Copper Metal Matrix Composites Research Articles

Modifying the Characteristics of the Electrical Arc Generated during Hot Switching by Reinforcing Silver and Copper Matrices with Carbon Nanotubes

Switching elements are crucial components in electrical and electronic systems that undergo severe degradation due to the electrical arc that is generated during breaking. Understanding the behavior of the electrical arc and modifying its characteristics via proper electrode design can significantly improve durability while also promoting optimal performance, reliability, and safety in circuit breakers. This work evaluates the feasibility of carbon nanotube (CNT)-reinforced silver and copper metal matrix composites (MMCs) as switching electrodes and the influence of CNT concentration on the characteristics of the arcs generated. Accordingly, three different concentrations per MMC were manufactured via powder metallurgy. The MMCs and reference materials were subjected to a single break operation and the electrical arcs generated using 100 W and 200 W resistive loads were analyzed. The proposed MMCs displayed promising results for application in low-voltage switches. The addition of CNTs improved performance by maintaining the arc’s energy in the silver MMCs and reducing the arc’s energy in the copper MMCs. Moreover, a CNT concentration of at least 2 wt.% is required to prevent unstable arcs in both metallic matrices. Increased CNT content further promotes the splitting of the electrical arc due to a more complex phase distribution, thereby reducing the arc’s spatial energy density.

Sustainable microwave processing and surface characterization of powdered tungsten reinforced copper metal matrix (Cu-Wx) castings

The present work focuses on in-situ melting and casting of powdered copper metal matrix composites using a microwave hybrid heating approach. The composites of copper metal matrix are developed in such a way that the conductivity is least affected and related mechanical properties like flexural strength, tensile strength and hardness can be improved. Present work reports the processing and characterization of tungsten (W) powder reinforcement copper metal composites with weight percentages of W varied from 1%, 3% and 5%. The complete mechanism of interactions of Cu-Wx (x = 1%, 3% and 5% weight of copper powder) based composite powders with microwave heating is explained. The processed composite castings are characterized metallurgically through metallurgical microscope, SEM/EDS and XRD analysis; which reveals even dispersion of W particles in Cu matrix phase with some agglomerations. Some intermetallic formations are observed due to intense heating characteristics of microwaves. Further, mechanical and electrical characterizations of developed castings are carried out through Vicker's microhardness testing and electrical conductivity tests respectively. Addition of reinforced particles in metal matrix leads to an increase in microhardness on the expense of conductivity of composite. The 5% W addition led to 1.5 times increase in microhardness and 18.25% increase in resistivity. The mechanical testing revealed that the 5% W reinforced casting led to ∼22% higher ultimate tensile stress in comparison to pure copper casting. However, there was a significant decrease in ductility of metal matrix composites.

Spark Plasma Sintering of Cu-Ti-Ni Ternary Alloy: Microstructural, Thermal and Electrical Properties

High strength and good conductivity are both critical parameters for copper-based alloys for electrical and other technological applications. This study is aimed to produce copper alloys and metal matrix composites (MMCs) with enhanced physical properties. Cu-Ti-Ni ternary alloys and MMCs samples were sintered at 600 to 700°C using spark plasma sintering (SPS), with a heating rate of 100°C/minutes, uniaxial pressure of 50 MPa, and a holding time of 10 minutes. Scanning electron microscopy (FE-SEM) was used to examine the microstructure, while the relative densities of the composites were obtained via the Archimedes Principle method. A four-point probe and differential thermal analyzer (DTA) obtained electrical resistivity and thermal properties. The results indicated that the sample density nominally increases with sintering temperature but decreases with aluminium nitride additions. The electrical conductivity increases with the sintering temperature and AlN nanoparticle content. Distinct phase changes were observed from the DTA, occurring with the addition of AlN.

