Mixture Of Cu Powders Research Articles

Optimization of viscosity and composition of mixture of Cu powder and acrylate based resin for vat photopolymerization of metal components

Vat photopolymerization is a technique that uses photocurable resin having photoinitiator (PI) to initiate polymerization reaction when exposed to UV light. This process forms long chains polymers by combination of small chains monomers and oligomers. Vat photopolymerization depends on various parameters. This work focusses on the optimization of viscosity and composition of acrylate resin-Cu powder mixture for vat photopolymerization of metallic samples. Anycubic acrylate-based photopolymer resin and fine copper powder is used. Five configurations (50%Cu-50%resin, 55%Cu-45%resin, 60%Cu-40%resin, 65%Cu-35%resin & 70%Cu-30%resin) are formed to determine the highest possible density in each sample. These samples are then sintered in order to optimize the sintering parameters like debinding and sintering temperatures, oxygen and carbon contents. Then, the sample with maximum Cu density is used to optimize the viscosity of mixture using ethylene glycol as diluent. It is observed that ethylene glycol is useable as it effectively reduces the viscosity of resin without altering the chemical nature and curing time of photocurable resin. By equating the viscosity of optimized Cu-resin mixture with pure resin, difference in curing times is calculated for finite thickness of layer. This shows that 28% increase in curing time is observed when Cu-resin mixture is used as compared to pure resin. Sintering profile used is good in terms of debinding and sintering temperatures however hydrogen curing environment is essential to reduce carbon and oxygen contents in final samples.

Electrochemical Behavior of Mixed Cu Powder and LiCl/Li13In3-Coated Li Powder Anodes in Lithium Metal Secondary Batteries

A novel anode consisting of a mixture of Cu powder and LiCl/Li13In3-coated Li powder was developed and tested for use in Li metal secondary batteries (LMSBs). The aim was to improve the electrochemical performance as suppress dendrite formation and volume change on the Li metal electrode. A LiCl/Li13In3 composite film was deposited on the surface of Li powder particles using a facile liquid treatment method. The coated Li powder was mixed with Cu powder to produce a Li–Cu composite electrode (LCE) for LMSBs. It has been proven through scanning electron microscopy (SEM) and analysis of the coating layer using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and depth profile analysis that LiCl/Li13In3 has formed well on the surface of the Li powder. The coated LCE exhibited improved electrochemical properties in both the symmetric cell and full cell tests. Through electrochemical impedance spectroscopy (EIS) measurement, it has been determined that after 50 cycles, the impedance of the coated LCE is 98 Ω. In particular, even when a large amount of Li was used (40%, 1544 mAh g−1), it exhibited improved electrochemical behavior over 50 cycles in a symmetric cell test. In addition, in a full cell test with LiV3O8 as a cathode at a 2 C rate, the capacity retention was 96% after 50 cycles. SEM images showed that dendrite growth and volume change were suppressed by the novel electrode architecture.

Sampling the Cu–Fe–Co phase diagram by severe plastic deformation for enhanced soft magnetic properties

Initial powder mixtures of Cu, Fe and Co are exposed to severe plastic deformation by high-pressure torsion to prepare solid solutions. A broad range of compositions is investigated, whereas this study aims at the synthesis of soft magnetic materials and therefore at the formation of a homogeneous and nanocrystalline microstructure. For intermediate ferromagnetic contents, high-pressure torsion at room temperature yields single-phase supersaturated solid solutions. For higher ferromagnetic contents, two consecutive steps of high-pressure torsion deformation at different temperatures yield the desired nanocrystalline microstructure. Depending on the Co-to-Fe-ratio, either a single-phase supersaturated solid solution or a nanocomposite forms. The composite exhibits an enhanced magnetic moment, indicating the formation of a (Fe,Co)-alloy upon severe plastic deformation. Soft magnetic properties are verified for large Co-to-Fe-ratios and this microstructure is found to remain stable up to 400 °C.

