Thermo-physical properties and TEM analysis of silver based MMCs utilizing metallized multiwall-carbon nanotubes

Metal matrix composites with embedded multiwall-carbon nanotubes (MWNT) are attractive because MWNTs exhibit high intrinsic thermal conductivity. Thus to improve the thermal conductivity of a metal matrix, silver matrix composites with MWNT were prepared by “chemical” mixing, different active elements were introduced enhancing the bonding between inclusions and matrix. The evolution of the thermal conductivity and the coefficient of thermal expansion CTE as a function of the MWNT concentration and the presence of active elements cobalt, molybdenum or nickel in the silver matrix in Ag–X/MWNT composites are presented. A transition from weak to strong matrix/MWNT bonding is observed by adding active elements, the latter leading concomitantly to an increase in thermal conductivity and a decrease in CTE. The thermal conductivity was found to increase by up to 10% for a composition of 0.2 wt.% MWNT and cobalt as active element and a 6% decrease in CTE compared to a pure silver reference.