Influence Of Cu Content Research Articles

Mechanical, corrosion and antibacterial properties of Ti-13Nb-13Zr-based alloys with various Cu contents

The development of Ti-based alloys with antibacterial properties and a low elastic modulus has become a major focus in recent years in metallic biomaterials. In this paper, the influences of Cu content on the microstructure, mechanical properties, corrosion resistance and antibacterial properties of Ti-13Nb-13Zr-xCu alloys were systematically discussed. The results showed that the Ti-13Nb-13Zr-xCu alloys were mainly composed of β-Ti, α-Ti, and Cu-containing phases (Ti2Cu, Cu10Zr7 and CuZr). Compared with the Ti-13Nb-13Zr alloy, the compressive strength and yield strength of the Ti-13Nb-13Zr-xCu alloys increased with increasing Cu content, but the elastic modulus decreased. The Ti-13Nb-13Zr-10Cu alloy exhibited high strength and low elastic modulus. The electrochemical experiments showed that the corrosion current density (Icorr) displayed a decreasing trend. The Ti-13Nb-13Zr-10Cu alloy had the lowest corrosion current (1.23 μA cm−2) and passivation current density (2.47 μA cm−2), indicating excellent corrosion resistance. Antibacterial tests showed that the antibacterial rate of the Ti-13Nb-13Zr-xCu alloy with 10 and 13% Cu content against S. aureus and E. coli were over 99.0%. Therefore, it could be deduced that the Ti-13Nb-13Zr-10Cu alloy with excellent mechnical and antibacterial properties had the potential for biomedical applications.

CrCuFeMnNi high-entropy alloys for semisolid processing: The effect of copper on phase formation, melting behavior, and semisolid microstructure

High-entropy alloys containing Cu can lead to the formation of phases with lower melting temperatures and large solidification intervals, making them potential candidates for semisolid processing. Accordingly, in this study we aimed to investigate the influence of Cu content on the phase formation, melting behavior, and semisolid microstructure of CrCuFeMnNi alloys. Ingots with varying CrCu x FeMnNi compositions (x = 0, 0.5, 1, 1.5, 2, and 2.5) were arc-melted, cross-rolled, heated to reach the semisolid state, and water-quenched. Microstructural characterization involved scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The CrCuFeMnNi alloys were composed of one BCC phase, rich in Cr, and two FCC phases, one rich in Cu (FCC1) and the other with a more balanced composition (FCC2). The melting of the CrCuFeMnNi alloys was characterized by three thermal events, which corresponded to the melting of each phase. The solidification interval increased with the Cu content, and it was found that the studied alloys could be processed in the semisolid state at temperatures below 1100 °C. Therefore, the cross-rolled samples were isothermally heat-treated at 1080 °C for 300 s, resulting in globular microstructures. The chemical composition of the phases was modified after semisolid treatment as compared to the as-cast condition. The fraction of the BCC phase in the quenched microstructures did not change with the alloy composition; in contrast, the fraction of FCC1 increased, whereas that of FCC2 decreased with increasing Cu content. • The CrCuFeMnNi alloys were formed by three phases: one BCC and two FCC. • The CrCuFeMnNi alloys exhibited the same melting behavior. • The globularization process was efficient for all compositions. • The BCC fraction was the same regardless the alloy composition. • The FCC1 fraction increased and the FCC2 fraction decreased with Cu content.

Influence of Cu content on the microstructure and high-temperature tensile and fatigue properties of secondary AlSi7Mg0.3VZr alloys

The effect of Cu content on the microstructure and high-temperature tensile and fatigue behaviours of heat-treated secondary AlSi7Mg0.3VZr alloys were evaluated. Thermodynamic calculations based on the CALPHAD method were carried out to evaluate the formation of different phases. Tensile and fatigue tests were performed at room temperature and high temperature (300 °C) on alloys that were solution treated at 485 °C for 24 h and artificially aged at 180 °C for 8 h. The results show that the addition of Cu significantly improved the room temperature tensile properties at the expense of ductility, thus decreasing the fatigue behaviour at lower stress amplitudes. At 300 °C, Cu-bearing precipitates were responsible for the AlSi7Cu3Mg0.3VZr alloy having a better thermal stability than the AlSi7Mg0.3VZr alloy, leading to higher tensile and fatigue properties. After increasing the testing temperature, the effect of casting defects on fatigue crack propagation decreased, thus reducing the scattering of data independently of the Cu content. The fatigue failure mode changed from brittle to ductile at 300 °C for both alloys.