High Performance Cu Matrix Nanocomposite Fabricated Through Spark Plasma Sintering of Cu and Cu-Coated CNT

In this paper, the effects of Cu coating of carbon nanotube (CNTs) as reinforcement on structural, microstructural, physical and mechanical properties of Cu–3 wt%CNT nanocomposite were investigated. CNTs were coated by Cu using the electroless technique for 1 and 2 h. Bulk nanocomposite samples were produced by spark plasma sintering of a mechanically milled powder mixture of Cu and CNT. Kinetic study showed a nucleation and growth mechanism for the Cu coating process. Microstructural characterization showed that the coated CNTs dispersed more homogeneously in the powder mixture. Results also revealed that 1 h coating of CNTs led to the higher relative density and thermal properties. The coating process increased 62 Brinell hardness (BHN) in hardness, 14% IACS in electrical conductivity for Cu–CNT nanocomposite. Transmission electron microscopy analysis showed a strong bonding between CNT and Cu matrix within the distinguishable interface. About 20 MPa increase in shear strength of nanocomposite was observed by 1 h coating of CNTs. Also, the fracture surfaces exhibit changes in the mode of fracture by well-bonded CNTs with the Cu matrix. The coefficient of thermal expansion and thermal distortion parameter revealed 12.7 ppm/k and 0.037 ppm.m/w for the sample including 1 h coated CNT, respectively.

Synthesis and Mechanical Characterization of a CuMoTaWV High-Entropy Film by Magnetron Sputtering.

Development of high-entropy alloy (HEA) films is a promising and cost-effective way to incorporate these materials of superior properties in harsh environments. In this work, a refractory high-entropy alloy (RHEA) film of equimolar CuMoTaWV was deposited on silicon and 304 stainless-steel substrates using DC-magnetron sputtering. A sputtering target was developed by partial sintering of an equimolar powder mixture of Cu, Mo, Ta, W, and V using spark plasma sintering. The target was used to sputter a nanocrystalline RHEA film with a thickness of ∼900 nm and an average grain size of 18 nm. X-ray diffraction of the film revealed a body-centered cubic solid solution with preferred orientation in the (110) directional plane. The nanocrystalline nature of the RHEA film resulted in a hardness of 19 ± 2.3 GPa and an elastic modulus of 259 ± 19.2 GPa. A high compressive strength of 10 ± 0.8 GPa was obtained in nanopillar compression due to solid solution hardening and grain boundary strengthening. The adhesion between the RHEA film and 304 stainless-steel substrates was increased on annealing. For the wear test against the E52100 alloy steel (Grade 25, 700–880 HV) at 1 N load, the RHEA film showed an average coefficient of friction (COF) and wear rate of 0.25 (RT) and 1.5 (300 °C), and 6.4 × 10–6 mm3/N m (RT) and 2.5 × 10–5 mm3/N m (300 °C), respectively. The COF was found to be 2 times lower at RT and wear rate 102 times lower at RT and 300 °C than those of 304 stainless steel. This study may lead to the processing of high-entropy alloy films for large-scale industrial applications.

Влияние лазерного легирования порошковыми смесями Cu–Zn–Ti и Si–Cu на структуру и свойства литейного алюминиевого сплава

Влияние лазерного легирования порошковыми смесями Cu–Zn–Ti и Si–Cu на структуру и свойства литейного алюминиевого сплава

Mechanochemical Activation of Cu–CeO2 Mixture as a Promising Technique for the Solid-State Synthesis of Catalysts for the Selective Oxidation of CO in the Presence of H2

A new ecologically clean method for the solid-phase synthesis of oxide copper–ceria catalysts with the use of the mechanochemical activation of a mixture of Cu powder (8 wt %) with CeO2 was developed. It was established that metallic copper was oxidized by oxygen from CeO2 in the course of mechanochemical activation. The intensity of a signal due to metallic Cu in the X-ray diffraction analysis spectra decreased with the duration of mechanochemical activation. The Cu1+, Cu2+, and Ce3+ ions were detected on the sample surface by X-ray photoelectron spectroscopy. The application of temperature-programmed reduction (TPR) made it possible to detect two active oxygen species in the reaction of CO oxidation in the regions of 190 and 210–220°C by a TPR-H2 method and in the regions of 150 and 180–190°C by a TPR-CO method. It is likely that the former species occurred in the catalytically active nanocomposite surface structures containing Cu–O–Ce bonds, whereas the latter occurred in the finely dispersed particles of CuO on the surface of CeO2. The maximum conversion of CO (98%, 165°C) reached by the mechanochemical activation of the sample for 60 min was almost the same as conversion on a supported CuO/CeO2 catalyst.

