Copper Matrix Composite Materials Research Articles

Effects of Diamond Content on the Thermal Conductivity of Copper Matrix Composite Materials Prepared by Cold Spraying

With the increasing demand for rapid heat transfer in electronic packaging materials, quickly transferring the large amount of heat generated is an urgent problem that needs to be solved in current electronic information manufacturing. Diamond is added to copper based composite materials to further improve the thermal conductivity of electronic packaging materials. In this paper, copper matrix composite materials were selected as the research object, and the effects of diamond content on the microstructure and thermal conductivity were systematically investigated. As the content of copper plated diamond in the mixed powder increases, the proportion of copper plated diamond in copper based composite materials gradually increases, but the deposited copper plated diamond exhibits fragmentation phenomenon. Increasing the content of copper plated diamond leads to a rapid decrease in thermal conductivity, and subsequent process optimization and heat treatment are needed to unleash the thermal conductivity of diamond.

Mechanical and electrical properties of graphene nanosheet reinforced copper matrix composites materials produced by powder metallurgy method

This study investigated the mechanical and electrical properties of copper matrix composite materials reinforced with graphene nanosheets. The composite materials were produced using the powder metallurgy method, with several weight percentages graphene nanosheets (0, 0.5, 1 and 1.5) added to the copper matrix powders. The mixed powders were compacted unidirectionally in a steel mold at different pressures (500, 600 and 700 MPa) and sintered in an argon atmosphere at different temperatures (850, 900 and 950?C). Furthermore, the sintered samples were subjected to microstructure analysis, hardness and electrical conductivity measurements. The results showed that the microstructure exhibited porosity and agglomeration with increasing amounts of graphene nanosheets, resulting in a decrease in relative density up to 87.4%. The highest electrical conductivity was 76.59 IACS (0% GNS-500 MPa-950?C), while the lowest was 43.49 IACS (1.5% GNS-500 MPa-850?C). The addition of graphene nanosheets resulted in a relative increase in hardness of up to 1%.

The Influence of Tuff Particles on the Properties of the Sintered Copper Matrix Composite for Application in Resistance Welding Electrodes

This paper presents modern copper-matrix composite materials in which volcanic tuff particles are used as a reinforcing phase. The aim of the research was to determine the optimal shares of volcanic tuff additive based on such criteria as softening temperature, relative density, electrical conductivity, and hardness. The properties of the produced and tested composites allowed us to determine the usefulness of this type of material for resistance welding electrodes. To confirm the assumptions made, preliminary investigations of the durability and behavior of electrodes made of the tested material during the processes of welding non-alloy steel sheets were carried out. As a result of the research, it was discovered that the addition of 5% tuff produces the best results in this type of composite. It was found that for the sample with a 5% share of tuff, a high softening point above 600 °C was obtained, high hardness after densification at the level of 62 HRB, and high relative density of approximately 95% and very good conductivity at the level of approximately 45 MS/m. The conducted tests did not show any electrode wear different from the commonly used alloys for resistance welding.

Elastic recovery induced strengthening effect in copper/ multilayer-graphene interface regions revealed by instrumental nanoindentation

To distinguish the strengthening effect of multilayer graphene (MLG) on the copper matrix from the intrinsic strengthening effect of copper grain boundary (GB), the nanoindentation behavior in the Cu/MLG interface boundary (IB) region is investigated and further compared with those in the copper GB region and pure copper grain interior (GI) regions. The indentation displacement recovery ratio, elastic work ratio, and indentation hardness in the Cu/MLG IB regions are significantly enhanced as compared with those in the copper GB region and copper GI regions. The strengthening effect in the Cu/MLG IB regions can be attributed to the elastic recovery behavior during the unloading period induced by the MLG, which is further confirmed in both the experimental and simulated indentation topography evolutions. In addition, gradient strengthening effect is revealed from the gradual increase in the indentation displacement recovery ratio, elastic work ratio, and indentation hardness with gradual decreasing distance from the MLG in the Cu/MLG IB regions. The findings in this paper can be utilized to precisely enhance the mechanical performance of copper matrix composite materials by tailoring the interfacial microstructure and property.

Data analytics approach to predict the hardness of copper matrix composites

Copper matrix composite materials have exhibited a high potential in applications where excellent conductivity and mechanical properties are required. In this study, the machine learning models have been applied to predict the hardness of the copper matrix composite materials (CuMCs) produced via the powder metallurgy technique. Six different machine learning regression models were employed. The observed CuMCs were reinforced with two different volume fractions (2 vol.% and 7vol.%) of ZrB2 particles. Based on experimental work, we extracted the independent variables (features) like the milling time (MT, Hours), dislocation density (DD, m-2), average particle size (PS, μm), density (ρ, g/cm3), and yield stress (σ, MPa) while the Vickers hardness (MPa) was used as the dependent variable. Feature selection was performed by calculation the Pearson correlation coefficient (PCC) between the independent and dependent variables. The predictive accuracy higher than 80% was achieved for Cu-7vol.% ZrB2 and lower for the Cu-2vol.% ZrB2.

