Copper Alloy Surfaces Research Articles

Corrosion Behaviour of HVOF-Sprayed CoCrNi Coating on Copper Alloy Surface in NaCl Solution

Corrosion Behaviour of HVOF-Sprayed CoCrNi Coating on Copper Alloy Surface in NaCl Solution

Microstructure, hardness, and tribological properties of CoCrFeNiX (X = Mo, Ti, W) high entropy alloy coating by red-blue composite laser cladding on copper alloy

In this study, the problem of high reflectivity of copper alloy surface to traditional infrared laser beam was overcome by red-blue composite laser cladding technology. The problem of cracks and other defects caused by the large difference in thermal expansion coefficient between copper substrate and high entropy alloy coating was overcome by electroplating Ni intermediate layer on the surface of copper alloy. A high-entropy alloy coating with tight bonding and no obvious defects was successfully prepared on the surface of copper alloy. The phase composition, microstructure evolution, hardness and tribological properties of high-entropy alloy coatings after adding different elements were studied. The experimental results show that all the CoCrFeNi coatings are FCC phase. After the addition of Mo, Ti and W elements, σ phase rich in Mo and Cr, TiCo2-type Laves phase and Fe7W6-type μ phase appeared in the high entropy alloy coating, respectively. The average microhardness of CoCrFeNiX (X = Mo, Ti, W) high entropy alloy coatings reached 730 HV0.2, 1090 HV0.2 and 378 HV0.2, respectively. The wear rates of CoCrFeNiMo, CoCrFeNiTi and CoCrFeNiW high-entropy alloy coatings were 47.17 %, 90.56 % and 22.64 % lower than those of CoCrFeNi coating, respectively. The wear scars were analyzed by SEM and EDS, and the friction and wear behavior mechanism of CoCrFeNiX (X = Mo, Ti, W) high-entropy alloy coating was investigated. It is mainly composed of abrasive wear, adhesive wear and oxidation wear. The research results provide practical guidance for the preparation of high-entropy alloy coatings on copper surface, and lay a theoretical foundation for laser cladding such high-entropy alloy materials and substrate materials.

Current-carrying tribological behavior of copper alloy matrix and molybdenum alloy coating at high current density

Improving the current-carrying friction and wear resistance of copper alloy current-carrying friction subsets effectively is a hot topic. In this paper, a method of preparing high melting point molybdenum-based coating on copper alloy surfaces by laser cladding technology is presented. A large current (106 A/m2) comparison experiment is carried out with a self-made current-carrying friction device, and the failure mechanism is analyzed. The results show that the molybdenum-based coating significantly improves the adhesion problem between the friction partner and the copper alloy substrate, while the thickness of the stress layer caused by the current-carrying friction is reduced by about 7 times. The molybdenum-based coating significantly reduces the surface arc rate and has a lower friction interface temperature, thus retaining the Al2O3 self-lubricating phase. The research in this paper is expected to provide extended research ideas for the surface protection of current-carrying friction subsets of copper alloys.

Fast Fabrication of Superhydrophobic Copper Alloy Fabricated by Commercial Fiber Laser-1062 nm and Stability of Superhydrophobic Surface

We present a fast, straightforward fabrication method to produce stable superhydrophobic copper alloy surfaces. The technique consists of irradiating copper with a fiber laser and then coating the surface with ethanol. The laser ablation generates surface morphology on the copper surfaces, such as line and grid patterns. We can modify the wetting properties and surface morphology by changing the step size. We assessed the change of the water contact angle on the raw surface, laser-based textures after natural aging, and laser-based textures post-low annealing. After that, we measured the stability of the water contact angle till 120 days. After low annealing heat treatment, water contact angles on grid pattern surfaces have superhydrophobic surfaces and are more stable till 120 days.

A Novel Superhard, Wear-Resistant, and Highly Conductive Cu-MoSi2 Coating Fabricated by High-Speed Laser Cladding Technique.

