Copper-based Composites Research Articles

Friction mechanism analysis of copper-based composites reinforced with ball-milled and modified composite ceramic powders

To achieve brake pads with high-temperature resistance and low-wear, copper-matrix composites reinforced by composite ceramic powder (after high-energy ball milling) are prepared. The results reveal that the SB4 brake-pad reinforced with 10% B4C–SiC powder has an excellent friction coefficient and friction stability coefficient. This improvement can be attributed to the formation of a tribo-film (80–100 nm) with high hardness and a large range. A higher content of composite ceramic powder results in an abnormal increase in the mechanical properties of SB4, which should have decreased due to weakened interface bonding. This phenomenon can be attributed to the generation of a sufficient number of new bonds during the ball milling process, combined with the high activity of the composite ceramic powder, promotes the sintering process of the copper-matrix composite material, resulting in increased densification of the brake pad. Consequently, the incompatibility between the improvements in the mechanical properties and friction properties is reduced, and the proportion of ceramic particles in the brake pad is increased, which significantly affects the improvement in the high-temperature stability of the friction properties.

Structure analysis of friction layer of copper matrix composites reinforced by composite ceramic (TiC-B4C) powder

To alleviate the issues of matrix softening and excessive wear faced by copper-based composites matched with C/C–SiC disc during high-speed braking, the research was conducted to investigate the impact of composite ceramic (TiC–B4C, TB) powder on copper matrix composites prepared through conventional powder metallurgy method. TiC–B4C powder was produced using the high-energy ball milling method, and a suitable milling time (48 h) was established to obtain the maximum disorder degree. The results revealed that TB2 (6% TB) had the highest densification and the best mechanical and thermal performance, as compared to other composites. However, there were differences in tribological properties, with TB4 (10% TB) achieving the maximum friction coefficient, while TB2 (6% TB) exhibited more stable friction performance. As the TB powder content increased, larger tribo-films were formed on the worn surface. However, the influence of TB powder content (less than 10% TB) on friction performance was mainly due to mechanical strength and structural tightness, rather than the formation of tribo-films. The friction layer consisted of three parts: the top nanostructure layer composed of nanoparticles (C, Cu, Fe, B, O, and Ti), the middle tribo-film composed of graphite and B2O3, and the lower elastic deformation zone.

Microstructure and electrical contact behavior of the nano-yttria-modified Cu-Al2O3/30Mo/3SiC composite

Abstract With the rapid development of the copper-based composite in the field of electrical contact material industry, the problem of poor arc erosion resistance of the copper-based material becomes more and more prominent. Improving the arc erosion resistance of the copper-based composite is an urgent problem to be solved. Cu-Al2O3/30Mo/3SiC and 0.5Y2O3/Cu-Al2O3/30Mo/3SiC electrical contact composites were prepared in a fast-hot-pressing sintering furnace. The microstructure and phase structure of the composites were analyzed by using a scanning electron microscope, transmission electron microscope, and X-ray diffraction meter, respectively. The arc erosion properties of the composites at 25 V, DC and 10-30 A were investigated by using a JF04C electric contact tester. The mass loss of the composites was reduced by 77.8%, and the arc erosion rate was reduced by 79.6% after the addition of nano-yttrium oxide under the experimental conditions of 25 V, DC and 30 A. At the same time, the arc energy and welding force of the composite after switching operations decreased, indicating that the addition of nano-yttria improved the arc erosion resistance of the composite. This work provides a new method for improving the arc erosion resistance of the copper-based composite contact material.

Influence of sintering temperature on mechanical and tribological characteristics of copper based composite reinforced by 2D hybrid material

The effect of sintering temperature on the mechanical and tribological characteristics of 2D phase reinforced copper-based composite has been investigated in the present study. The Cu-based composites containing 2 wt. % of(GO + MoS2)NP were sintered at different temperatures (1023, 1073, 1123, and 1173 K) by microwave sintering process. The microstructural features observed by SEM and HRTEM of composites suggest that as the sintering temperature increases (GO + MoS2)NP pocket formation tendency also increases, which also governs the mechanical and tribological characteristics of composites. As the sintering temperature elevated, the ultimate tensile strength of the composite decreases, whereas friction and wear rate decrease with increase in temperature up to 1123 and beyond 1123 increase in friction and wear has been observed. The decrease in strength with increasing sintering temperature has been attributed to the grain size increment and increase in (GO + MoS2)NP pocket size at the grain boundaries. However, the decrease in friction and wear rate has been ascribed to the ease of extrusion of (GO + MoS2)NP from the pockets for the composites sintered at high temperature, rather than extrusion of (GO + MoS2)NP of fillers from the intra-grainular sites, i.e., for the composites sintered at lower temperature.

