Pure Copper Coatings Research Articles

Investigation on the interface microstructure and phase composition of laser cladding pure copper coating

Laser cladding is an efficient and clean method that can prepare a corrosion-resistant pure copper coating on the nuclear fuel container surface to ensure service safety. In this study, the single-layer and double-layer pure copper coatings were prepared on 20# steel tubes by laser cladding. The microstructure, elements distribution, phase composition, and interface structure, as well as strain distribution, were characterized by Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), and transmission kikuchi diffraction (TKD). The results show that the kernel average misorientation (KAM) and geometry necessary dislocation (GND) density at the coating/substrate interface in the double-layer Cu coating decrease compared to the single-layer Cu coating. Under the thermal action during laser cladding of double-layer coating, the phase composition in the substrate transforms completely from austenite, FeO, and ferrite to the entire ferrite. The Cu/Fe interface maintains certain orientation relationships, namely the Kurdjumov-Sachs (KS) and the Nishiyama-Wassermann (NW) relationships, with a mismatch of only 3.01 % for the coherent interface. Thus, the lattice distortion at the interface reduces, slightly alleviating the strain concentration.

Benefits of Core-Shell Particles over Single-Metal Coatings: Mechanical and Chemical Exposure and Antimicrobial Efficacy.

One of the greatest challenges worldwide is containing the spread of problematic microorganisms. A promising approach is the use of antimicrobial coatings (AMCs). The antimicrobial potential of certain metals, including copper and zinc, has already been verified. In this study, polyethylene terephthalate and aluminum (PET-Al) foils were coated with copper, zinc, and a combination of these two metals, known as core-shell particles, respectively. The resistance of the three different types of coatings to mechanical and chemical exposure was evaluated in various ways. Further, the bacteria Staphylococcus aureus and the bacteriophage ϕ6 were used to assess the antimicrobial efficacy of the coatings. The best efficacy was achieved with the pure copper coating, which was not convincing in the abrasion tests. The result was a considerable loss of copper particles on the surfaces and reduced effectiveness against the microorganisms. The core-shell particles demonstrated better adhesion to the surfaces after abrasion tests and against most chemical agents. In addition, the antimicrobial efficiency remained more stable after the washability treatment. Thus, the core-shell particles had several benefits over the pure copper and zinc coatings. In addition, the best core-shell loading for durability and efficacy was determined in this study.

Corrosion property investigation of laser-cladding copper coating in the simulated nuclear waste disposal solution

To explore the efficient corrosion protection for the nuclear waste storage containers, pure copper coatings were successfully prepared on the 20# steel pipe surface using an infrared laser system under different laser powers. The study was conducted on the copper coatings, encompassing the surface quality, defects, microstructure, elemental distribution, phase composition, and corrosion products. The electrochemical and immersion corrosion behavior of the copper coatings in simulated nuclear waste disposal solutions was analyzed. The pure copper coating prepared by 2800 W laser power has fewer amounts and smaller sizes of defects inside the coating with only a slight fusion of Cu and Fe elements at the interface, which exhibits the highest corrosion potential and the smallest self-corrosion current density. During the immersion corrosion process, pores and unfused defects inside the coating, as well as the pits formed by galvanic coupling corrosion, lead to enhanced acidity inside these defects, resulting in a higher corrosion rate. As the immersion time proceeds, the corrosion rate slows down gradually and the content of Cu2+ corrosion product increases significantly.

Effect of laser power on microstructure and properties of laser assisted cold sprayed copper coatings on steel

