Coatings Of Cu Research Articles

Obtaining Multicomponent Coatings of a Stable Composition for Electromagnetic Radiation Screens

The formation processes of coatings of Cu–Ni and Ag–Cu systems with a stable elemental composition by the method of electron-beam evaporation are considered. It is shown that in the zone of action of the electron beam on the ingot placed in the crucible at the total vapor pressure of the alloy elements Σp above the pressure under the cap of the installation, the melt boils, and in the outer zone adjacent to the melt zone, the process of sublimation of the hard alloy occurs. The microrelief and elemental composition of the surface layer of the Cu–Ni alloy ingot in the zones of evaporation and sublimation, as well as the elemental composition of the coatings deposited in this case, have been studied. It is shown that the most acceptable way to obtain coatings of the Cu–Ni system with a stable elemental composition is the simultaneous electron-beam evaporation of copper and nickel from two crucibles. The azeotropic composition of the alloy of the Ag–Cu system was calculated and experimentally verified. The research results are used in the manufacture of multilayered screens of electromagnetic radiation.

Influence of Parameters and Regimes of the Electrodeposition on Hardness of Copper Coatings

Correlation among morphological, structural and hardness characteristics of electrodeposited copper coatings is presented in this review paper. Cu coatings were produced applying constant galvanostatic (DC) and pulsating current (PC) regimes on hard silicon (Si(111)) and brass substrates. The parameters of the electrochemical deposition were analyzed, which include the kinds of electrolyte and cathode, the coating thickness and the electrolyte stirring, as well as the parameters defining PC regime, such as the average current density and the current density amplitude, were analyzed. Morphology and structure of Cu coatings were examined by scanning electron microscope (SEM), atomic force microscope (AFM) and by X-ray diffraction (XRD), while hardness was examined by Vickers microindentation. The coatings of Cu on both Si(111) and brass cathodes belong to “soft film (coating) on hard substrate” composite hardness system, and the Chicot–Lesage (C–L) composite hardness model was applied to estimate a hardness of the Cu coatings. Analyzing the examined parameters and regimes of electrodeposition, the critical relative indentation depth (RID)c of 0.14 has been defined by the C–L model. Based on done analyses, it is shown that this RID value, separating a zone where measured hardness corresponds to the coating hardness and a zone where it is necessary to apply the C–L model to determine an absolute hardness of the Cu coatings, has an universal character for the electrolytically produced Cu coatings on Si(111) and brass substrates.

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.

Domestic pottery sherds used in non-ferrous metalworking: a study from early medieval Prague

Among archaeometallurgical remains from Prague of the tenth and eleventh centuries AD, attention has been focused on a single type of finds: fragments of common ceramic kitchenware secondarily utilised in assaying ores and in the production and refinement of non-ferrous metals. Fifteen samples from several sites were selected for EDS-SEM analyses of various parts of glassy, slaggy and metallic coatings, of metallic prills and of the primary and secondary mineral phases in these solidified melts. Variable intermediate products of silver and gold extraction were identified, as were examples of the successful cupellation and refinement of these metals. The secondary utilisation of silver scrap has been ruled out by the chemical composition of the coatings on the majority of sherds with a significant Ag content. In contrast, substantial concentrations of other metallic elements (e.g. Bi, Sn) and coatings of Cu- and Fe-sulphide mixtures in some samples correspond to the early stages of the metallurgical processing of non-ferrous metals (ore concentrates) or initial metallurgical intermediate products.

Thermally evaporated Cu–Al thin film coated flexible glass mirror for concentrated solar power applications

This paper reports the development of mechanically flexible reflective coatings of Cu–Al intermetallic alloy on flexible glass (FG) substrates for possible concentrated solar power application. Thin films of Cu–Al intermetallic alloys were deposited on 100 μm thick FG substrates using resistive thermal evaporation of arc melted Cu–Al bulk alloy. At the optimized evaporation conditions, smooth intermetallic alloy thin films with homogeneous composition (Cu0.78Al0.22) were obtained. At a coating thickness of 160 nm, average specular and total reflectance of ∼84% and ∼92% respectively, were achieved. The films exhibited hydrophobic nature with a contact angle of 102°, implying the possibility of developing a self-cleaning ability. The analytical calculation involving alloy compositional dependence of plasma frequency reveals the prospect of further modulating the reflectance property by carefully tailoring thin film composition. Additionally, hard intermetallic thin film provides the opportunity of developing mirrors that may not require top protective coatings.

