in socio-ecologically sensitive environments. We focused on the impact of different wood treatments (i.e., copper-based coatings and thermal modification) on microbial biofilm formation in the Grado Lagoon. Wooden samples were placed in 2 areas with diverse hydrodynamic conditions and retrieved after 6, 20, and 40 days. Light, confocal and scanning electron microscopy were employed to assess the treatment effects on the microalgal community abundance and composition. Lower hydrodynamics accelerated the colonisation, leading to higher algal biofilm abundances, regardless of the treatment. The Cu-based agents induced modifications to the microalgal community, leading to lower densities, small-sized diatoms and frequent deformities (e.g., bent apices, frustule malformation) in the genera Cylindrotheca and Cocconeis. After 20 days, taxa forming 3D mucilaginous structures, such as Licmophora and Synedra, were present on chemically treated panels compared to natural ones. While in the short term, the treatments were effective as antifouling agents, in the long term, neither the copper-based coatings nor the thermal modification successfully slowed down the biofouling colonisation, likely due to the stimulating effect of nutrients and other substances released from these solutions. The need to develop more ecosystem friendly technologies to preserve wooden structures remains urgent.

Assessing Efficacy of “Eco-Friendly” and Traditional Copper-Based Antifouling Materials in a Highly Wave-Exposed Environment

Biofouling control on human-made structures and seagoing technologies that minimize environmental impacts is a major focus of research in marine industries. However, the most widely used antifouling (AF) method is still copper-based coatings. Some “eco-friendly” approaches are commercially available but have been scarcely tested in natural conditions, especially high-energy environments. We conducted a replicated long-term field experiment in a highly wave-exposed, high productivity coastal environment to test three untreated materials used in maritime industries, two traditional copper-based AF coatings, and two materials offered as “eco-friendly” AF in the market (i.e., a slow-copper release and a self-adhesive, fiber-covered, skin-like coating). We showed that biofouling cover and biomass increased at similar rates over time among all untreated materials, including the skin-like AF. The two traditional copper-based AF coatings and the slow-release AF paint both showed similarly low biofouling biomass and richness, demonstrating their efficacy after 12 months in the field. Although the “eco-friendly” slow-release technologies are not completely innocuous to the environment, we suggest this approach over the more environmentally aggressive traditional copper paints, which are the most widely used in aquaculture and shipping industries today. However, further research is needed to test whether their environmental impact is significantly lower in the long-term than traditional AF paints, and therefore the search for non-toxic coating must continue. The fortuitous settlement and growth of sea urchins in our experiments also suggest that a combination of “eco-friendly” AF and biological control would be possible and should be further investigated. The skin-like coatings must be tested under different environmental conditions, and they are not recommended in wave-exposed coastal habitats.

Efficiencies of cobalt- and copper-based coatings applied by different deposition processes for applications in intermediate-temperature solid oxide fuel cells

Solid Oxide Fuel Cells (SOFCs) are electrochemical conversion devices that produce electricity directly by oxidising a fuel. The interconnects between the individual cells need to be coated to limit Cr(VI) evaporation from the steel and to preserve electrical conductivity. Physical Vapour Deposition (PVD)-coated samples with Ce/Co, Ce/Cu, and Ce/MnCu, and Thermal Spray (TS)-coated Mn/Co, Cu and Mn/Cu and AISI 441 steel samples were exposed at 650 °C for up to 1000 h. The PVD Ce/Co and Ce/Cu coatings, as well as the TS Mn/Co coating, exhibited the formation of a thin protective Cr2O3 scales underneath the coating. These samples also exhibited the lowest area-specific resistance (ASR) values. The remainder of the samples exhibited much higher mass gains and higher ASR values. Cr(VI) evaporation measurements showed that all the coatings behaved approximately the same despite the PVD coatings being only about one-tenth of the thickness of the TS coatings.

Marine Natural Products: A Promising Source of Environmentally Friendly Antifouling Agents for the Maritime Industries

Biofouling in the marine environment refers to an unwanted build-up of marine organisms on subsea surfaces including harbor docks, hulls of ships and offshore installations. The first stage of marine fouling occurs as a microbial biofilm which forms via the aggregation of bacterial, algal, and fungal cells. This biofilm provides a favorable substrate for the larval settlement of larger organisms such as mussels, barnacles and hard corals which accumulate to uncontrollable extents, causing issues for the maritime industries. Since the ban of tributyltin (TBT) in 2008 by the International Maritime Organisation, alternative antifouling agents have been used such as algaecides and copper-based coatings. Recent studies are showing that these can accumulate in the marine environment and have toxic effects against non-target species. Marine microbes and invertebrates are known to be prolific producers of bioactive molecules, including antifouling active compounds. These compounds are often produced by marine organisms as a means of chemical defense to deter predators and prevent fouling of their own surfaces, making them a promising source of new antifouling agents. This article discusses the effects of biofouling on the maritime industries, the environmental dangers of currently used antifouling compounds and why natural products from marine organisms could be a source of environmentally friendly antifouling agents.