Laser assisted cold spraying (LACS) is a promising technology for preparing high performance copper-steel composite materials for grounding electrode applications. Laser power is a critical LACS parameter, however, in literature there is a lack of studies on the influence of laser power on coatings. In this study, the effect of laser power on microstructure and properties of LACS copper coatings on steel is investigated. The results show that with the increase of laser power, the copper coating generally shows reduced porosity and microhardness, as well as increased bonding strength. However, the grains are first refined and then coarsened, while the electrical conductivity and corrosion resistance both increased and then decreased. This is because when the laser power exceeds 4 kW, the grain is coarsened and the amount of large angular grain boundaries (HAGBs) increases because excessive temperature increases the recrystallization driving force, ultimately leading to decrease in coating electrical conductivity and corrosion resistance. 4.0 kW, 5 MPa, 800 °C is considered as optimal LACS parameters for preparation of pure copper coatings on Q235 steel. The coating has a porosity of <0.04 %, grain size of 0.634 μm, microhardness of 99.4HV0.1, bonding strength exceeds 62 MPa, electrical conductivity of 99 % IACS, and corrosion current density of 6.092 × 10−8 A/cm2. In addition, mechanisms of LACS particle deposition and corrosion of copper coatings in simulated soil solution were discussed. With the increase of laser power, more heat absorbed by the powder and the substrate promotes thermal softening and plastic deformation, resulting in stronger mechanical bonding. The corrosion mechanism gradually changes from pitting corrosion to uniform corrosion due to the reduced porosity and tighter grain boundaries, and finally to intergranular corrosion due to grain coarsening and high HAGBs content. Overall, this study provides guidance and reference for the practical application of LACS.

Tribology of Copper Metal Matrix Composites Reinforced with Fluorinated Graphene Oxide Nanosheets: Implications for Solid Lubricants in Mechanical Switches.

The potential for the use of copper coatings on steel switching mechanisms is abundant owing to the high conductivities and corrosion resistance that they impart on the engineered assemblies. However, applications of these coatings on such moving parts are limited due to their poor tribological properties; tendencies to generate high friction and susceptibility to degradative wear. In this study, we have fabricated a fluorinated graphene oxide-copper metal matrix composite (FGO-CMMC) on an AISI 52100 bearing steel substrate by a simple electrodeposition process in water. The FGO-CMMC coatings exhibited excellent lubrication performance under pin-on-disk (PoD) tribological sliding at 1N load, which reduced CoF by 63 and 69%, compared to the GO-CMMC and pure copper coatings that were also prepared. Furthermore, FGO-CMMC achieved low friction and low wear at higher sliding loads. The lubrication enhancement of the FGO-CMMCs is attributed to the tribochemical reaction of FGO with the AISI 52100 steel counterface initiated by the sliding load. The formation of an asymmetric tribofilm structure on the sliding track is critical; the performance of the FGO/Cu tribofilm formed in the track is boosted by the continued fluorination of the counterface surface during PoD sliding, passivating the tribosystem from adhesion-driven breakdown. The FGO-CMMC and GO-CMMC coatings also provide increased corrosion protection reaching 94.2 and 91.6% compared to the bare steel substrate, allowing for the preservation of the long-term low-friction performance of the coating. Other influences include the improved interlaminar shear strength of the FGO-containing composite. The excellent lubrication performance of the copper matrix composite coatings facilitated by FGO incorporation makes it a promising solid lubricant candidate for use in mechanical engineering applications.

Antibacterial and Virucidal Evaluation of Ultrafine Wire Arc Sprayed German Silver Coatings.

The online version contains supplementary material available at 10.1007/s11666-022-01528-4.

Bonding Characteristics of Cold Sprayed Copper Coating on Alumina Coated Q235 Steel Substrate

Cold spraying metallic coatings on ceramics (Ceramics Metallizing) are widely concerned in electrical industry due to its high density, low oxidation and high electrical conductivity. However, the bonding reliability of cold spraying coating on ceramics is usually considered to be poor since the metal particles don’t experience melting. The present paper is to exam the bonding quality of a cold spraying copper coating on a thermal sprayed alumina layer influenced by ceramics roughness and copper particle hardness. Pure copper coatings were successfully deposited on Al2O3 coated Q235 steel substrate with different roughness by cold spraying at 260 ℃ and 1.6 MPa using different hardness pure copper powders. The bonding quality and characteristics were studied by analyzing the surface, the cross-sectional microstructure of the coating and its interface after pull-off test. The results indicate that the high bonding quality (ranging from 8.26 MPa to 11.35 MPa) between copper coating and Al2O3 layer attributes to both metallurgical and interlock effect, which is mainly influenced by the hardness of the copper powders instead of Al2O3 surface roughness. The soft character of the pure copper powder makes it ready for deformation, subsequently interlocks with Al2O3, fills into the pores more completely, which increases the bonding quality between the copper coating and the Al2O3 layer.

