جستجوی مقالات مرتبط با کلیدواژه « nickel » در نشریات گروه « مواد و متالورژی »

In this research, the properties of zinc phosphate (single cation), zinc/nickel (double cation) and zinc/nickel/manganese (three cation) coatings were investigated.

The basic phosphating solution was prepared based on previous experiences including phosphoric acid, nitric acid, accelerators and modifiers to create an optimal coating structure. The concentration of compounds and operational parameters of temperature, time and solution pH were fixed during the process. The amount of zinc-nickel-manganese cations by zinc oxide is 1.5; Nickel nitrate 4 and manganese carbonate 3.8 (g/liter) were added to the bath. In the zinc phosphate coating solution (monocation), manganese nitrate and nickel nitrate were removed from the solution in Table 1. Zinc/nickel phosphating solution (bi-cationic) was also obtained by removing manganese carbonate from the solution. Measuring the thickness and weight of the surface unit, determining the amount of total and free acid, studying the morphology and microstructure of the coating; Corrosion resistance tests including resistance to alkali solubility, salt spray test were performed. Also, after painting the phosphated samples, paint layer thickness test, scratch and bending test, impact test and paint layer hardness were performed.

The comparison of phosphating baths showed that the weight of the coating decreased with the introduction of nickel and manganese ions. The low zinc phosphate coating has a cluster structure, while the zinc-nickel phosphate coating crystals are clustered and sheet-like, and the tri-cationic phosphate coating has a mixture of cubic and sheet-shaped structures. The difference in height and height in zinc-nickel-manganese phosphate coating; It has the lowest Ra and Rz values compared to single-cationic and double-cationic phosphate coatings. Also, the optimal three-cation coating has the highest corrosion resistance, which is due to greater uniformity, less porosity, fine crystal structure, and a high percentage of corrosion-resistant phases in the coating composition.The coating color studies indicate that the best adhesion of the paint layer is related to the tri-cationic coating. According to the researches, the zinc-nickel-manganese three-cation coating provided better results than the zinc-nickel and zinc-nickel two-cation coatings.

U-500 is a nickel-based superalloy which has significant amounts of some precious elements such as cobalt and chromium. Due to the economic and strategic value of these metals, their recovery from the used superalloys is of great importance. Hydrometallurgy is an economical and effective method for recovering these valuable metals from the superalloy scraps. So in this investigation, the dissolution behavior of nickel, cobalt and chromium elements from the used U-500 superalloy in the electro leaching process as well as the effect of different process parameters (such as: sulfuric acid concentration, applied voltage, process temperature, stirring and cathode-anode distance) on the dissolution of these elements are studied in details. The results show clearly that by increasing the concentration of sulfuric acid in the electrolyte, the applied voltage, and temperature, as well as decreasing the cathode-anode distance, the anodic dissolution of the superalloy U-500 is improved. Electrolyte stirring has no significant effect on increasing the anodic dissolution of the superalloy. The optimum conditions for the anodic dissolution of superalloy U-500 in sulfuric acid electrolyte was determined as acid concentration of 125 g/L, applied voltage of 4 V, stirring speed of 300 rpm, and cathode-anode distance of 3 cm without temperature control (starting with ambient temperature as the initial temperature(. Under these conditions, about 75% nickel, 84% cobalt and 67% chromium were durnig 25 minutes.

In this study, iron-based alloy with Fe65B15Si10Ti5Al5 was prepared by mechanical alloying method . The effect of nickel content on its microstructure with 200 hours of milling was investigated. In this study X-ray diffraction and scanning electron microscopy equipped with chemical composition analyzer. Addition of nickel in the Fe65Ti5Al5B15Si10 alloy system and its increase reduced the intensity of all peaks, their broading and also the shift of peaks to lower angles. This indicates a decrease in the size of iron-alpha phase crystals and an increase in lattice strain due to an increase in nicke elmentl. Also, an increase in nickel reduced the particle size due to milling at the same hours of alloying. 

The Ni-NiO powder was produced by solution combustion synthesis with two fuels of urea and glycine and different molar ratios of fuel to the oxidizer. The adiabatic temperatures were calculated for different molar ratios of fuel to the oxidizer. Then, the final products at any molar ratio of fuel to the oxidizer were characterized and compared to those were estimated according to the reactions' stoichiometry. The effect of different fuels, glycine and urea, and using mixed fuels were considered. Characterizations and analyses such as XRD, PSA, and FESEM were carried out to determine the compound and morphology of the products. At lower fuel to oxidizer ratio, the final product was NiO for both fuels (urea and glycine). However, with increasing the molar ratio of fuel to oxidizer, the Ni particles were synthesized adjacent to the NiO particles. Generally, the particle size of powders that were synthesized with glycine was smaller than those of urea. However, with increasing the molar ratio of fuel to oxidizer, the particle size of powders increased because of changing the composition to Ni and decreasing the adiabatic temperature. The smallest particle size was related to the sample synthesized by 75% glycine and 25% urea which was 35 nm. The morphology of Ni and NiO were compared at the different molar ratios of fuel to the oxidizer. The morphology of NiO is finer and contains more porosity.

