Fabrication, Microstructure, Thermal and Electrical Properties of Copper Heat Sink Composites

Abstract

Copper as well as copper base composites reinforced with coated and uncoated 1 wt% diamond, graphite particles or short carbon fibers are prepared by powder metallurgy process. The reinforcement particles were encapsulated with silver as well as copper layer by using the electroless deposition technique to investigate the influence of the reinforcement surface coating on the microstructure, density, electrical and thermal properties of the sintered samples. The coated and the uncoated powders were cold compacted at 600 MPa, and then sintered at 1173 K (900˚C) for 2 h under hydrogen atmosphere. The phase composition, morphology and microstructure of the prepared powders as well as the copper base sintered composites were investigated using X-ray diffraction analysis (XRD) and Scanning Electron Microscope (SEM) equipped with an Energy Dispersive Spectrometer (EDS) respectively. The density of the sintered composites was measured by Archimedes method. The copper base consolidated composites had a density up to 96% and the reinforcement coated particles were distributed uniformly within the copper matrix better than the uncoated one. The electrical resistivity at room temperature and the heat transfer conduction of the produced samples were measured in a temperature range between 323 K (50˚C) and 393 K (120˚C). The results observed that the sintered materials prepared from the coated powder have lower electrical resistivity than the sintered materials prepared from the mixed powders. On the other hand the thermal conductivity values were calculated using the heat transfer conduction values by means of the Fourier formula. The results observed that the thermal conductivity of copper is (391

Microstructure and properties of BN/Ni-Cu composites fabricated by powder technology

“…A preliminary study was takes place to optimize the compaction pressure and the sintering conditions of the prepared BN/Ni-Cu powder mixtures according to our previous work [17,[21][22][23][24][25][26]. The obtained compacts are sintered for 2 h in a closed furnace in controlled atmosphere of 3:2 N 2 /H 2 gas mixtures at 1000 C. Finally, the furnace is turned off and the sintered specimens are maintained in the furnace for cooling in N 2 atmosphere.…”

An Equivalent Heat Transfer Model Instead of Wind Speed Measuring for Dynamic Thermal Rating of Transmission Lines

“…After the convective heat transfer coefficient h of the Al ball is determined, the correlation of convective heat losses between the Al ball and conductor is established based on the characteristic numbers in the experimental correlations of heat convection. In the experimental correlations, the convective heat transfer coefficient h of the Al ball is related to a series of characteristic numbers (including Nusselt number Nu, Reynolds number Re s , Prandtl number Pr, and Grashof number Gr) [35,38]. Specifically, the relationship between Nusselt number Nu and the convective heat transfer coefficient h of the Al ball is as follows:…”