The pursuit of an advanced functional coating that simultaneously combines high hardness, wear resistance, and superior electrical conductivity has remained an elusive goal in the field of copper alloy surface enhancement. Traditional solid solution alloying methods often lead to a significant increase in electron scattering, resulting in a notable reduction in electrical conductivity, making it challenging to achieve a balance between high hardness, wear resistance, and high conductivity. The key lies in identifying a suitable microstructure where dislocation motion is effectively hindered while minimizing the scattering of conductive electrons. In this study, a novel Cu-MoSi2 coating was successfully fabricated on a CuCrZr alloy surface using the coaxial powder feeding high-speed laser cladding technique, with the addition of 10-30% MoSi2 particles. The coating significantly enhances the hardness and wear resistance of the copper substrate while maintaining favorable electrical conductivity. As the quantity of MoSi2 particles increases, the coating's hardness and wear resistance gradually improve, with minimal variance in conductivity. Among the coatings, the Cu-30%MoSi2 coating stands out with the highest hardness (974.5 HV0.5) and the lowest wear amount (0.062 mg/km), approximately 15 times the hardness of the copper base material (65 HV0.5) and only 0.45% of the wear amount (13.71 mg/km). Additionally, the coating exhibits a resistivity of 0.173 × 10-6 Ω·m. The extraordinary hardness and wear resistance of these coatings can be attributed to the dispersion strengthening effect of MoxSiy particles, while the high electrical conductivity is due to the low silicon content dissolved into the copper from the released MoSi2 particles, as well as the rapid cooling rates associated with the high-speed laser cladding process.

In vitro comparison of methods for sampling copper-based antimicrobial surfaces.

Self-sanitizing surfaces such as copper (Cu) are increasingly used on high-touch surfaces to prevent the spread of harmful viruses and bacteria. Being able to monitor the antimicrobial properties of Cu is fundamental in measuring its antimicrobial efficacy. Thorough investigations into reliable methods to enumerate bacteria from self-sanitizing surfaces are lacking in the literature. This study demonstrates that direct use of Petrifilm on Cu surfaces most likely revives stressed and dying bacteria, which induces increased bacterial counts. This phenomenon was not observed with indirect collection methods. Studies assessing time-kill kinetics or long-term efficacy of Cu should consider the impact of the collection method chosen.

Investigation of copper and zinc alloy surface exposed to corrosion environment by digital image processing

Usually, corrosion processes on brass, which are manifested by discoloration of the metal or alloy surface, are a little destructive and slow in natural environment or non-acid solutions. In this context, investigation of the corrosion process under the above conditions can be a research area of great relevance because standard analysis such as weight loss and electrochemical techniques can not be applied. Here, we report on a digital image processing analysis of the evolution of copper and zinc alloy surfaces corrosion due to exposure to air, alcohol-aqueous solutions, and sugarcane liquor. For our analysis, we investigated 2D image produced by a confocal microscope from a topographic surface survey, by calculating parameters such as correlation coefficient, Hurst exponent, and bright/dark ratio to follow the early stage of the corrosion process evolution due to exposure to several conditions for different periods of time. The best fits are presented together with the image processing data to show the evolution of the surface characteristics as a function of time and treatment. We show that digital image of rough surfaces that have undergone early stage of the corrosion processes can be used to monitor surface changes. For all tested solutions, the changes in the surface can be better sensed by using the B/D ratio due to the large vertical scale but the fit was better for the correlation coefficient. Particularly for sugarcane liquor and 100% C2H5OH alcohol solution, B/D ratio varies slower than for the other solutions, thus, suggesting an inhibitory effect of this solution.

EBSD and Raman Spectroscopy Analysis of Copper Alloy H62/GOp-modified Layer Prepared by Friction Stir Surface Processing

Graphene oxide particles (GOp) were implanted on the surface of H62 copper alloy to prepare an H62/GOp-modified layer by friction stir surface processing (FSSP). The Raman spectrum and microstructure of the modified layer were tested and analyzed. The results showed that the H62/GOp-modified layer prepared under different parameters by FSSP had characteristic Raman spectrum peaks graphene oxide (GO), which indicates that the modified layer containing GO can be prepared by FSSP on the copper alloy surface. The surface grain structure of the H62/GOp-modified layer of each sample was refined, and their large-angle grain boundary ratios were above 85 % and higher than that of the base metal. In addition, the grain volume fraction in the dynamic recrystallization region of each sample was above 60 vol%, and the maximum was 73.9 vol%, which indicates the desirable microstructure consistency of the H62/GOp-modified layer prepared under different parameters by FSSP.

