Influence of Carbon Nanowalls Interlayer on Copper Deposition

This research deals with the deposition of copper on a steel substrate. Two different methods were investigated: electrochemical and magnetron sputtering. The deposition parameters were optimized to obtain a coating layer with uniform granular structure and good adhesion to the substrate. As a novelty, carbon nanowalls (CNW) were used as reinforcement in copper coatings on the steel surface. The morphology of the coatings, adhesion and Vickers microhardness were performed to emphasize the CNW influence on the coating properties. Open circuit potential and Tafel analysis were used for electrochemical characterization. These kinds of CNW-copper composite with improved hardness and adhesion and surface electrical resistance around 1 Ω·cm could have miscellaneous applications in different domains such as aerospace, electronics, automotive and power-generation.

Implementation of the Chicot–Lesage Composite Hardness Model in a Determination of Absolute Hardness of Copper Coatings Obtained by the Electrodeposition Processes

The influence of various electrolysis parameters, such as the type of cathode, composition of the electrolyte and electrolysis time, on the morphology, structure and hardness of copper coatings has been investigated. Morphology and structure of the coatings were analyzed by scanning electron microscope (SEM), atomic force microscope (AFM) and X-ray diffraction (XRD), while coating hardness was examined by Vickers microindentation test applying the Chicot–Lesage (C–L) composite hardness model. Depending on the conditions of electrolysis, two types of Cu coatings were obtained: fine-grained mat coatings with a strong (220) preferred orientation from the sulfate electrolyte and smooth mirror bright coatings with a strong (200) preferred orientation from the electrolyte with added leveling/brightening additives. The mat coatings showed larger both measured composite and calculated coating hardness than the mirror bright coatings, that can be explained by the phenomena on boundary among grains. Independent of electrolysis conditions, the critical relative indentation depth (RID) of 0.14 was established for all types of the Cu coatings, separating the zone in which the composite hardness can be equaled with the coating hardness and the zone requiring an application of the C–L model for a determination of the absolute hardness of the Cu coatings.

Formation of Graphite-Copper/N-Silicon Schottky Photovoltaic Diodes Using Different Plasma Technologies

Plasma spraying and magnetron sputtering were used to form graphite–copper films on an n-type silicon surface. The main objective of this work was to compare the properties of the obtained graphite–copper Schottky photodiodes prepared using two different layer formation methods and to evaluate the influence of copper content on the surface morphology, phase structure, and photovoltaic characteristics of the graphite–copper films. Surface morphology analysis shows that the surface of the formed layers using either plasma spraying technology or the magnetron sputtering method consists of various sphere-shaped microstructures. The X-ray diffraction measurements demonstrated that the graphite–copper coatings formed by plasma spraying were crystalline phase. Meanwhile, the films deposited by magnetron sputtering were amorphous when the copper concentration was up to 9.7 at.%. The increase in copper content in the films led to the formation of Cu crystalline phase. Schottky diodes formed using magnetron sputtering technology had a maximum current density of 220 mA/cm2 at 5 V. Meanwhile, the maximum electric current density of Schottky photodiodes formed using plasma spraying reached 3.8 mA/cm2. It was demonstrated that the efficiency of Schottky diodes formed using magnetron sputtering was up to 60 times higher than Schottky diodes formed using plasma spraying.

Study of the effect of electrolyte composition on adhesion and other properties of a coating-base system

Aluminum alloys with electroplated coatings and copper plated in particular gained multiple applications. However, pre-zincate treatment often fails to provide the desired adhesion of the coating. We present the results of studying the effect of the electrolyte composition on the adhesion and other properties of the coating-base system. It is shown that an electrolyte with a reduced content of sulfuric and phosphoric acids can be used for anodizing and the oxide films formed during anodizing are stable in the usual copper-plating sulfuric acid electrolyte which eliminates contact exchange and increases adhesion. The use of a modern scratch-test method provides numerical determination of the values of adhesion of copper coatings. The adhesion value depends on the surface porosity of the oxide film and on the type of anodized alloys. The results can be used to improve the technology of applying copper coatings, both as an independent coating and as an underlayer in multilayer coatings.

Aluminum and copper deposition through the process of thermal flame spray on polypropylene-pine wood fiber composite filaments and their applications

This paper presents a study about polypropylene-pine wood composites, both as filaments and products, coated with aluminum (Al) or copper (Cu), obtained through flame thermal spray process after subjecting the composites to thermal treatments in the second and third step of the study. Results revealed that a previous aluminum layer was needed in order to obtain copper coatings on the composites. The physical and mechanical properties of both metal coated composite filaments were also evaluated and compared with the uncoated composite filaments with and without heat treating these. Consequently, it was observed that the nature of the coating adhesion on the substrates was mechanical, and therefore abrasion blasting of filaments or the use of a higher wood fiber content in the composite improved the Al or Cu adhesion. Also, it was observed that extruded wood fiber/PP filaments should not be cooled in water because pieces might be molded directly once the moisture affects the metal coatings adhesion onto the substrates.

Thiocarbamide-Citrate Electrolytes as an Alternative to Cyanide Electrolytes in Solving the Problems of Environmental Protection and Prevention of Emergency Situations

A comparative analysis of the occupational hazard was done when working with widely known cyanide electrolytes and new thiocarbamide and citrate acid-based electrolytes. For this purpose, we made use of available reference data on maximum permissible substance concentrations, i.e. process solution components. Appropriate computations were done to define the environmental hazard of the electrolytes used for the application of silver, gold and copper coatings and also for the electrochemical silver polishing. Consideration was given to the reactions that proceed in cyanide and thiocarbamide-citrate bathes. The main drawbacks and advantages of given electrolytes have been established. Special attention was paid to the quality of galvanic products. It was proved that the suggested electrolytes are highly competitive with cyanide analogues as for their visual appearance, density and other characteristics of the condition of treated surface. These turned out to be labor saving and energy efficient and have substantially lower harmful effect on the human health and environment.

Laser Assisted Cold Spray for Improved Adhesion of Soft Materials to Hard Substrates—Case Study for Copper Coatings on Steel

In cold spray, high adhesion of soft materials on hard substrates is commonly achieved by using helium as the propelling gas. This is the case of copper coatings on steel where adhesion may reach values as high as 60 to 80 MPa (glue failure), however, helium is a limited, expensive natural resource, and the use of more abundant nitrogen gas is preferred in an industrial setting. Unfortunately, when using nitrogen gas, little to no adhesion is obtained. In order to eliminate the use of helium gas we studied how laser assisted cold spray could lead to an improvement in adhesion of nitrogen sprayed copper coatings. In this work, several laser parameters (e.g., power and spot size) and process parameters (traverse speed, relative position laser spot vs. gas jet) were varied at a coupon level. Upon optimization, an equivalent adhesion to the coatings prepared with helium was obtained. Furthermore, the cross section of the coatings showed that the copper particles penetrated the steel, similar to what is observed when using helium gas. Optimization of these parameters for application to large diameter (~559 mm) cylinders was also performed. A discussion on the mechanisms which contribute to achieving high adhesion considering the use of helium versus laser assistance is provided.