Preparation and Properties of Copper-Based Composites Containing Nb1-x(Ti/Ta)xSe2

In this study, copper-based-Nb1-x(Ti/Ta)xSe2 composites were prepared by powder metallurgy, and Nb1-x(Ti/Ta)xSe2 copper-based composites with different Ti/Ta doping atomic fractions were studied. physical, electrical and tribological properties. Among them, the doping amount of Ti and Ta has an important influence on the properties of the composite material. The doping amount of Ti can improve the mechanical, electrical and tribological properties of copper matrix composites within a certain range, especially when the doping amount of Ti is At 10at.%, the copper matrix composites exhibited excellent tribological properties. The addition of Ta greatly improved the tribological properties of the composites, and with the increase of Ta doping content, the friction coefficient of the copper-based composites gradually decreased. The research shows that the copper-based Nb1-x(Ti/Ta)xSe2 composite is a very promising new composite material.

Tribosynthesis of friction films and their influence on the functional properties of copper-based antifriction composites for printing machines

Abstract This article is devoted to research of the tribosynthesis mechanism of antifriction films and their influence on the functional properties of antifriction composites based on copper alloyed with nickel and molybdenum with the CaF2 solid lubricant additions for operation at rotation speeds of 3,000–7,000 rph and increased loads of 3.0–5.0 MPa in air. Studies have shown that antifriction films are complex, dynamically changing formations on the surfaces of the composite and counterface, developing according to the bifurcation mechanism. The antifriction layer is decisive in the formation of the friction pair's tribological high-level properties, which provide the self-lubrication mode of the friction unit. The formation and permanent presence of the anti-seize film is associated with a balanced wear rate of the film and its constant formation again on these worn areas at rotation speeds of up to 7,000 rph and loads of up to 5.0 MPa. Due to the steady self-lubrication mechanism, the copper-based composite has significant advantages over cast bronze CuSn5ZnPb, which can only work with liquid lubrication in the friction units of printing machines. The performed studies make it possible to choose rational modes for operation of new high-speed antifriction Cu-composites based on the friction films analysis, predicting their high functional properties.

Surface modification of CNTs to improve comprehensive properties of CNTs/Cu composites

ABSTRACT In order to improve the dispersibility and uneven distribution of carbon nanotubes (CNTs) in the copper matrix, the surface of CNTs were modified to enhance their dispersibility in the copper matrix. In this paper, different concentrations (7.5%, 15%, 30%) of HNO3 were used to functionalize the surface of CNTs to improve the chemical inertness of CNTs, and surface modification was performed on the purified and de-hybridized CNTs to make the CNTs better dispersed in the metal matrix. At the same time, the mechanical properties and electrical conductivity of the carbon nanotube-reinforced copper-based composites were analyzed. According to research result, 15% HNO3 combined with subsequent surface treatment have the best effect on surface modification of CNTs, significantly improving the dispersibility of CNTs and better exerting the excellent coordination effect of CNTs in copper-based composite. In addition, it is confirmed that the obtained Cu-CNTs/Cu composites have excellent comprehensive properties, which provide a new idea to improve the characteristics of copper-based composites doped with CNTs.

Effects of ball milling and load on transfer film formation of copper-based composites

PurposeThis paper aims to investigate how ball milling (BM) and load influence transfer film on counterbody and the correlation between transfer film and tribological properties of copper-based composites.Design/methodology/approachThe copper-based mixed powders preprocessed by BM for different times were used to manufacture sintered materials. Specimens were tested by a custom pin-on-flat linear reciprocating tribometer and characterized prior and after tests by optical microscope, scanning electron microscope and energy-dispersive spectroscopy. Image J® and Taylor-hobson-6 surface roughness meter were used to quantify the coverage and thickness of the transfer film.FindingsMain results show that an appropriate amount of BM time and applied load can contribute to the formation of the transfer film on counterbody and effectively improve the tribological properties of the copper-based material. The transfer film coverage is linearly related to the friction coefficient, thickness of transfer film and wear volume. As the transfer film coverage increases, the coefficient of friction decreases. As the thickness of the transfer film increases, the amount of wear increases.Originality/valueThis work intends to control and optimize the formation of transfer film, thereby helping improve the tribological properties of materials and providing a reference to guide the preparation of Cu-based composites with excellent tribological properties.