Influence of the Process Parameters on the Microhardness and the Wear Resistance of Friction Stir Processed H65 Copper Alloy

Friction stir processing (FSP) was used to modify a larger-size surface of H65 copper alloy. The influence of the traverse speed and the rotation speed on the microstructure, the microhardness and the wear resistance of the modified surface were analyzed. The wear mechanism of the modified H65 copper alloy was revealed. The results indicate that the grain size was greatly refined after FSP compared with the parent metal and that the grain size increased with the increment of the rotation speed. The average microhardness of the modified surface was higher than that of the parent metal. The average microhardness had a highest value of 174.13 HV when the traverse speed was 200 mm/min and the rotation speed was 200 rpm, i.e., 21% higher than that of the parent metal. The average microhardness decreased with the increase of the rotation speed. When the traverse speed was 200 mm/min and the rotation speed was 600 rpm, the average friction coefficient of the modified surface was the smallest (0.3213), which was lower than that of the parent metal (0.3810). The wear mechanism of the H65 copper alloy modified by FSP was mainly adhesive wear accompanied by local abrasive wear.

Analysis of the microstructure and wear resistance of H62/GOp modified layer by friction stir surface processing

Graphene oxide particles (GOp) were implanted on the surface of H62 copper alloy by friction stir surface processing (FSSP) to obtain a H62/GOp modified layer. The recrystallization microstructure, friction, and wear property, and hardness of the modified layer were studied and analyzed. The results show that the GOp has a good dispersion in the copper matrix without obvious aggregation. The recrystallization on the layer of the modified copper alloy resulted in obvious grain refinement. When the rotating speed of the tool was 900 rpm, and the feed speed of the tool was 200 mm/min, the highest hardness value and wear resistance of the modified layer samples were obtained. The hardness value was 25.2% higher than that of the base metal. The average friction coefficient was 39.5% lower than that of the base metal. When the tool rotating speed was 1300 rpm, and the tool feed speed was 160 mm/min, the hardness value and wear resistance of the modified layer were relatively low. The hardness value was approximately 4% higher than that of the base metal. The average friction coefficient was 15.8% less than that of the base metal. The hardness and wear resistance of the modified layer were better than those of the base material under various parameters of FSSP.

Laser marking of non-ferrous metal and alloy products using ultradense barcodes: process features

This paper describes the results of a study that looked at the effect of laser pulses on the surface of copper, aluminium and titanium alloys during laser marking. A series of studies has been carried out aimed at developing a process that would enable putting high-density barcodes on the surface of nonferrous metals in order to keep a great amount of data about the products and to protect them from counterfeiting. The paper explains why nanobarcodes are unique and how they outperform common standard markings. The colours of the markings are defined by the characteristics of the oxide films that form as the result of surface modification by laser pulses. They include the thickness of the oxide film and its phase and chemical compositions, which impact the chemical composition of the alloy and the temperaturetime modes of the laser marker. To ensure quality in marking, the authors selected the most contrasting tones of the resultant markings. Sets of such colours are presented that were obtained on the studied materials. The paper also describes the results of optical and electronic microscopy of the oxide films of the resultant markings demonstrating the structure of furrows and craters, which are the result of surface melting and evaporation under laser treatment. The paper analyzes the quality of the resultant nanobarcodes in terms of their readability and decodability by means of special software.

Aesculus hippocastanum seeds extract as eco-friendly corrosion inhibitor for desalination plants: Experimental and theoretical studies

In this work, Aesculus Hippocastanum Seeds (AHS) extract has been used as a sustainability and environmentally corrosion inhibitor to reduce the risk of copper alloy corrosion during the acid cleaning process in desalination plants. This extract contains mostly Quercetin 3,4-diglucoside, Aesculin, escin Ia, escin Ib, isoescin Ia, isoescin Ib, Leucocyanidin, Fraxin, Procyanidin A2, Quercetin, and Kaempferol, according to HPLC analysis. At 100 ppm, the AHS extract showed a 96.1 percent inhibitory efficacy as a corrosion inhibitor. The findings demonstrate that AHS is an effective mixed–type corrosion inhibitor. The AHS extract solution has a greater activation energy value (i.e. 7.32 kJ mol−1) than the blank system (i.e. 15.65 kJ mol−1), indicating a physical adsorption process. Furthermore, the Langmuir adsorption pattern is applied to describe AHS extract adsorption. The electron dispersion in inhibitor compounds was revealed by quantum calculations, revealing their capacity to accept/donate charges from Cu-Ni atoms in vacuum and in water solvation. The extract molecules adsorbed on the copper alloy surface in a nearly flat orientation to acquire maximal surface coverage and contact, according to a molecular dynamics simulation.

