Dual Bath Technique Research Articles

Role of heat treatment on the friction and wear behavior of duplex electroless nickel deposits

In the present investigation, duplex electroless Ni-P/Ni-Cu-P and Ni-P/Ni–W-P coatings are deposited on mild steel specimens using the dual bath technique. Both the coatings are developed with Ni-P as the inner layer. The scanning electron microscope (SEM), X-ray diffraction techniques (XRD) and energy dispersive X-ray analysis (EDX) are used to characterize the duplex coatings at pre and post-heat treatment state. Heat treatment is carried out at a temperature range between 200 °C and 800 °C. The surface morphology of the as-deposited coatings is nodular. Grain growth and grain boundaries are clearly visible in heat treated coatings. The EDX of Ni-P/Ni-Cu-P and Ni-P/Ni–W-P coating showed the phosphorus content as 12% and 9% respectively indicating high-P deposits. The copper and tungsten content of the coatings are 10% and 3% respectively. XRD analysis of both the as-deposited coatings indicate amorphous phase while heat-treated ones have crystalline phase structure. The crystalline structure increases the hardness of coating along with its wear resistance. The friction and wear behavior are assessed by a pin on disc tribometer. Overall, it can be seen that Ni-P/Ni–W-P system performs better compared to Ni-P/Ni-Cu-P in terms of friction and wear. However, heat treatment at higher temperature has negative impact on both the coatings as far as the tribological behavior is concerned.

Electrodeposition and Corrosion Resistance of Cu/Zn/Cu Multilayer Coatings

Cu/Zn/Cu multilayer coatings were prepared on mild steel substrates by dual bath technique in order to improve the corrosion resistance of mild steel in seawater. The microstructures of the coated substrates and its resistance to corrosion in simulated seawater were evaluated by scanning electron microscopy (SEM), the brine immersion test and electrochemical impedance spectroscopy (EIS). Salt water immersion test results show that the Cu/Zn/Cu multilayer coatings exhibited the highest corrosion resistance. The red rust spot appeared on the coating surface for the first time when the time of the coating soaked in salt water reached 2520h. The trend of the impedance variation reflected by the electrochemical impedance spectroscopy was the same as the change tendency of corrosion resistance was analyzed by the salt water immersion test. The results of SEM showed that the layer of copper were deposited by round cell structure, the middle layer of zinc coating was flat and compact.

Electrodeposition of nanocrystalline Ni/Ni–Al2O3 nanocomposite modulated multilayer coatings

In this research, nanocrystalline Ni/Ni–Al2O3 nanocomposite modulated multilayer coatings were fabricated by direct current electrodeposition using dual bath technique. A Watts-type bath was used as the main solution of the baths. Saccharin was added to the first bath for producing nanocrystalline nickel layers and γ-alumina nanoparticles were added to the second bath to produce nanocomposite layers. The effect of coating's configuration like number of layers and their order was evaluated. The microstructures of the coatings, including relative texture coefficient and grain size, were studied by X-ray diffraction analysis. Energy dispersive spectroscopy and scanning electron microscopy were used to investigate the chemical composition and morphology of the coatings. Their tribological properties were investigated. The results exhibited that variation of order and configuration of layers had a significant effect not only on the adsorption of nanoparticles in the nanocomposite layers, but also on their growth texture in each multilayer coatings. In general, the results of tribological studies revealed that the optimum number of layers is 6 and all Ni–Al2O3/Ni CMM coatings, consisting soft layers (nanocomposite) and approximately hard layers (nanocrystalline), had better tribological properties than single layer nanocomposite coating and also worse performance than nanocrystalline one with the same total thickness.

Multilayer of Ni/Cu Coating Produced via Electroplating Process

Nickel (Ni)/ Copper (Cu) multilayer were deposited on Cu substrate by electroplating process using dual bath technique. Individual sample of multilayer with sublayer thicknesses of 1 μm, 5 μm, 10 μm and 50 μm have been produced. The structure of the multilayer was characterized by X-Ray Diffraction and Scanning Electron Microscopy whereas one of the mechanical properties of the samples was investigated by means of Vickers Hardness. The results showed that the surface hardness of the coated Cu substrate increases if compared to that of pure Cu substrate. Additionally, these values increased when sublayer thickness of samples were decreased.

