Ni Al2O3 Nanocomposite Coatings Research Articles

Influence of the Duty Cycle of Pulse Electrodeposition-Coated Ni-Al2O3 Nanocomposites on Surface Roughness Properties

In this study, the viability of duty cycle variation was explored as a potential method to improve the mechanical and surface roughness properties of Ni-Al2O3 nanocoatings through pulse electrodeposition. The areal and surface roughness properties of nanocomposite pulse electrodeposition-coated materials with varying duty cycles from 20% to 100% was studied with the analysis of bearing area curves and power spectral densities. Results demonstrate that with decrease in duty cycle, there was an enhancement in aerial roughness properties from 0.348 to 0.195 µm and surface roughness properties from 0.779 to 0.245 µm. The change in surface roughness was due to grain size variation, resulting from the varying time intervals during pulse coatings. This increase in grain size with the change in duty cycle was confirmed with the scanning electron microscope. In addition, an increase in grain size from 0.32 to 0.92 µm with an increase in duty cycle resulted in a decrease in nanohardness from 4.21 to 3.07 GPa. This work will provide a novel method for obtaining Ni-Al2O3 nanocomposite coatings with improved surface roughness and hardness properties for wider industrial applications.

The Effect of Ni-Al2O3 Nanocomposite Coatings on the Wear and Corrosion Resistance and Thermal Diffusivity of 316 Stainless Steel Plates of Heat Exchangers

The Effect of Ni-Al2O3 Nanocomposite Coatings on the Wear and Corrosion Resistance and Thermal Diffusivity of 316 Stainless Steel Plates of Heat Exchangers

Exploiting magnetic sediment co-electrodeposition mechanism in Ni-Al2O3 nanocomposite coatings

• Magnetic sediment co-electrodeposition (MSCD) mechanism of Ni-Al 2 O 3 nanocomposites. • Coating morphology, crystal structucture, e, microhardness, nanoparticles loading and zeta potential were the main criteria. • Two phenomena control MSCD: (i) magnetohydrodynamic (MHD) and (ii) gravitational force. • MHD predominates for nano-sized particles (<100 nm) by reducing the thickness of the diffusion layer. • Gravitational force is dominant for agglomerated particles (>300 nm). Our focus in this work is to exploit a mechanistic view of magnetic sediment co-electrodeposition (MSCD). Ni-Al 2 O 3 nanocomposite coatings were electrodeposited in the presence and absence of an external magnetic field using sediment co-deposition (SCD) cell design. The dispersion, zeta potential, and size of Al 2 O 3 particles in solution were measured and interpreted for the MSCD mechanism. The effects‌ of magnetic field on morphology, crystallographic texture, microhardness, dispersion of Al 2 O 3 nanoparticles in Ni metal matrix were studied and a co-deposition kinetic model was accordingly postulated. Magnetic sediment co-electrodeposition not only changes the surface morphology of Ni-A 2 O 3 from pyramidal-shaped to spherical grains, but it also increases the microhardness (from 365 to 500 HV) by decreasing the crystallite size (from 130 to 110 nm). Calculations of relative texture coefficient (RTC) values and Rietveld analysis showed that the growth of texture (2 0 0) of Ni-Al 2 O 3 composite coatings is reinforced in the presence of a magnetic field. Based on our assumed model, two determining phenomena control the magnetic sediment co-deposition process: (i) magnetohydrodynamic (MHD) and (ii) gravitational force. MHD predominates for nano-sized particles (<100 nm) by reducing the thickness of the diffusion layer, whereas, the gravitational force is dominant for agglomerated particles (greater than300 nm).

Erosion-corrosion of electrodeposited superhydrophobic Ni-Al2O3 nanocomposite coatings under jet saline-sand slurry impingement

For the first time, this study developed a detailed insight into the correlation between superhydrophobicity, erosion-corrosion resistance, and reinforcing phase amounts of Ni-Al2O3 nanocomposite coatings electrodeposited on Cu. Erosion-corrosion was electrochemically investigated at a 90° impact angle via a jet-impingement slurry erosion setup with erodent particles primarily under 100 µm. The preferred crystallographic growth orientation was along (220). No synergy emerged between superhydrophobicity and erosion-corrosion resistance. Ni-(2.9 wt%) Al2O3 resistance to erosion-corrosion outperformed Ni-(0, 2.0, 2.4 wt%) Al2O3. Depend on the duration of slurry exposure, either kinetic or a mixed kinetic and diffusion control mechanism was predominant at the OCP.

