Copper Diamond Research Articles

Thermostructural characterization and structural elastic property optimization of novel high luminosity LHC collimation materials at CERN

The CERN Large Hadron Collider is currently being upgraded to operate at a stored beam energy of 680 MJ through the High Luminosity upgrade. The LHC performance is dependent on the functionality of beam collimation systems, essential for safe beam cleaning and machine protection. A dedicated beam experiment at the CERN High Radiation to Materials facility is created under the HRMT-23 experimental campaign. This experiment investigates the behavior of three collimation jaws having novel composite absorbers made of copper diamond, molybdenum carbide graphite, and carbon fiber carbon, experiencing accidental scenarios involving the direct beam impact on the material. Material characterization is imperative for the design, execution, and analysis of such experiments. This paper presents new data and analysis of the thermostructural characteristics of some of the absorber materials commissioned within CERN facilities. In turn, characterized elastic properties are optimized through the development and implementation of a mixed numerical-experimental optimization technique.

Reaction fabrication and wear performance of TiCx/(Cu–A1) bonded diamond composites

AbstractCu–TiCx-bonded diamond composites were prepared by in-situ reaction sintering of Cu, Ti3AlC2, and diamond powders. The effect of Ti3AlC2 content on the phase composition, microstructure, and grinding properties was investigated. Ti3AlC2 was decomposed to TiCx and Al. Then, Al was dissolved into the crystal lattice of Cu to form a Cu(Al) solution. A carbon-rich transition layer was formed at the interface between the diamond and the matrix. Excess Al inhibited the formation of Cu solid solution and reacted with Cu to form Cu3Al2. Diamond may be damaged to some extent by adding excess Ti3AlC2 in the raw materials, which may deteriorate the grinding performance of the composites. The grinding ratio value of copper–diamond composite was only 132, whereas that of the composites containing higher Ti3AlC2 content in the raw materials was approximately 350.

RETRACTED ARTICLE: Enhanced tensile strength and thermal conductivity in copper diamond composites with B4C coating

Boron carbide (B4C) coating on diamond particle is synthesized by heating diamond particles in a powder mix of H3BO3 and B in Ar atmosphere. The composition, bond state and coverage fraction of boron carbide coating on diamond particles are investigated. The boron carbide coating favors to grow on diamond (100) surface rather than on diamond (111) surface. Cu matrix composites reinforced with B4C-coated diamond particles were made by powder metallurgy. The addition of B4C coating gave rise to a dense composite. The influence of B4C coating on both tensile strength and thermal conductivity of the composite were investigated. When the B4C fully covered on diamond particles, the composite exhibited a greatly increase in tensile strength (115 MPa) which was much higher than that for uncoated-diamond/Cu (60 MPa) composites. Meanwhile, a high thermal conductivity of 687 W/mK was achieved in the B4C-coated-diamond/Cu composites.

Cu/synthetic and impact-diamond composite heat-conducting substrates

Composite material with high thermal conductivity was obtained by the method of thermal sintering of diamonds (synthetic and impact) and copper powder and by further hot isostatic pressing. The content of diamond (the particle size is 20 - 250 μm) in the diamond copper composite was 30 - 45 weight percent. The coefficient of thermal conductivity of copper diamond composite materials based on synthetic diamonds was measured to be 700 - 750 Wm-1K-1. The coefficient of thermal conductivity of copper diamond composite materials based on impact diamonds was measured to be 850 - 900 Wm-1 K-1. The coefficient of thermal expansion (CTE) was measured to be 5.5 - 6.5 • 10-6/°C for synthetic diamonds and 6.1 - 6.5 •10-6/°C for impact diamonds. The obtained copper diamond composite materials are promising to be used as crystal holders for semiconductor crystals in THz and microwave devices.

Cu/Diamond composite heat-conducting shims

Composite material with high thermal conductivity was obtained by the method of thermal sintering of a diamond (50 – 75%) with a size of 20 to 250 μm in a matrix of copper.Coefficient of thermal conductivity of copper diamond composite materials was measured and is 450 – 650 W·m-1·K-1. The coefficient of thermal expansion CTE was measured and is 5.5 – 7.5 · 10-6/°C. The obtained copper diamond composite materials are promising objects for use in THz and microwave devices.