Fabrication of ZnNi/NiP compositionally modulated multilayer coatings

ZnNi/NiP compositionally modulated multilayer (CMM) coatings which have a novel three-dimension (3d) latticed multilayer structure were prepared by dual-bath technique. The formation of the special 3d latticed structure was investigated. The adhesion and corrosion resistance of the CMM coatings were studied. The results showed that the special 3d latticed multilayer structure, which was different from the structure of traditional CMM coatings, was formed during NiP electroless plating. The 3d latticed structure benefited the adhesion and corrosion resistance of the novel CMM coatings. The barrier effect of the 3d latticed structure is enhanced.

Corrosion resistance of Ni/Zn–Fe/Zn and Ni/Zn/Zn–Fe compositionally modulated multilayer coatings

Compositionally modulated multilayer coatings of Ni/Zn, Ni/Zn–Fe/Zn and Ni/Zn/Zn–Fe, for corrosion protection performance, were deposited on steel substrates using a dual bath technique. The coating protection performance was evaluated using Tafel extrapolation, anodic polarisation and salt fog corrosion tests. The performance of Ni/Zn–Fe/Zn and Ni/Zn/Zn–Fe multilayers was found to be better than that of Ni/Zn multilayer. Considering the corrosion mechanism, this can be attributed to an improvement in the corrosion resistance of the sacrificial layers by substitution of zinc within the Zn/Zn–Fe or Zn–Fe/Zn layers.

Electrodeposition, characterization and morphological investigations of NiFe/Cu multilayers prepared by pulsed galvanostatic, dual bath technique

NiFe/Cu multilayers were grown sequentially by pulsed electrodeposition on copper (Cu) substrates. The layers were prepared in galvanostatic mode using a dual bath technique. The morphology, thickness, roughness and composition of the layers were studied using scanning electron microscopy, scanning transmission electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction and atomic force microscopy. Analysis showed that the resulting multilayers were continuous layers with a root mean square roughness of 30 nm and a grain size of 20–60 nm. The Cu substrate and the electrodeposited Cu layer were preferentially (200) oriented while the NiFe layers were polycrystalline but with a preferred (200) texture. The thinnest multilayers produced were 20/40, NiFe/Cu, respectively.

Study of surface roughness and corrosion performance of Ni/Zn–Fe and Zn–Fe/Ni compositionally modulated multilayer coatings

Compositionally modulated multilayer coatings consisting alternative layers of nickel and zinc–iron alloy were electroplated using dual bath technique. The coating's surface morphology was studied using a scanning electron microscope. The effects of coatings configuration, i.e., order and the number of layers on the coatings surface roughness was investigated. It was observed that as the number of layers increases in the different Ni/Zn–Fe CMM coatings, 2 and 4-layer Zn–Fe/Ni CMM coatings the final surface roughness is decreased due to the lower grain growth of zinc–iron individual layers. The coatings corrosion protection performance was evaluated using Tafel extrapolation, anodic polarization and salt spray tests. The results of corrosion study showed that all Ni/Zn–Fe and Zn–Fe/Ni CMM coatings, except the 8-layer Zn–Fe/Ni coating, had a better corrosion protection performance compared to the single layer zinc–iron alloy coating or nickel coating.

Corrosion study of Ni/Zn compositionally modulated multilayer coatings using electrochemical impedance spectroscopy

Ni/Zn compositionally modulated multilayer (CMM) coatings were deposited using dual bath technique. Coatings corrosion performance was evaluated using electrochemical impedance spectroscopy (EIS) during extended immersion times up to 48 h. The results of electrochemical impedance spectroscopy showed that Ni/Zn CMM coatings had better corrosion resistance compared to that of the zinc single layer coating. The modified corrosion product which is formed on the Ni/Zn CMM coatings during extended exposure times and also a good barrier effect of the nickel layer against aggressive species in these coatings can be two important reasons for high corrosion performance and so protection performance of the Ni/Zn CMM coatings.