Mechanical and Microstructural Properties of B4C/W Reinforced Copper Matrix Composite Using a Friction Stir-Welding Process

Copper metal matrix composites (CMC) are broadly employed in various applications in the fields of space, aviation, automobile and electronics industries. The welding of CMC in using conventional methods is very difficult and expensive due to its crystallographic nature. Friction stir welding (FSW) is a more prominent and reliable technique for welding than conventional methods. Therefore, this work is based on work with CMC material, which is prepared with a stir-casting technique. Pure copper (Cu) is reinforced with tungsten (W) and boron carbide (B4C) particles in different combinations and welded using the FSW process to study the mechanical and micro-structural properties. Multi-objective decision-making methods, such as the technique for order preference by similarity to ideal solution (TOPSIS) and grey relational analysis (GRA) are used to find optimal parameter combination. The experiments are planned according to the L 18 orthogonal array (OA) using the most influential parameters, such as reinforcement the percentage of B4C, tool rotational speed, welding speed, and axial force. The performance of outcomes is measured based on the responses such as tensile strength, hardness, and impact strength of the weld joint. Based on the results 15 % of B4C reinforcement, 900 RPM rotational speed, 15 mm/min welding speed and 6 kN axial forces are optimal for better mechanical strength in the welding with TOPSIS and GRA techniques. Additionally, scanning electron microscopic image (SEM) analyses were carried out for better understanding of weldments’ microstructure changes.

Fractural analysis, microstructural, mechanical and tribological behaviour of vanadium trioxide-reinforced copper metal matrix composite by ultrasonic-assisted stir casting technique

In this work, pure copper is reinforced with vanadium trioxide (V2O3) at various weight percentages, such as Cu–0.5V2O3, Cu–1V2O3, Cu–1.5V2O3, and Cu–2V2O3. This copper metal matrix composite (CMMC) with primary copper element and secondary V2O3 is fabricated through an ultrasonic-assisted stir casting technique. The uniform distribution of secondary particles is achieved using ultrasonic waves generated by the probe and mechanical stirrer. The characterization of developed CMMC is done by X-ray diffraction and energy-dispersive X-ray spectroscopy. The samples are subjected to grain measurement using an optical microscope, which showed the relationship between grain size and enhancement of mechanical properties. The fabricated samples are also subjected to mechanical testing to determine their tensile strength, ultimate strength, Vickers hardness and impact strength. Fractography is also done by using a scanning electron microscope to understand the mechanism for the failure of tensile specimens. Dry sliding wear behaviour is also carried out to determine the wear resistance of CMMC. The results of numerous experiments showed that the grain size of CMMC improved with V2O3 addition. The increased strength-to-weight ratio leads to obtaining better properties at low cost. The enhancement in wear behaviour and mechanical properties of CMMC also paves the way for a newly developed material with V2O3 as secondary reinforcement along with copper as the primary element to be used in various applications.

Electrical Characterization of Carbon Nanotube Reinforced Silver and Copper Composites for Switching Contacts

Carbon nanotube (CNT)-reinforced silver and copper metal matrix composites—at three different reinforcement phase concentrations (0.5 wt.%, 0.75 wt.%, and 1 wt.%)—were produced via powder metallurgy and sintered via hot uniaxial pressing. Optical and electron microscopy techniques were used to characterize the powder mixtures and sintered composites. The latter were also electrically characterized via load-dependent electrical contact resistance (ECR) and surface fatigue tests. Particle size and morphology play a crucial role in CNT deposition onto the metallic powder. CNT were deposited exceptionally well onto the dendritic copper powder regardless of its larger size (compared with the silver flakes) due to the higher surface area caused by the grooves and edges of the dendritic structures. The addition of CNT to the metallic matrices improved their electrical performance, in general outperforming the reference material. Higher CNT concentrations produced consistently low ECR values. In addition, high CNT concentrations (i.e., 1 wt.%) show exceptional contact repeatability due to the elastic restitutive properties of the CNT. The reproducibility of the contact surface was further evaluated by the fatigue tests, where the composites also showed lower ECR than the reference material, rapidly reaching steady-state ECR within the 20 fatigue cycles analyzed.

Tribology of Copper Metal Matrix Composites Reinforced with Fluorinated Graphene Oxide Nanosheets: Implications for Solid Lubricants in Mechanical Switches.

