Iranian Journal of Materials Science and Engineering

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Electrochemical coating processes are significantly affected by applied magnetic fields due to the generation of electromagnetic forces. The present research work has been undertaken to study the effect of coating parameters such as current density and alumina concentration on the characteristics of Ni-Al2O3 composite coating under static magnetic field. Ni-Al2O3 composite coating was applied on a mild steel substrate using conventional Watts solution containing Al2O3 particles with and without magnetic field. The coating microstructure and Al2O3 particle density in the coating layer were examined by scanning electron microscopy (SEM). It was found that the applied magnetic field made the coating structure finer and leads to the increases of the particle content in the coating. However, the results confirmed that the magnetic forces inversely affected the particle density in the coating at higher current density than that of normal coating process.

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Abstract: Nickel was electrodeposited onto copper substrates with high {111} and {400} peak intensities. The grain size of coatings deposited onto the copper substrate with a higher {111} peak intensity was finer. Spheroidized pyramid morphology was obtained at low current densities on both copper substrates. By increasing the deposition current density, grain size of the coating was increased for both substrates and eventually a mixed morphology of pyramids and blocks was appeared without further increase in grain size. This decreased the anodic exchange current density probably due to the decrease of surface roughness and led to a lower corrosion rate.

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Ni-P Electroless coatings provide appropriate resistance to wear and corrosion. Co-deposition of particles between layers can improve their properties, especially general corrosion and erosion-corrosion behavior by means of nano diamond as reinforcing particles. In this study Ni-P/nano diamond composite deposition were deposited on steel substrate. Structure of the coatings and corrosion resistance of theme were investigated by scanning electron microscopy and corrosion tests in salty media. The composite structure of the deposit was evaluated as nano size without using any surfactants. Also results for the composite coating show better corrosion protection and higher hardness comparing with as -deposited Ni-P. The optimum concentration of diamond nanometer particles were found by evaluation of scanning electron microscopy pictures, hardness measurement, linear polarization and electrochemical impedance spectroscopy results

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In the present research, to form niobium carbide coating on the surface of AISI L2 steel Thermo-Reactive Deposition method (TRD) in a molten bath was used. Niobium carbide coating treatment was carried out at 1173 K, 1273 K, and 1373 K for 2, 4, and 8 hours. The molten bath contained 20wt.% borax (Na2B4O7), 5 wt.% boric acid (B2O3), and 75 wt.% ferro-niobium. The presence and properties of the coated layer were studied by means of Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and X-Ray Diffraction (XRD) analysis. The thickness of coating ranged between 6.6 µm to 33µm depending on treatment time, and temperature. The effects of treatment time and temperature on the coating thickness were studied. Kinetic study of the formation of NbC coating showed that growth of the coating is under the control of diffusion. The activation energy of the process was estimated to be 122 kJ/mol. A practical formula to estimate the coating thickness was suggested.

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Silver nanoparticles are being given considerable attention because of their interesting properties and potential applications. One such exploitable use is as the major constituent of conductive inks and pastes used for printing various electronic components. This paper presents a novel direct-writing process for fabrication of the first deposited silver nanoparticles (AgNPs) (50-200nm) electrode via a thermal inkjet printer. In this method, AgNPs were chemically deposited by ejection of ascorbic acid and silver nitrate solutions onto different substrates such as paper and textile fabrics. Silver deposited patterns were used as electrodes in different electrochemical experiments and their morphology was also investigated in SEM observations. The highest conductivity of deposited electrodes obtained on paper as the substrate was found to be around 5.54x105 S/m. Inkjet fabricated electrodes exhibited acceptable electrochemical behavior in experiments designed for measuring the concentration of hydrogen peroxide as a fundamental procedure for early determination of glucose. This novel inkjet silver deposition technique is introduced to be considered as a promising method for ultimate single step fabrication of different electrochemical bio-sensors.