Effect of substrate surface roughness on properties of cold-sprayed copper coatings on SS316L steel

The development of thick pure copper coatings on SS316 substrates with desired properties for Tokamaks is still a challenging task. The solution to this task can help to fulfill the demanding requirements of in-vessel materials for plasma passivation. In the present work, the effect of substrate surface roughness on several properties of cold-sprayed copper coatings was investigated. Effect of post-heat-treatment on the properties of the developed coatings was also studied. The developed coatings were characterized using various techniques viz.; scanning electron microscopy/energy dispersive spectroscopy, X-ray diffraction, optical microscopy, microhardness, nanoindentation, electrical and thermal conductivity measurements, and density and porosity analyses. The novelty of the article includes in-situ micro-tensile testing of the developed coatings to understand their fracture mechanism, which showed multi-crack failure. Moreover, the cracks were found to be originating from the multi-splat boundary junctions, followed by growth along the splat boundaries. Additionally, γ-rays and heavy-nuclei irradiation along with thermal cyclic exposure studies were also performed to elucidate the actual environmental performance of the coatings. The coatings developed on the mirror-finished surface were found to have better mechanical and physical properties as compared to the coatings developed on the rough substrate surface; prior as-well-as post-heat-treatment.

Synthesis and Electrochemical Characterisation of Novel Hybrid Copper / Poly (diphenylamine) (PDPA) Nanocomposites

The Poly (diphenylamine) (PDPA) nanoparticles was synthesized by surfactant assisted dilute polymerization method and characterized by UV-Visible, FTIR and Cyclic Voltammetry techniques. The PDPA nanoparticles were then suspended in an acidified copper sulphate electrolytic bath to prepare Cu-PDPA nanocomposites by simple electrodeposition technique. The XRD analysis revealed that the crystallite structure of Cu-PDPA nanocomposites and pure copper coatings was crystalline fcc and the grain size was 32 nm for pure Cu and 27 nm for Cu-PDPA nanocomposites. This decrease in crystallite size of Cu-PDPA nanocomposites shows the inclusion of PDPA nanoparticles was uniformly distributed throughout the copper matrix. The microstructure of the Cu-PDPA nanocomposites was examined by SEM analysis shows cauliflower like crystallites with layer by layer outward growth compared to electrodeposited pure copper coatings. The Electrochemical AC impedance and Tafel polarization studies were performed for electrodeposited copper and Cu-PDPA nanocomposites in 3.5% NaCl solution. It revealed that the Cu-PDPA nanocomposite coatings were found to be more corrosion resistance than electrodeposited pure copper coating.

Electrodeposition of CNTs/copper composite coatings with enhanced tribological performance from a low concentration CNTs colloidal solution

A novel colloidal solution containing low concentration carbon nanotubes (CNTs) is proposed as the plating solution of electrodeposition to prepare CNTs/copper (CNTs/Cu) composite coatings. The CNTs/Cu composite coatings are characterized by X-ray diffraction and scanning electron microscope. Their tribological behaviors are evaluated in dry conditions over a range of applied loads and CNTs content in plating solution. Negatively charged CNTs stably coexist with [CuIIEDTA]2− complexes due to the electrostatic repulsion between them, which facilitates the homogenous electrodeposition of individual CNTs in the Cu matrix and reduction of CNTs content required in the plating solution. The CNTs concentration in plating solution significantly affects the surface morphology and compactness of the deposits. CNTs/copper composite coatings obtained from the plating solution with moderate CNTs concentration, e.g. 0.12gL−1, show obviously lower and steadier friction coefficient and higher wear resistance than pure copper coatings.

Production and Characterization of Copper-Niobium Composite Electrocoatings

Copper-niobium composite electrocoatings were obtained by co-electrodeposition in acidic copper sulfate bath containing suspended niobium particles. The amount of incorporated particles was evaluated using a Central Composite Design (CCD) with three factors of control (cathodic current density, stirring rate and particle concentration in the bath) at three levels each. A great influence of particle concentration was observed. The stirring rate also had influence but to a lower extent and the cathodic current density was the least significant factor. The combination, both cathodic current density and particle concentration at the highest levels and stirring rate at the lowest level, led to the highest amount of incorporated particles. The behavior was not linear between the high and low levels for all factors. The roughness of the composites was higher than the pure copper coatings and increased with increasing current density. The microhardness of the composite layers was higher than that of pure copper deposits obtained under the same conditions due to copper matrix grain refinement and increased with the increase of both current density and incorporated particle volume fraction.