Influence of Cu Content on Structure, Thermal Stability and Magnetic Properties in Fe72-xNi8Nb4CuxSi2B14 Alloys.

The effect of substitution of Fe by Cu on the crystal structure and magnetic properties of Fe72−xNi8Nb4CuxSi2B14 alloys (x = 0.6, 1.1, 1.6 at.%) in the form of ribbons was investigated. The chemical composition of the materials was established on the basis of the calculated minima of thermodynamic parameters: Gibbs free energy of amorphous phase formation ΔGamorph (minimum at 0.6 at.% of Cu) and Gibbs free energy of mixing ΔGmix (minimum at 1.6 at.% of Cu). The characteristic crystallization temperatures Tx1onset and Tx1 of the alpha-iron phase together with the activation energy Ea for the as-spun samples were determined by differential scanning calorimetry (DSC) with a heating rate of 10–100 °C/min. In order to determine the optimal soft magnetic properties, the wound cores were subjected to a controlled isothermal annealing process in the temperature range of 340–640 °C for 20 min. Coercivity Hc, saturation induction Bs and core power losses at B = 1 T and frequency f = 50 Hz P10/50 were determined for all samples. Moreover, for the samples with the lowest Hc and P10/50, the magnetic losses were determined in a wider frequency range 50 Hz–400 kHz. The real and imaginary parts of the magnetic permeability µ′, µ″ along with the cut-off frequency were determined for the samples annealed at 360, 460, and 560 °C. The best soft magnetic properties (i.e., the lowest value of Hc and P10/50) were observed for samples annealed at 460 °C, with Hc = 4.88–5.69 A/m, Bs = 1.18–1.24 T, P10/50 = 0.072–0.084 W/kg, µ′ = 8350–10,630 and cutoff frequency at 8–9.3 × 104 Hz. The structural study of as-spun and annealed ribbons was carried out using X-ray diffraction (XRD) and a transmission electron microscope (TEM).

Influence of Cu Content on the Negative Effect of Natural Aging in SiC/Al-Mg-Si-Cu Composites

Influence of Cu Content on the Negative Effect of Natural Aging in SiC/Al-Mg-Si-Cu Composites

Effects of partial substitution of Cu for Co on the microstructure and properties of WC-Co-Mo cemented carbides

In this work, Co–Cu metals were used as binder phase of cemented carbides. The influence of Cu content (0.8, 1.2, 1.6, and 2.0 wt%) on microstructure and properties of WC-Co-Cu-Mo alloys was discussed compared with WC-Co and WC-Co-Mo alloys. The results showed that the relative density, hardness, and transverse rupture strength of WC-Co alloys were significantly improved, and the WC average size, wear rate and corrosion resistance were greatly decreased by adding 1.2 wt% Cu. Among them, the hardness and density of WC-Co alloy increased from 1713 HV30 and 98.83% to 1908 HV30 and 99.31%, respectively. The average WC grain size and the corrosion rate of WC-Co alloy under HCl solution decreased from 0.68 μm and 303.23 μA cm−2 to 0.53 μm and 27.32 μA cm−2, respectively. These phenomena indicated that the doping of proper Cu into WC-Co-Mo alloys could enhance the comprehensive performance of WC-Co alloy.

