Browsing by Keyword "Thermal conductivity"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Graphene and its application in polymer composites(European Conference on Composite Materials, ECCM, 2014) Flórez, S.; Chapartegui, M.; Bustero, I.; Gaztelumendi, I.; Mendizábal, M.; Iraola, B.; Atxaga, G.; Jurado, M.; POLIMEROS; PRINTEX; EXTREMAT; Tecnalia Research & InnovationThis paper looks at the development of graphene/polymer nanocomposites to be used as adhesives for Thermal Interface Materials (TIMs) and lightweight high performance CFRP composite laminates with conductive properties. The addition of graphene, even at a very low concentration level (usually less than 5%), into a polymeric matrix can significantly improve its thermal conductivity. The achievement of a good dispersion of graphene and the interfacial bonding of graphene and the polymer matrix is a key aspect. Different qualities of graphene material have been characterised and tested to obtain good dispersion in the polymer matrixes tested. High improvements in the thermal conductivity for both applications under study have been achieved.Item Microstructural characterisation of copper/carbon nanofibre composites(International Committee on Composite Materials, 2009) Lloyd, J. C.; Barcena, J.; Clegg, W. J.; EXTREMATThe thermal conductivity and microstructure of a CuTi-0.5/CNF composite has been investigated. Microstructural characterisation involved FIB milling coupled with SEM microscopy, to obtain fibre distribution, and TEM microscopy, to study the fibre/matrix interface. From this, predictions of κcomposite were made and compared to measured values.Item Power-substrate static thermal characterization based on a test chip(2008-12-01) Jordà, Xavier; Perpiñà, Xavier; Vellvehi, Miquel; Coleto, Javier; MercadoThermal simulation is, nowadays, a basic tool to predict temperature distributions and heat fluxes of complex packages and modules. These variables are of main importance in high-power assemblies to analyze and predict their reliability limits. Nevertheless, the simulation results can be inaccurate due to the uncertainty of the values of the physical parameters involved in the models, as it is the case for the thermal conductivity of the dielectric layers (ceramics and composites) of the main families of power substrates [direct copper bonded (DCB) and insulated metal substrate (IMS)]. We propose a methodology for the in situ determination of these thermal conductivities under true operation conditions. Three test assemblies based on a thermal test chip and different types of power substrates (two IMS and one DCB) have been characterized in order to deduce their thermal resistance. Three-dimensional numerical models of the assemblies have also been developed. Thereby, the thermal conductivity of the critical layers is derived by minimizing the error between the experimental and the simulated thermal resistances. From the subsequent simulation results, the vertical temperature distributions are analyzed in order to predict the thermal stresses of the different layers inside the substrates.Item Study of thermal conductivity and microstructure of copper-5 wt%titanium/carbon nanofibre composites(2010) Lloyd, J. C.; Barcena, J.; Clegg, W. J.; EXTREMATCarbon nanofibres have high thermal conductivities of approximately 1200 W m-1 K-1, thus have great potential as the high conducting phase in composite materials for use as heat distributors in high heat flux applications. A copper-5wt% titanium/carbon nanofibre composite was fabricated, and its thermal conductivity and microstructure was studied. Microstructural characterisation involved focussed ion beam milling coupled with scanning electron microscopy, to obtain the fibre distribution, and transmission microscopy, to study the fibre/matrix interface. The composite thermal conductivity was determined from laser flash measurements and was found to be much lower than that predicted using the Eshelby mean field approach. A study of the structure showed that this was the result of cracking at the CNF/matrix interface and degradation of the carbon fibre graphitic structure.