Mechanical properties of a diamond–copper composite with high thermal conductivity

Abstract Using pressureless infiltration of copper into a bed of coarse (180 μm) diamond particles pre-coated with tungsten, a composite with a thermal conductivity of 720 W/(m K) was prepared. The bending strength and compression strength of the composite were measured as 380 MPa. As measured by sound velocity, the Young's modulus of the composite was 310 GPa. Model calculations of the thermal conductivity, the strength and elastic constants of the copper–diamond composite were carried out, depending on the size and volume fraction of filler particles. The coincidence of the values of bending strength and compressive strength and the relatively high deformation at failure (a few percent) characterize the fabricated diamond–copper composite as ductile. The properties of the composite are compared to the known analogues — metal matrix composites with a high thermal conductivity having a high content of filler particles (~ 60 vol.%). In strength and ductility our composite is superior to diamond–metal composites with a coarse filler; in thermal conductivity it surpasses composites of SiC–Al, W–Cu and WC–Cu, and dispersion-strengthened copper.

Simulation of matrix conductivity in copper–diamond composites sintered by field assisted sintering technology

This research investigates thermal conductivity properties of Cu/Zr alloys combined with diamond particles to form a composite that possess superior thermal conductivity. This article describes the use of a theoretical calculation and finite element analysis to compare to previously published experimental observations. Both theoretical calculations and finite element analysis indicate that experimental results cannot be explained solely by an improved interface between the matrix and diamond particles, as originally suggested. This study shows that the experimental results, theoretical calculations, and finite element analysis are in agreement when the thermal conductivity of the matrix is adjusted to compensate for the amount of zirconium lost to the interface. This finding can be used to predict the thermal conductivity of a composite material composed of a Cu/Zr matrix with diamond particles.

Thermal reliability of copper alloy–diamond composites produced by field-assisted sintering technology

This paper highlights the thermal properties of copper–diamond composites fabricated by field assisted sintering technology. The samples were fabricated using a matrix of copper alloyed with silver and zirconium. Previous reports have shown that these samples possess high thermal conductivity. This work examines the thermal conductivity of the samples after being subjected to thermal cycling. Coefficient of thermal expansion is also reported in this work.

Micro–Macro Analysis of Capacitor Discharge Sintering in Copper–Diamond Bead

Capacitor Discharge Sintering (CDS) is an ultrafast electric current assisted sintering method (ECAS) suited for electrically conductive metallic and metal‐ceramic composite powders. The technique is a solid state near net shape sintering process which is in general characterized by a very short discharge time (tens of milliseconds), very high current intensity peak (up to 350 kA) and relatively high pressure (up to 1 GPa) with minimum shrinkage. Computer modeling comes to aid in the setup of industrial processes to produce enhanced sintered products such as copper–diamond beads for stone cutting applications. The simulation of the CDS process introduces a new class of nonlinear problems, involving a complex bulk and contact multiphysics with an intricate coupling of micro–macro phenomena. The work presents a micro–macro CDS model along with the solution strategy developed to assess the densification behavior of a copper–diamond bead for stone cutting applications. The overall CDS model implements a four‐way coupling strategy which combines the relevant partial differential equations governing the electrical, thermal, and stress–strain fields over the macroscopic scale of the CDS system, with the densification kinetic model governing the particle scale phenomena. The results are presented in terms of field and shrinkage variables as a function of space and time.

Heat Slug Material Variation Analysis on Thermal Dissipation of High Power LED

Accession of power in high power LED light source has resulted in thermal issue which causes reliability malfunction due to deficient heat dissipation. However, the heat disspation of high power LED can be enhance by improving packaging material selection.Thus, in this work, the connotation of heat slug material on the thermal performance of high power LED package was analyzed through simulation method. The significance of two heat slug materials, copper (Cu) and copper diamond (CuDia) were evaluated in terms of junction temperature, von Mises stress and thermal resistance. The simulation was executed using Ansys version 11 at ambient temperature of 25 °C with natural convection condition.