The potential for the use of copper coatings on steel switching mechanisms is abundant owing to the high conductivities and corrosion resistance that they impart on the engineered assemblies. However, applications of these coatings on such moving parts are limited due to their poor tribological properties; tendencies to generate high friction and susceptibility to degradative wear. In this study, we have fabricated a fluorinated graphene oxide-copper metal matrix composite (FGO-CMMC) on an AISI 52100 bearing steel substrate by a simple electrodeposition process in water. The FGO-CMMC coatings exhibited excellent lubrication performance under pin-on-disk (PoD) tribological sliding at 1N load, which reduced CoF by 63 and 69%, compared to the GO-CMMC and pure copper coatings that were also prepared. Furthermore, FGO-CMMC achieved low friction and low wear at higher sliding loads. The lubrication enhancement of the FGO-CMMCs is attributed to the tribochemical reaction of FGO with the AISI 52100 steel counterface initiated by the sliding load. The formation of an asymmetric tribofilm structure on the sliding track is critical; the performance of the FGO/Cu tribofilm formed in the track is boosted by the continued fluorination of the counterface surface during PoD sliding, passivating the tribosystem from adhesion-driven breakdown. The FGO-CMMC and GO-CMMC coatings also provide increased corrosion protection reaching 94.2 and 91.6% compared to the bare steel substrate, allowing for the preservation of the long-term low-friction performance of the coating. Other influences include the improved interlaminar shear strength of the FGO-containing composite. The excellent lubrication performance of the copper matrix composite coatings facilitated by FGO incorporation makes it a promising solid lubricant candidate for use in mechanical engineering applications.

Influence of ferrochromium type on micro and macro tribology behavior of copper metal matrix composites

Ferrochromium, an important emerging abrasion component, is added to Cu metal matrix composites (Cu-MMCs) to enhance the high-energy braking properties of such composites. This study examined the microstructures, interfacial characteristics, and micro-tribology behaviors of two kinds of ferrochromium, and their effects on the braking performance of Cu-MMCs. The high-carbon ferrochromium (HCF) with higher hardness, consisting of (Cr,Fe)7C3 and (Cr,Fe)23C6-CrFe phases, formed a poor mechanical-diffusion mixed interface with the matrix and exhibited a low coefficient of friction (COF) in micro-friction tests. By cracking or crushing of HCFs, as well as third-body wear debris formed by HCFs, the COF in macro-friction tests was increased, helping Cu-MMCs maintain their braking performance at medium and high breaking energy densities (BEDs). The extra low-carbon ferrochromium (ELCF), consisting of a CrFe phase, generated a diffusion interface with the matrix, exhibited a greater COF, promoted the formation of a tribo-layer at high BED, and provided better wear resistance for Cu-MMCs. The wear mechanisms changed from plowing to severe plastic deformation-induced delamination and oxidation-induced delamination for Cu-MMCs with ELCF and HCF, respectively.

Size effect of CrFe particles on tribological behavior and airborne particle emissions of copper metal matrix composites

Brake wear particles emitted from vehicles during friction have become an important source of airborne particulate matter (PM) that causes adverse health effects. Particle emissions might be reduced by optimizing the composition of friction materials. Effects of CrFe particle size on tribological behavior and airborne particle emissions of copper metal matrix composites (Cu-MMCs) were investigated using a pin-on-disc tribometer at sliding speeds ranging from 2.5 to 5.0 m/s. The results indicate that the frictional properties, particle emission behavior and worn surface characteristics of Cu-MMCs were strongly influenced by the size of CrFe particles. With decreasing the CrFe particle size, the friction coefficient was relatively stable at 3.8 m/s, decreased gradually at 2.5 m/s, and decreased first then increased at 5.0 m/s. Basically, Cu-MMCs with medium-sized CrFe particles (100–150 mesh) produced the highest levels of particle emissions, followed by Cu-MMCs with large-sized CrFe particles (60–100 mesh), and then Cu-MMCs with small-sized CrFe particles (150–250 mesh) in succession. The level of particle emissions from Cu-MMCs increased substantially with increasing sliding speed. The obtained results were explained considering the evolution of the worn surface characteristics during the friction process.

