Papers by Author: Łukas Ciupiński

Abstract: One of the key problems in copper-diamond composites is the interface between the metal matrix and the diamond reinforcement. In order to take advantage of the high thermal conductive diamond filler in a composite the design of the interface is crucial. One approach to minimize the thermal contact resistance between metal and diamond reinforcement is to coat the diamonds with functional layers, e.g. Mo or W. For coating of diamonds PVD and CVD have been used followed by characterization of coating thickness by different methods. The coated diamonds were used for composite manufacturing and the thermal diffusivity of the compacted materials was measured.

Abstract: Thermal management materials frequently have multi-phase composite character with complex architecture of the constituents. As a result, design rules are needed which can be used in selection of the phases and optimizing their volume fractions. The study shows that such are provided by finite element modeling of these composites. This is demonstrated for a diamond-SiC-Si-(Al) composites, which have been optimized in terms of the volume fraction of SiC, contact area between the components and presence of open porosity.

Abstract: A Pulse Plasma Sintering (PPS) process was employed to manufacture Cu-diamond composites with a 50% volume fraction of each constituent. Pure and Cr (0.8wt.%) alloyed copper matrices were used and commercial diamond powders. The composites were sintered at temperature of 900°C for 20 min and under pressure of 60 MPa. In these sintering conditions diamond becomes thermodynamically unstable. Cu0.8Cr-diamond and Cu-diamond composites with relative densities of 99,7% and 96% respectively were obtained. The thermal conductivity of Cu0.8Cr-diamond composite is equal to 640 W(mK)-1 whereas that of Cu-diamond is 200 W(mK)-1. The high thermal conductivity and relative density of Cu0.8Cr-diamond composite is due to the formation of a thin chromium carbide layer at the Cu-diamond interface.