Low-temperature densification of diamond/Cu composite prepared from dual-layer coated diamond particles

High-density diamond/Cu composites with good thermal properties were fabricated by low-temperature hot-press sintering via designing dual layers on diamond. The microstructure observations indicate that a good interface bonding is obtained between diamond and copper. The inner tungsten coating on diamond is uniform and the formed carbides establish chemical and covalent interaction at the interface. The outside copper coating changes the sintering system of diamond–copper to copper–copper and thus favors the low-temperature densification of diamond/Cu composites. Finally, the sintered composites with dual-layer coated diamond have excellent thermal conductivity of 695 W m−1 K−1 compared with the single coating diamond composites of 386 W m−1 K−1.

Microstructure and thermal properties of copper–diamond composites with tungsten carbide coating on diamond particles

An effective method for preparing tungsten carbide coating on diamond surfaces was proposed to improve the interface bonding between diamond and copper. The WC coating was formed on the diamond surfaces with a reaction medium of WO3 in mixed molten NaCl–KCl salts and the copper–diamond composites were obtained by vacuum pressure infiltration of WC-coated diamond particles with pure copper. The microstructure of interface bonding between diamond and copper was discussed. Thermal conductivity and thermal expansion behavior of the obtained copper–diamond composites were investigated. Results indicated that the thermal conductivity of as-fabricated composite reached 658Wm−1K−1. Significant reduction in coefficient of thermal expansion of the composite compared with that of pure copper was obtained.

Optimization of sintering parameters for diamond–copper composites in conventional sintering and their thermal conductivity

The diamond–copper composite system has become the most attractive material in the research and development of new materials for thermal management applications. In this work, copper matrix composites reinforced with diamond particles were produced by conventional sintering method through powder metallurgy route. Diamond particles were used as uncoated, copper(nickel) coated (CuD) and chromium coated (CrD). Diamond particles were mixed with copper powder mechanically and cold compacted under uniaxial conditions. The cold compacted pellets were sintered in a vacuum tube furnace. Cold compaction pressure, sintering temperature and holding time were optimized for maximum densification and the composites were produced with different volume percent of diamond particles at optimized parameters. The densification was found maximum for the composite samples cold compacted at 525MPa and sintered at 900°C for 2h. The best thermal conductivities achieved with uncoated, CuD and CrD particles were 275, 284 and 312W/mK respectively. In comparison, better densification and good interfacial bond with copper matrix was observed in the CrD reinforced composites.

A New Cutting Wire Prepared by Copper-Diamond Composite Electroplating

iamond cutting wire, as a new one, could overcome the defects of traditional cutting wire and would have a wide potential application. Electroplating diamond wire was prepared by composite electroplating in this article. The influence of cathodic current density, the diamond content in the electrolyte and other process conditions on the amount of diamond in the composite coating was checked by EDTA titration analysis. Effects of the diamond content in the electrolyte on electrochemical process of copper-diamond composite electro-deposition were investigated by measuring electrochemical polarization curves. With increasing the cathode current density and the diamond content in the electrolyte, the amount of diamond in the composite increased firstly, and reached a maximum, then decreased. The cathode current decreased with the increase of diamond content in the electrolyte. Copper-diamond composite plating process could be explained by Guglielmi two-step adsorption mechanism. The influence of plating parameters on the deposition behaviors of copper–diamond composite coating layers is ascribe to the change of diamond adsorption state on the cathode surface. After heat treatment, the largest wire tensile force is 159.7 N and the tensile strength reaches to 2258.8 MP.

LED Heat Dissipation Analysis Using Composite Based Cylindrical Slug

The optical efficacy and reliability of light emitting diode is extensively influenced by the operating junction temperature of the LED. Therefore, the evaluation of junction temperature is significant. This paper reports a simulation analysis on the heat dissipation of single chip LED package with based material, copper diamond (Cu/Dia) cylindrical heat slug.Ansys version 11 was utilized as the simulation platform. The junction temperature and stress of the LED chip under natural convection condition were evaluated with varied input power of 0.1 W, 0.5 W and 1 W. Results indicated the maximum junction temperature of LED chip was attained at input power of 1 W.