Assessment and effect of reinforcement of multi-walled carbon nanotubes in Ni-Al2O3 and Ni-SiC nanocomposite coatings using pulse reverse electrodeposition technique

The nanocomposite coating provides a higher degree of corrosion resistance, microhardness, wear resistance and significantly improves the tribological qualities of the base metal. This research work is aimed at investigating the effect of the proportion of multi walled carbon nanotubes (MWCNT) mixed with Ni-Al2O3 and Ni-SiC nanocomposite coatings on a mild steel AISI 1018 specimen against its tribological characteristics through experimental investigation. The pulse reverse electro deposition technique is deployed for coating formulation with optimized coating parameters. The proportions of carbon nanotubes vary in three different ratios ranging from 1:1 to 2 :1. Tribological characteristics (microhardness and surface morphology) are assessed using a Vickers microhardness testing machine and a scanning electron microscope (SEM). Nine different coating combinations are considered in this study and their tribological attributes are compared with the un-coated sample. From the results, it can be observed that the samples coated with Al2O3 nanoparticles reinforced with carbon nanotubes (CNTs) possess excellent magnitudes of micro-hardness in comparison with the uncoated and SiC-CNT coated samples with an enhancement factor of 2.88 and 1.37, respectively. Moreover, the variation of the CNT proportion in the coating blend has the tleast significant effect and therefore, addition of CNT particles beyond the blend ratio of 1:1 may be avoided to reduce the coating cost of samples significantly. Also, SEM images clearly reveal a uniform coating distribution owing to the application of optimized coating parameters. .

Microstructure and mechanical properties of sol-enhanced nanostructured Ni–Al2O3 composite coatings and the applications in WC-Co/steel joints under ultrasound

Reliable brazing of WC-Co to steel is crucial for the applications in shield tunneling and temping machines. However, the interface could not be effectively connected with high strength due to the large difference in coefficients of thermal expansion. We developed a sol-enhanced method to electroplate Ni–Al2O3 nanocomposite coatings on steel in order to improve the bonding and strength of the joints. Al2O3 sol was fabricated with mean size of 59 nm, which was identified through TEM analysis. The change of Al2O3 concentration of the coatings with different Al2O3 sol addition was investigated through LA-ICP-MS test. The phase, microstructure, mechanical properties and corrosion performance of the coating were strongly affected by the sol concentration through the XRD and TEM analysis. At very high sol concentration, cracks appeared on the coating surface, which deteriorated the properties. It was found that the Ni–Al2O3 coating improved the micro-hardness and corrosion resistance by polarization Tafel tests and EIS analysis. Specifically, 35CrMo with a Ni–Al2O3 coating was joined with tungsten carbide by ultrasound-assisted brazing in air. The shear strength of the joints was increased by 31% (approximately 427 MPa) than conventional method.

Wear Performance Analysis of Ni⁻Al₂O₃ Nanocomposite Coatings under Nonconventional Lubrication.

This article presents a wear study of Ni–Al2O3 nanocomposite coatings in comparison to uncoated steel contacts under reciprocating motion. A ball-on-flat type contact configuration has been used in this study in which a reciprocating flat steel sample has been used in a coated and uncoated state against a stationary steel ball under refrigerant lubrication. The next generation of environmentally friendly refrigerant HFE-7000 has been used itself as lubricant in this study without the influence of any external lubricant. The thermodynamic applications and performance of HFE-7000 is being studied worldwide, as it is replacing the previous generation of refrigerants. No work however has been previously performed to evaluate the wear performance of HFE-7000 using nanocomposite coatings. The wear scar developed on each of the flat and ball samples was studied using a Scanning Electron Microscope (SEM). The micrographs show that a combination of adhesive and abrasive wear occurs when using uncoated steel samples. Micro-delamination is observed in the case of Ni–Al2O3 nanocomposite coatings accompanied by adhesive and abrasive wear. Wear volume of the wear track was calculated using a White Light Interferometer. Energy-Dispersive X-ray Spectroscopic (EDS) analysis of the samples reveals fluorine and oxygen on the rubbing parts when tested using coated as well as uncoated samples. The formation of these fluorinated and oxygenated tribo-films helps to reduce wear and their formation is accelerated by increasing the refrigerant temperature. Ni–Al2O3 nanocomposite coatings show good wear performance at low and high loads in comparison to uncoated contacts. At intermediate loads the coated contacts resulted in increased wear, especially at low loads. This increase in wear is associated with the delamination of the coating and the slow formation of protective surface films under these testing conditions.

