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

In this study, a copper-silicon carbide composite consisting of SiC particulate with an average size of 7 micrometers was produced using the electroforming method. An acidic electrolyte bath containing sulfuric acid and copper sulfate with a concentration of 5 g/L was used at a temperature range of 23 to 25 degrees Celsius, and a mechanical stirrer with a speed of 250 rpm was used to prepare the samples. Silicon carbide powder was added to the bath at different concentrations between 15 to 45 g/L. The composite samples were produced after 12 hours at an optimal current density of 5.6 A/dm2 and then were examined for the amount of SiC entered into the composite matrix, microstructure, and morphology using SEM. To determine the corrosion behavior properties of the produced composites, potentiodynamic testing and electrochemical impedance spectroscopy were used. The results showed that the highest volume percentage of SiC entered into the composite sample was 30% at a concentration of 35 g/L. The corrosion resistance of the composite samples increased with an increase in SiC percentage, and protective layers were formed on the surface to prevent corrosion.

In the present work we report the development of carbon nanotube reinforced copper-zinc alloy nanocomposites. The carbon nanotubes were used in both uncoated and nickel coated conditions to reinforce copper matrix. The nanocomposites with different carbon nanotubes (0.25 to 1.0) weight percentage were developed using a combination of ultrasonication, ball milling and sintering processes. The developed nanocomposites were subjected to microstructural characterization using scanning and transmission electron microscopes to observe the dispersion of carbon nanotubes. The effect of carbon nanotubes on friction and wear properties of copper nanocomposites were studied using pin on disc testing rig as per ASTM G99 standard. The coefficient of friction of both 1 wt% uncoated and nickel coated carbon nanotubes reinforced nanocomposites was found when compared to copper-zinc alloy. Similarly the wear rate of nanocomposites were found to decrease with the incoporation of carbon nanotubes. The low coefficient of friction and wear rate were attributed to uniform dispersion of carbon nanotubes and formation of carbonaceous layer on the surface of nanocomposites during dry sliding wear.

In this research, Cu/Ag core-shell nanoparticles were synthesized by laser ablation in liquid using a nanosecond Nd:YAG laser. The synthesis of Cu/Ag core-shell nanoparticles by the laser ablation in liquid method was done in a single step by setting the process parameters at 450 mj/pulse energy, 1064 nm wavelength, 3 Hz frequency and 6 mm/s scanning speed in an acetone environment. Characterization of the synthesized nanoparticles using ultraviolet visible spectroscopy (UV-Vis), atomic absorption spectroscopy (AAS), dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD) were performed. The investigations confirmed that CACS nanoparticles had nanometric size, spherical morphology, and core-shell structure of pure copper/silver.

In this research, transparent multi-layer graphene nanocoating was used to protect copper against oxidation at low temperature and the role of this coating on maintaining brightness and preventing copper color change was evaluated. For this purpose, multilayer graphene coatings were applied on copper substrate using chemical vapor deposition (CVD). The multilayer graphene coating before and after the oxidation test was characterized using Raman analysis, optical and scanning electron microscopes. In addition, the color changes in the CIE-L*a*b* color space and the reflectance percentage in the range of the visible spectrum were studied. The results showed that the transparent multilayer graphene coating can maintain the appearance properties of copper after thermal oxidation for up to 4 hours. The results of the present research show that the multilayer graphene coating is effective in protecting the oxidation and as a result maintaining the color of copper. In addition, the results of this research showed that graphene oxidation starts and spreads from the defects and graphene grains boundaries.

After the discovery of carbon nanotubes, observations showed that carbon nanotubes have multi-purpose properties and can be used as a reinforcing material for metal nanocomposites. In this research, multi-walled carbon nanotubes have been used as nanocomposite reinforcement with Cu-5Zn alloy base. Carbon nanotubes were added to the nanocomposite in percentages of 0.25-1. Ultrasonic waves were used for good dispersion of carbon nanotubes in the field. Pressing and sintering processes were used to make nanocomposite samples. The microstructure was studied using a scanning electron microscope. The effect of carbon nanotubes on mechanical properties such as microhardness and tensile strength of nanocomposite was investigated. The results showed that the mechanical properties are improved by adding carbon nanotubes. The proposed mechanism for increasing the strength in nanocomposites reinforced with carbon nanotubes is the bridging mechanism. The microhardness of nanocomposites increases linearly with the increase of carbon nanotubes up to 0.75%, and the increase in hardness of nanocomposite with carbon nanotube reinforcing phase is 36% more than copper-zinc base alloy. The tensile strength of copper nanocomposites is 289 MPa by increasing the amount of carbon nanotube reinforcement, which is a significant increase compared to the base copper-zinc alloy with a strength of 165 MPa.