Effect of Hot Rolling on Friction and Wear Characteristics of TiC Reinforced Copper-Based Metal Matrix Composites

The current study examines the effect of titanium carbide reinforcement (TiC) on the tribological behavior of copper metal matrix composites. The stir-casting process followed by hot rolling was employed to fabricate the composite parts. Hot rolling was performed at 510°C temperature with a 90% reduction ratio. An optical microscope, scanning electron microscope with energy dispersion spectroscopy, and Brinell hardness tester were used to investigate the microstructure, reinforcement particle distribution, and hardness. The microstructural investigations witness the uniform distribution of titanium carbide reinforcing agents along with the excellent binding with the copper matrix. The hardness was improved with the addition of titanium carbide content in both casting and rolling specimens. Dry sliding friction and wear tests were employed on a pin-on-disk setup with load values ranging from 30 to 120 N and sliding velocity values ranging from 0.628–2.512 m/s. In both casting and rolling conditions, the composites have a less coefficient of friction and wear rate than the matrix element. Wear rates of the unreinforced and reinforced cast and hot rolled alloys were enhanced as load and sliding velocity was raised. The incorporation of titanium carbide lowered the coefficient of friction and wear rate. In comparison to the unreinforced cast and rolled alloys, the coefficient of friction and wear of cast and rolled copper metal matrix composites was significantly reduced. Scanning electron microscopy was employed to investigate the worn surfaces and wear debris to confirm the possible wear mechanisms.

The effect of reduced graphene oxide content on the microstructural and mechanical properties of copper metal matrix composites

This study focuses on the relationship between the microstructure and the resulting mechanical and thermal properties of copper (Cu)/reduced graphene oxide (rGO) composites produced by spark plasma sintering as a function of rGO content (varying from 0 to 0.4 wt%). At the lowest rGO loading (0.025 wt%) the strength of the composite was double that of unreinforced Cu, with higher rGO fractions showing progressively lower improvements. Unexpectedly, the composites displayed a tensile yield drop (discontinuous yielding) on straining in contrast to the unreinforced Cu, ascribed to the influence of rGO nanoparticles pinning dislocations, causing a shortage of mobile dislocations. At loadings below 0.1 wt% rGO, the Cu-rGO interface was free of cracks, impurities, and voids, and the composites contained nano-sized Cu grains and well-distributed rGO nanoparticles with negligible agglomeration. However, at loadings beyond 0.1 wt% rGO, pores and rGO agglomerates were observed. The results suggest that an effective dispersion of rGO is critical, and the primary strengthening mechanisms relate to microstructure refinement, load transfer strengthening, and dislocation pinning. This work points to the efficacy of very low loadings in significantly improving strength with only a minor decrement in thermal diffusivity (<10%), opening up a number of applications.

Copper Based Powder Metallurgy Composite for Electrical Applications

This paper discusses Copper Metal Matrix Composites. It is obvious that copper matrix composites have been heavily relied upon by many industries because of their high wear resistance, corrosion resistance, excellent electrocatalytic properties, and high strength. The excellent electrical conductivity of copper-based materials also enables these materials to function as lubricants and anti-frictional materials. These materials were widely used in transportation, electrical contact transmission, and aerospace. Copper-based metal matrix composites have wide application due to their excellent mechanical, electrical, and thermal characteristics. Copper based metal matrix composites are also corrosion resistant and have a high strength. A contemporary study evaluated the effects of different parameters on powder metallurgy fabricated copper matrix metal composites. The focus was on understanding the applications and mechanical properties of copper-based composite materials.

Friction and wear behavior of copper metal matrix composites at temperatures up to 800 °C

High Temperature may exert a great impact on the service life and reliability of friction materials during friction sliding. Tribological behavior of a new developed copper metal matrix composite (Cu-MMC) against a steel disc was investigated using a home-built pin-on-disc tribometer in the ambient temperature range of 25–800 °C. Detailed analyses of worn surfaces and subsurfaces were performed using scanning electron microscope, optical microscope, X-ray diffractometer and 3D optical profiler. The worn surface of Cu-MMC exhibited different features at various ambient temperatures, resulting in a significant difference in tribological properties. The friction coefficient increased slightly from 0.563 to 0.640 as the ambient temperature varied from 25 °C to 400 °C, then a further increase in the ambient temperature led to a sharp decrease in the friction coefficient to 0.323 at 800 °C. A prompt increase in the mass loss of Cu-MMC was evident with increasing the ambient temperature from 25 °C to 400 °C, and then a slight increase occurred in mass loss of Cu-MMC upon increasing the ambient temperature up to 600 °C after which a significant declining trend of Cu-MMC was observed. The worn surfaces with a rugged and fluctuant morphology contributed to the high and unstable friction coefficient, as well as the high mass loss of Cu-MMC. The dominant wear mechanisms of Cu-MMC were severe oxidation, abrasive wear and adhesive wear at 400 °C and 600 °C, then delamination wear and oxidation at 800 °C.