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High energetic aluminum nanoparticles are mainly used as additive in solid rocket propellants. However, fabrication of these aluminized energetic materials is associated with decreasing the burning rate of propellants due to problems such as oxidation and agglomeration of nanoparticles. In this study, to improve combustion performance of aluminum nanoparticles, coating by metallic Ni shell was studied. Nickel coating of aluminum nanoparticles was performed through electroless deposition (ED) subsequently, morphology and chemical composition of Ni-coated nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). These studies show that a uniform Ni layer with a thickness of 10nm is coated on the surface of Al nanoparticles. Thermal analysis of uncoated and Ni-coated aluminum nanoparticles was done using differential thermal analysis (DTA) and thermo gravimetric analysis (TGA). The results of thermal analysis indicate that, coating the aluminum particles by Ni, leads to improvement in combustion performance of aluminum nanoparticles through decreasing critical ignition temperature, ignition delay time of the nanoparticles and promoting the ignition by exothermic chemical reactions between Al and Ni

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In the present study, CrN, TiN and (Ti, Cr)N coatings were deposited on D6 tool steel substrates. Physical and mechanical properties of coatings such as microstructure, thickness, phase composition, and hardness were evaluated. Phase compositions were studies by X-ray diffraction method. Mechanical properties were determined by nano-indentation technique. The friction and wear behaviour of the coatings were investigated using ball-on-disc tests under normal loads of 5, 7 and 9 N at sliding distance of 500 m, at room temperature. Scanning electron microscope equipped with energy dispersive spectroscopy, optical microscope, and 2D/3D profilometry were utilized to investigate the microstructures and wear mechanisms. Wear test results clarified that the wear resistance of (Ti, Cr)N and TiN coatings was better than that of CrN coating. The wear resistance of the (Ti, Cr)N coatings was related to the Ti content in the coatings and reduced by decreasing the Ti content. The dominant wear mechanisms were characterized to be abrasive and tribochemical wear

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A homogenous TiO₂ / multi-walled carbon nanotubes(MWCNTs) composite film were prepared by electrophoretic co-deposition from organic suspension on a stainless steel substrate.  In this study, MWCNTs was incorporated to the coating because of their long structure and their capability to be functionalized by different inorganic groups on the surface. FTIR spectroscopy showed the existence of carboxylic groups on the modified carbon nanotubes surface. The effect of applied electrical fields, deposition time and concentration of nanoparticulates on coatings morphology were investigated by scanning electron microscopy. It was found that combination of MWCNTs within TiO₂ matrix eliminating micro cracks presented on TiO₂ coating. Also, by increasing the deposition voltages, micro cracks were increased. SEM observation of the coatings revealed that TiO₂/multi-walled carbon nanotubes coatings produced from optimized electric field was uniform and had good adhesive to the substrate.

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Tin-Zinc alloy coatings have many applications because of their unique properties such as corrosion resistance, solderability and flexibility. In this study, the effect of current density, temperature and pH on chemical composition, cathodic current efficiency, morphology and structures of the coatings was investigated. The results illustrated that, at low current densities (<0.5 mA/cm²), the coatings were relatively pure tin, but Zn content increased with enhancing the current density. At higher currents a relatively pure Zn film was obtained. Temperature and pH also affected chemical composition of the alloy films. Zn content of the coatings was decreased by increasing the temperature, while its variation with pH had ascending-descending trend. Morphological investigation of the coatings revealed that increasing Zn content of deposits led to porous, rough and fine grained films.

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The main purpose of this investigation is to assess the effect of post-deposition annealing treatment on the electrochemical behavior of TiN coating developed on AISI 304 stainless steel substrate using cathodic arc evaporation physical vapor deposition (CAE-PVD). Post-annealing treatment at 400 ºC was performed on the coated substrate for 1 h. The studied samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) tests. The preferred orientation of TiN (111) was identified by XRD patterns and the crystallinity of the coating increased after annealing treatment. SEM observations indicated that TiN coatings free of cracks were successfully developed on the substrate. The electrochemical measurements elucidated that the annealed coating had better corrosion resistance compared to that of the as-deposited coating with a lower current corrosion density. This investigation implied that improved corrosion performance of the TiN coating can achieved by performing post-deposition annealing treatment.