Analysis of single spray beads prepared using low-pressure cold spraying

Cold spraying is a coating deposition method for the production of high-quality metallic coatings. Copper, for instance, is widely used as a coating material due to its suitability for cold spray process. Cold-sprayed copper coatings are known to have interesting technical properties such as high electrical and thermal conductivity. Low-pressure cold spraying (LPCS) is a cold spray technique of preparing relatively dense and pure copper coatings. The deposition behaviour of low-pressure cold-sprayed spherical and dendritic copper particles impacting the substrate was evaluated in this study. The effect of powder type was clearly detected in the observations of single spray beads. Higher deposition efficiency and denser coatings were prepared by using the spherical copper powder.

Electrodeposition of Cu-Ni Incorporated with Layered Silicates for Microbial Corrosion Protection

Electrodeposition of different metals and alloys has become popular for corrosion resistance and hardness in the oil and gas industry because of the major problems that persist with corrosion. The off-shore oil rigs in the ocean are exposed to highly corrosive spray zones and low flow submerged components. The cost of corrosion weighs a heavy burden of about $1.372 billion dollars on the oil and gas industries in the United States [1]. Breaking down the total amount, this accounts for $589 million in surface pipeline and facility costs, $463 million in down hole tubing expenses and $320 million in capital expenditures related to corrosion [1].Electrodeposition has become a popular technique to produce new materials for science and engineering applications. The technique has become favorable in synthesizing coatings because of low cost, convenience, and the ability to work at low temperatures. When determining the structure, morphology, and composition of the film; the pH, current, and applied potential play an important role [2]. For use in marine environments, copper alloys are used to defend against biofouling of materials by inhibiting microbial induced corrosion (MIC). Copper ions are able to eliminate bacteria, viruses, fungi, algae and other microbes. Copper alloys have been examined due to their increased feasibility, material strength, and cost as compared to pure copper coatings [3]. The two major copper alloys that are most commonly examined are Cu-Ni 90-10 and Cu-Ni 70-30. 90-10 Cu-Ni coatings show good protection in more stagnant conditions, where as the 70-30 Cu-Ni coatings are employed in higher flow conditions because of the increased hardness provided by the higher concentration of nickel. Copper alloys are usually employed when long term durability is needed. Incorporation of ceramics into the metal coating improve the mechanical properties. Layered silicates are the ceramic compounds being analyzed in this study, which hold many lucrative properties such as a high surface area, good chemical resistance, resistance to extreme temperatures, and resistance to pH. Scientists have been able to prove that layered silicates improve the resistance to corrosion when it comes to conductive polymer composite coatings, scientists have proved that layered silicates increase the resistance to corrosion [4]. With the addition of montmorillonite (MMT) into the Cu-Ni matrix, an increase in strength, adhesion, wear and fracture toughness of the coating occurs, which provides for better corrosion resistance and hardness.The Cu-Ni-MMT coatings were analyzed with many different instrumental and electrochemical techniques. Scanning electron microscopy (SEM) was chosen to analyze the morphology of the electrodeposited films. X-ray diffraction (XRD) was used to analyze the crystal structure of the films. The copper to nickel metal ratio was determined using atomic absorption spectroscopy (AAS) and the presence of the clay in the film; silicon, alumina, magnesium and iron was confirmed with energy dispersion x-ray spectroscopy (EDX). The corrosion resistance and hardness of the films were analyzed using Tafel polarization, immersion tests, impedance spectroscopy, and nanoindentation. Also, solution studies were performed with zeta potential, particle size, and viscosity to determine the optimum amount of loading for MMT into the Cu-Ni films.In conclusion, copper and copper alloys are commonly used in marine environments to resist biofouling of materials by inhibiting microbial growth. Two major alloys of copper-nickel, 90-10 and 70-30, were electrodeposited with a layered silicate, montmorillonite, for microbial corrosion protection in marine environments on a stainless steel substrate. The overall corrosion resistance and hardness was improved with the film in comparison to the bare stainless steel substrate, which proves to be advantageous for the off-shore drilling environment in the oil and gas industry.