Stepwise methane to methanol conversion: Effect of copper loading on the formation of active species in copper-exchanged mordenite

This work investigates the influences of Cu content, Si/Al ratio, and sample preparation method on the active Cu species in mordenite (MOR). The Cu/MOR prepared by multiple Cu-exchange procedures showed an optimum Cu/Al ratio for the formation of the most active species for methanol formation. XANES spectra indicated that isolated Cu+ species were formed after CH4 interaction and were re-oxidized under a flow of water steam. The Cu-MOR samples obtained by ion-exchange method presented well-dispersed CuO in the zeolite pores, while samples obtained by impregnation method presented segregated CuO and were inactive for CH4 activation. The methodology used for in situ UV–vis spectra analyses indicated that different Cu species were active for CH4 oxidation. Isolated Cu2+ species were not involved in CH4 activation at temperatures lower than 300 °C. The isolated Cu2+ species were partially hydrolyzed by O2 treatment and species like [CuOH]+ and [CuOx]n or polynuclear Cu2+-oxyhydroxide were formed. The formation of polynuclear species in substitution of di-copper would impact the specific activity with the Cu content and decrease the activity for methanol production.

Unveiling the impact of Cu content on the physical properties and photovoltaic performance of solution‐processed Cu(In,Ga)Se2solar cell absorber

Cu/Ga + In (CGI) ratio in Cu(In,Ga)Se2 (CIGSe) semiconductor plays a decisive role in solar energy conversion. Investigations published so far relevant to CIGSe at different CGI values are solely based on the expensive vacuum process and as a result, there is a strong urge to explore a low-cost process. In this regard, we herein report the preparation of CIGSe at diverse CGI value from 0.70 to 0.97 by a facile and cost-effective solution process for the first time. From structural analysis, the blue shift is perceived by decreasing CGI value, which is related to shrinkage in the unit cell volume because of the reduction in the Cu content. As CGI value increases, crystal diameter of CIGSe vastly changed from nano to micro (50-1300 nm), whereas crystal shape reformed from irregular to hexagonal flake-like shape, which could be due to excessive influence of Cu content that alters nucleation and growth of crystals. Diverse CGI value modified Se/(Cu + In + Ga) ratio while Ga/(Ga + In) ratio remains unchanged. Bandgap energy is increased from 1.22 to 1.41 eV as Cu-deficiency increases. The morphological analysis showed a uniform, smooth and crack-free CIGSe films with a thickness of ~1 μm. The electrical properties of CIGSe are greatly changed. For instance, at higher CGI value (0.97), the carrier concentration is increased by five-order magnitude, whereas mobility improved by 109 times and resistivity decreased by 87 times as compared to lower CGI value (0.70). Moreover, photocurrent is markedly enhanced by six-order magnitude explicitly from nA to mA. As a proof of concept, solar cells are fabricated and power conversion efficiency significantly enhanced from 0.16% to 3.38% by altering CGI value. Hence, this work eminently evidences the importance of tuning CGI value by low-cost solution process and provides new perceptions into properties of CIGSe solar cell absorber as a function of CGI value.

Mechanical properties and oxidation resistance of Sn-Zn-xCu (2.3 ≤ x ≤ 20.2) solder alloys prepared by high-throughput strategy

Sn-Zn-Cu solder alloys are predominantly developed through a sequential and time-consuming trial-and-error approach. Here, it is presented that Cu-doped Sn-Zn-based solder alloy thin films can be fabricated by high-throughput strategy. The influence of Cu content on the phase constitution, mechanical properties and oxidation resistance of the Sn-Zn-Cu thin films was investigated in detail. The highest Young’s modulus of the film can be obtained with the addition of 2.3 wt% Cu. Superior oxidation resistance is expected to be acquired with low Cu content. Our results demonstrate that the combination of multiple target co-sputtering deposition is an effective way for rapidly developing lead-free solder.