Fabrication of Unidirectionally Orientated Carbon Fiber Reinforced Cu-Based Composites by Hot Extrusion and Evaluation of Their Thermal Properties

Unidirectional orientation of the carbon fiber is essential in the fabrication of Cu-carbon fiber composites with high thermal conductivity, because the fiber exhibits its very high thermal conductivity only in the longitudinal direction. In this study, hot extrusion of a mixture of Cu powder and carbon fiber was applied to fabricate the unidirectionally orientated carbon fiber reinforced Cu-based composite and the effects of the volume fraction of carbon fiber on the thermal conductivity have been investigated. It has been demonstrated that hot extrusion of the Cu powder-carbon fiber mixture successfully align the fiber to orient along the extrusion direction, and consequently, the thermal conductivity in this direction increases with the volume fraction of carbon fiber. For the composite with more than 30 vol% carbon fiber, the application of ultrasonic vibration treatment to the powder-fiber mixture is effective for improving the homogeneity of the mixing and hence increasing the relative density and the thermal conductivity of the composite.

ChemInform Abstract: Synthesis and Characterization of Kesterite Cu2ZnSnTe4 via Ball‐Milling of Elemental Powder Precursors.

AbstractThe title compound is synthesized by ball‐milling of powder mixtures of Cu, Zn, Sn, and Te (planetary ball mill, 450 rpm, 30 h).

Copper matrix composites reinforced by aligned carbon nanotubes: Mechanical and tribological properties

The hardness, strength, and abrasion resistance of copper for electrical contact materials is poor. Thus, we aligned carbon nanotubes in Cu matrix composites through die-stretching for their excellent mechanical properties and abrasion resistance. The Cu matrix composites with varying CNTs volume fraction from 0 to 10vol.% were fabricated under protective atmosphere sintering of a mixture of Cu powders and Ni/Cu coated CNTs. This was followed by forging and die-stretching. The CNTs were uniformly dispersed in the dense composites, and the trend of their alignment along the stretching direction was obvious. The composites were anisotropic, and their mechanical properties and abrasion resistance increased obviously with the addition of CNTs. The 5vol.% CNTs/Cu composite showed the best hardness, tensile strength, and abrasion resistance. The mechanisms underlying the improved mechanical and tribological behavior were evaluated, and this research provides novel ideas and technology for the distribution and directional alignment of CNTs in the matrix.

Synthesis and Consolidation of Nano-Sized Cu Coated SiC Powders by a Chemical Method and Spark Plasma Sintering

Cu-70 vol% SIC composites with dense microstructure and sound interface between Cu and SIC grains were fabricated by solution chemistry route and spark plasma sintering. Two methods for developing powder mixtures of Cu and uncoated or pre-coated SIC were compared on the basis of the resulting microstructures. The pre-coating of Si(Al)OC onto SiC powders was prepared by curing and pyrolysis of Al-modified polycarbosilane. SiC/Cu composites were obtained by hydrogen reduction and densified using spark plasma sintering of pre-coated SIC and Cu-nitrate powder mixtures. The powder mixture showed a homogenous dispersion of nano-sized Cu particles on the surface of SIC powers. Microstructural observation revealed that the sintered composite using powder mixture with pre-coating of Al-PCS onto SiC powders showed dense microstructure and good contact between Cu and SIC grains due to the improved wettability by barrier coating. The results suggested that the SiC/Cu composite with required microstructural characteristics can be fabricated by using Al-PCS coated SIC powder mixture, more effectively.