Characterization and performance evaluation of Cu-based/TiO2 nano composites

Copper and copper alloys are used in industrial applications and food contact surfaces due to their desirable properties; copper metal matrix composites have been exciting researchers' attention in recent years since they can offer many valuable characteristics. The present study investigated the effects of the TiO2 nanoparticles addition with different weight percent on the hardness and corrosion behavior of copper nanocomposites. The powder metallurgy method was used to fabricate the Cu/TiO2 reinforced with different weight fractions of TiO2 nano particles up to 12 wt.%. The corrosion behavior of fabricated specimens is evaluated using potentiodynamic polarization curves and electrochemical impedance spectroscopy in different solutions. These solutions were 3.5wt.% NaCl, 0.5 NaOH and 0.5 M H2SO4 reflected different pH. The results showed that the addition of TiO2 nano particles improves pure copper's hardness. The hardness of pure copper increased from 53 to 91 HV by adding 12 wt.% TiO2. The corrosion current density (Icorr) of copper nanocomposites test specimens was higher than Icorr of pure copper in all test solutions. As TiO2 nano particles increase, the corrosion resistance of Cu nano composites decreased. All test specimens exhibited little corrosion current density in 3.5 wt.% NaCl solution as compared with other test solutions.

Effect of (SiC+Gr) Addition on the Corrosion Behavior of Powder Metallurgy Copper MMC

Copper metal matrix composites are seeing tremendous growth due to their properties, which are suitable for a wide range of applications. The potential for combining reinforcements uniformly in the matrix via powder metallurgy is stimulating new research. In the present study, copper powder is used as the matrix and SiC and graphite are used as reinforcements for the fabrication of a hybrid metal matrix composite using the powder metallurgy route. Silicon Carbide (SiC) and graphite are used as reinforcements in copper Metal Matrix Composite (MMC). SiC is a ceramic material that increases the hardness of the composite by adding it as reinforcement, and graphite is a material that helps increase corrosion resistance when used as reinforcement. In each sample, SiC and graphite mixture reinforcement is in equal proportion, varying this composition from 0 to 10% of the weight percentage. These samples are investigated for Vickers hardness, densities, and electrochemical corrosion properties after being prepared by powder metallurgy with dimensions of 16 mm x 16 mm x 25 mm. The sample with 8% reinforcement showed good corrosion resistance and poor corrosion resistance for the 4% reinforcement sample. These composition samples were subjected to X-ray diffraction (XRD) analysis and Scanning Electron Microscopy (SEM) characterizations, which showed good correlation for the hardness and corrosion test values.

Characterization of Copper MMC Reinforced with SiC and Graphite in Equal Proportion Made by the Powder Metallurgy Route

Powder metallurgy is playing a very important role in the manufacturing industry. In this research, an attempt is made with copper Metal Matrix Composites (MMC) reinforced with an equal proportion of Silicon Carbide (SiC) and graphite powders. The powders are taken in such a way that the reinforcement weight percentage varies from 0 to 10%. The materials are fabricated through the powder metallurgy route. The powder mixtures are blended and then compacted with a uniaxial pressure of 500 MPa to make the green compacted composites with different compositions. The dimensions of all samples are 25 mm x 16 mm x 16 mm, with an average weight of 40 g. Compacted green samples are sintered by the inert gas sintering process. Sintering is performed at 8000C in an inert argon gas furnace for 120 minutes for all the samples. The obtained samples are made suitable for different tests like porosity, the Vickers hardness test, the wear test, Raman spectroscopy, Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray (EDX) Analysis. From the values obtained from the hardness test, it is observed that for all MMCs, the minimum value is obtained at Cu-4% (SiC+Gr) and the maximum value at Cu-8% (SiC+Gr), and in between these percentages of composition, there is a little bit of an increase and decrease in values. Wear test results give the maximum wear rate at Cu-4% (SiC+Gr) and the minimum wear rate at Cu-8% (SiC+Gr). Raman spectroscopy test results are given the calculations of Full Width at Half Maximum (FWHM), depth of incident, absorbance, and Id/Ig values, and they are better at 8% of SiC+Gr, which gives the indication of good bonding between molecules of the powder particles. Image analysis is performed using optical microscopy, SEM, and EDX. The microstructures were revealed in such a way that there was good correlation between the properties at different compositions.