Influence of Cu content on the physical characteristics of CuxGaCr0.1S2 thin films for intermediate band solar cells

Intermediate band semiconductors can increase the efficiency of photovoltaic solar cells via sequential absorption of photons in a wider range of the solar spectrum. The introduction of Cr substituting Ga atoms in the chalcopyrite CuGaS2 is proposed to create a suitable intermediate band, investigating the influence of the Cu/Ga ratio on the structural, morphological, optical, and electrical characteristics. For this purpose, CuxGaS2 and CuxGaCr0.1S2 thin films (with x ranging from 0.8 to 1.2) are prepared by modulated evaporation from elemental sources and analyzed comparatively by X-ray diffraction, Raman spectroscopy, atomic force microscopy, spectrophotometry, and Hall effect measurements. The incorporation of Cr produces an in-gap absorption that is independent of the Cu/Ga ratio. The mean crystallite size, surface roughness, and electrical conductivity increase with the Cu content in both CuxGaS2 and CuxGaCr0.1S2.

Influence of copper doping on structural, morphological, optical, and vibrational properties of ZnO nanoparticles synthesized by sol gel method

Cu-doped ZnO nanocrystals (with 0, 0.5, 1.0, 1.5, and 2.0 at.% Cu) have been successfully synthesized by a sol-gel method. The influence of Cu content on the properties of ZnO nanoparticles have been studied by various characterization techniques. XRD analysis reveals the formation of hexagonal wurtzite structure in all samples, confirming the incorporation of Cu ions into the ZnO lattice. The crystallite size and unit cell volume are modified with the Cu content. Morphology characterization by SEM and HRTEM revealed that Cu-doped samples consist of mixture of nanoparticles and nanowires. The energy band gap of the samples was red shift due to Cu incorporation in the ZnO lattice. The PL emission intensity of the Cu-doped samples decreases with increasing Cu content. Vibrational spectroscopy confirms metal oxide bond formation and reveals stress present in the samples. Under visible light illumination, the photocatalytic performance of all samples was studied by using methylene blue as a model molecule.

Effects of Cu content on crystallization behavior, mechanical and soft magnetic properties of Fe80-xCuxP13C7 bulk metallic glasses

Bulk Fe80-xCuxP13C7 (x = 0, 0.1, 0.3 and 0.6 at.%) amorphous alloys were successfully fabricated utilizing the combining fluxing treatment and J-quenching technique. The influence of Cu content on the crystallization characteristic temperatures and primary crystallization phase evolution, glass formation ability, mechanical and soft magnetic properties of Fe-Cu-C-P BMGs have been systematically investigated. Additionally, the proper addition of Cu content can significantly improve the compression plasticity of present Fe-Cu-C-P bulk glassy alloys, and the Fe79.4Cu0.6P13C7 bulk glassy rod exhibits an excellent plasticity of 5% as well as a high fracture strength (over 2700 MPa). Then, the multiple effects of annealed Fe80-xCuxP13C7 BMGs on mechanical properties and soft magnetic property have been investigated. More importantly, Fe79.4Cu0.6P13C7 BMG annealed at Tg-30 K for half an hour exhibits excellent soft magnetic properties with relatively high saturation magnetization of 1.5 T, and mechanical properties with the fracture strength of 3280 MPa and plastic strain of 4%.

Influence of Cu Content on Structure and Magnetic Properties in Fe86-xCuxB14 Alloys.

Influence of Cu content on thermodynamic parameters (configurational entropy, Gibbs free energy of mixing, Gibbs free energy of amorphous phase formation), crystallization kinetics, structure and magnetic properties of Fe86-xCuxB14 (x = 0, 0.4, 0.55, 0.7, 1) alloys is investigated. The chemical composition has been optimized using a thermodynamic approach to obtain a minimum of Gibbs free energy of amorphous phase formation (minimum at 0.55 at.% of Cu). By using differential scanning calorimetry method the crystallization kinetics of amorphous melt-spun ribbons was analyzed. It was found that the average activation energy of α-Fe phase crystallization is in the range from 201.8 to 228.74 kJ/mol for studied samples. In order to obtain the lowest power core loss values, the isothermal annealing process was optimized in the temperature range from 260 °C to 400 °C. Materials annealed at optimal temperature had power core losses at 1 T/50 Hz—0.13–0.25 W/kg, magnetic saturation—1.47–1.6 T and coercivity—9.71–13.1 A/m. These samples were characterized by the amorphous structure with small amount of α-Fe nanocrystallites. The studies of complex permeability allowed to determine a minimum of both permeability values at 0.55 at.% of Cu. At the end of this work a correlation between thermodynamic parameters and kinetics, structure and magnetic properties were described.