Corrosion performance of zinc and zinc-cobalt alloy compositionally modulated multilayer (CMM) coatings

Varieties of zinc and Zn−Co alloy compositionally modulated multilayer (CMM) coatings were electrodeposited onto steel substrates using dual bath technique. The surface and cross-sectional morphologies of coated samples were examined using scanning electron microscopy (SEM). The existence of internal stress in Zn−Co alloy deposits was confirmed by the cross-sectional morphologies for the occurrence of micro-cracks in the thick Zn−Co alloy deposit alone. The corrosion performance was evaluated using neutral salt spray testing, corrosion potential measurement and anodic polarization methods. The experimental results show that the zinc and Zn−Co alloy CMM coatings were more corrosion-resistant than the monolithic coatings of zinc or Zn−Co alloy alone with a similar thickness. The analysis on the micrographic features of zinc and Zn−Co alloy CMM coating, using field emission gun scanning electron microscopy (FEGSEM) after corrosion testing, explains the probable reasons why the Zn−Co/Zn CMM coating system has a better protective performance.

Electrodeposition of Ordered Arrays of Multilayered Cu/Ni Nanowires by Dual Bath Technique

Abstract An ordered multilayered Cu/Ni nanowires array was electrodeposited into the pores of an anodic aluminum oxide(AAO) template, with layer thickness in the range of 3–100 nm. To avoid codeposition of Cu in the Ni layers, two separate Ni and Cu baths were used. Scanning electronic microscopy and transmission electron microscopy were used to characterize the morphology of Cu/Ni multilayered nanowires array. The results showed that the layer thicknesses are quite uniform and the multilayered structure is clear and regular. The nanowire diameter is about 100 nm, which corresponds to the pore size of the used AAO template. Selected-area electron diffraction (SAED) result demonstrates that those multilayered wires exhibit single crystal structures. Hysteresis curves for multilayered Cu/Ni nanowires array with the AAO membrane support were tested using vibrating sample magnetometer (VSM) at room temperature (293 K). It is found that the Cu/Ni nanowires arrays have strong perpendicular magnetic field anisotropy. When the magnetic field is perpendicular or parallel to the AAO template, the squareness ratio is 0.701 or 0.101, and the coercivity is 589 Oe or 202 Oe, respectively. The diameter and the layer thickness of Cu/Ni multilayered wires could be changed according to the demands by adjusting the technological parameters of anodization and electrodeposition.

Fabrication of multi-layered CoPtP alloy with high coercivity and squareness by electrochemical deposition

Abstract An attempt to overcome the inherent difficulties of producing thick ferromagnetic CoPtP films with high magnetization and coercivity were made by adopting the electrodeposition of [CoPtP/Cu] n multilayer films by dual bath technique. Multilayered [CoPtP (100 nm) /Cu (100 nm) ] 10 film exhibited coercivity of 4130 Oe and squareness of about 0.7. These results imply that good PMA (perpendicular magnetic anisotropy) characteristics previously obtained in a monolithic, thin (typically less than 1 μm) CoPtP films could be improved by electrochemical multilayer fabrication.

The electrolytic plating of compositionally modulated alloys and laminated metal nano-structures based on an automated computer-controlled dual-bath system

Compositionally modulated alloys (CMAs) and laminated nano-structures of metals are attracting ever-increasing enthusiasm due to their unique mechanical, electrical and, in particular, magnetic properties when compared to those of the respective bulk metals, and as evidenced by new and fascinating applications reported in the literature. Until recently, however, producing such multilayered coatings has been difficult at best, especially for larger samples of irregular configuration and in mass production. We will explain the design, objective and the use of our newly developed automated computer-controlled plating system for producing large-scale CMA coatings and laminated nano-structures of metals. Electroplating bath constituent concentrations, pH, temperature, mode of agitation, etc, as well as galvanostatic modes, e.g. direct current (d.c.) versus pulsed and/or pulse reversal currents, were optimized. Employing the automated dual-bath technique, multilayered composite materials of copper - nickel and copper - cobalt with more than 1000 alternating layers of varying dimensions, if desired, have been investigated and manufactured. The thickness of each sub-layer ranges from 25 nm to several micrometres (). Effort was also expended in the generation of CMA structures from single electroplating baths where the two metals of interest were present. The characterization results, as elucidated with scanning electron microscopy (SEM), atomic absorption spectroscopy and x-ray fluorescence and diffraction methods, and applications for such multilayered systems, in general, as well as the possibilities and limitation of the plating system are discussed.

New dual-bath technique for electrodeposition of short repeat length multilayers

An electrodeposition technique for making multilayered thin films, based on controlled deposition from two different solutions, is described. Ni/NiPx and NiPx/NiPy multilayered thin films with repeat lengths as low as 20 Å have been prepared. They show up to three low-angle x-ray peaks corresponding to the electron density modulation.