Preparation and properties of nanocomposite coatings on sintered NdFeB magnets

To enhance corrosion resistance of sintered NdFeB magnets, Ni–Al2O3 nanocomposite coatings were prepared on the magnets by pulsed current-jet electrodeposition. The effects of average current density and nanoparticles on the properties of coatings were evaluated. The surface morphology, microstructure, adhesion strength, and corrosion resistance of coatings were characterized by scanning electron microscopy, x-ray diffraction, scratch tester, and electrochemical workstation, respectively. The results showed that proper increase of current density was beneficial to the performance of coatings, and that protective properties of coatings decreased when the current density exceeded 120 A dm−2. Properties of coatings were enhanced by the addition of nanoparticles. Nanocomposite coatings showed better adhesion strength and corrosion resistance than pure nickel coatings.

Electrodeposition and Characterization of Ni-Al2O3 Nanocomposite Coatings on Steel

Monodispersed alumina particles were synthesized by the homogeneous precipitation under reflux boiling. The particles were employed as reinforcement additives in the electrodeposited Ni-Al2O3 composite coatings on steel. The deposited pure Ni and Ni-Al2O3 composite coatings were analyzed by SEM, XRD, and microhardness tester. The wear resistance and friction coefficient of the coated samples were determined by using a ball-on-disk tribometer. Furthermore, XRD analysis showed that coating temperature and the presence of particles in the deposited coatings had a noticeable effect on the preferred orientation of the crystalline faces of the nickel grains. Significant differences were noted in the texture coefficient of the pure Ni and Ni-Al2O3 composite coatings produced at different temperatures. These differences were attributed to the changes in the microstructure of the matrix caused by the embedded Al2O3 particles. Results revealed that wear resistance and the friction coefficient were turned out to be higher and smaller, respectively, for the composite coatings as compared to pure Ni coating at a given sliding distance. It was noted that the corrosion resistance of these specimens increased in the following order: bare substrate < pure Ni coating < Ni-Al2O3 nanocomposite coatings.

Effect of carbamide concentration on electrodeposition and tribological properties of Al 2 O 3 nanoparticle reinforced nickel nanocomposite coatings

Abstract Ni-Al2O3 nanocomposite coatings were electrodeposited from Watt's bath containing alumina nanoparticles, dispersed with the aid of carbamide. The effect of carbamide concentration on the amount of embedded alumina nanoparticles, zeta potential, microstructure, microhardness and tribological behavior of nanocomposite coatings were investigated. The results revealed that using of carbamide in the range of 10–15 g/L increased the microhardness up to 85% compared with the coating fabricated without carbamide. The adsorption of alumina nanoparticles increased from 4.6 vol% to 11.3 vol% by the aid of carbamide and it also caused grain refinement in the nickel matrix. Increasing the carbamide concentration up to 15 g/L led to decrease in the wear rate, approximately to 30% of the coating electrodeposited without carbamide.

Wear and corrosion resistance of AZ91 magnesium alloy coated by pulsed current electrodeposited Ni–Al2O3 nanocomposite

In this work, Ni and Ni–Al2O3 nanocomposite coatings were applied on AZ91 magnesium alloy using a pulse plating process and the corrosion resistance of coated samples was evaluated by means of the potentiodynamic polarisation method in 3.5 wt-% NaCl solution. Field emission scanning electron microscopy was employed to identify microstructure and morphology of the coatings. Vickers microhardness and pin-on-disc wear tests were also used to investigate mechanical properties of the coatings. The polarisation test revealed that the pure Ni coating on AZ91 along with the presence of nanoparticles were key factors leading to a reduction in the corrosion current density and the improvement of corrosion resistance so that the corrosion current density of 210.45 µA cm−2 for the substrate (AZ91) decreases to 31.92 and 1.54 µA cm−2 by applying pure Ni and Ni–Al2O3 nanocomposite coatings, respectively. Furthermore, Ni–Al2O3 nanocomposite coating increased the microhardness and wear resistance compared to the substrate up to 435 and 340%, respectively.