Study on the Corrosion Resistance of the H65 Copper Alloy Surface Modified by Friction Stir Surface Processing

Study on the Corrosion Resistance of the H65 Copper Alloy Surface Modified by Friction Stir Surface Processing

Study on preparation and durability of surface microstructure of copper alloy

Superhydrophobic surfaces have huge applications in wetting fields. However, the surface is prone to mechanical abrasion and environmental damage in the application. This paper provides an alternative approach to preparing durable superhydrophobic surfaces, reveals the wear mechanism of the copper alloy surface and compares the tribological properties of different surfaces. Then, take the superhydrophobic surface of the circular truncated cone microstructure as an example to verify the durability under friction and wear, atmospheric environment, and acid and alkali media. The results show that compared with the polished surface, the copper alloy surface with microstructures can effectively reduce the friction coefficient of the surface and improve the tribological performance. The prepared superhydrophobic surface can endure abrasion under certain pressure and distance, and keep great stability in the atmospheric environment and acid–base conditions.

Efficacy and Mechanisms of Copper Ion-Catalyzed Inactivation of Human Norovirus.

The antinoroviral effect of copper ions is well known, yet most of this work has previously been conducted in copper and copper alloy surfaces, not copper ions in solution. In this work, we characterized the effects that Cu ions have on human norovirus capsids’ and surrogates’ integrity to explain empirical data, indicating virus inactivation by copper alloy surfaces, and as means of developing novel metal ion-based virucides. Comparatively high concentrations of Cu(II) ions (>10 mM) had little effect on the infectivity of human norovirus surrogates, so we used sodium ascorbate as a reducing agent to generate unstable Cu(I) ions from solutions of copper bromide. We found that significantly lower concentrations of monovalent copper ions (∼0.1 mM) compared to divalent copper ions cause capsid protein damage that prevents human norovirus capsids from binding to cell receptors in vitro and induce a greater than 4-log reduction in infectivity of Tulane virus, a human norovirus surrogate. Further, these Cu(I) solutions caused reduction of GII.4 norovirus from stool in suspension, producing about a 2-log reduction of virus as measured by a reverse transcriptase-quantitative polymerase chain reaction. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) data indicate substantial major capsid protein cleavage of both GI.7 and GII.4 norovirus capsids, and TEM images show the complete loss of capsid integrity of GI.7 norovirus. GII.4 virus-like particles (VLPs) were less susceptible to inactivation by copper ion treatments than GI.7 VLPs based upon receptor binding and SDS-PAGE analysis of viral capsids. The combined data demonstrate that stabilized Cu(I) ion solutions show promise as highly effective noroviral disinfectants in solution that can potentially be utilized at low concentrations for inactivation of human noroviruses.

An application of Neural Networks for Prediction of Surface Texture Parameters in Turning

Surface roughness, an indicator of surface quality is one of the most specified customer requirements in a machining process. Mastering of surface quality issues helps avoiding failure, enhances component integrity, and reduces overall costs. Copper alloy (GCCuSn12) surface quality, achieved in turning, constitutes the subject of the current research study. Test specimens in the form of near-to-net-shape bars and a titanium nitride coated cemented carbide (T30) cutting tool were used. The independent variables considered were the tool nose radius (r), feed rate (f), cutting speed (V), and depth of cut (a). Process performance is estimated using the statistical surface texture parameters Rα, Ry, and Rz. To predict the surface roughness, an artificial feed forward back propagation neural network (ANN) model was designed for the data obtained.

Tailor the antibacterial efficiency of copper alloys by oxidation: when to and when not to

Copper and its relevant species, such as oxides and many alloys, have been recognised as potential antibacterial surfaces. Despite the relatively low antibacterial efficacy of cuprous oxide (Cu2O) compared to pure copper, it is still worth consideration in some scenarios. Taking copper-nickel co-sputtered thin films with two copper contents (55 and 92 at.%) as examples, this work investigated the potential of oxidation in altering the antibacterial behaviour of copper alloy surfaces. By heat treatment at 200–250 °C for 20–24 h, a layer mainly composed of Cu2O was successfully fabricated on the top of the Cu-Ni alloys. Antibacterial efficiency against Escherichia coli in 1 h was obtained by the droplet method and further compared. The coupons with 92 at.% copper became less effective after oxidation: the reduction rate declines from 97.0 to 74.3%; whereas the coupons with 55 at.% copper showed a large increase after oxidation, rising from 15.0 to 66.8%. The experiments described herein reveal a promising concept of oxidation in enhancing the less effective copper alloy surfaces for antibacterial applications.Graphical abstract

Quantitative Evaluation of Nucleic Acid Degradability of Copper Alloy Surfaces and Its Correlation to Antibacterial Activity.

