Ni Al2O3 Composite Coatings Research Articles

Characterisation of Ni-Al2O3 composite coatings at different Al2O3 concentrations

This study develops Ni-based metal matrix composite (MMC) coatings on copper substrate with varying Al2O3 concentrations. Adding Al2O3 to Ni-Al2O3 improves its qualities, such as microhardness, friction, wear resistance, corrosion resistance, etc. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were employed to characterize these MMC’s coatings. In the present work, the microhardness and corrosion resistance of the composite coatings are improved when Al2O3 content is increased to 9%. Secondary particle reinforcement was found to be an influencing factor in microhardness. Further, work is being carried out to study the effect of rising current density and Al2O3 concentration. However, coatings containing 12% Al2O3 nanoparticle agglomeration led to structural weakness, reduced hardness, and poor corrosion resistance. It was determined that an adequate amount of nanoparticles is crucial for enhancing the microhardness and anticorrosion properties of the coatings.

Investigating corrosion resistance in Ni–Al2O3 composite coatings: a fuzzy logic-based predictive study

Investigating corrosion resistance in Ni–Al2O3 composite coatings: a fuzzy logic-based predictive study

Microstructure Study and Morphology of Ni / Nano Al2O3 Composite Coating Synthesied by Electroless Plating

The electroless deposition method was used to prepare Ni-based nanocomposite coatings, this approach represents an alternate way of having coatings on the different substrates. Most of the previous literatures on this subject and work deals with a study the effect of the process conditions and, Bath composition on the microstructure at the macroscale of Ni-Al2O3 composite coatings. Though, effect on the step structure of the composition of the bath and microstructure are little, the present work aims to study the effect of hard ceramic Al2O3 nanoparticles at different concentrations (0.0, 0.5, 1.0, 2, 4) g/L, on the phase structure, microstructure and morphology of Al2O3 nanocomposite coating, in order to enhance the mechanical, plysical and chemical properties of nanocomposite coating. In this paper, An X-Ray diffraction method, spectroscopy (EDS), energy dispersive, and scanning electron microscope (SEM) were studied in the phase structure, chemical composition and morphological nanocomposition coatings. In the present paper, is evident from EDS study that the composite coating consists of Ni and nanoparticles of Al2O3. The micrograph study of the EDS showed that A flat and smooth surface is present in the deposited nanocomposite coating. Uniform distribution of nanoparticles of alumina within Ni-Matrix. And the XRD study showed the crystalline structure of the Ni- Al2O3 nanocomposite coating.

Study on surface roughness parameters of nano composite coatings prepared by electrodeposition process

The hard nano Al2O3 particles are successfully embedded in the Ni composite coating. The presence and distribution of nano particles is analyzed by EDS method. The roughness of the composite coating surface is greatly influenced on the specific wear rate and coefficient of friction. The Ni-Al2O3 composite coatings have shown better specific wear rate in comparison with bare Ni coating. The coefficient of friction of the Ni- Al2O3 composite coating was found to decrease with increase in the roughness value. The maximum COF and minimum specific wear rate were found to be 0.457 and 0.85 × 10−4 mm3/Nm is observed at a Ra value of 1.032 μm respectively.

Improvement of microstructure and properties of Ni–Al2O3 composite coating via jet electrodeposition

Ni–Al2O3 composite coatings were prepared with a modified Watt’s bath by using jet electrodeposition method. As the key process parameter, current density and the addition of Al2O3 nanoparticles in electrolyte were studied about the effect on the surface morphology and co-deposition of Al2O3 nanoparticles of composite coating. The mechanical and tribological properties of the composite coating were also tested. The results show that properly increasing the current density and Al2O3 addition can increase the co-deposition of nanoparticles in the coating and promote the formation of a dense and refined coating structure. Using the optimized process parameters of current density (300 A/dm2) and Al2O3 addition (30 g/L), the co-deposition of Al2O3 in the composite coating can reach a maximum of 13.1 at.%. The hardness of the coating reaches the peak at 623 HV. The wear rate of the composite coating is also greatly reduced with optimized parameters.

Tribological studies of Ni-SiC and Ni-Al2O3 composite coatings by Pulsed Electrodeposition

A new class of materials which are mostly used for tribological applications are Composite coating. Pulse Electrode position is an area which has more interest both in research and technological applications, particularly its more used to produce low cost pieces with high abrasion mechanical resistance materials. To investigate the electro deposition by using pulse current the theoretical and experimental investigations of galvanized process have been conducted. The Current Density, Duty cycle and Frequency were identified as the important grain refining parameters. This paper considers the materials, experimental conditions and characterization of the coatings. Remaining part is to study the tribological friction resistance and wear properties of the co-deposits. Friction and wear tests were carried out using a Reciprocating wear monitor.