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In this study, CrN/ZrN multilayer nanostructured coatings with different bilayers (10, 20, and 30) were created by the cathodic arc evaporation. The electrochemical behavior of samples was evaluated by polarization and impedance spectroscopy tests in the Ringer medium and the pin on disk test was used to investigate the tribological behavior of the samples. The results of measurements showed that the electrochemical and tribological behavior of the coatings depends on the number of bilayers and by rising the number of bilayers, the coating shows higher corrosion resistance and better tribological performance. Field emission scanning electron microscopy (FE-SEM) images of the specimens after exposure to the corrosion medium showed that the number of surface cavities were formed by the coating that had the highest number of bilayers comparing with other coatings were quite fewer in number and smaller in diameter. The results of the pin on disk test showed that by increasing the number of bilayers from 10 to 30, the coefficient of friction and wear rate decreased and the 30L coating ‌showed better wear resistance.

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This study investigates the synthesis of Al/MoS₂ nanocomposite coating by the electro spark deposition (ESD) method for its lubricating properties. ESD method was selected because it is a very easy, rapid, and cost-saving method and the resulting coating has a strong bonding with the substrate. As a substrate, a Ti-6Al-4V alloy sheet containing 6.12 % Al, 4.06 % V, 0.19% Fe, and 0.05 % Ni was used. For coating, an aluminum-molybdenum disulfide composite electrode in the form of a cylindrical rod was employed. Three frequencies of 5, 8, and 11 kHz, three current limits of 15, 25, and 35 amps, and three duty cycles of 50, 60, and 70% were used in the coating operation. AFM analysis was used to study the topography, morphology, and calculate roughness. The samples were then subjected to hardness tests. To determine the wear resistance of the samples, pin on disk tests were performed. XRD analysis was performed to identify the phases on the surface of the coated samples. SEM was used to examine the microstructure of the coating before and after wear testing, in order to determine the wear mechanism. The results indicated that the Al/MoS2 nanocomposite coating was synthesized on the substrate surface. The hardness of the reference sample is 353 Vickers, and that of the coated samples is about 200 Vickers. For the reference sample, the roughness was measured at 15.7 nm, and for the coated sample at 268.1 nm. As spark energy increased, the coefficient of friction increased by approximately 0.09. As spark energy increased, the wear rate increased by 27%. A significant increase in the Lancaster coefficient occurred around 5 joules of energy. According to the wear rate results, the sample with the lowest thickness wears 4% less than the sample with the highest thickness. The wear rate of sample 351170 is 78% lower than that of sample 150550.

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Several extensive researches are being carried out in the field of 3D printing. Polymer matrices, such as High-Density Polyethylene (HDPE), are less explored in particular on the microstructure and mechanical properties of HDPE composites developed via Fused Deposition Modelling (FDM) process. Very scarce amount of works is devoted to study HDPE’s reinforced with carbon nano-tubes (CNT’s) . In the present work, we report on the mechanical properties of  HDPE composites prepared via FDM process. Varying proportions of CNTs ( 0.5, 1, 1.5 and 2%) are used as reinforcements. It is found that increasing CNT content enhances impact and tensile strength, with HDPE/2.0%CNT outperforming pure HDPE by approximately 71.6% and 25.4%, respectively. HDPE/2.0%CNT composite also showed Young's modulus approximately 49.2% higher than pure HDPE. According to fracture analysis, pure HDPE failed near ductile, whereas composites failed brittle. CNTs occupy the free positions in the polymeric chains, and their tendency to restrict chain mobility causes HDPE to lose ductility and begin to behave brittle. The use of CNTs as reinforcement successfully improved the mechanical properties of HDPE.

