On one hand, two electro-deposition processes, from copper based industrial wastes, have been optimised for copper coating of carbon-based materials (small graphite particles and short carbon fibber based commercial felts) to be used as suitable reinforcements for CuMCs manufacturing. On the other hand, two CuMC alternative manufacturing techniques have been also optimised: Squeeze casting and Diffusion Bonding. The copper composite materials produced by means of both technologies have been characterized from different points of view: micro-structural, physical, thermal and mechanical. Moreover, a CuMC heat sink electronic component as well as two CuMC plates for both an air-air thermal exchanger and electrical applications (in general) have been produced. Finally, different tests in-service conditions have been performed to evaluate the suitability of the new CuMC prototypes for the three applications of interest for the end-users involved in the Project. At the end, a first technico-economical evaluation of the main results achieved within the Project has been made.
Nowadays, copper and aluminium alloy components used in electronic, electrical and thermal management devices do not comply all the basic requirements needed in working conditions. Breakage of electronic devices due to coefficient of thermal expansion (CTE) mismatch between electronic and adjacent components, failure of integrated circuits because of device overheating, excessive weight for electronic devices in aeronautic and aerospace applications, erosion in electrical contacts at high density currents, low hardness for high current switching operation, etc.., are some of the most important problems related to the use of conventional materials in these applications. Therefore, there is a need for improving performance and reliability of materials for demanding processes through the use of advanced materials such as copper matrix composites (CuMC). CuMC is a new kind of material which most attractive properties are higher electrical and thermal conductivities, higher modulus and stiffness, improved creep resistance and resistance at high temperatures, lower and tailorable coefficient of thermal expansion and density in comparison to unreinforced copper. Therefore, CuMC will meet the needs arising from key issues such as increasing packaging density, increasing requirements reliability, more severe environments, weight restrictions for aeronautic or aerospace systems, etc.., in the electronic, electrical and thermal management industries. On the other hand, a recovery method based on electrochemical deposition of heavy metals (copper, nickel, etc...) on to the surface of graphite cathodes (either felts, fibres or particles), will be combined with CuMC manufacture as a suitable, cheap method to obtain a copper coating onto graphite or silicon carbide particles as precursor to their incorporation in a copper matrix (CuMC). Once the fibre is coated by the matrix, it is submitted to a secondary process for CuMC manufacture. The technologies to be developed in this second step are pressure infiltration of preforms (squeeze casting or vacuum infiltration) and diffusion bonding process. They will compete with the commercially available CuMC manufactured by expensive powder metallurgy processes not only in an economic basis but also in physical and mechanical properties achieved. This project will cover several scientific and technological Brite Euram objectives, such as 2.1.1.S, 2.1.2.S, 2.1.3.S and 2.1.1.M. The research developed in this project will be related to the optimisation of copper recovery technique through its electrochemical deposition of cathode surface and its subsequent use in CuMC manufacture. This will allow to get technological improvements to the partners involved in it. Moreover, the alternative of using graphite coated as raw material for CuMC would become the recovery process more profitable apart from the environmental benefits. Industrial companies will be able to incorporate materials and technologies developed in this project that, nowadays, are not viable in commercial industrial sector. Therefore they will become more competitive in European and worldwide scale.
Funding SchemeCRS - Cooperative research contracts
CH1 6ES Chester
EN8 7HL Waltham Cross
20009 San Sebastián