Corrosion and wear behaviour of multilayer pulse electrodeposited Ni–Al2O3 nanocomposite coatings assisted with ultrasound

In this study, the Ni–Al2O3 nanocomposite multilayer coatings with six consecutive layers were electrodeposited on the mild steel by pulse electrodeposition with ultrasound agitation from nickel Watts-type bath. The structure and morphology of the etched coatings cross-section were characterized by scanning electron microscopy (SEM). The corrosion behaviour of these coatings was investigated in 1 M H2SO4 solution. All of the coatings showed the active–passive transition and the distinct difference in structure had negative influence on their corrosion resistance. Moreover, the tribological behaviour of these coatings was evaluated by pin-on-disc type. The results showed that wear resistance increased with increase in duty cycle and frequency.

STUDY OF Zn-Ni ALLOY COATINGSMODIFIED BY NANO-AL2O3 PARTICLES INCORPORATION

Zn–Ni–Al2O3 nano-composite coatings were electrodeposited on mild steel using a novel sol enhanced electroplating method. The effect of alumina sol on the electrodeposition process, and coating properties was investigated using, X-ray diffraction, scanning electron microscopy (SEM), measurement of microhardness and chronoamperometry and electrochemical impedance spectroscopy were studied in a solution of 3% NaCl. The results indicated that the electro-crystallization processes of Zn–Ni and Zn–Ni–Al2O3 were governed by a three-dimensional nucleation process controlled by diffusion. XRD results showed that the phase structure of both alloy and composite coatings was single Ni5Zn21-γ phase, and the addition of alumina sol in the Zn-Ni matrix increases the microhardness, and we note the maximum hardness is obtained for 50 g/L Al2O3. Conversely, these coatings showed smaller crystallite size and Surface of coatings was uniform and compact, the values of Rct and Zw increase, while the values of Cdl decrease with increasing alumina nano-particles content values for the Zn–Ni– Al2O3 alloy clearly confirm the better corrosion resistance.

Electrochemical studies of sol-enhanced Zn–Ni–Al2O3 composite and Zn–Ni alloy coatings

Zn–Ni–Al2O3 nano-composite coatings were electrodeposited on mild steel using a novel sol enhanced electroplating method. The effect of alumina sol on the electrodeposition process, and coating properties was investigated using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The results indicated that the electro-crystallization processes of Zn–Ni and Zn–Ni–Al2O3 were governed by a three-dimensional nucleation process controlled by diffusion. Evaluation of nucleation mode in the presence and absence of alumina sol showed that the progressive nucleation was predominant for the Zn–Ni alloy deposit. However, for the Zn–Ni composite coating, the nucleation mode was closer to instantaneous nucleation. Nucleation parameters such as density of active nucleation sites and nucleation rate were increased in the presence of alumina nano-particles in the bath. Zn–Ni–Al2O3 nano composite coatings produced more uniform and compact deposits, with fine grained microstructure when compared to Zn–Ni coatings. XRD results showed that the phase structure of both alloy and composite coatings was single Ni5Zn21-γ phase, and that the incorporation of alumina in the Zn–Ni coating refined the crystal grain size.

Zn–Ni–Al2O3 nano-composite coatings prepared by sol-enhanced electroplating

Zn–Ni–Al2O3 nano-composite coatings were electroplated by our newly developed sol-enhanced electroplating method. In order to obtain the optimal chemical composition, corrosion resistance and mechanical properties, a systematic study of Zn–Ni–x–Al2O3 coatings with different sol concentrations (where x is the sol-doping concentration from 0 to 20ml/l) has been conducted. It was found that the Ni content, phase structure, surface morphology, mechanical properties and corrosion resistance of the nano-composite coatings were strongly affected by the sol concentration. The mechanical properties and corrosion resistance of sol-enhanced nano-composite coating were significantly improved compared to Zn–Ni alloy coatings. The microhardness of the sol-enhanced Zn–Ni–6ml/l Al2O3 coating was ∼312HV100 compared to ∼237HV100 of Zn–Ni coating. Meanwhile, the wear resistance has also been improved remarkably.