Grain and nanoparticle coarsening of an ultrafine structured Cu–5 vol.%Al2O3 nanocomposite during isochronal annealing

Cu grain growth, Al2O3 nanoparticle coarsening and changes in microhardness of an ultrafine structured Cu–5vol.%Al2O3 nanocomposite during 1h isochronal annealing over a temperature range of 500–900°C were investigated. The material was produced using high energy mechanical milling of a mixture of Cu powder and Al2O3 nanoparticles followed by powder compact extrusion of the milled powder at 900°C. The grains of the ultrafine structured Cu matrix of the nanocomposite exhibited a very high thermal stability, with their average size increasing from 263 to 336nm after annealing at 900°C for 1h. This is likely due to the pinning effect of the Al2O3 nanoparticles on the migration of Cu grain boundaries. With annealing at 500, 600 or 900°C, the volume fraction and average size of the Al2O3 nanoparticles increased slightly. Annealing at 700 or 800°C did not cause any change of the volume fraction of the Al2O3 nanoparticles, but led to a slight decrease of the average size of the Al2O3 nanoparticles from 100 to 95nm. The microhardness of the samples did not decrease monotonically with increasing annealing temperature. Analysis of the contributions of various strengthening mechanisms reveals that hardening caused by the grain boundaries and nanoparticles plays a major role in sustaining the hardness (and strength) of the as-extruded and annealed ultrafine structured Cu–5vol.%Al2O3 nanocomposite samples.

CuO가 코팅된 Cu 분말을 혼합한 Camphene 슬러리의 동결건조에 의한 Cu 다공체 제조

This study reports a simple way of fabricating the porous Cu with unidirectional pore channels by freeze drying camphene slurry with Cu oxide coated Cu powders. The coated powders were prepared by calcination of ball-milled powder mixture of Cu and Cu-nitrate. Improved dispersion stability of camphene slurry could be achieved using the Cu oxide coated Cu powders instead of pure Cu powders. Pores in the frozen specimen at <TEX>$-25^{\circ}C$</TEX> were generated by sublimation of the camphene during drying in air, and the green bodies were sintered at <TEX>$750^{\circ}C$</TEX> for 1 h in <TEX>$H_2$</TEX> atmosphere. XRD analysis revealed that the coated layer of Cu oxide was completely converted to Cu phase without any reaction phases by hydrogen heat treatment. The porous Cu specimen prepared from pure Cu powders showed partly large pores with unidirectional pore channels, but most of pores were randomly distributed. In contrast, large and aligned parallel pores to the camphene growth direction were clearly observed in the sample using Cu oxide coated Cu powders. Pore formation behavior depending on the initial powders was discussed based on the degree of powder rearrangement and dispersion stability in slurry.

Factors controlling the tensile properties of ultrafine structured Cu–5vol%Al2O3 nanocomposite prepared by high energy mechanical milling and powder compact extrusion

The microstructures and tensile properties of two ultrafine structured Cu–5vol%Al2O3 nanocomposite samples made by a combination of high energy mechanical milling of a mixture of Cu powder and gamma Al2O3 nanopowder and powder compact extrusion were studied. The sample extruded at 750°C exhibited a microstructure consisting of Cu grains with sizes in the range of 100–500nm and a dispersion of Al2O3 nanoparticles with sizes in the range of 20–345nm. With the extrusion temperature increasing to 900°C, the Cu grain sizes remained almost unchanged, but a large fraction of the Al2O3 nanoparticles were dissolved, leading to possible formation of nanometer sized Al3+/O2− clusters. This microstructural difference of the two samples causes an interesting difference in tensile properties, with the sample extruded at 900°C showing approximately 150MPa higher yield strength and ultimate tensile strength and also better ductility than the sample extruded at 750°C. It appears that this significant beneficial effect of dissolution of Al2O3 nanoparticles is mainly caused by the significant strengthening effect of the nanometer sized Al3+/O2− clusters through Orowan mechanism.