A novel mixing method for powder metallurgy copper‐carbon nanotube composites

AbstractIn this study, copper matrix composite materials with different ratios of carbon nanotubes were produced. The biggest problem faced in the production of carbon nanotube‐reinforced composites is that carbon nanotubes do not distribute homogeneously in the matrix. A novel mixing technique was applied to overcome this problem. Hot pressing was used in sample production. A second high‐pressure densification process was applied following the hot pressing process for enhancing the properties. The properties of both the hot‐pressed specimens and the specimens to which a second high‐pressure densification process was applied were characterized with the density measurements, microstructure examinations, and mechanical tests. The microstructure examinations showed that carbon nanotubes could be distributed homogeneously in the copper matrix with the mixing process applied. It was found out that the high‐pressure densification process applied following the hot‐pressing process increased the relative density and thus, all mechanical properties.

Effect of titanium and zirconium carbide interphases on the thermal conductivity and interfacial heat transfers in copper/diamond composite materials

Thermal properties of metal matrix composite materials are becoming ever more relevant with the increasing demand for thermally efficient materials. In this work, the thermal conductivity and heat transfers at the interfaces of copper matrix composite materials reinforced with diamond particles (Cu/D) are discussed. The composite materials contain either ZrC or TiC interphases and exhibit, respectively, higher and lower thermal conductivities with respect to their pure Cu/D counterparts. These thermal conductivities are accounted to the presence of strong covalent bonds and increased relative densities. The role of these interphases is also discussed regarding the phonon transmission at the interfaces.

Thermal conductivity of copper-diamond composite materials produced by electrodeposition and the effect of TiC coatings on diamond particles

Copper matrix composite materials with diamond particles are considered to be among the leading candidates as the heat sink materials for future electronic devices. However, today, these materials are mostly produced by high temperature-high pressure (HTHP) processes, which can be very costly. In order to explore an economically more viable approach of producing copper-diamond composite materials, we used electrodeposition to synthesize such materials and measured their thermal conductivities. The maximum thermal conductivity observed was 454 W/mK at 68.2 vol % diamond. In an attempt to improve the thermal conductivity further, titanium carbide (TiC) coatings were implemented on the diamond particles. The TiC coated diamond particles embedded in the electrodeposited copper matrix improved the thermal conductivity to 557 W/mK at 34.7 vol %, which is ∼40 % higher than 400 W/mK for pure copper. This value is comparable to currently available commercial HTHP heat sink materials. These results show that there is a potential of using electrodeposition an alternative synthesis method for producing copper-diamond composite materials for thermal managements. However, the formation of the microstructure at different electrodeposition current densities suggests that a careful process optimization is required to obtain a void-free Cu matrix between the embedded diamond particles.

The Influence of Technological Factors on Physico-Mechanical Properties and Electrical Conductivity of Copper Matrix Composite Materials

The Influence of Technological Factors on Physico-Mechanical Properties and Electrical Conductivity of Copper Matrix Composite Materials

Dynamic solutions of mode III crack in copper matrix composites

By utilising the methods of the theory of complex variable functions, dynamic propagation problems on symmetrical mode III crack in copper matrix composite materials were analysed. The crack extension should also appear in the form of self-similarity because failure is ascertained by the maximum tensile stress in actual engineering structions and everyday applications occurring in usually dynamic conditions. The formulation and the development of a Riemann–Hilbert problem were involved in this kind of issue. According to self-similar functions, the queries considered in this paper can be very easily translated into a Riemann–Hilbert problem. Analytical solutions of stresses, displacements and dynamic stress intensity factors K 3(t) for the edges of symmetrical mode III crack, subjected to motive alterable loads, P x 5/t 5 and P t 6/x 5 were obtained. In view of the relative material properties, the changeable law of dynamic stress intensity factor was illustrated very well. After the solutions were applied by the use of the superposition principle, the solutions of discretionally complicated problems were easily acquired.

Effect of metallic coating on the properties of copper-silicon carbide composites

In the presented paper a coating of SiC particles with a metallic layer was used to prepare copper matrix composite materials. The role of the layer was to protect the silicon carbide from decomposition and dissolution of silicon in the copper matrix during the sintering process. The SiC particles were covered by chromium, tungsten and titanium using Plasma Vapour Deposition method. After powder mixing of components, the final densification process via Spark Plasma Sintering (SPS) method at temperature 950°C was provided. The almost fully dense materials were obtained (>97.5%). The microstructure of obtained composites was studied using scanning electron microscopy as well as transmission electron microscopy. The microstructural analysis of composites confirmed that regardless of the type of deposited material, there is no evidence for decomposition process of silicon carbide in copper. In order to measure the strength of the interface between ceramic particles and the metal matrix, the micro tensile tests have been performed. Furthermore, thermal diffusivity was measured with the use of the laser pulse technique. In the context of performed studies, the tungsten coating seems to be the most promising solution for heat sink application. Compared to pure composites without metallic layer, Cu-SiC with W coating indicate the higher tensile strength and thermal diffusitivy, irrespective of an amount of SiC reinforcement. The improvement of the composite properties is related to advantageous condition of Cu-SiC interface characterized by well homogenity and low porosity, as well as individual properties of the tungsten coating material.

