Hardness of nickel electrodeposition on aluminium alloys : influence of temperature and duration of heat treatment (original) (raw)
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International Letters of Chemistry, Physics and Astronomy, 2016
In this research a surface hardening process by Ni coating and subsequent diffusion heat treatments was studied at 7075 Aluminum alloy. Nickel coatings with different thickness were obtained by change the coating time and current density. Heat treatments at 450 °C, 500 °C, and 550 °C for times (6, 12, 24) hours were performed in order to obtain surface hardening required of the aluminum alloy by diffusion of nickel into the substrate. The effect of temperature and diffusion time on surface hardness of Al 7075 alloy was studied. Surface hardness about 800 [HV] were achieved after heat treatment at 500 °C for 24 hour by diffusion of Ni in the substrate and cause of formation of Al 3 Ni 2 intermetallic phase, as x-ray diffraction tests of samples showed. While is about 670 [HV] after heat treatment at 550 °C for 24 hour because of diffusion of aluminum toward the surface of sample, as x-ray diffraction tests of samples showed.
Microstructure and surface mechanical properties of electrodeposited Ni coating on Al 2014 alloy
The surface of Al 2014 was modified by electrochemical deposition of Ni with an aim to improve the surface mechanical properties of the alloy. The deposition was performed at various values of DC current, potential and time using standard Watt's bath. The samples were heat treated to improve the adhesion and hardness of Ni coatings. Material characterization was performed using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, atomic force microscopy and X-ray diffraction. Microhardness, nanohardness, microscratch and coefficient of friction measurements were undertaken to determine the surface mechanical properties of the electrodeposited Ni coating. Experimental results indicate that electrochemical deposition combined with heat treatment can be used to improve the surface properties of Al alloys.
Archives of Metallurgy and Materials, 2014
In this study, the effect of zinc interlayer on the adhesion of nickel coatings reinforced with micrometric Al2O3 particles was examined. Nickel coating was applied by electroplating on EN AW - 5754 aluminium alloy using Watts bath at a concentration of 150 g/l of nickel sulphate with the addition of 50 g/l of Al2O3. The influence of zinc intermediate coating deposited in single, double and triple layers on the adhesion of nickel coating to aluminium substrate was also studied. The adhesion was measured by the thermal shock technique in accordance with PN-EN ISO 2819. The microhardness of nickel coating before and after heat treatment was additionally tested. It was observed that the number of zinc interlayers applied does not significantly affect the adhesion of nickel which is determined by thermal shock. No defect that occurs after the test, such as delamination, blistering or peeling of the coating was registered. Microhardness of the nickel coatings depends on the heat treatmen...
2019
Aluminium is a very important metal among the engineering materials. Owing to its importance, several researches are being conducted on its characteristics and the effects of other materials on its characteristics. This paper investigated the effects of various composition of nickel on the characteristics of aluminium. The characters of interest were strength, hardness, electrical conductivity and microstructural evolutions. Alloys were developed with variation of nickel from 2%, 4%, 6%, 8%, to 10%, these included the tensile specimens, hardness specimens, electrical conductivity specimens, and the microscopic specimens. Each set were produced in threes: one annealed, one age-hardened and the other left untreated. The results of the various test show that CN5 has the highest hardness, with hardness value of 435, followed by HN4, with the value of 416 and then AN4 with 403. All the rest are below these three values. The cast samples produced more elongations than the annealed and har...
Morphology, Hardness, and Wear Properties of Ni-Base Composite Coating Containing Al Particle
Coatings
Ni–Mo/Al composite coatings were obtained by electrodeposition from a Ni–Mo plating bath containing suspended Al particles. The factors including temperature, current density, and stirring rate affecting coating composition, wear, roughness, and morphology have been studied. It was found that properties such as hardness, roughness, wear, and the Al particle content showed parabolic behavior when changing each parameter. That means that there is a critical value for the mentioned parameters at which the properties of coatings become maximal.
Effect of Temperature and Time on Nickel Aluminide Coating Deposition
Mehran University Research Journal of Engineering and Technology, 2018
The NiAl coating was deposited onto Nickel based CMSX-4 superalloy by in-situ CVD (Chemical Vapor Deposition) method. Main focus of this contribution was to study the influence of aluminizing time and temperature on the microstructure and thickness of the coating; this was followed by examination by XRD (X-Ray Diffraction), electron microscope. Results suggest that an incremental variation in temperature alters the coating activities from HA (High Activity) to LA (Low Activity). This is exhibited by the resultant CT (Coating Thickness) since HA coatings are thicker than LA counterparts. The microstructure of the coating formed at low temperature (or HA ones) showed a large amount of -Cr precipitates while one formed at high temperature (or LA ones) exhibited lower amounts of such precipitates. Moreover, incremental aluminizing time showed linear trend of CT at initial stage, thereafter (10 hrs) it leveled off. Whereas it does not affect microstructure of the coating.