Copper (Cu) and its alloys have bactericidal activity known as “contact killing” with degradation of nucleic acids inside the bacteria, which is beneficial to inhibit horizontal gene transfer (HGF). In order to understand the nucleic acid degradability of Cu and its alloy surfaces, we developed a new in vitro method to quantitatively evaluate it by a swab method under a “dry” condition and compared it with that of commercially available antibacterial materials such as antibacterial stainless steel, pure silver, and antibacterial resins. As a result, only Cu and its alloys showed continuous degradation of nucleic acids for up to 6 h of contact time. The nucleic acid degradability levels of the Cu alloys and other antibacterial materials correlate to their antibacterial activities evaluated by a film method referring to JIS Z 2801:2012 for Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Nucleic acid degradation by copper (I) and (II) chlorides was confirmed at the ranges over 10 mM and 1–20 mM, respectively, suggesting that the copper ion release may be responsible for the degradation of the nucleic acids on Cu and its alloy surfaces. In conclusion, the higher Cu content in the alloys gave higher nucleic acid degradability and higher antibacterial activities.

Modifying Copper and Copper Alloy Surface with Depocolin and 5-Chloro-1,2,3-Benzotriazole from a Neutral Aqueous Solution

Modifying Copper and Copper Alloy Surface with Depocolin and 5-Chloro-1,2,3-Benzotriazole from a Neutral Aqueous Solution

The COVID-19 Pandemic, Part 2: Understanding the Efficacy of Oxidized Copper Compounds in Suppressing Infectious Aerosol-Based Virus Transmission

In CORROSION’S June 2020 editorial,1 we explored the COVID-192 pandemic and the antimicrobial function of copper and silver enabled by corrosion Since that editorial was written, we have gone from 2 1 million confirmed infections and over 143,000 related deaths worldwide3 to 114,582,356 cases and 2,541,808 deaths as of March 1, 2021, according to the John Hopkins University COVID-19 Dashboard 3 A cause of this large increase is the high rate of the spread of SARS-CoV-2 (the virus that causes the coronavirus disease COVID-19), which is 40-fold greater than that of SARS-CoV-1 4 Recently, a more highly contagious mutation has been reported which makes this virus (referred to as the COVID-19 virus throughout this editorial) even more transmittable 5 This makes the COVID-19 virus even more difficult to control4 than SARS-CoV-1 Surgical masks are often made of three different fiber layers to prevent the entry of viruses: the outside layer is designed to stop liquids from traveling inwards towards the face, mouth, and nose without encountering an obstacle;an interlayer acts as a barrier against viruses and bacteria;and an inner layer absorbs moisture exhaled by the wearer 7,8 Different materials can be synthesized to act as protective coatings where the fabric can be designed to control pore size relative to airborne aerosol and particulate dimensions,4 as well as function in other ways such as by electrostatic attraction of aerosol particles (a) Possible pathways for transmission of the COVID-19 virus involving human atomization of viruses during the coughing or sneezing of an infected person Elemental copper and silver10 possess intrinsic antimicrobial properties that are enabled by corrosion which releases free metal cations 25,32,34 The free ions are distinct from copper ion sequestering in the oxide layer formed over the surface of the alloy or dissolved but chelated (to form a compound usually with an organic species in the environment, whereupon the organic is bonded to the copper ion) with some molecular species in solution 25,32,34-37 Inactivation time (>99 9% reduction) of Escherichia coli (HCB1) and Legionella pneumophila bacteria in various soluble [Cu2+] concentrations Because the corrosion thermodynamics, kinetics, and the stability of the oxidized products formed can all differ with the molecular identity of the product, inoculum, saliva,40 and perspiration “solution chemistry,”32 these considerations need to be evaluated carefully to fully understand the efficacy of both Cu as a surface disinfectant and Cu compounds as disinfecting agents impregnated in PPE