Copper–Ruthenium Composite as Perspective Material for Bioelectrodes: Laser-Assisted Synthesis, Biocompatibility Study, and an Impedance-Based Cellular Biosensor as Proof of Concept

Copper is an inexpensive material that has found wide application in electronics due to its remarkable electric properties. However, the high toxicity of both copper and copper oxide imposes restrictions on the application of this metal as a material for bioelectronics. One way to increase the biocompatibility of pure copper while keeping its remarkable properties is to use copper-based composites. In the present study, we explored a new copper–ruthenium composite as a potential biocompatible material for bioelectrodes. Sample electrodes were obtained by subsequent laser deposition of copper and ruthenium on glass plates from a solution containing salts of these metals. The fabricated Cu–Ru electrodes exhibit high effective area and their impedance properties can be described by simple R-CPE equivalent circuits that make them perspective for sensing applications. Finally, we designed a simple impedance cell-based biosensor using this material that allows us to distinguish between dead and alive HeLa cells.

Improving mechanical properties of copper composite by interconnected MoO2 quantum dots

The strengthening effect of particle-reinforced copper-based composites mainly depends on the interfacial bonding strength and dispersibility of the reinforcement. However, agglomeration of nanoparticles, as a bottleneck, restricts Orowan's strengthening mechanism. Different from the traditional preparation method for stacked nanoparticles, a hydrothermal method was developed to prepare interconnected bridge-like MoO2 quantum dots. Based on the interconnected structure and the brittleness of MoO2, it can be easily broken and uniformly dispersed into copper matrix during the ball milling process. Due to the dispersion strengthening effect and coherence of the interface between MoO2 and copper, these factors improve the mechanical performance of the composite material synergistically, resulting in simultaneous increases in YS (145.76 MPa), UTS (321.67 MPa), and hardness (94.79 Hv). The effectiveness of YS and UTS enhancement is 234% and 41%, respectively, while maintaining appropriate elongation (20.29%) and conductivity (94.9 IACS). MoO2 quantum dots are used for the first time in this work as particle reinforcements, and we demonstrate that the addition of oxide quantum dots to metal matrix composites can significantly enhance the mechanical properties of the composites by changing the morphology of the quantum dots.

Effect of Coordinated Solvent Molecules in Cu-MOF on Enzyme Free Sensing of Glucose and Lactate in Physiological pH

Developing a nonenzymatic sweat sensor for selective determination of glucose and lactate holds great significance in clinical diagnostics. Among various catalysts, transition metal-based metal-organic frameworks (MOF) have recently drawn more attention due to their tunable porosity and enhanced electrocatalytic activity. The presence of the solvent molecule in the framework can influence both structural and electrochemical properties. In the present work, Copper-terephthalate (CuBDC) MOF was synthesized in a solvothermal method with different time durations. The effect of the coordinated solvent molecules on the metal centre on structural and electrocatalytic properties was systematically investigated using various characterization techniques. As most of the copper-based composites reported so far showed performance in an alkaline medium, we demonstrate the detection of glucose and lactate in a neutral medium that enables direct analyte measurement from the body fluid. Electrochemical studies indicate that the solvated structure shows superior sensitivity to the desolvated MOF for glucose and lactate. The high sensitivity of the solvated MOF is attributed to the favourable solvent exchange mechanism and ion diffusion through the channels of the MOF. Furthermore, CuBDC12E and CuBDC48E show negligible interference toward competing analytes. The proposed sensor also exhibits good sensing performance in artificial sweat, making it suitable for a non-invasive, practical sweat sensor.

Preparation and properties of copper matrix composites synergistically strengthened by Al2O3 and CPD

The development of copper-based composite materials is increasingly requiring both high electrical conductivity and better mechanical properties. In this paper, a novel copper-based composite was prepared by combining carbonized polymer dot (CPD) with flake copper powder (BMCu) and Al2O3 with molecular-level copper powder (MLCu). The composite obtained good mechanical properties with the yield strength of 157.00 MPa and the tensile strength of 366.14 MPa, which are increased by 17.4% and 25.1% compared with those of pure copper matrix (133.76 MPa and 292.72 MPa). The hardness of the composite is 124.7 HV, 27.4% higher than that of pure copper (97.9 HV), and the conductivity is 93.15% IACS. Besides, the strengthening mechanism of tensile property is also discussed, and the improvement of composite strength is mainly due to the dislocation strengthening. This study provides a new idea for the preparation of copper-based composite materials with high electrical conductivity and mechanical properties.