In this research, friction stir welding of aluminum 1050 to copper with variable speed was investigated. For friction stir welding, rotational speeds of 900 and 1200 rpm and traverse speeds of 36, 63, and 125 mm/min were used. In order to check the phases and microstructure, scanning electron microscope analysis, X-ray spectrometry, and hardness testing were used. The disturbance zone included Al2Cu3, Al4Cu9, AlCu4, Al2Cu, and AlCu phases. The results showed that the formation of intermetallic phases and severe plastic deformation in the welding area caused an increase in hardness. The highest hardness value in the stirred area was 97.8 Vickers at a rotation speed of 900 rpm and an advance speed of 36 mm/min.

The FSP is a method for solid state processing of metal alloys. FP4M milling machine and non-consumable rotary-tools were used to create the necessary heat and further mix copper with titanium-dioxide powder. The base plate is made of copper with a purity of 99.9%. The heat created during the process on the copper piece and the titanium-dioxide nanoparticles in the groove leads to metallurgical changes in the microstructure of the base metal and leads to changes in the size and shape of the grains. The samples were subjected to metallography and microstructure investigations by OP, XRD, corrosion and wear tests. The results show that in the HAZ area, the grains were in the form of a fine grain structure of copper solid solution, containing twin regions with an average grain size of 14, but in the process area, the grains were formed as a distorted and disturbed structure of copper solid solution. The average friction coefficient in the base copper wear diagram is less than one. By matching with the corrosion graph, the base copper sample has better corrosion resistance.

Nano copper powder is prepared by various methods, which can be mentioned as chemical regeneration, evaporation-deposition, plasma, chemical mechanical, electric explosion, electrolytic deposition and liquid metal atomization methods. Among these, the electrolytic method is more ideal due to the simplicity of the process, low energy consumption, high efficiency, easy control, and low environmental pollution. In this research, the role of electrode material and protective concentration in the electrochemical synthesis of copper nanoparticles was investigated.

constant current density and temperature equal to 0.04 A/cm2 and 50 C° and the distance between cathode and anode 2.5 cm were considered as research constants. Research variables included copper, gold, steel and rubidium cathode electrodes as well as CTAB protective concentration

. The results showed that smaller crystals can be obtained with copper and gold cathodes. XRD analysis showed that the best purity of copper nanoparticles is obtained by copper cathode. SEM results showed that the gold cathode leads to the formation of spherical and non-cubic particles; and the copper cathode caused the formation of cubic particles. By increasing the amount of CTAB, the purity of copper increased and the growth of copper nanoparticles was effectively prevented. The crystallinity index is more than one and the copper metal is polycrystalline.

Copper has long been widely used by humans and due to its properties, such as excellent ductility, high thermal conductivity, antimicrobial properties, and also the highest electrical conductivity after silver, it has gained this high position of consumption. This metal has been used in cases such as power transmission wires, copper pipes, laboratory equipment, electromagnetic motors, kitchen utensils, extensive alloying with gold, etc. This study investigated the corrosion behavior of copper metal in a solution of 1.0 M HCl and the inhibitory effect of Silybum marianum oil (SMO). The test method is that the corrosion behavior of copper in a solution of 1.0 M HCl was first measured using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests. one and two gr of SMO were measured in liters. The results show that according to the potentiodynamic polarization diagrams and electrochemical impedance spectroscopy of the sample a solution containing one gr of SMO in one liter of 1.0 M HCl solution has higher corrosion resistance and higher corrosion potential and lower corrosion current density than the solution. It is oil-free. Also, the sample in a solution containing 2 g of SMO in one liter of 1.0 M HCl solution has much better corrosion resistance, lower corrosion rate, and more noble behavior. Therefore, it can be concluded that SMO as a green inhibitor has an acceptable inhibitory effect on the copper piece in the solution, and with increasing the amount of oil, the inhibition increases.

