No abstract

Improving the efficiency of manufacturing processes becomes more and more important. This paper describes a new approach where two technologies are combined to manufacture wear-resistant mold inserts for powder injection molding. By combining laser ablation and electrical discharge machining (EDM) specific advantages of the respective technology can be utilized while drawbacks can partially be eliminated.In the following machining results of die-sinking EDM, EDM milling and laser ablation with structure sizes down to 20 lm are presented and a concept for a new type of electrode for EDM is introduced. Furthermore the combined machining center is presented.

No abstract

This paper describes a measurement method and a measuring system to determine absolute Seebeck coefficients of thermoelectric bulk materials with the aim of establishing reference materials for Seebeck coefficients. Reference materials with known thermoelectric properties are essential to allow a reliable benchmarking of different thermoelectric materials for application in thermoelectric generators to convert thermal into electrical energy or vice versa. A temperature gradient (1 to 8) K is induced across the sample, and the resulting voltage is measured by using two differential Au/Pt thermocouples. On the basis of the known absolute Seebeck coefficients of Au and Pt, the unknown Seebeck coefficient of the sample is calculated. The measurements are performed in inert atmospheres (N 2 ) and at low pressure (30 to 60) mbar in the temperature range between 300 K and 860 K. The measurement results of the Seebeck coefficients of metallic and semiconducting samples are presented. Achievable relative measurement uncertainties of the Seebeck coefficient are on the order of a few percent.

In this paper, we describe a measuring system based on the Van der Pauw principle with four calibrated type S thermocouples. By means of this system, we conducted traceable measurements of the absolute Seebeck coefficients and the electrical conductivity of thermoelectric bulk materials to establish a precise determination of the power factor. The results of a comparative investigation of metallic (ISOTAN® and Nickel) and semiconducting (SiGe) materials in the temperature range of 300 K–1100 K are presented. The good agreement of the Seebeck coefficients and electrical conductivities measured using the system and the data reported from the literature and values of these transport properties premeasured using another measuring system forms the basis for the usage of the system for the further certification of thermoelectric reference materials for the power factor up to 1100 K.