THICKNESS DETERMINATION AND CONTROL OF FUNCTIONAL Ni–COMPOSITE ELECTRODEPOSITED COATINGS (original) (raw)
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The Ni-TiO2 and Ni-CeO2 composite coatings with varying hydrophilic/hydrophobic characteristics were fabricated by the electrodeposition method from a tartrate electrolyte at ambient temperature. To meet the requirements of tight regulation by the European Chemicals Agency classifying H3BO3 as a substance of very high concern, Rochelle salt was utilized as a buffer solution instead. The novelty of this study was to implement a simple one-step galvanostatic electrodeposition from the low-temperature electrolyte based on a greener buffer compared to traditionally used, aiming to obtain new types of soft-matrix Ni, Ni-CeO2, and Ni-TiO2 coatings onto steel or copper substrates. The surface characteristics of electrodeposited nickel composites were evaluated by SEM, EDS, surface contact angle measurements, and XPS. Physiochemical properties of pure Ni, Ni-CeO2, and Ni-TiO2 composites, namely, wear resistance, microhardness, microroughness, and photocatalytic activity, were studied. Poten...
2016
The nanocrystalline nickel and nickel-cobalt coatings were electrodeposited on an A60 steel substrate in a modified Watts bath. The observation of the coatings produced by scanning electron microscopy (SEM) showed that the nickel coatings have a granular structure whereas the Ni-Co alloy deposits have a lens-shaped structure with a considerable increase in the grains size of the Ni-Co alloy deposits. Analysis by profilometer confirms these results where we find that the surface roughness of nano-crystalline nickel coatings is less than that of Ni-Co alloy coatings. The results of XRD showed that the nickel coatings having an fcc phase structure while the Ni-Co coatings have a mixed phase structure hcp + fcc. . The study of micro-hardness of the coatings show that this latter follow the Hall Petche effect where nickel deposits which have the small grain size compared to that of the Ni-Co alloy show a higher microhardness to that of Ni-Co coatings. Pin on disk tribometric analysis und...
Metallurgical and Materials Transactions A, 2019
Ni-Co composite coatings reinforced with ZnO particles are prepared by either pulsed current (PC) or direct current (DC) electrodeposition methods. X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and EDX mapping are employed to investigate phase structure, surface morphology, elemental composition, and elemental distribution of coating, respectively. The effects of electrodeposition parameters such as stirring rate, average current density, and ZnO particles concentration on the microhardness of electrodeposited composite coating reinforced with nano and micro ZnO particles are investigated. Optimal values are determined for all of the above-mentioned parameters, which result in the maximum hardness of the coating. Any deviation from the optimal parameters leads to a reduction of the coating's microhardness. The SEM, atomic force microscopy (AFM), wear test, and electrochemical examinations revealed that changing the electrodeposition method from DC to PC and varying the size of ZnO particles from micro to nano affect the surface morphology from rough to smooth and reduce the surface friction coefficient, both of which enhanced the wear resistance of the coating and improved its corrosion resistance. The SEM results from worn surfaces illustrated that the size of reinforcing ZnO particles and the electroplating method change the wear mechanisms and worn surface morphology.
Synthesis and characterization of Ni-TiO 2 composite coatings by electro-co-deposition
Surface & Coatings Technology, 2011
Ultrafine TiO 2 dispersed nickel composite coatings have been prepared by direct current deposition process on steel substrate from Watt's bath to improve the surface mechanical property of conventional nickel coating. To resist agglomeration of ultra fine particles in plating bath due to high surface free energy and to get homogeneous coating, magnetic stirring was applied during deposition with prior ultrasonic agitation. For deagglomeration, Hexa decylpyridinium bromide (HPB) was used in varying quantity in plating bath as surfactant. Characterization of TiO 2 powder as well as microstructure, hardness and wear properties of the coatings were studied by means of XRD, SEM, microhardness tester and ball-on-plate type wear tester. TiO 2 incorporation in the coatings was uniform and dispersion of TiO 2 was below 100 nm size along with the faceted nickel matrix. Selective amount of HPB addition produces hard orientation of nickel in the composite coating along with better TiO 2 co-deposition rate leading to higher microhardness and wear resistance. Wear is mainly adhesive in nature and the worn out TiO 2 particles shift it nominally to abrasive mechanism.