In this study, the effect of copper addition on the microstructure of the 410s stainless steel was investigated by means of scanning electron microscopy which was equipped with energy dispersive X-ray spectroscopy (EDS). Also the phase equilibria and the phase fractions at 1000℃ were calculated using the software package MatCalc version 6.00. The samples were solution annealed at 1000℃ and quenched in oil. According to the results of thermodynamic calculations and scanning electron microscopy images, dual-phase steel with microstructure including ferrite and martensite was formed. It was found that by increasing the amount of copper in the chemical composition of steel, the weight fraction of the ferrite phase in the microstructure decreases remarkably. The phase fraction of ferrite decreases with increasing copper content in agreement with the thermodynamic calculations. The addition of about 5 wt.% copper eliminated the ferrite phase and led to a fully martensite microstructure in the quenched samples.

Cu-substituted 58S bioactive glasses (0-10%mol CuO) were synthesized by sol-gel method and the effect of copper substitution for calcium on their biodegradability, bone-like apatite formation, cell proliferation, alkaline phosphatase activity of M3T3-E1 osteoblast cells and antibacterial efficiency were investigated. The results of x-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) and surface analysis using SEM confirmed the formation of a layer of bone-like apatite on the BGs after 7 days of immersion in SBF. The surface analysis with SEM indicated that the addition of copper to the structure led to a reduction of the amount of apatite formed on the surface. The evaluation of cellular response by MTT assay and alkaline phosphatase activity showed that the proliferation and differentiation of MC3T3-E1 cells in 58S BG substituted with 5 mol% CuO had the highest value compared to other samples while, the substitution of 10 mol% CuO in composition led to a reduction in cell proliferation and differentiation and induction of cell cytotoxicity. In addition, Cu-substituted glasses showed significant antibacterial effect against Escherchia coli (E.coli) and Staphylococcus aureus (S.aureus) bacteria so that the antibacterial activity coefficient against E.coli in 58S containing 5 mol% CuO has doubled compared to base glass and was more than 99% (p<0.01). Taken together, 58S glass containing 5% mol CuO has been recommended for use in repair of bone defects in tissue engineering due to its in vitro bioactivity, stimulation of MC3T3-E1 cell proliferation and differentiation and excellent antibacterial activity.

The results showed that the microhardness and tensile strength of the heat-affected zone as the weakest welding zone in some samples reduced up to 30% compared to the base metal. On the other hand, a decrease in rotational speed, an increase in tool movement speed, and the number of welding passes cause grain refinement and improve mechanical properties. However, the effect of decreasing the rotation speed and increasing the tool movement speed were shown to be more favorable due to less heat production. Accordingly, the hardness in the welded zone with a rotational speed of 600 rpm and a movement of 80 mm/min increased from 90 to 125 HV  compared to the base metal, and the hardness reduction in the zones around the welded zone was only 5 Vickers. It was also found that reducing the grain size of the stir zone, while improving the mechanical properties leads to increasing the density of the surface pasive layer, preventing the attack of aggressive chlorine ions and thus reducing the corrosion intensity by 50 times in saline seawater.

In-situ Al-15Mg2Si composite due to their low density and good strength and wear properties are considered as potential candidates to substitute the Al and cast iron parts used in automotive and aerospace industries. The improved properties of these composites are governed by controlling the size and morphology (modification) of the primary Mg2Si particles. In the current study the effect of Cu addition (1.0, 3.0, and 5.0 wt. %) on metallurgical structure and quality index of Al-15Mg2Si composite was investigated. According to the results, Cu addition modified the morphology and reduced the average size of primary Mg2Si particles. The addition of Cu up to 3.0 wt. % improved the composite tensile strength by up to 34% whilst its further addition impaired the tensile properties. Moreover, the addition of Cu up to 1.0 wt. % improved the composite elongation by about 7%. This is while its further addition deteriorated the composite ductility. The maximum quality index was observed in 3.0 wt. % Cu containing composite where its quality index was 8% higher than that of the base sample. The microstructural observations, micro-hardness testing, precipitates chemical analysis, and fractography of fractured surfaces revealed that solid-solution-strengthening, dispersion hardening of Cu-containing precipitates, and modification of Mg2Si particles are the main factors improving the composite quality. Moreover, increasing the volume fraction of hard Cu-precipitates and micro-pores, negatively affected the composite tensile properties and quality index.