Experimental investigation of mechanical and wear behaviour of Cu-V2O5-Gr(L) reinforced composites

In this work, copper is reinforced with 2% Vanadium pentoxide along with Multi layered graphene (0.5%, 1.0%, & 1.5%). The stir casting method is used to fabricate Copper Metal Matrix Composite (CMMC). Material characterization is done by X-ray diffraction and Energy Dispersion X-ray Analysis. Tensile testing, hardness, impact test is carried out to determine the mechanical Behaviour of CMMC. The wear testing is also carried out to determine the wear Behaviour of composites. From the above experimentation, it is found that with the increase in graphene content along with the addition of vanadium pentoxide, the mechanical and wear properties of composites are enhanced making copper as one of the reliable material for varied applications.

Microstructures and tribological behaviors of Cf/C‐SiC composites tailored by Cu and Fe‐Si matrices

AbstractTernary Cu‐Fe‐Si alloy were applied to modify tribological behavior of carbon fiber/carbon‐silicon carbide (Cf/C‐SiC) composites by reactive melt infiltration. Microstructures, physical properties and tribological properties on a full‐scale train brake test rig of the modified composites were studied. Results indicate that both Cu and Fe‐Si alloy as matrices lead to significantly enhanced thermal conductivity and compressive strength for Cf/C‐SiC composites. Moreover, the average friction coefficient of the modified composites is between 0.25 and 0.55, which is higher than that of copper metal matrix composites. In addition, the average volume wear rate of the modified composites is only 0.168 cm3/MJ. The Cf/C‐SiC composites modified by Cu and Fe‐Si alloy with improved physical properties and tribological properties meet the technical requirement and show high application potential in express train brake systems.

Preliminary Evaluation and Wear Properties Optimization of Boron Carbide and Molybdenum Disulphide Reinforced Copper Metal Matrix Composite Using Adaptive Neuro-fuzzy Inference System

This paper presents a comprehensive research on the influence of boron carbide and molybdenum disulphide hybrid reinforcement on physical, mechanical and tribological characteristics of copper metal matrix composite dedicated for electrical appliances application. The synthesis of novel copper metal matrix composite reinforced with boron carbide (0 to 3%) and molybdenum disulphide (0 to 4.5%) were fabricated using liquid stir casting technique. There is an uptrend in the physical and mechanical characteristics of the copper metal matrix composite with higher reinforcement addition in comparison to pure copper. The Taguchi experimental design is applied to plan the experiments and S/N ratio is used to determine optimal factor settings for minimum wear loss of the copper metal matrix composite. Furthermore, adaptive neuro-fuzzy inference system (ANFIS) model is developed to predict the wear loss with respect to changes in input parameters viz. composition, load, sliding speed, and sliding distance. The confirmation experiments results reveal conformity between the ANFIS model and experimental results with 97.99% accuracy implying that the established ANFIS model can be precisely used for predicting the wear loss. Moreover, the novel copper metal matrix composite reinforced with boron carbide and molybdenum disulphide shows enhanced wear resistance in respect to unreinforced composite that make it appropriate for electrical appliances application.

Tribological behavior and mechanism of h-BN modified copper metal matrix composites paired with C/C–SiC

The thermal stability of hexagonal boron nitride (h-BN) plays a crucial role in stabilizing the braking performance of friction pairs (i.e., brake-pad/disc) in high-speed trains. In this study, h-BN modified copper metal matrix composites (Cu-MMCs) were fabricated via powder metallurgy, and their tribological behavior and mechanism upon pairing with C/C–SiC were investigated. Results show that as the h-BN content increased, the wear mechanism of the Cu-MMCs switched from abrasive to severe fatigue, followed by switching from mild oxidation to adhesive abrasion. Additionally, Cu-MMCs containing 2 wt% h-BN exhibited a high, stable coefficient of friction (COF) during repeated high-speed braking cycles together with a smoothed braking process at high braking speeds.