Powder injection moulding of conductive glass-carbon composites for electrical resistors

A new promising material for power resistors which are used in power supplies, power conversion circuits or as heating elements are electrically conductive glass-carbon composites. Their resistivity can be adjusted by the carbon type and the carbon content. Manufacturing such resistor components by powder injecting moulding gives the advantage of shape complexity without machining of sintered parts. This allows forming of cooling rips, incorporating holes or integrating suspensions, thus no additional housings need to be assembled. The application of such light weight sintered glass-carbon-composites minimizes the need of cost intensive metals or alloys in power resistor applications or for heating elements. Within the presented work graphite was used as conductive phase and feedstocks wer e prepared based on a glass powder and a polyethylene-wax binder system. Debinding was conducted under inert gas in order to prevent graphite oxidation. The sintered specimens had a resistivity between 0.4 and 1.9 Ocm, depending on glass particle size and graphite content. By applying an electric power of 14 W on a test structure for heating applications homogenously distributed temperatures up to 140 °C were reached.