Structure Characterization of Ni/Al2O3 Composite Coatings Prepared by Electrodeposition
Solid State Phenomena, 2010
In the present study, the electrodeposition of composites consisted of metal matrix (nickel) and inert particles (hard nano-sized Al 2 O 3 oxide) has been carried out in a Watt's type bath of pH 4, at room temperature in a system with the steel rotating disk electrode. The influence of dispersed Al 2 O 3 powder on structure characteristics (morphology, phase composition, texture, residual stresses) of Ni/Al 2 O 3 coatings has been investigated. The crystallographic texture of Ni and Ni/Al 2 O 3 coatings deposited on the steel substrates was analyzed by XRD technique based on the back-reflection pole figures. The "sin 2 ψ" X-ray diffraction method was used to determine the residual stress as a function of X-ray penetration depth. The influence of Al 2 O 3 particles on the value of the Ni coating microhardness was also analyzed.
Structure Characterization of Ni/Al 2 O 3 Composite Coatings Prepared by Electrodeposition
Solid State Phenomena, 2010
In the present study, the electrodeposition of composites consisted of metal matrix (nickel) and inert particles (hard nano-sized Al 2 O 3 oxide) has been carried out in a Watt's type bath of pH 4, at room temperature in a system with the steel rotating disk electrode. The influence of dispersed Al 2 O 3 powder on structure characteristics (morphology, phase composition, texture, residual stresses) of Ni/Al 2 O 3 coatings has been investigated. The crystallographic texture of Ni and Ni/Al 2 O 3 coatings deposited on the steel substrates was analyzed by XRD technique based on the back-reflection pole figures. The "sin 2 ψ" X-ray diffraction method was used to determine the residual stress as a function of X-ray penetration depth. The influence of Al 2 O 3 particles on the value of the Ni coating microhardness was also analyzed.
Surface hardening of Al 7075 alloy by diffusion treatments of electrolytic Ni coatings
2013
Asurface hardening process based on Ni coating and subsequent diffusion heat treatments was studied for Al7075 alloy. Nickel coatings with different thickness on 7075 Al alloy were obtained by electrolytic and electroless processes . Heat treatments in inert atmosphere at 500 °C and 530 °C for different times were performed in order to obtain surface hardening of the aluminum alloy by diffusion of Ni into the substrate. The effect of temperature and time on the depth of hardening was studied by SEM, EDS, Glow discharge optical spectrometry, microhardness tests and tribological tests. Surface hardness higher than 1000 HV and depth of hardening higher than 100 mm were achieved by diffusion of Ni layers and formation of Al3Ni2 and Al3Ni intermetallic phases . The tribological test on Al7075 alloy against a hard Cr coated steel cylinder in air showed an average coefficient of friction ? of about 0.5 with a wide variation range, while all the coated and treated samples exhibited a coeffi...
Journal of Alloys and Compounds, 2017
In this work, we proposed a novel mechanical alloying method to deposit Ni x-Ti x intermetallic coating on various metallic substrates using laser treatment. Three different substrates (Al-based alloy, Ti-based alloy, and hypoeutectoid steel) were used, and 50-70 µm thick Ni x Ti x coating was deposited during the process. For mechanical alloying, we used a self-constructed vibratory ball mill (single chamber) and for laser treatment, we used a "TrumpfTruDisk 1000" machine equipped with a four-dimensional control system "Servokon" designed specifically for experimental studies. Different laser beam intensities were used for laser operation. The cross-sectional microstructures of coatings were studied using a scanning electron microscope equipped with a Bruker energy-dispersive X-ray Spectrometer (EDS). Additional investigation of a cross-sectional area of one of the Ni x Ti x-coated samples was performed with field emission high-performance SEM and focused ion beam (FIB). Phase compositions of the obtained coatings, before and after laser treatment, were analyzed using X-Ray diffraction method. After the deposition process, the micro-hardness of the coatings was measured using a Vickers hardness tester. The structure and morphology of the obtained coatings were investigated.