Journal of Rare Earths, 2018
A simple electrodeposition technique was used to prepare Ni-CeO 2 nanorods composite coating (Ni-CeO 2 NRs) using Watt's nickel plating bath containing CeO 2 nanorods (NRs) as the reinforcement phase under optimized process conditions. The X-ray diffraction analysis (XRD) was used for the structural analysis of Ni-CeO 2 NRs composite coatings and their average crystalline size is ~22 nm for pure Ni and ~18 nm, respectively. The crystalline structure is fcc for the Ni-CeO 2 nanocomposite coatings. The surface morphology of the electrodeposited Ni-CeO 2 NRs composite coatings was analyzed by scanning electron microscopy (SEM). Microhardness of pure Ni, and Ni-CeO 2 NRs composite coatings are found to be 253 HV and 824 HV, respectively. The inclusion of CeO 2 NRs increases the microhardness of Ni-CeO 2 NRs composite coatings. The corrosion resistance behavior of Ni-CeO 2 NRs composite coating was evaluated by Tafel polarization and AC impedance methods. It is revealed that CeO 2 NRs reinforced Ni matrix shows higher microhardness and corrosion resistance than existing reported electrodeposited pure Ni and CeO 2 nanoparticles reinforced Ni coatings.
Influence of SiC, Si3N4 and Al2O3 particles on the structure and properties of electrodeposited Ni
Materials Letters, 2008
The structure and properties of electrodeposited nickel composites reinforced with inert particles like SiC, Si 3 N 4 and Al 2 O 3 were compared. A comparison was made with respect to structure, morphology, microhardness and tribological behaviour. The coatings were characterized with optical microscopy, Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) technique. The cross-sectional microscopy studies revealed that the particles were uniformly distributed in all the composites. However, a difference in the surface morphology was revealed from SEM studies. The microhardness studies revealed that Si 3 N 4 reinforced composite showed higher hardness compared to SiC and Al 2 O 3 composite. This was attributed to the reduced crystallite size of Ni -12 nm compared to 16 nm (SiC) and 23 nm (Al 2 O 3 ) in the composite coating. The tribological performance of these coatings studied using a Pin-on-disk wear tester, revealed that Si 3 N 4 reinforced composite exhibited better wear resistance compared to SiC and Al 2 O 3 composites. However, no significant variation in the coefficient of friction was observed for all the three composites.
Archives of Metallurgy and Materials, 2016
MIcrostructurE and propErtIEs of ni and ni/al2o3 coatIngs ElEctrodEposItEd at VarIous currEnt dEnsItIEs The study presents investigations of an influence of various direct current densities on microstructure, residual stresses, texture, microhardness and corrosion resistance of the nickel coatings electrodeposited from modified Watt's baths. The properties of obtained coatings were compared to the nano-crystalline composite Ni/Al2O3 coatings prepared under the same plating conditions. The similarities and differences of the obtained coatings microstructures visible on both their surfaces and cross sections and determined properties were presented. The differences in the growth character of the Ni matrix and in the microstructural properties were observed. All electrodeposited Ni and Ni/Al2O3 coatings were compact and well adhering to the steel substrates. The thickness and the microhardness of the Ni and Ni/Al2O3 deposits increased significantly with the current density in the range 2-6 A/dm 2. residual stresses are tensile and they reduced as the current density increased. The composite coatings revealed better protection from the corrosion of steel substrate than pure nickel in solution 1 M NaCl.