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In the third generation of solar cells, cheaper absorbent layers such as Cu₂ZnSnS₄ (CZTS) have been developed with specifications similar to Cu₂InGaS₄ (CIGS). This CZTS material is known as a material with good structural and optical properties where the CZTS material has a series of atoms bonded to each other to form a kesterite or stannite crystal arrangement. In its use as an absorbent layer for solar cells, CZTS material is synthesized using the electrochemical deposition method. In this electrochemical deposition technique, an electrical circuit will be connected to the electrode and inserted into the electrolyte. Several voltage variations from 1 volt to 5 volts will be applied to the electrical circuit, which will then trigger ions from the precipitating material in the electrolyte to stick to one of the electrodes. Variation of deposition voltage was carried out to determine the effect of deposition stress on the electrochemical deposition method on the characteristics of the CZTS absorbent layer. The characterizations used are X-Ray Diffraction (XRD), UV-Vis Spectrometry, and I-V meter. XRD results show that the resulting crystal size is getting smaller with greater deposition voltage around 6.07 - 7.27 nm. The optical absorption results show that the CZTS absorber layer is sensitive at low wavelengths around 300 – 480 m,, with Light Harvesting Efficiency (LHE) ranging from 13.3 - 24.75%. The band gap energy values obtained ranged from 1.4 to 1.48 eV. The cell efficiency test results show an excellent efficiency value according to the reference ranges from 2.56-8.77%. These results indicate that the deposition voltage affects the characteristics of the CZTS absorbent layer for solar cell applications.

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The trimanganese tetraoxide (Mn₃O₄) nanostructured thin films doped with 2 mol % of nickel (Ni) and molybdenum (Mo) ions were deposited by a simple electrophoretic deposition technique. The structural, optical, and morphological studies of these doped thin films were compared with pure Mn₃O₄ thin films. X-ray diffraction (XRD) confirmed the tetragonal Hausmannite spinel structure. The Fourier transform infrared spectroscopy (FTIR) provided information about the molecular composition of the thin films and the presence of specific chemical bonds. The optical study and band gap energy values of all thin films were evaluated by the UV visible spectroscopy technique. The scanning electron microscopy (SEM) illustrated the morphological modifications of the Mn₃O₄ thin films due to doping of the nickel and molybdenum ions. The Brunauer Emmett Teller (BET) method has confirmed the mesoporous nanostructure and nanopores of the thin films. The supercapacitive performance of the thin films was studied by cyclic voltammetry (CV), and galvanostatic charge discharge (GCD) techniques using the three-electrode arrangement. An aqueous 1M Na₂SO₄ electrolyte was used for the electrochemical study. The 2 mol % Ni doped Mn₃O₄ thin film has shown maximum specific capacitance than pure and Mo doped Mn₃O₄ thin films. Hence, this study proved the validity of the strategy - metal ion doping of Mn₃O₄ thin films to develop it as a potential candidate for electrode material in the futuristic energy storage and transportation devices.

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The Nickel tungsten (Ni-W) alloy was electrodeposited on stainless steel (SS) substrate using potentiostatic mode at room temperature. Potentiostatic electrodeposition was carried out by varying the deposition time. The physicochemical properties of Ni-W alloys were studied using X-Ray diffraction (XRD), Electron Microscopy and micro-Raman spectroscopy. Recorded XRD spectra was compared with standard JCPDS card and the presence of Ni was confirmed, no such peaks for W were observed. Further study was extended for micro-Raman analysis. From Raman spectroscopy study the appearance of Ni-O and W⁶⁺=O bonds confirms that the Ni-W present in amorphous phase. Several cracks were observed in SEM images along with nanoparticles distributed over the electrode surface. The appearance of cracks may be correlated with the in-plane tensile stresses, lattice strains and stacking faults and may be related to the substrate confinements.
 

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The sensitivity of lead dioxide coating properties to the deposition conditions and electrolyte composition has allowed the preparation of coatings with different properties for different applications. In this study, the effects of electrolyte additives on the electrodeposition process were investigated using electrochemical measurements such as cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The results showed that the presence of fluoride ions significantly reduce the possibility of TiO₂ formation. The addition of copper ions not only prevents lead loss at the cathode, but also leads to the formation of copper oxide on the surface at initial stages, which hinders nucleation of PbO₂. The presence of sodium dodecyl sulfate (SDS) also interferes with the nucleation process as it occupies active nucleation sites. The α-PbO₂ interlayer prevents copper oxidation and solves the problem of lead dioxide nucleation. Finally, it was found that the simultaneous use of all additives together with the α-PbO₂ interlayer has a positive effect on the coating process.