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.

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.

Hardness, wear resistance and bonding strength of nano structured functionally graded Ni-Al2O3 composite coatings fabricated by ball milling method

Using initial powder mixtures with different Ni:Al2O3 weight ratios ranging from 1:1 to 16:1, nano structured Ni-Al2O3 composite coatings were deposited onto an aluminum plate by means of a planetary ball mill. It was shown that initial charges with Ni:Al2O3 weight ratios of 4:1 and greater, yielded well-compact coatings. Coating deposited from the powder charge with Ni:Al2O3 weight ratio of 4:1, contained 20 vol% of alumina particles in the Ni matrix and submitted the highest hardness value (657 ± 28 Hv) and wear resistance. Nevertheless, composite coating containing smallest amount of alumina particles showed the highest cohesive strength of 9.8 ± 0.3 MPa. In the next step, nano structured functionally graded composite coatings were produced by the deposition of two separate layers containing different amounts of alumina particles. Although the graded coating showed superior hardness and wear resistance compared with the non-graded coatings, it suffers from low cohesive strength attributed to the presence of alumina particles at the interface region between the two layers. To overcome the poor adhesion between two layers, a thin intermediate plain Ni one was deposited between two layers leading to 80% and 30% improvement in the adhesion strength and wear resistance, respectively.

A facile method for fabrication of nano-structured Ni-Al 2 O 3 graded coatings: Structural characterization

Abstract Powder charges of micron-size Ni and Al2O3 were utilized to deposit nano-structured Ni-Al2O3 composite coatings on an aluminum plate fixed at the top end of a milling vial using a planetary ball mill. Composite coatings were fabricated using powder mixtures with a wide range of Ni/Al2O3 mass ratio varying from 1:1 to plain Ni. XRD, SEM and TEM techniques were employed to study the structural characteristics of the coatings. It was found that the composition of the starting mixture strongly affects the Al2O3 content and the microstructure of the final coating. Mixtures containing higher contents of Al2O3 yield higher volume fractions of the Al2O3 particles in the coating. Though Ni-Al2O3 composite coatings with about 50% of Al2O3 particles were successfully deposited, well-compacted and free of cracks and/or voids coatings included less than 20% (volume fraction) of Al2O3 particles which were deposited from powder mixtures with Ni/Al2O3 mass ratios of 4:1 or higher. Moreover, mechanical and metallurgical bondings are the main mechanisms of the adhesion of the coating to the Al substrate. Finally, functionally graded composite coatings with noticeable compaction and integrity were produced by deposition of two separate layers under identical coating conditions.

Wear and Friction Properties of Electrodeposited Ni-Based Coatings Subject to Nano-enhanced Lubricant and Composite Coating

This paper presents research findings on the tribological performance of electrodeposited coatings subject to nano-lubricants with the addition of nano-Al2O3 and graphene and Ni/nano-Al2O3 composite coatings. Electrodeposited coatings were produced by using a pulse electrodeposition method. Tribological experiments were conducted by using a linear reciprocating ball on flat sliding tribometer. Experimental results confirmed that the wear and friction resistance properties were significantly enhanced by doping of nano-effects in the lubricating oil and composite coating. The addition of Al2O3 nanoparticles in the lubricating oil showed the best tribological properties, followed by Ni–Al2O3 composite coatings and nano-oil with graphene. The surface morphology and microstructure of electrodeposited coatings were examined by scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. The wear mechanisms of these coatings subjected to tribological testing were investigated by post-test surface analyses. This research provides a novel approach to design durable nano-coatings for tribological applications in various industries such as automotive, aerospace, locomotive and renewable energy technologies.

Electrodeposition of Ni-Al2O3 composite coatings with combined addition of SDS and HPB surfactants