Rev. Adv. Mater. Sci, 2007
Composite Ni+Mo coatings were obtained by electrodeposition of Ni with Mo particles on a steel substrate from the nickel bath in which metallic powder was suspended by stirring. The deposition was conducted under galvanostatic conditions. Deposits were characterized by the presence of Mo microsize particles embedded into the nanocrystalline nickel matrix. The influence of the metal powder amount in the bath, as well as the deposition current density on the chemical composition of the coatings was investigated. The content of incorporated Mo increases with the increase in the amount of metal powder in the bath, and diminishes with the increase in the deposition current density. The mechanism of metallic particles embedding is explained on the base of Ni 2+ ions adsorption process. Incorporation of Mo particles into electrolytic nickel matrix causes an increase in the real surface area of deposits. Thermal treatment of deposited coatings leads to chemical reactions in the solid state and in a consequence exerts significant influence on their phase composition and surface morphology. As a result of the interaction between the nickel matrix and incorporated Mo particles Ni 3 Mo intermetallic phase and Ni-Mo solid solution are arising. The obtained composite coatings were tested as electrode materials for hydrogen evolution in alkaline environment. Electrochemical characterization of the composites was carried out by steadystate polarization method. It was ascertained, that as-deposited Ni+Mo coatings are characterized by enhanced electrochemical activity for this process, which was confirmed by considerable decrease in the hydrogen evolution overpotential, by a nearly 170-260 mV compared to nickel electrode. Thermal treatment decreases the electrochemical activity of the investigated materials, as the values of hydrogen evolution overpotential on heated coatings are much higher.
Synthesis and properties of electrodeposited Ni/ceria nanocomposite coatings
Surface and Coatings Technology, 2006
Composite plating is a method of co-depositing fine particles of metallic or non-metallic compounds or polymers in the plated layer to improve material properties such as lubrication, wear resistance and corrosion resistance. In the present study, Ni was chosen as the matrix material and ceria nanoparticles were chosen as the distributed phase. Nanocrystalline ceria powder was synthesized by the solution combustion process and characterized by powder X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanosize ceria particles were co-deposited with nickel from a nickel sulfamate bath using conventional electrodeposition method. The electrodeposition was carried out at current densities of 0.23, 0.77, 1.55, 3.1 and 5.4 A/dm 2. The microhardness of the Ni matrix was enhanced by the incorporation of ceria particles. Potentiodynamic polarization, electrochemical impedance spectroscopy and SEM were used to characterize the corrosion behaviour of Ni and Ni/CeO 2 coatings. These studies showed improved corrosion resistance for Ni/CeO 2 when compared to Ni. The microhardness, corrosion resistance and wear resistance of Ni and Ni/CeO 2 were compared.
TURKISH JOURNAL OF CHEMISTRY, 2021
Introduction Electroplating is a common electrochemical method, which improves the surface of various materials. The improvement relies on the formation of single or multilayer coatings on the surface of metals. Electroplated nickel is used extensively to enhance the utility, value, and appeal of manufactured products such as consumer goods. Other nickel coatings are used to improve the physical properties, the nickel coating serves the dual purpose of providing a bright, attractive finish as well as imparting improved corrosion resistance or other functional properties. Due to the excellent properties of these coatings, such as high hardness, excellent corrosion and wear resistance, self-lubricating properties and high thermal stability, they have good potential to replace based coatings of chrome. Their mechanism of deposition and optimization of process parameters must be well understood to produce better coatings with improved surface properties. Many experimental works were published [1-5] to understand the relation between electrodeposition parameters and metallurgical states of the electrodeposits. The mechanism of nucleation and growth of Ni coatings was thoroughly described and, in most cases, illustrated from results coming from Watts baths [6, 7]. Properties of the deposited are strongly dependent on the experimental parameters of electrodeposition, such as bath composition, pH value, stirring solution, temperature, substrate, and applied current [8]. The current density plays an important role on the grain size and crystal structure of electrodeposited coating. The microstructure and grain size refinement in electrodeposited nickel can be controlled by several deposition parameters [8] like bath temperature, pH value, and applied current density. Generally, the grain size increases with temperature, whereas the grain size variation with current density is controversial. Therefore, this present work aims to study the effect of the current density on the microstructure of nickel deposits. In this paper, an additive-free watts bath is used in order to limit the incorporation of impurities. The thickness of the deposition layer of all the samples was 50µm, which is thick enough to attain a steady-state crystal growth condition. We also used a pure nickel substrate to avoid contamination of the bath. Special attention was devoted to avoid contamination of the bath. 2. Materials and methods Nickel coatings were deposited on quite pure 99.5% polycrystalline nickel substrates with an average grain size of 165mm by direct current using a free-additive Watts bath. No additives were used. The composition of the conventional Watts bath is described in table 1.