Novel polyethersulfone ultrafiltration membranes modified with Cu/titanate nanotubes

The influence of addition of titanate nanotubes modified with copper (Cu/TNTs) on the physicochemical, antifouling and antibacterial properties of polyethersulfone (PES) membranes obtained under various conditions is presented. The effect of polymer concentration (15 and 16 wt%) in casting dope and temperature of coagulation bath (10 and 20 °C) was investigated. Furthermore, the influence of Cu content in the Cu/TNTs (1.86 vs 12.23 wt%) on the properties of the membranes was evaluated. The physicochemical characterization of the membranes was based on scanning electron microscopy, atomic force microscopy, isoelectric point and contact angle measurements. The permeability of the mixed matrix membranes was higher compared to the neat ones, and the improvement was the most significant for 15 wt% PES content in the casting dope and Cu/TNTs with higher Cu loading. On the opposite, the best antifouling performance exhibited the membranes characterized by the lowest pure water flux (16 % PES, 10 °C) and a lower Cu content. The addition of Cu/TNTs improved the antibacterial activity of the membranes. The inhibition of the growth of Staphylococcus epidermidis was depended on the kind of Cu/TNTs used, while no significant influence in case of Escherichia coli was observed.

INFLUENCE OF Cu CONTENT ON PREFERRED ORIENTATION AND PROPERTIES OF CrCuN COATINGS

CrCuN coatings were deposited using double target co sputtering by DC pulsed magnetron reactive sputtering. The Cu content increases from 0.7[Formula: see text]at.% to 5.5[Formula: see text]at.% with the increase of Cu target current from 0.08 to 0.24[Formula: see text]A. The influence of Cu content on preferred orientation and properties of CrCuN coatings was investigated. The results show that CrCuN coatings are mainly composed of CrN phase. Except for the coating containing 4.2[Formula: see text]at.% Cu, the other CrCuN coatings show CrN(111) preferred orientation. All the coatings have loose structure, which is chiefly responsible for unsatisfactory hardness. The oriented growth plays an important role in the change of coating hardness with Cu content.

Influence of Cu Content on Microstructure and Corrosion Behavior of Flux-Cored Arc-Welded Metal with 10CrNi3MoV Steel

Influence of Cu Content on Microstructure and Corrosion Behavior of Flux-Cored Arc-Welded Metal with 10CrNi3MoV Steel

Kinetic role of Cu content in reaction process, behavior and their relationship among Cu-Zr-C system

The influence of Cu content on the reaction process, reaction behavior and obtained products in the Cu-Zr-C system, as well as their relationships, were investigated. The results showed that ZrC was synthesized through the diffusion and dissolution of C into a Cu-Zr liquid. Increasing the Cu content enhanced the amount of Cu-Zr liquid formed at the early stage but decreased the amount of C atoms dissolving into the melt at unit time. Consequently, the ignition time initially decreased and then increased. Conversely, with an increased Cu content, the energy required for igniting the neighboring unreacted powders increased, while the heat released by the reaction and the dwell time of the compact at high temperatures decreased. These effects then resulted in the reduction of combustion wave velocity, combustion temperature and ZrC particle size. Furthermore, the synthesis of ZrC is a multistage process, which provides a nonuniform distributed ZrC particle size. The sub-μm ZrC particle reinforced Cu matrix composite was fabricated by adding a ZrC-Cu master alloy prepared through a self-propagating high-temperature synthesis reaction into liquid Cu.