Study on tribological behavior of electrodeposited Cu–Si3N4 composite coatings

Cu–Si3N4 composite coatings were prepared by electrolysis from a copper sulphate solution containing dispersed Si3N4 particles of 0.4 or 1μm mean size. Wear behavior of Cu–Si3N4 composite and pure copper coatings were evaluated using a pin-on-disc test machine under dry condition sliding. Effects of current density and particle concentration on the incorporation percentage of Si3N4, the preferred orientation of copper crystallites, the microstructure, the microhardness and the wear resistance of the coatings were determined. Si3N4 particles in the copper matrix resulted in the production of composite deposits with smaller grain sizes and led to change the preferred orientation growth from [100] to [110]. It was proved that the presence of Si3N4 particles decreases the wear loss and the friction coefficient of the coating. According to the results, the friction coefficient decreased dramatically from 0.52 to 0.26 for pure copper coatings to 0.16–0.24 for Cu–Si3N4 composite coatings. In addition, fluctuation of friction coefficient values for Cu–Si3N4 composite coating was lower compared with the pure copper coating. The wear properties of Cu–Si3N4 composite coatings were shown to depend on the weight fraction, the size and the distribution of co-deposited particles.

Parameter study influencing thermal conductivity of annealed pure copper coatings deposited by selective cold spray processes

When two copper splats are in contact, a resistance to heat transfer exists between the splats. In thermal spraying, the conductivity of the coating is mainly reduced by non-metallic bonds at internal interfaces and trapped oxides. In cold spraying, however, almost no oxidation occurs during spraying. To demonstrate the capabilities and advantages of Cold Spray for the manufacturing of a conductive copper coating, the present study is focused at comparing the different processing methods in the as-sprayed and the annealed state. As a result, the coatings sprayed with spherical copper particles showed superior thermal conductive characteristics than coatings sprayed with non-spherical particles. There was a critical annealing temperature giving the maximum thermal conductivity. Up to a critical temperature, the annealing process enhanced the thermal conduction between adjacent splats. But, over that temperature, the voids in the coating rearrange and concentrate along the grain boundaries.

Mechanical and anticorrosive properties of copper matrix micro- and nano-composite coatings

In the frame of the research domain of the production of metal matrix composite coatings, the aim of the present work was the production of copper electrodeposits containing micro- and nano-particles of SiC. The electrodeposition was carried out under dc conditions using a copper pyrophosphate plating bath into which micro- or nano-SiC particles were suspended. The composite coatings were tested and compared to pure copper coatings regarding their microstructure, mechanical and anticorrosive properties. The codeposition of SiC in the metal matrix changed the microstructure of the copper leading to improvement of both their mechanical and, in some cases, their protective properties. The Vickers microhardness presented an increase of about 35% and 61% in the case of SiC micro- and nano-particles incorporation while the increase of the abrasion resistance was 88% and 58%, respectively. The incorporation of the micro-particles lead to gaps formation among the SiC micro-particles and the metal matrix, thus lowering the resistance on both uniform and localized corrosion in comparison to the pure copper-coated specimens while the codeposition of SiC nano-particles produced deposits with higher resistance to both uniform and localized corrosion.

Sliding wear studies of ni-cu composition-modulated coatings on steel

Sliding wear measurements have been conducted on Ni-Cu composition-modulated coatings on steel. The electrodeposited coatings consisted of alternate layers of nickel and copper with equal layer spacings of either 10 or 100 nm. Pure nickel and pure copper coatings were also prepared in a similar manner and studied. The coated cylinders were slid against AISI type 52100 steel in a crossed cylinder geometry under clean conditions without lubrication at various loads and sliding distances. It was found that the most wearresistant coating was the composition-modulated alloy having the smallest layer spacing, 10 nm. This effect was most pronounced at low loads. Both composition-modulated coatings showed less wear than coatings of pure copper and nickel deposited from the same solution. The layer microstructure in these composition-modulated coatings may provide internal barriers to wear damage, thus leading to the increases in wear resistance. Results from examination of the worn specimens and collections of wear debris are also described.

Physicome chanical properties of electroplated pseudoalloys based on copper

1. Electroplated copper-corundum composites have a high microhardness and an elevated yield strength and high-temperature strength. Electroplated composite coatings are hardened in the same way as composite materials obtained by PM technique. 2. The heat resistance of copper-corundum composites is higher than that of pure copper coatings from pyrophosphate and ethylene diamine electrolytes.