Thermal conductivity enhancement of copper–diamond composites by sintering with chromium additive

The thermal diffusivity (TD) and thermal conductivity (TC) of Cu–Cr–diamond composite materials were examined in the temperature range from 50 to 300 °C for diamond volume fractions of 22, 40, 50, 55, and 60 %. The samples were fabricated by the plasma pulse sintering (PPS) method. TC does not increase proportionally with the diamond fraction in the particular composite materials. The highest TD was determined for 50 % diamond volume fraction, and the evaluated TC reached 658 W m−1 K−1 at 50 °C. This article complements earlier articles concerning synthesis and characterization of the diamond–copper composites produced by the PPS method.

CuDia Slug Size Variation Analysis on Heat Dissipation of High Power LED

The current advancement of LED has prompt thermal challenges from the packaging point of view. The reliability of the LED is significantly influenced by each of its packaging component. This paper presents the investigation of heat slug size effect on the junction temperature and stress of single chip LED through simulation method. Ansys version 11 was utilized and the analysis was done with copper diamond rectangular heat slug under natural convection condition at ambient temperature of 25 °C.The simulation results indicated that junction temperature and the stress of the single chip LED is influenced by the size of heat slug.

Preparation of copper–diamond composites with chromium carbide coatings on diamond particles for heat sink applications

Cr7C3 coatings were formed on diamond particles for improving the wettability between diamond particles and copper. The coatings were formed with a reaction medium of chromium in mixed molten salt. Copper–diamond composites with Cr7C3 coatings on diamond particles have been fabricated by vacuum pressure infiltration method. The microstructure of interfacial bonding between diamond and copper was discussed. Thermal conductivity and thermal expansion behavior of the obtained copper–diamond composites with various fractions of diamond particles were investigated. The as-fabricated composite exhibit a thermal conductivity of 562 W m−1 K−1 associated with coefficient of thermal expansion of 7.8 × 10−6 K−1 with a Cr7C3-coated diamond volume fraction of 65%. These results indicate that the obtained composites are suitable for being heat sink applications.

Effect of molybdenum carbide intermediate layers on thermal properties of copper–diamond composites

Abstract Molybdenum carbide (Mo 2 C) coated diamond particles were prepared by molten salts method and the copper–diamond composites were obtained by vacuum pressure infiltration of Mo 2 C-coated diamond particles with pure copper. The formation mechanism of the Mo 2 C layers was investigated, and the microstructure, thermal conductivity and thermal expansion behavior of the obtained copper–diamond composites were studied. The coated layers were formed by using a reaction medium of MoO 3 in mixed molten salts, and the formation mechanism of the Mo 2 C layers on diamond particles was investigated. The result indicates that the formation of Mo 2 C layers occurred in two steps, that is, the reduction of MoO 3 to MoO 2 and the reduction of MoO 2 to Mo 2 C. The wettability between diamond particles and copper was effectively improved, and the relative density of the copper–diamond composites achieved 99.5%. The thermal conductivity reached 596 W m −1 K −1 , and the coefficient of thermal expansion was 7.15 × 10 −6 K −1 of the composites with 60 vol.% Mo 2 C-coated diamond. This composite is expected to be suitable for electronic packaging applications.

Preparation of high thermal conductivity copper–diamond composites using molybdenum carbide-coated diamond particles

Molybdenum carbide (Mo2C) coatings on diamond particles were proposed to improve the interfacial bonding between diamond particles and copper. The Mo2C-coated diamond particles were prepared by molten salts method and the copper–diamond composites were obtained by vacuum pressure infiltration of Mo2C-coated diamond particles with pure copper. The structures of the coatings and composites were investigated using X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The results indicated that the Mo2C coatings effectively improved the wettability between diamond particles and copper matrix, and Mo2C intermediate layers were proved to decrease the interfacial thermal resistance of composites. The thermal conductivity of the composite reached 608 Wm−1 K−1 with 65 vol.% Mo2C-coated diamond, which was much higher than that with uncoated diamond. The greatly enhanced thermal conductivity is ascribed to the 1-μm-thick Mo2C coatings. Mo2C coatings on diamond particles are proved to be an effective way to enhance the thermal conductivities of copper–diamond composites.