Influences of Cu Content on the Microstructure and Strengthening Mechanisms of Al-Mg-Si-xCu Alloys

The effects of the Cu content on the microstructure and strengthening mechanisms of the Al-Mg-Si-xCu alloys were systematically investigated using scanning electron microscopy (SEM), electron probe microanalysis (EPMA), transmission electron microscopy (TEM), and mechanical tensile tests. The results show that, the strengthening mechanisms change with the Cu content. For as-quenched alloys, solution strengthening (σSS) is predominant when the Cu content ≥2.5 wt.%, and of equivalent importance as grain size strengthening (σH-P) when the Cu content ≤1.0 wt.%. With respect to peak-aged alloys, precipitation strengthening (σppt) is predominant when the Cu content ≥2.5 wt.%, but σSS becomes predominant when the Cu content is 4.5 wt.%. As the Cu content increases from 0.5 to 4.5 wt.%, the main type of precipitates in alloy tends to change from a β″ phase to Q′ phase, and then to a θ′ phase. Among the three types of precipitates, θ′-precipitate causes the largest increase in yield strength (σ0.2) and the largest decrease rate in elongation. β″-precipitate leads to the smallest increase in σ0.2 and the smallest decrease rate in elongation. The increase of Cu content reduces Si solubility in the Al matrix and thus decreases the nucleation rate of β″ phase during subsequent aging.

Combustion Synthesis of Non-Precious CuO-CeO₂ Nanocrystalline Catalysts with Enhanced Catalytic Activity for Methane Oxidation.

In this study, xCuO-CeO2 mixed oxide catalysts (Cu weight ratio x = 1.5, 3, 4.5, 6 and 15 wt.%) were prepared using solution combustion synthesis (SCS) and their catalytic activities towards the methane (CH4) oxidation reaction were studied. The combustion synthesis of the pure CeO2 and the CuO-CeO2 solid solution catalysts was performed using copper and/or cerium nitrate salt as an oxidizer and citric acid as a fuel. A variety of standard techniques, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were employed to reveal the microstructural, crystal, thermal and electronic properties that may affect the performance of CH4 oxidation. The CuO subphase was detected in the prepared solid solution and confirmed with XRD and Raman spectroscopy, as indicated by the XRD peaks at diffraction angles of 35.3° and 38.5° and the Ag Raman mode at 289 cm−1, which are characteristics of tenorite CuO. A profound influence of Cu content was evident, not only affecting the structural and electronic properties of the catalysts, but also the performance of catalysts in the CH4 oxidation. The presence of Cu in the CeO2 lattice obviously promoted its catalytic activity for CH4 catalytic oxidation. Among the prepared catalysts, the 6% CuO-CeO2 catalyst demonstrated the highest performance, with T50 = 502 °C and T80 = 556 °C, an activity that is associated with the availability of a fine porous structure and the enhanced surface area of this catalyst. The results demonstrate that nanocrystalline copper-ceria mixed oxide catalysts could serve as an inexpensive and active material for CH4 combustion.

The influence of Cu content on high temperature corrosion behavior of heat - resistant molten salt steel

This work studies the high temperature corrosion behavior of new heat-resistant steel with salt coating method of 75%Na2SO4+25%NaCl coating on the steel surface at 700℃. The chemical composition of corrosion products and surface morphology of the corrosion layer were analyzed using X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and investigate the effect of Cu content on high temperature corrosion behavior of heat resistant steel. The results show that the thermal corrosion kinetics curve of tested steel follows the parabolic law and the surface is composed of Fe2O3 and FeCr2O4. The corrosion layer were divided into two layers, the outer layer was loose and porous while the inner layer was dense and continuous. The structure of the oxide film consists of various protective oxide films; with increasing of Cu content, the high-temperature corrosion resistance of heat-resistant steel was improved and the thickness of the corrosion layer was decreased which led to improving the bonding strength between the inner layer and the matrix. The results of EDS analysis shows that Cu elements can promote the outward diffusion of Cr elements to oxidation of the steel to form a Cr2O3 protective oxide film for preventing the diffusion of chlorine elements, oxygen elements into the interior toward the steel with slow down the process of activation oxidation, reduce the sensitivity of intergranular corrosion and achieve the function of protecting materials. Keywords: Heat-resistant steel. Thermal corrosion. Molten salt. Corrosion layer.