This study aims at investigating changes in microstructure and strength of W alloy and Cu bimetals with varying spark plasma sintering (SPS) temperature and percentage of copper in W-Cu-Ni alloy. After SPS of W (12 wt%)-Cu (14 wt%)-Ni (3 wt%) alloy powder into consolidated discs at 1350 ° C, they were spark plasma sintered to copper discs at various temperatures. Assessment of the interface microstructure and shear strength was performed by field emission scanning electron microscpe (FESEM) and shear strength test, respectively. Results indicated SPS is successful in forming a perfect metallic bond with monolithic interface and high shear strength of about 45 MPa in Cu/W-12Cu-3Ni bimetal that is extra high quality and not reported in previous investigations.

In this work, the effect of Ni addition on the glass forming ability (GFA) of FeMoPCB composite alloy was investigated and the optimal amount of Ni to improve GFA was determined. So, the thermal stability of this alloy with the various percent of nickel was investigated by not only experimental methods including; differential scanning calorimetry, X-ray diffraction, optical microscope and transmission electron microscopy but also computational methods such as α، β، γ and etc. The results of XRD test, TEM showed that in the presence of 10 at.% nickel , the glass-forming ability of this alloy increased, while in the presence of lower or higher percent nickel, different crystalline phases were detected. The presence of crystalline phases was also investigated by microhardness test. Finally, it was found that the results of the computational methods regardless of the experimental results don’t have enough accurate .

In this study, solvent extraction of copper from nickel in the presence of tartaric acid and sodium acetate with D2EHPA was studied. To investigate the behavior of carboxylates, parameters such as pH, carboxylate concentration and time were varied. According to the results, with the addition of 0.04 and 0.03 g/L of tartaric acid, and sodium acetate, pH of 5.12, and time of 10 min, 90% and 20% copper and nickel were extracted, respectively. At this condition, the separation factor reached a maximum value of 25.75. Therefore, the mixture of tartaric acid and sodium acetate resulted in the selective extraction of copper.

Al–Si alloys are widely used in automotive components, especially with eutectic composition, for cylinder heads, pistons and valve lifters. In the current study, the effect of different concentration of nickel has been investigated on microstructural evolution and tensile strength properties of Al-12%Si-1%Mg-1%Cu-X%Ni alloys. The microstructural assessment of alloys was carried out by an optical (OM) and scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS) analysis. The tensile testing method was performed for both modified and unmodified specimens. The obtained result indicated that the Ni can effectively refine eutectic silicon particles. Depending on the chemical composition of the alloy specimens, different containing phases such as Τ-Al9FeNi, δ-Al3CuNi, γ-Al7Cu4Ni, Q-Al5Cu2Mg8Si6, α-Al15(MnFe)3Si2 and ε-Al3Ni intermetallic in interdendritic regions have been detected. Furthermore, with the increasing of nickel concentration, Ni-containing intermetallics translate from Al3Ni to Al7Cu4Ni or Al3CuNi and their morphologies change from short and long strip-like to chines-script or reticular-shape. Moreover, the results showed that the mechanical performance has been related to the microstructural features. The ultimate tensile strength (UTS) at room temperature increases from 157 MPa to 220 MPa and then decrease to 195 MPa.

This research aims to produce Ni-Vanadium Carbide composite nano powder, known as a hard metal, from oxide raw materials and magnesium as a reductant, using mechano-chemical method. With regard to the adiabatic temperature (T=3964 K), this reaction is a mechanically induced Self-sustaining (MSR) type. Raw materials were mixed according to stoichiometry reaction with a ratio of (1:1:6:2) for Nickel oxide, Vanadium oxide, Magnesium and graphite respectively. Milling was carried out in a planetary ball mill with a powder to ball ratio of 1:20 under argon gas atmosphere. After 40min of milling, combustion occurred out in the mill chamber. With regard to the results of X-ray difraction after the combustion, the intended products; that are, Nickel, Vanadium Carbide and Magnesium Oxide which is by-product of the reaction, were completely produced. HCl with a concentration of 9% was used to remove the magnesium oxide phase. The crystallite size and lattice strain were calculated using Williamson-Hall method, and the crystallite size and lattice strain of Ni and Vanadium Carbide were obtained 40nm, 0.00595, 54nm, 0.00615, respectively.