Thermal Conductivity of Composite Materials Copper-Fullerene Soot.

Copper-based composites strengthened with fullerene soot nanoparticles of 20–30 nm size in concentration up to 23 vol.% were prepared via two methods: mechanical mixing and molecular level mixing. The dependence of thermal conductivity on the carbon concentration was studied. Maxwell’s model describes well the change in the thermal conductivity of the composite obtained by molecular level mixing. However, thermal conductivity of the composite produced by mechanical mixing is significantly lower than the calculated values, due to structural inhomogeneity and residual stresses. Comparison of the thermal conductivity of Cu-fullerene soot composites with that of Cu-based composites described in the literature showed that the prepared materials are not inferior in thermal conductivity to composites containing carbon nanotubes, despite the fact that fullerene soot has a much lower thermal conductivity.

Copper-Based Nanocatalysts with SiO2 and Carbon Dual-Layer Coatings and Metallic Ni/CuNi Decoration toward Highly Efficient Nitroaromatics Reduction.

Nanocomposites with novel architectures and multifunctional properties have attracted extensive attention among related researchers. Herein, we develop a magnetically responsive Ni/CuNi nanoparticle (NP) decoration of Cu-based composites that could serve as recoverable nanocatalysts for nitroaromatics reduction. The nanocatalysts consist of an inner copper core and abundant tiny satellite Ni/CuNi NPs, which are tightly combined as a stable whole part by a silica interlayer and a carbon outer layer. In addition to the high catalytic activity, the outer Ni/CuNi NPs exhibit a strong magnetic response toward the external magnetic field, thereby offering a convenient way to separate the composites from the reaction solution. Moreover, characterization results reveal that high annealing temperature (above 700 °C) favors the construction of yolk-shell nanostructures and the formation of outer bimetallic CuNi NPs. As a result, owing to the excellent catalytic performance of the Cu inner cores, the high coverage of outer Ni or CuNi NPs, and the unique sandwich-like structure, the resultant Cu@SiO2@C-Ni composites show the use of such magnetically responsive recoverable nanocatalysts for the 4-nitrophenol reduction. Hence, this research could provide new guidelines for designing and synthesizing novel and efficient copper-based composites for other fields, such as carbon dioxide reduction, energy storage, and batteries.

A Novel "Turn on" Chemiluminescence Aptasensor for Alpha Fetoprotein Detection Based on Oligonucleotide Chain Functionalized Magnetic Graphene Oxide and Co-Catalyzed Copper-Based Organic Framework Composites

A Novel "Turn on" Chemiluminescence Aptasensor for Alpha Fetoprotein Detection Based on Oligonucleotide Chain Functionalized Magnetic Graphene Oxide and Co-Catalyzed Copper-Based Organic Framework Composites

Электроконтактный материал на основе медного порошка, плакированного Fe – Cu псевдосплавом

By pressing, rolling and sintering, a composite material (CM) based on copper powder clad with Fe-Cu pseudo-alloy (PA) was created for the working layer of two-layer ruptured electrical contacts. Powder of activated carbon (CA) with a surface of 1000 m2/g served as the arc suppression component. Highly dispersed powders of Al2O3, Fe2Al5, and Fe were also used as additional components. Experimental linear dependences of the conductivity and hardness of copper-based composites on the concentration of individual functional additives have been established. With the addition of mixtures of additional components, CMs were obtained for the working layer of the contact with the following characteristics: electrical resistance — 3.2 – 4.5 μOhm·cm, hardness HB — 790 – 1030 MPa. For a given conductivity of a two-layer contact, which is ≥ 75 % of the conductivity of copper, the dependence of the maximum allowable resistivity of theworking layer (ρ) on the ratio of its thickness to the thickness of the copper layer is calculated. The optimal chemical composition of the working layer of the contact has been determined — 97 % Cu + 1 % CA + 2 % PA, providing high hardness 1030 MPa and electrical resistance 3.2 μOhm·cm. These characteristics allow creating an electrical contact with a ratio of the thickness of the working and copper layer equal to 1:1.