Microstructure and Tribological Properties of the Copper Matrix Composite Materials Containing Lubricating Phase Particles

Abstract The paper presents results of the studies into influence of individual particles of lubricating phase on microstructure and tribological properties of copper based composite materials for slide bearings. The studied material was composed of copper alloys with lubricating phase particles, e.g. in a form of graphite and glassy carbon. The metallic matrix of composite materials consisted of Cu-Sn type alloys. Production of the examined materials included processes with complete or partial participation of liquid phase and was conducted in two ways. In production of composites both classical powder metallurgy technology was applied and a method of melting with simultaneous mechanical stirring in liquid state (stir casting). Particles of lubricating phases were heated up to the temperature of 200°C and introduced into a liquid metal and then stirring process at constant rate of 1500 rpm rotational speed was applied. To improve wettability of graphite and glassy carbon particles titanium was introduced into the metallic matrix. In production of the composites by powder metallurgy methods the process consisted of mixing of bronze powders and particles of non-metallic phases and then their consolidation. Both quantitative and qualitative structure analysis of the produced composites was performed. Also through evaluation of tribological properties (friction coefficient, wear) with CSM Instruments high temperature tribometer THT was conducted.

Research on the Simulation of Friction Material Surface Topography

Through analysis and research on the surface topography of reinforced copper matrix composite materials, taking advantage of fractal statistical method to discuss distribution law about characteristics parameter which symbolizes the asperity, combining Monte-Carlo method with fractal theory to set up mathematics model of characteristics parameter which symbolizes size of asperity , talking about the construction of iterated function system in fractal interpolated theory, a easy realizable friction materials surface topography simulation algorithm was put forward.

Performance Study of Copper Matrix Composite Materials with CNTs, Al2O3 Double Reinforced by Powder Metallurgy Method

Carbon nanotubes(CNTs)/alumina(Al2 O3)/copper matrix composite materials by magnetic stirring process(MS) and spark plasma sintering(SPS) technology are studied.The characterization of specimens is carried out by field emission scanning electron microscopy.And then Brinell hardness,electrical conductivity,thermal conductivity and wear resistance performance are tested.The results show that CNTs and Al2 O3 obtained uniform dispersion within Cu matrix.The copper matrix composite has the best comprehensive performance when adding 0.5% CNTs and 3.5%Al2 O3.The relative density is 98.4%.Brinell hardness is 83.52 N/mm2and average friction coefficient is 0.106,increases by 33.2% and decreases by 47% compared with pure Cu respectively.The thermal conductivity is 184.99 W/(m·K).The electrical conductivity is 4.93×107Ω-1·m-1,equivalent to 91.5% IACS.

Use Copper Slag to Prepare Copper Matrix Composites

Copper slag was used to prepare copper powder by way of slurry electrolysis, and the copper powder was used to fabricate copper matrix composite materials reinforced with chemical plating surface modified alumina particulates. Alumina particulates were pretreated in ultrasonic field by chemical copper plating in order to make alumina particulates covered with a layer of copper film and form Al2O3/Cu composite powders. Copper matrix composite materials strengthened with alumina particulates were synthesized by means of pressure molding and sintering. Microstructure of copper matrix composites was researched by means of SEM. SEM analysis shows that alumina particulates distribute in the copper-based body evenly, and combine with copper closely. The effects of sintering temperature, pressure and alumina content on the compactness and hardness of copper matrix composites were studied by orthogonal tests. The compactness of composites increases with the sintering temperature and pressure increasing, and decreases with the alumina content increasing. The hardness of composite materials increases with the sintering temperature, pressure and alumina particulates increasing.

Theoretical approach to the study of the stability of metal matrix composite interfaces

The problem of stability of interfaces in metal matrix composites is reduced to the investigation of the solubility and diffusion processes of fiber atoms in the metal matrix. The calculations of excess thermodynamic functions of interstitial solid solutions is performed. The influence of additives on the stability of intermetallic phases formed at the interfaces is discussed. The height of diffusion barriers for aluminium and copper matrix composite materials with carbon or boron fibers is calculated. It is shown that the alloying of the matrix by additional element, substituting aluminium or copper in the interstitial metal-metalloid solid solution, changes the value of the barrier and influence the diffusion of metalloid. Some additives as the best alloying elements for preventing the diffusion in the alloys studied are predicted.