Abstract The effect of hexadecylpyridinium bromide (HPB) combined with sodium dodecyl sulfate (SDS) on electrodeposition of Ni-Al 2 O 3 composite coatings using fine Al 2 O 3 particles of average size of 150 nm and a typical watt's bath was investigated by evaluating the dispersibility, migration of alumina particles in the plating bath and their capture and embedding in the resulted coatings with varying HPB concentrations. The dispersibility and stability of the Al 2 O 3 particles suspended in the electroplating bath were evaluated through measuring the particle size distribution and the particle sedimentation. The depositing dynamics of Al 2 O 3 particles was discussed based on analysis of particle surface chemistry, zeta potential with simultaneous particle motion observation, and contact angle of bath on the substrate and coatings, respectively. The dispersibility and stability of the alumina particles in Watt's bath seemed not to have been improved by the surfactants according to the static measurement results of particle size distribution and sedimentation. However, the dynamics of Al 2 O 3 particles co-deposition were apparently modified by the surfactant addition with analysis of Al 2 O 3 particle motion in the electroplating bath as increasing the HPB addition at a fixed SDS content, where a random movement of particles in the bath is observed correlating to a fluctuation of zeta potential, in contrast to continuous increasing of zeta potential in water-diluted case as also reported in previous studies for co-electrodeposition of both oxide and carbide particles reinforced composite coatings. It is concluded that, directional electrophoresis migration of ceramic particles across the bath is limited due to the high ionic concentration in the bath environment. The combined addition of HPB with SDS led to the highest concentration of co-deposition of Al 2 O 3 particles into composite coatings, over both the cases of SDS addition and without surfactants. Moreover, HPB addition alone deteriorated the coating quality with notable coating exfoliation. The adsorption of cationic HPB on the surface of Al 2 O 3 particles promoted the particle capture onto cathodes and favored particle dispersion especially with agitation of the bath by forming “soft” agglomerates of the particles, while the anionic surfactant of SDS may facilitate a smooth and dense coating without pore defect by significantly improving wetting of bath on both copper substrate and nickel coating.

The effect of pulse electroplating on Zn–Ni alloy and Zn–Ni–Al2O3 composite coatings

Zn–Ni alloy and Zn–Ni–Al2O3 composite coatings were electrodeposited on mild steel substrate by direct and pulse current in sulphate bath. The effect of pulse electroplating on Ni content, phase structure, microhardness, surface morphology and corrosion resistance of coatings were investigated. Applied pulsed current increased the Ni content for both Zn–Ni alloy and Zn–Ni–Al2O3 composite coatings, which also increased the microhardness of the coatings. XRD results showed that the phase structure of all direct current (DC) and pulsed electroplated coatings was single Ni5Zn21-γ phase. Surface of coatings was smoother and more uniform with smaller nodules’ size for coatings deposited by pulse current. Pulse frequency did not have significant effect on the chemical and mechanical properties of deposits. Corrosion resistance of pulse plated Zn–Ni alloy coatings were improved significantly compared to the DC electroplated coatings. However, this effect was less pronounced for Zn–Ni–Al2O3 composite coatings.

Electrodeposition of Ni-Al2O3 composite coatings employing supercritical CO2 baths

The co-deposition of Ni and Al2O3 by electrodeposition in supercritical CO2 (sc-CO2) baths with and without emulsification was studied. The material characteristics of the Ni-Al2O3 composite coatings, including its crystal structure, surface morphology, chemical composition, micro-hardness, wear resistance, and corrosion resistance, were all examined and compared with those of pure deposited Ni. Although a reduction in electrodeposition rate and a lower solid Al2O3 particle content in the composite coatings were obtained incorporating sc-CO2 bath, substantial increases in the micro-hardness and wear resistance of the coatings were observed comparing with those formed in conventional bath. The advantages of sc-CO2 electrodeposition, with and without surfactant addition, over the conventional electrodeposition of composite coatings, are addressed.

Corrosion behaviour of sediment electro-codeposited Ni–Al2O3 composite coatings

Ni–Al2O3 composite coatings were produced by the sediment electro-codeposition (SECD) technique at various particle loadings and current densities. The submicron Al2O3 particles were found to distribute uniformly in the coating, and 12–18 vol.% particles can be incorporated in the coating depending on deposition current density and particle loading in the plating bath. Electrochemical corrosion testing was conducted in 0.9 wt.% NaCl solution. The results show that the incorporation of Al2O3 particles in the coating did not affect the general corrosion behaviour of the Ni coating. However, at higher anodic potentials approaching the breakdown potential and with prolonged polarization, the composite coatings showed deteriorated corrosion resistance in terms of increased anodic current density, reduced pitting potential and quicker breakdown of the passive film. The detrimental effects of Al2O3 particle incorporation could be explained by the existence of numerous boundaries between the particles and the matrix, which would serve as active sites for anodic dissolution and micro-pit formation.

Characterization of novel Ni–Al2O3–SiC nanocomposite coatings synthesized by co-electrodeposition

In the present work, Ni–Al2O3, Ni–SiC and novel Ni–Al2O3–SiC metal matrix composite (MMC) coatings were electrodeposited onto pure copper samples using a modified Watt’s nickel electroplating bath containing nano alumina and silicon carbide particles with an average particle size of 50 nm. The composition, crystalline structure and surface morphology of the deposits were characterized by X-ray diffractometry (XRD), energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscopy (FESEM). The results indicated that Ni–Al2O3–SiC hybrid composite films with an acceptable homogeneity and granular structure having 9.2 and 7.7 % vol. Al2O3 and SiC nanoparticles, respectively were developed successfully. The nanoparticles incorporated in the nickel layer effectively increased the micro hardness and wear resistance owing to dispersion and grain-refinement strengthening, changing the nickel matrix morphology as well as the texture and preferred grain growth direction from to the close-packed . The oxidation resistance of the Ni–Al2O3–SiC hybrid composite coatings was measured to be approximately 41 % greater than the unreinforced Ni deposit and almost 30 % better than the Ni–Al2O3 composite coatings.