Effect of PC electrodeposition on the structure and tribological behavior of Ni–Al2O3 nanocomposite coatings

In this study, Ni–Al2O3 metal matrix composite (MMC) coatings were prepared from a modified Watt's type electrolyte by pulse current (PC) plating under current densities varying between 1 and 9A/dm2. The tribological tests were performed with a reciprocating ball-on-disk apparatus sliding against a M50 steel ball (Ø 10mm). The wear tests were carried out at sliding velocities of 50, 100 and 150mm/s under a constant load. The results compared with our previously published work of DC electrodeposited coatings. The results showed that the electrodeposition method can significantly affect the microstructure and tribological behavior of Ni–Al2O3 nanocomposite coatings. For the same current density, PC electrodeposition creates coatings with higher co-deposited particle content, more homogenous particle distribution, higher wear resistance at high sliding distance and improved friction coefficients. The superior dispersion of Al2O3 nanoparticles in PC-coated materials contributed to its increased load bearing capacity. Detailed tribological tests and characterization showed that DC- and PC-coated nanocomposite layers yielded different wear mechanisms depending on the sliding velocity.

A Study on Ni-Al2O3 Nanocomposite Coating Prepared by Jet Electrodeposition

Ni-Al2O3 nanocomposite coatings were fabricated by jet electrodeposition process. Effect of concentration of Al2O3 in the electrolyte, current density and electrolyte jet speed on nano-Al2O3 content were analyzed. The composite coatings’ micro structure, energy spectrum was observed under the scanning microscope(SEM). Effect of nano-Al2O3 content on the microhardness and corrosion resistance were evaluated. The results shows that the Ni deposited layers have nanocrystalline micro structure with average size of 50 nm. Al2O3 particles are well dispersed in layer and the particles content is up to 12.2 at %. Microhardness of the coating increase, bond strength and corrosion resistance of the coatings first increase then decrease with increase of Al2O3. content in coatings.

Investigation on the corrosion and oxidation resistance of Ni-Al 2O 3 nano-composite coatings prepared by sediment co-deposition

Abstract Ni–Al2O3 composite coatings were prepared by using sediment co-deposition (SCD) technique from a Watt's type electrolyte containing nano-Al2O3 particles. The corrosion resistance and high temperature oxidation resistance of resulting composite coatings were investigated. It was found that the incorporation of nano-Al2O3 particles in Ni matrix refined the Ni crystal and changed the preferential orientation of composite coatings. Meanwhile, the corrosion and oxidation resistance were improved after the incorporation of nano-Al2O3 particles into Ni matrix. The nano-Al2O3 content in deposits plays an important role for improving the corrosion and oxidation protection. The corrosion and oxidation resistance of Ni-Al2O3 nano-composite coatings produced via SCD technique are superior to that of CEP technique. Compared to pure Ni and Ni-Al2O3 composite coatings fabricated using CEP technique, the Ni–7.58 wt.% Al2O3 composite coating obtained by SCD technique exhibits better corrosion resistance and enhanced high temperature oxidation resistance. Moreover, the mechanism of corrosion and high temperature oxidation resistance of Ni–Al2O3 nano-composite coatings are discussed.

Significance of Additive Content on the Properties of Electrodeposited Ni-Al2O3 Nanocomposite Coatings

The present paper explains the efforts made in synthesizing Ni- Al2O3 nonocomposite coatings with enhanced properties by varying the additive concentration systematically. Microstructural, morphological and microhardness measurements revealed that the optimized additive concentration helped in improving the coatings properties considerably. The ceramic particles were distributed uniformly over nanocrystalline nickel matrix for the optimized additive concentration as evidenced from different characterization techniques. It was stressed that the addition of optimum content of additive is highly essential in order to obtain nanocomposite coatings with enhanced properties. Finally, the mechanism involved in improving the enhanced properties of nanocomposite coatings was described.

Significance of Additive Content on the Properties of Electrodeposited Ni-Al2O3 Nanocomposite Coatings

not Available.