TY - THES ID - 3257992 TI - Electro-erodable ceramic composites AU - Salehi, Arezou S. AU - Katholieke Universiteit Leuven PY - 2008 SN - 9789056829711 PB - Leuven Katholieke Universiteit Leuven DB - UniCat KW - 666.3 KW - Academic collection KW - Ceramics in general. Ceramic raw materials KW - Theses KW - 666.3 Ceramics in general. Ceramic raw materials UR - https://www.unicat.be/uniCat?func=search&query=sysid:3257992 AB - ZrO2 based composites with the ability to be machined by electrical discharge machining (EDM) are developed. The importance of EDM is in its capability for shaping complex ceramic parts, which are difficult to be machined by conventional machining techniques. A minimum electrical conductivity threshold, which is a prerequisite for EDM, was obtained by incorporating hard and electrically conductive TiN, TiCN, NbC and WC phases into the ZrO2 matrix. The effect of the type and content of the secondary phases, pressure assisted sintering method, sintering temperature and ZrO2 stabiliser type and content on the mechanical properties and hydrothermal stability of the composites is investigated. As a result, a new class of ZrO2-based ceramic composites, including real nanocomposites, was developed which not only allow EDM machining, but also offer a unique combination of hardness, strength and fracture toughness. An innovative hot isostatic pressing method is developed in order to upscale the production of the ZrO2-based composites. A finite element tool was developed to calculate the thermal expansion coefficient, thermal and electrical conductivity, stiffness and thermal residual stresses in the constituent phases of the ZrO2-based composites from their densified microstructure using the intrinsic properties of the constituent phases. The results of the FE model were compared with analytically calculated and experimentally measured data. Omwille van de moeilijke en dure conventionele bewerking van keramische materialen werden vonkerodeerbare ZrO2-basis composieten ontwikkeld. De minimale elektrische geleidbaarheid, een kritische voorwaarde voor vonkerosie, werd bekomen door het toevoegen van een harde elektrische geleidende TiN, TiCN, NbC of WC fase aan de isolerende ZrO2 matrix. Als resultaat werd een nieuwe klasse ZrO2-basis composieten ontwikkeld die niet alleen te bewerken is via vonkerosie, maar tevens een unieke combinatie aan hardheid, sterkte en beuktaaiheid heeft. ZrO2 based composites with the ability to be machined by electrical discharge machining (EDM) are developed. The importance of EDM is in its capability for shaping complex ceramic parts, which are difficult to be machined by conventional machining techniques. A minimum electrical conductivity threshold, which is a prerequisite for EDM, was obtained by incorporating hard and electrically conductive TiN, TiCN, NbC and WC phases into the ZrO2 matrix. As a result, a new class of ZrO2-based ceramic composites, including real nanocomposites, was developed which not only allow EDM machining, but also offer a unique combination of hardness, strength and fracture toughness. ER -