Deposition Mechanism and Wear Resistance Nano Ni-Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Composite Coatings

Nano Ni-Al2O3 composite coatings were prepared on pure copper substrate. The surface morphology and distribution of nano-particles of coatings were observed by SEM, the components of the coatings analyzed by X-ray diffractometer, and the microhardness of coatings tested by HXD-1000 microhardness tester. The microstructure of nano Ni-Al2O3 composite coating was different from that of the electrodeposited nickel coatings. The inserted Al2O3 particle can effectively hinder the growth of crystals. The microhardness of composite coatings around the inserted particles was much higher than that of electrodeposited nickel coatings. The more the size of Al2O3 decreased, the more the microhardness and wear resistance of the composite coatings increased.

Electro co-deposition of Ni–Al2O3 composite coatings

Nickel–Al2O3 composite coatings have been successfully deposited galvanostatically on to stainless steel substrates by electro co-deposition from a Watts bath containing between 50 and 150 g/l of sub-micron or nano- sized alumina particles applying current density of −10, −20 and −32 mA cm−2. The alumina distribution in the composite films on the two sides of the substrate was remarkably different due to solution hydrodynamics and electric field effects. The effect of current density, particle concentration in the bath and particle size are studied systematically producing a comprehensive set of data for better understanding the effects of these variables on the amount of particles co-deposited. The amount of Al2O3 co-deposited in the films increases with the particle concentration in the bath and strongly depends on the current density and on particle size. The effect of the current density and of the alumina inclusions on the crystallinity of the Ni matrix and on the Ni crystallites grain size has also been studied. The inclusions of nano or sub-micron-Al2O3 particles are found to strongly influence the metallic nickel microstructure.

Corrosion- and wear-resistant properties of Ni–Al2O3 composite coatings containing various forms of alumina

This article describes the effect of the addition of different phases of alumina particles on the properties of electrodeposited Ni–Al2O3 composite coatings. The corrosion- and wear-resistant properties of Ni–Al2O3 composite coatings electrodeposited from a nickel sulfamate bath containing (i) alpha-alumina particles (Ni–Al2O3-1), (ii) gamma-alumina particles (Ni–Al2O3-2), and (iii) mixture of alpha, gamma, and delta alumina particles (Ni–Al2O3-3) have been studied. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies showed superior corrosion resistance of Ni–Al2O3-2 composite coatings compared with other two coatings. The SEM images and EDAX spectra also corroborated well with the observed corrosion results. The pin-on-disk wear studies showed improved wear resistance of Ni–Al2O3-1 composite coating containing alpha alumina compared with other two coatings. The transfer of material from the pin onto the disk was evident from the optical microscopy images of the wear tracks and Raman spectra of the wear track. This study shows that the addition of pure gamma-alumina particles enhances the corrosion resistance, and that pure alpha-alumina particles enhance the wear resistance of Ni composite coatings to a greater extent.

Synthesis and characterization of Ni–Al2O3 composite coatings containing different forms of alumina

Electrodeposited Ni–Al2O3 composite coatings were prepared using alumina powders synthesized from solution combustion method, precipitation method and a commercial source. Solution combustion synthesized alumina powder yielded α-phase; precipitation method yielded purely γ-phase; commercial alumina powder was a mixture of α-, δ- and γ-phases. A nickel sulfamate bath was used for electro-codeposition. The current densities (0.23 A dm−2 for 20 h, 0.77 A dm−2 for 6 h, 1.55 A dm−2 for 3 h and 3.1 A dm−2 for 1.5 h) and bath agitation speeds (100, 200, 600 and 1000 rpm) were varied. The pH variations of the bath were higher during the electrodeposition of combustion synthesized alumina. The effect of different forms of alumina particles on the microhardness and microstructure of the nickel composite coating was studied. Composite coating containing combustion synthesized alumina particles was found to have higher microhardness (550 HK). It was found that at lower agitation speed (100 rpm), bigger particles were incorporated and at higher agitation speed (1000 rpm), smaller particles were incorporated. The area fraction of alumina particles incorporated in nickel matrix was highest for commercial alumina (24%). This study shows that it is not suffice to take just the current density and stirring speeds into account to explain the properties of the coatings but also to take into account the source of particles and their properties.