Brazing of Martensitic Stainless Steel to Copper Using Electroplated Copper and Silver Coatings

Brazing of 3 mm thick sheets of low-carbon martensitic stainless steel and Cu-Cr-Zr-Ti alloy was attempted using electroplated coatings of Cu and Ag. Ni coating of 5 µm thick was provided on the MSS base metal to enhance the wettability. Brazing experiments were carried out at 985 °C for a holding of 15 min. Detailed microstructural studies, hardness, lap-shear, tensile, and pressure tests were carried out on the brazed joints. The reaction between the Cu and Ag coatings lead to the formation of in situ braze metal. The microstructure of the braze metal was found to consist of Cu-rich primary alpha (αP) and Ag-rich eutectic mixture (β + αE). In lap-shear tests, the brazed joints produced with an overlap of 9 and 6 mm were found to fail in copper base metal, while the joints produced with an overlap of 3 mm failed in the braze metal exhibiting a lap-shear strength of 147 MPa. In tensile tests, the butt brazed joints were found to fail in copper base metal as well with an average tensile strength of 213 MPa. The braze metal hardness was found to be higher than the hardness of the copper base metal. In pressure tests, the brazed panels were found to survive a pressure of 750 bar without undergoing any damage. These results show that electroplated coatings of Cu and Ag can be advantageously utilized for brazing of large, complex-shaped parts such as thrust chambers in space industry.

Deposition of Al2O3 ceramic film on copper‐based heterostructured coatings by aluminizing process: Study of the electrochemical responses and corrosion mechanism of the coating

AbstractThe effect of deposition of the Al2O3 ceramic film by the aluminizing method on electrochemical responses and corrosion mechanism of copper‐based heterostructured coatings was studied. The single layer coatings of Cu and Al2O3 and Cu/Al2O3 double layers were produced using reverse pulsed current electroplating process followed by powder cementation of aluminum on a substrate made of Inconel 600 superalloy. The produced coatings were then characterized using Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and X‐ray Diffraction (XRD) methods. In order to evaluate the behavior and corrosion mechanism of the produced coatings, potentiodynamic polarization and electrochemical impedance spectroscopy methods were also used in 1 mol/L HCl solution at immersion times of 1, 12, 24, and 48 hours. The results of the study showed that the mechanism of the formation of Cu/Al2O3 copper‐based coatings is that in the aluminizing step, first, the diffusion of Al from the surface layers to the interior occurs and then the diffusion of Cu from the plating layer to the exterior takes places. It was also found that the deposition of the Al2O3 ceramic film resulted in the formation of α‐Al2O3 and CuAl2O4 phases and increased corrosion resistance in Cu/Al2O3 copper‐based coatings at all immersion times and the corrosion mechanism has changed from uniform to localized state.

Investigation of the wavelength dependence of laser stratigraphy on Cu and Ni coatings using LIBS compared to a pure thermal ablation model

In this study, galvanic coatings of Cu and Ni, typically applied in industrial standard routines, were investigated. Ablation experiments were carried out using the first two harmonic wavelengths of a pulsed Nd:YAG laser and the resulting plasma spectra were analysed using a linear Pearson correlation method. For both wavelengths the absorption/ablation behaviour as well as laser-induced breakdown spectroscopy (LIBS) depth profiles were studied varying laser fluences between 4.3–17.2 J/cm^2 at 532 nm and 2.9–11.7 J/cm^2 at 1064 nm. The LIBS-stratigrams were compared with energy-dispersive X-ray spectroscopy of cross-sections. The ablation rates were calculated and compared to theoretical values originating from a thermal ablation model. Generally, higher ablation rates were obtained with 532 nm light for both materials. The light–plasma interaction is suggested as possible cause of the lower ablation rates in the infrared regime. Neither clear evidence of the pure thermal ablation, nor correlation with optical properties of investigated materials was obtained.

Caracterización microestructural, mecánica y de desgaste de recubrimientos de CuxAly depositados mediante proyección térmica

En este trabajo se caracterizó la microestructura, la adherencia y el coeficiente de desgate de recubrimientos de CuxAly depositados mediante proyección térmica sobre sustratos de latón. En el estudio se utilizaron como parámetros de evaluación la preparación superficial del sustrato y un recubrimiento intermedio que actúa como capa adhesiva. El análisis de la composición química se hizo mediante la fluorescencia de rayos X (FRX), el análisis estructural se realizó por medio de la difracción de rayos X (DRX) y la microscopía electrónica de transmisión (MET). La adherencia se determinó mediante los ensayos de rayado transversales, la respuesta mecánica se evaluó mediante la medición de la dureza Knoop y pruebas de desgaste abrasivo tres cuerpos y "Pin en disco". Los resultados permitieron establecer que el recubrimiento sin capa adhesiva y preparada por granallado metálico puede ser utilizado en la recuperación de piezas debido a que presenta menor falla cohesiva.