In the present study, the mechanical alloying process was used to produce the Ni-Nb-Si amorphous alloy. X-ray diffraction (XRD)analysis and high-resolution transmission electron microscopy (HRTEM) were used to approve the amorphous phase formation after 12 hours of mechanical alloying. The results obtained from the SEM morphological images of powder particles during mechanical alloying showed that increasing the milling time caused the reduction of the powder particles size and uniformity in the shape of the particles. Enhancing the embrittlement and fracturing rate caused brittleness and the increase in the failure rate; these were followed by a decrease in the powder particle size to 1-5μm. Cold welding and flattening of the pure elemental powders after mechanical alloying for 2 hours formed a lamellar structure of the alternative layers of different elements lying over each other. SEM image of cross-section of powder particles showed that by increasing the milling time, the interlamellar spacing was decreased, the elements were distributed more uniformly, and finally, a uniform structure of theamorphous phase was completed.

Boron carbide due to properties such as high hardness, high Young's modulus and low density is highly regarded; however its application is limited because of unsuitable sinterability, low fracture toughness and the low wettability of it with melt of most metals. In this study, the surface of B4C is coated with electroless method and the effect of ethylene diamine (C2H8N2) complexing agent at temperatures of 75 and 85 °C and a pH of 13 is examined. Scanning electron microscope equipped with EDS analyzer for investigation of microstructure and morphology of coated B4C powder and X-ray diffraction to determine the composition and phases were used. The results indicate that in the electroless coating process, the amount of the C2H8N2 complexing agent in the plating bath has significant effect on the quantity of coating and uniformity of it on the surface of the B4C particles. By increasing the C2H8N2 complexing agent in the electroless plating bath in each of the constant temperatures of 75 and 85 °C, the nickel coating is reduced. The phase analysis of coated B4C particles in the electroless nickel plating bath with different amounts of the C2H8N2 complexing agent as compared to nickel salt at a temperature of 85 °C showed that in all four composition of complexing agent, B4C and Ni phases are present. However, in ratios of 1: 1 and 1: 3 of C2H8N2 complexing agent to nickel salt, Ni(OH)2 phase is also visible.

Abstract Li-Ion and Ni-MH batteries are the best candidate for Electric Vehicles. Despite higher energy densities of Li-Ion batteries, because of economical reason Ni-MH Batteries are still attractive for scientist. In this investigation Cerium rich MmNi3.55Co0.75Mn0.4Al0.3 has been produced via Vacuum Arc Remelting Process. Phase characterization has shown that the predominant crystallographic phase is Hexagonal type with AB5 chemical formulation. Volumetric Sievert test has shown that the alloy could store 1%wt percent hydrogen at room temperature. Electrochemical analysis with Evium-Stat has shown that the energy density which the alloy can reversibly deliver is about 150 mAh/g.

In this research, nanostructured cobalt oxide and nickel cobalt oxide active materials were successfully synthesized by a hydrothermal route. Structural characterizations of the prepared active materials were performed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and elemental analysis (EDS). The results of these experiments showed that nickel has been successfully doped in the cobalt oxide spinel structure. Also, the microscopic examination showed the nano-rod morphology for the cobalt oxide and nickel cobalt oxide, which yields the high specific surface area for electrochemical reactions, leading to increase energy storage capacitance. Energy storage performance of the prepared active materials was investigated using electrochemical experiments of cyclic voltammetry and galvanostatic charge-discharge in a solution of 6 M KOH in Swagelok standard cell. The specific capacitance of nickel containing cobalt oxide sample (1624 F g-1) was obtained higher than that of cobalt oxide (1020 F g-1) at a current density of 2 A g-1.

In this study, two- and three-dimensional polyester fabrics were coated with nickel via electroless plating method in order to produce X-band radar absorbing coatings. Morphology, thickness, coating composition, conductivity and radar absorption behavior of them were evaluated. After coating, the conduction of two- and three-dimensional fabrics was increased to 0.023 and 0.0043 cm2/?, respectively. Checking the morphology of the coatings by scanning electron microscopy showed that the nickel particles on the surface of fibers have the dome-shaped structures. Microstructure investigation of fabricated polyester coatings by X-ray spectral energy distribution showed that the amount of loaded nickel is 64.56%. The study of the radar absorption behavior of two- and three-dimensional coatings showed that the both of them can absorb more than 96.45% X-band radar waves (8-12 GHz). The investigation of the washing, rubbing and light fastness of fabricated coatings showed that electroless plating method can fix nickel on the surface of fibers well so that these coatings show high stability against these environmental factors.