In this paper, the effective parameters on bioleaching of copper from low grade copper-sulfide ore from Shahrbabak copper complex were investigated using design of experiments. Mesophelic bacteria of A. ferrooxidans (T.f) and A. thiooxidans (T.t) were used. A two-factorial methodology was used to find the effective parameters. Response surface methodology was applied to optimize the leaching of copper. The individual effects and possible interactions of pulp density, percent of T.t bacteria and amount of Fe on the bioleaching of copper were investigated. The optimum conditions were determined using statistical analysis and analysis of variance (ANOVA). The optimum conditions for the copper recovery of 99.4% were pulp density of 7.55 g/mL, 80% of T.t bacteria and 20 g/L of Fe. Also, the most effective factor for the copper recovery was the percent of T.t bacteria. Furthermore, the statistical analysis indicates that the model fits the experimental data well.

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.

Improvement of copper surface properties, such as wear resistance and corrosion resistance, increases the application of this metal in various industries .For this purpose, Inconnell 625 alloy was coated with Gas Tangsten Arc Welding (GTAW) on copper. Phase analysis and solidification behavior of coating were performed using X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the coating structure contains the γ phase, with the secondary products of niobiumrich. Due to the full solubility of nickel and copper in solid state, it was observed that the region created between the coating and the substrate has a chemical composition of Cu-24.26 Ni-9.31 Cr-5.77 Mo and is free from metallurgical defects. The microhardness of sunstrate and coating was measured 50 and 338 vickers, respectively. In order to investigate the wear behavior of the coating and the substrate, the pin on disk test was used at ambient temperature. The wear surfaces produced at ambient tempreture characterised at micro-scale level using SEM and EDS. The presence of coating increased wear resistance of about 85%, which can be attributed to the change in the wear mechanism from delamination wear (related to copper) to oxidation wear (related to inconell 625). The oxide layer formed from the wear pair, in addition to reducing the wear rate, reduced the friction range from about 0.2 - 1.5 (related to copper) to 0.3 - 0.8 (for inconell 625). The study corrosion property of coating and substrate was also done by polarization test. The results showed a significant increase corrosion resistance of copper in the presence of this coating and corrosion current decreased from 239 nA/cm2 to 0.27 nA/cm2 .

In this research, the effect of the amount of strain and rolling temperature on the microstructure and the hardness of the explosively bonded 304 stainless steel- copper sheets were investigated. Explosive welding was performed using two explosive thickness of 46 and 79 mm with a stand-off distance of 2 and 3 mm. The results of the optical microscope after welding showed that all samples had a common wavy interface. The results of scanning electron microscopy and EDS analysis showed that in all samples the melting region was observed in the joint. The results of micro-hardness tests showed that the most hardness in interface was the sample with the highest thickness of the explosive and the stand-off distance. Rolling operations were carried out with a thickness reduction of 2 mm in two different conditions without preheating and preheating at 300 ℃ and 30 minutes. The results of the optical microscopy after rolling showed that in all cases after rolling, a decrease in the amplitude of the waves (wavelength thickness) was created. The results of the scanning electron microscopy and EDS analysis in the post-rolling and pre-heat conditions indicated that as a result of pre-heat before rolling operation, the copper and iron elements diffused from the interface of copper melting-metal region. Investigating the results of post-rolling non-treating samples showed that hardness after rolling in all samples increased. But in pre-heated samples, the hardness was less than that of as-welded samples.

In this study, metallurgical properties lap joint of pure copper and 6065 aluminum alloy with friction stir welding technique were investigated. To purpose the metallurgical properties of joint optical microscopy, X-ray diffraction analysis (XRD), energy dispersive X-ray (EDS) and Vickers hardness junction of micro gauge were used. The results shows that due to the direct contact between aluminum alloy and tool shoulder, the microstructure change of AA6065 was more than copper. With increasing tool rotation speed the microstructure size of AA6065 and copper became smaller and with increasing linear speed and cooling rate, the microstructure size of base material became more. The results shows that the structured layers were formed in stir zone which with increasing heat generation they geometry became thinner and stretcher. The combination of base materials in high tool rotation and low travelling speed caused the CuAl2 and Cu9Al4 intermetallic compounds were formed in base metal interface. For changes in microstructure size and formation of intermetallic compounds, the hardness of stir zone was more than other area of joint. The maximum hardness of joint area was 111 Vickers which allocated to the joint that welded with 1130 rpm and 24mm/min tool speed.