Synergistic effects of iron and hexagonal-Boron Nitride additions in copper-based composites for braking application

This paper explores the addition of h-BN and iron to Cu-based brake pads on the performance benefits. It also investigates the effect of graded layering by synthesizing three and four-layer brake pads by powder compaction and sintering route. The top one or two layers are made of Cu-based composite containing Fe, h-BN, and W, while the middle layer is pure Cu and, bottom steel plate. Two different compositions were explored for the composites by varying Fe content. From the two composite compositions, brake pads with single-layer composite or two-layer composite were synthesized. Characterization of brake pad specimens was carried out using density measurements, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy. The brake pads were subjected to simulated braking tests at braking energy/cycle of 60, 96, and 136 K Joules. Wear rate, coefficient of friction, stopping distance, stopping time, and hardness were measured and compared among other brake pads. The brake pad containing single-layer Fe rich Cu composite showed the best performance in the simulated braking tests. EDS analysis of wear debris shows the formation of iron (boride, nitride, oxide) complex which is indicative of a surface with superior dry lubricating properties. This surface is a result of synergetic interaction between h-BN and Fe particles. The iron particles which are scattered in the Cu matrix composite act as low friction regions on the brake pad surface that interrupt the high friction regions on the Cu matrix, thus reducing the local and bulk temperature rise. The two-layer composite brake-pad showed performance intermediate to the two single-layer brake pads. No advantage due to higher thermal conductivities in Fe deficient composite was observed as the two composite layers, showed similar Fe contents in their matrix phases.

Metallic Copper-Containing Composite Photocatalysts: Fundamental, Materials Design, and Photoredox Applications.

Semiconductor photocatalysis has long been regarded as a potential solution to tackle the energy and environmental challenges since the first discovery of water splitting by TiO2 almost 50 years ago. The past few years have seen a tremendous flurry of research interest in the modification of semiconductors because of their shortcomings in the aspects of solar harvesting, electron-hole pairs separation, and utilization of photogenerated carriers. Among the various strategies, the introduction of metallic copper into the photocatalysis system can not only enhance the absorption of sunlight and the separation efficiency of photogenerated electrons and holes, but also increase the adsorption ability of substrate and the number of active sites, so as to realize the high solar to chemical energy conversion efficiency. This review focuses on the rational design of copper-based composites and their applications in photoredox catalysis. First, the preparation methods of metallic copper-containing composites are discussed. Then, the applications of different types of copper-based composites in the photocatalytic removal of pollutants, splitting of water to hydrogen production, reduction of carbon dioxide, and conversion of organic matter are introduced. Finally, the opportunities and challenges in the design and synthesis of copper-based composites and their applications in the photocatalysis are prospected.

Influence of compaction temperature on the mechanical properties and micro morphology of Cu/CNTs composites prepared by electromagnetic impacting

Carbon nanotubes reinforced copper-based composites (Cu/CNTs) had excellent physical properties and were widely used in industrial production and manufacturing. In this work, the mechanical properties and micro morphology of Cu/CNTs composites prepared by electromagnetic powder compaction (EMPC) at 25–200 °C were investigated. Results showed that the relative density, hardness and compressive stress of Cu/CNTs compacts gradually increased as the temperature increased. The growth trend had an obvious turning point at 150 °C. The maximum relative density and compressive stress were 95.74% at 200 °C and 520.95 MPa at 150 °C, respectively. The micro morphology of the end faces and cross sections became denser. The temperature had a weakening effect on the compressive strain, but the opposite was true for compressive stress. The optimal temperature was 150 °C. The relationships between temperature and compressive stress and strain of Cu/CNTs composites were revealed.

Copper-based composites derived from metal-organic frameworks on carbohydrates-rich corncobs as efficient catalysts for organic compounds removal

It is of great significance to exploit environmentally friendly, efficient and economical catalysts for dealing with wastewater and other aquatic environments. In this study, a series of P-doped Cu/Cu2O/C heterostructures were obtained by controlled calcination of corncobs supported Cu-MOF in different temperature. Comprehensive structural characterizations indicate the polyhedron morphology and high porosity of HKUST-1-P@corncob-400. The composites were further explored as an efficient catalyst for catalytic reduction of 4-nitrophenol (4-NP). Remarkably, HKUST-1-P@corncob-400 could efficiently catalyze the reduction of 4-NP, and the reduction could be finished within 90 s with a 4-aminophenol (4-AP) selectivity of >99%, demonstrating the excellent performance of Cu-based catalysts for 4-NP reduction. The application scope could be further expanded to the catalytic reduction of ofloxacin and a conversion of 95.7% could be achieved within 10 min. Reproducibility studies and characterizations comprehensively demonstrate the promising potential of HKUST-1-P@corncob-400 acting as efficient catalyst for the reductive removal of environmental pollutants. This work provides a facile strategy for the fabrication of highly active catalysts for high-performance environmental purification, and the employment of renewable bioresources and functional MOFs represents a promising strategy for design and synthesis of highly active catalysts towards various advanced applications.