INFLUENCE OF DISPERSANT ON RHEOLOGY OF ZIRCONIA-PARAFFIN FEEDSTOCKS AND MECHANICAL PROPERTIES OF MICRO PARTS FABRICATED VIA LPIM

摘要

The interest in miniaturization of components is rising in many sectors such as medical technology. Due to their specifically good mechanical, chemical, thermal, tribological and other physical properties ceramic micro components are gaining importance in microsystems technology (MST). Micro powder injection molding (μ-PIM) enables accurate manufacturing of complex-shaped micro parts. In particular, low-pressure injection molding (LPIM) is predestined for the fabrication of prototypes and small series production of ceramic micro components, as tooling costs are low and simple molds can be used. In this study the dispersant's influence on the Theological properties of zirconia-paraffin LPIM feedstocks and on the mechanical properties of sintered micro bending bars (200 x 200 x 1200) μm~3 was investigated. A considerable time dependency of the viscosity and the yield stress of the feedstocks were found, which affects further processing and reproducibility. Dispersant concentration has also an impact on the bending strength calculated from three-point bending tests. During thermal debinding the surface tension of the binder phase is influenced by the dispersant and, thus, leveling and healing of surface defects of the micro parts can take place. The thermal debinding step was investigated with real-time observations to assess the effect of various parameters on the defect healing process.