Ultrasonic-assisted electrodeposition of Cu-Sn-TiO2 nanocomposite coatings with enhanced antibacterial activity

Copper-based coatings are known for their high antibacterial activity. In this study, nanocomposite Cu–Sn–TiO2 coatings were obtained by electrodeposition from an oxalic acid bath additionally containing 4 g/dm3 TiO2 with mechanical and ultrasonic agitation. Ultrasound treatment was performed at 26 kHz frequency and 32 W/dm3 power. The influence of agitation mode and the current load on the inclusion and distribution of the TiO2 phase in the Cu–Sn metallic matrix were evaluated. Results indicated that ultrasonic agitation decreases agglomeration of TiO2 particles and allows for the deposition of dense Cu–Sn–TiO2 nanocomposites. It is shown that nanocomposite Cu–Sn–TiO2 coatings formed by ultrasonic-assisted electrodeposition exhibit excellent antimicrobial properties against E. coli bacteria.

Copper Surfaces in Biofilm Control.

Biofilms are structures comprising microorganisms associated to surfaces and enclosed by an extracellular polymeric matrix produced by the colonizer cells. These structures protect microorganisms from adverse environmental conditions. Biofilms are typically associated with several negative impacts for health and industries and no effective strategy for their complete control/eradication has been identified so far. The antimicrobial properties of copper are well recognized among the scientific community, which increased their interest for the use of these materials in different applications. In this review the use of different copper materials (copper, copper alloys, nanoparticles and copper-based coatings) in medical settings, industrial equipment and plumbing systems will be discussed considering their potential to prevent and control biofilm formation. Particular attention is given to the mode of action of copper materials. The putative impact of copper materials in the health and/or products quality is reviewed taking into account their main use and the possible effects on the spread of antimicrobial resistance.

Determination of the Seizure load of copper-based coatings on steel obtained by laser surfacing

The paper considers the process of surfacing a copper-based powder PR-BrAlFe 9.5-1, PR-L63, PR-BrSnPb10-1.5 on 40r steel samples using continuous CO2 -laser radiation and cross-beam scanning with a frequency of 227 Hz. It is shown that the jamming load depends on the powder material and processing modes. The influence of transverse beam vibrations on the quality and productivity of the surfacing process is studied.

Development and Validation of High-Performance SARS-CoV-2 Antiviral Coatings for High-Touch Surfaces

Abstract A joint Canadian project aims to curb the COVID-19 pandemic and future epidemics with cold sprayed, copper-based coatings. The objectives are: (1) to tailor the microstructure and surface state of Cu/Cu alloy cold spray coatings to maximize the antiviral activity and provide an economically viable solution that can be rapidly upscaled and industrialized; (2) to identify the most relevant high-touch surface components based on a systematic data-driven analysis and simulation of public infrastructure usage; and (3) to demonstrate viable production capability with real component demonstrators to be installed in public transport facilities for in situ testing.

Structure and Properties of Antifriction Cu, Cu–C, and DLC Coatings

Single-component coatings of Cu and C and coatings in the Cu–C system with different carbon contents have been obtained by the magnetron sputtering method. The structure of coatings was investigated by the following techniques: scanning electron microscopy, energy-dispersive and X-ray diffraction analysis, Raman spectroscopy, and radio-frequency glow-discharge spectroscopy. The mechanical and tribological properties have been determined using the nanoindentation and testing by the “rod–disk” scheme. It has been established that the introduction of carbon into the composition of copper-based coatings is accompanied by an increase in the density of the structure and by the reduction of the crystallite size from 35 to 21 nm. It has been revealed that the characteristics of the Cu–C coatings exceeded those of the Cu coatings. The Cu‒C coatings obtained using the best regimes had a hardness of more than 1.5 GPa and coefficient of friction ~0.19.

Experimental Studies of Wear Resistance of Anti-Friction Coatings of Bimetal Fluid-Film Bearings

The paper presents experimental results of wear resistance measurements of anti-friction coatings of bimetal fluid-film bearings. As a result, nature and peculiarities of wear process of anti-friction coatings and steel base have been identified. An analysis of antifriction properties of studied copper-based coatings is presented. The paper also features recommendations for application of the studied coatings obtained by means of gas-flame spraying.

Photocatalytic performance of copper-based coatings deposited by thermal spraying

Visible light-activated photocatalysts are gaining general importance in advanced methods for removing persistent organic compounds. In this study, two types of composite oxide-metal coatings are obtained on copper substrates through thermal spraying of an aluminum bronze powder with different time-of-flight distances between the spraying nozzle and the substrate (150 and 200 mm). The surfaces of the coatings consist of nanopatterned α-Fe2O3 and CuxO produced by oxidation of the metal phase during the thermal spraying process. The optical band gap energies of the coating assemblies are 2.573 and 2.131 eV, respectively, and the Brunauer–Emmett–Teller (BET) specific surface areas are 4.65 and 4.87 m2 g−1, respectively. The photocatalytic performance of the two types of thermally sprayed coatings in the visible region is studied using methylene blue as a model compound. The coatings present remarkable stability in aqueous environments, good hydrophilicity, high photodegradation rates (0.20–0.26 h−1), high organic dye mineralization efficiencies (75.69 and 92.36%) and unaltered methylene blue removal efficiencies during three successive 12 h photodegradation cycles (91–99.60%).