Formation of metal coatings on magnesium using a galvanic replacement reaction in ionic liquid

Surface coatings of Cu, Ni, Zn, and Ti on magnesium are deposited using a galvanic replacement reaction in butylmethylpyrrolidinium–dicyanamide ionic liquid. The coated samples show improved corrosion resistance compared to bare Mg.

Evaluation of coated urea for ammonia volatilization loss, nitrogen mineralization and microsite pH in selected soil series

The increase in microsite soil pH due to surface application of urea to the soil is an important reason of ammonia volatilization loss and fast hydrolysis process. The use of Cu and Zn with biodegradable materials coatings were assumed to reduce ammonia volatilization losses by reducing soil pH and slowing down hydrolysis process. The present study was conducted to evaluate the effects of coated urea with the combination coatings of Cu, Zn, palm stearin, agar and gelatine on microsite pH. For this purpose, six urea treatments named; uncoated urea or control, Cu and palm stearin coated urea, Cu and agar coated urea, Cu and gelatine coated urea, Cu coated urea, Cu and Zn coated urea were prepared and evaluated for their effects on microsite pH, ammonia volatilization loss and mineralization of N in three tropical soil. For the each soil; soil properties, soil microsite pH, ammonia volatilization loss and N mineralization were determined with slandered methods. The results reveal that the microsite pH in the three soils varied significantly due to the variability in texture. The pH of microsite treated with coated urea was lower than the uncoated urea treatments in each soil. The reduction in the microsite soil pH was associated with urea hydrolysis. The rate of mineralization (30%) and ammonia volatilization (50%) reduced in the soils where the pH was low or stable on the fertilizer microsite after adding the fertilizer treatments. The results of this study proved the positive effectiveness of coating material and potential to control fast hydrolysis process and ammonia volatilization losses. Key words: Ammonia volatilization, microsite pH, nitrogen, urease inhibitors.

Influence of electroless coatings of Cu, Ni–P and Co–P on MmNi 3.25Al 0.35Mn 0.25Co 0.66 alloy used as anodes in Ni–MH batteries

Electroless coatings of Ni–P, Co–P and Cu were applied on the surface of non-stoichiometric MmNi 3.25Al 0.35Mn 0.25Co 0.66 (Mm: misch metal) metal hydride alloy. Elemental analysis was made with Energy Dispersive X-ray Analysis (EDAX). The structural analysis of bare and coated alloys was done by X-ray diffraction (XRD) whereas surface morphology was examined with scanning electron microscope (SEM) and transmission electron microscope (TEM). The electrode characteristics inclusive of electrochemical capacity and cycle life were studied at C/5 rate. Superior performance is obtained with copper coated alloy. Microstructure observations indicate that the observed excellent performance could be attributed to uniform and efficient surface coverage with copper. Also, lanthanum surface enrichment in samples during Cu coating leads to improvement in performance. It is inferred from electro analytical investigations that copper coatings act as microcurrent collectors with alterations in hydrogen transport mechanism and facilitate charge transfer reaction on the alloy surface without altering battery properties. Moreover, supportive first time TEM evidence of existence of such copper nano current collectors (about 8 nm in diameter and length about 20 nm) is reported.

Manufacture of dense coatings of Cu 3(BTC) 2 (HKUST-1) on α-alumina

By a seeding approach coatings of copper benzene tricarboxylate (Cu 3(BTC) 2, also known as HKUST-1) are obtained on α-alumina. The obtained crystal densities, order and intergrowth improve the best results reported up to now in the literature for any metal-organic framework material. The effect of synthesis conditions on the morphology and crystal size of Cu 3(BTC) 2 was determined to optimize the strategies for the synthesis of continuous layers. Seeding with coordination polymers of different morphology resulted in control of crystal growth of the coating. Two seeding suspensions yielded the best intergrowth of crystals. Spin-coating the support with a one-dimensional Cu(II)–BTC coordination polymer suspension resulted in a high density coating with randomly oriented crystals of ∼2 μm, while using amorphous MOF precursors (proto-MOFs) as seeds, coatings with crystals of ∼5 μm were obtained.