A study on the microstructure and properties of Cu-based shape memory alloy produced by hot extrusion of mechanically alloyed powders

Powder Metallurgy is used widely to produce Cu‐based shape memory alloys having maximum of desired properties. It is better to use P/M to produce near‐net shape alloy products and have better controllability on the composition and grain size. In this study, the high‐energy planetary ball milling was applied to convert the elemental powder mixtures of Cu, Al and Ni into pre‐alloyed powders. The effect of milling time on composition and particles size distribution was studied and the pre‐alloyed powders were compacted by pressing and then hot extruded to obtain the final alloy sample. Strain recovery of the bended samples was studied to evaluate the effect of milling on shape memory properties. The densities of samples were calculated in green, sintered and extruded conditions to investigate the changes in the density of the samples, and influence of porosity on shape memory effect. The results showed that milling time has a variable influence on the density of samples, which can takes effect on the shape memory recovery due to amount of porosity.

309 摩擦圧粉法を用いた均一気孔径を有するポーラスCuの作製

Open-cell porous copper (Cu) was fabricated by friction powder compaction (FPC) process, which requires no external heat sources. In this process, a mixture of Cu powder and sodium chloride (NaCI) powder as spacer particle are used as starting materials. The compacting of the powder mixture are conducted only by rotating tool plunged into the mixture. NaCl is removed by placing the sintered mixture in water, and pores are formed. Porous Cu with porosities of 60-80 pct was successfully fabricated. In this study, a relationship between leaching time and removal of NaCl were investigated, and pore structures of obtained porous Cu were nondestructively observed by X-ray CT. In addition the compressive response of obtained porous Cu was investigated.

Mechanical Behaviour of Ultrafine Grained Cu and Cu-(2.5 and 5) Vol.%Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Composites Produced by Powder Compact Forging

Nanostructured Cu-(2.5 and 5)vol.%Al2O3 composite powders were produced from a mixture of Cu powder and Al2O3 nanopowder using high energy mechanical milling, and then compacted by hot pressing. The Cu and Cu-Al2O3 composite powder compacts were then forged into disks at temperatures in the range of 500-800°C to consolidate the Cu and Cu-Al2O3 composite powders. Tensile testing of the specimens cut from the forged disks showed that the Cu forged disk had a good ductility (plastic strain to fracture: ~15%) and high yield strength of 320 MPa, and the Cu-(2.5 and 5)vol.%Al2O3 composite forged disks had a high fracture strength in range of 530-600 MPa, but low ductility.

ChemInform Abstract: Bis(μ3‐iodo)‐pentakis(μ2‐iodo)‐penta‐copper (I) — A Fully Ordered, Isolated [Cu5I7]2‐ Cluster.

Abstract(Bu4P)2[Cu5I7] (I) and (Bu4P)2 [Cu5I7]·Me‐CO‐CH2OH (II) are synthesized by refluxing a mixture of Cu powder, iodine, and (Bu4P)I in hydroxyacetone.

Nanostructure Cu–Cr alloy with high dissolved Cr contents obtained by mechanical alloying process

A nanostructural solid solution of Cu–Cr was prepared by the mechanical alloying process. Three mixtures of Cu powders with 1, 3 and 6 wt-%Cr powders were milled under 250 rev min−1 for different milling times of 4, 12, 48 and 96 h. The mixtures were subsequently compacted and sintered at 450, 600 and 750°C for half an hour. Milled powder mixtures were examined by X-ray diffraction technique, which showed the presence of nanoscale crystallites in the samples and the decrease of lattice parameter of Cu crystals. Sintered powders were investigated by optical microscope and their hardnesses were measured by microhardness. Results showed increasing trends in hardness of the compacted powder mixtures with increasing milling time. Sintering temperature had also evident effects on the behaviour of powder mixtures. As sintering temperature increased, microhardness increased and a peak appeared then a decreasing trend was observed.

The silicon-rich corner of the system Si–Cu–Co

Abstract Phase equilibria and miscibility in the silicon-rich corner of the system Si–Cu–Co were analyzed in the present work. Powder mixtures of Cu, Co and Si at 1400 °C were molten and slowly cooled to RT. At the resulting samples, the miscibility of silicide phases was found to be limited: ≤0.5 at% Cu in CoSi 2 , 1.5 at% Cu in CoSi and 3 at% Co in Cu 3 Si. Furthermore, a ternary phase Cu 3 CoSi 2 was detected in the region of intermediate Si contents.