Antiwear Properties of Coatings on Artillery Barrels

Copper-based coatings obtained by nonabrasive antifrictional finishing in a metal-coating bath increase the wear resistance of frictional pairs by a factor of 2.2 and prevent the diffusion of hydrogen into the surface layers of the steel.

Facile Fabrication of Durable Copper-Based Superhydrophobic Surfaces via Electrodeposition.

Superhydrophobic surfaces have myriad industrial applications, yet their practical utilization has been limited by their poor mechanical durability and longevity. We present a low-cost, facile process to develop superhydrophobic copper-based coatings via an electrodeposition route, that addresses this limitation. Through electrodeposition, a stable, multiscale, cauliflower shaped fractal morphology was obtained and upon modification by stearic acid, the prepared coatings show extreme water repellency with contact angle of 162 ± 2° and roll-off angle of about 3°. Systematic studies are presented on coatings fabricated under different processing conditions to demonstrate good durability, mechanical and underwater stability, corrosion resistance, and self-cleaning effect. The study also presents an approach for rejuvenation of slippery superhydrophobic nature (roll-off angle <10°) on the surfaces after long-term water immersion. The presented process can be scaled to larger, durable coatings with controllable wettability for diverse applications.

Antimicrobial properties of protective coatings produced by plasma spraying technique

In this work, protective copper-based coatings were deposited on stainless steel substrates by plasma spraying. The coatings were produced from copper alloys and copper composite with addition of titanium dioxide. They are intended for use on sensitive surfaces of furniture and accessories in medical facilities, i.e. operating tables, tables for medical products and surgical instruments. The phase composition and microstructure homogeneity of the produced coatings were examined. The effect of chemical composition and surface development on the biological activity of the obtained coatings was also investigated.

Larval release and attachment modes of the hydroid Ectopleura larynx on aquaculture nets in Norway

[Extract] In the finfish industry, clean cage nets are essential for the health of the stock (Braithwaite & McEvoy 2005). The accumulation of biofouling, the unwanted attachment of marine organisms on submerged surfaces, decreases the water flow through nets. Subsequently, the water quality within sea cages is reduced, which may affect fish health negatively (Cronin, Cheshire, Clarke & Melville 1999; de Nys & Guenther 2009). Over the last decade, the hydroid Ectopleura larynx (syn. Tubularia larynx) has become one of the most common fouling organisms in the Norwegian fish farming industry, causing increasing problems for farmers (Guenther, Carl & Sunde 2009). The rapid growth of E. larynx on aquaculture nets requires fish farmers to clean their nets regularly, often on a fortnightly basis during the peak of the biofouling season between July and November (Guenther et al. 2009). To reduce biofouling, the majority of Norwegian salmon farmers use copper-based coatings on nets, combined with regular underwater high-pressure washing (200–300 bar) with rotating discs (Olafsen 2006). Anecdotal observations suggest that hydroids grow back faster once the first washing has taken place (B. Jensen, salmon farm manager, pers. comm.).

The development of biofouling, particularly the hydroid Ectopleura larynx, on commercial salmon cage nets in Mid-Norway

The Norwegian fish farming industry mainly uses copper-based coatings on nets combined with washing to reduce the amount of biofouling. This study quantified the net aperture occlusion at 1, 5, 10 and 15 m depth of two cages, which were irregularly washed in situ, at a commercial salmon farm in Mid-Norway from August to December 2008. Before in situ washing, the net aperture occlusion was the highest at the upper depths of the water column. Afterwards, the fouling community dynamics and distribution changed; the net aperture occlusion varied significantly with time for both cages, and also with depth for one cage, which had significantly higher net aperture occlusions at lower depths. Laboratory experiments quantified the regrowth of the dominant fouling organism, the hydroid Ectopleura larynx, because some damaged hydroids may remain on the nets after in situ washing and then regrow. Two experiments, determining the effects of different numbers of polyps cut off (all, half and none of the polyps cut off) and different time intervals between cuttings (all polyps cut off on days 0, 2, 4 and 6, on days 0 and 6, and not at all) on the regrowth of E. larynx, were conducted. Both experiments demonstrated that E. larynx can regrow its polyps. Five days after cutting, the hydroids with all of their polyps cut off had more polyps (115 ± 9 polyps) than the hydroids with half of their polyps cut off (99 ± 10 polyps) and the control hydroids (88 ± 8 polyps). Similarly, six days after the final cutting, the hydroids repeatedly cut had more than twice the amount of polyps (90 ± 8 polyps for the hydroids cut on days 0, 2, 4 and 6; and 101 ± 6 polyps for the hydroids cut on days 0 and 6) than the control hydroids (41 ± 3 polyps). The results of these experiments suggest that in situ washing of nets is only a temporary measure to control biofouling as E. larynx regrows and occludes the net apertures rapidly.