Regina Knitter

Microstructure Analysis of Melt-based Lithium Orthosilicate/Metatitanate Pebbles

Lithiumhaltige Keramiken wie Lithiumorthosilikat (Li4SiO4) und Lithiummetatitanat (Li2TiO3) werden zur Verwendung als Tritiumquelle zukünftiger Fusionsreaktoren entwickelt. Im aktuellen Design des heliumgekühlten Schüttbettblankets werden diese Keramiken als Schüttbetten mit Kugeldurchmessern von etwa 1 mm in den das Plasma umgebenden sogenannten Blanketmodulen eingesetzt. Die Herstellung der Kugeln erfolgt über einen modifizierten, Einzeltropfen erzeugenden Schmelzprozess. Dieses Verfahren bietet bezüglich des Ertrags und des Recyclingpotenzials des verwendeten Materials zahlreiche Vorteile.

Heating Concepts for Ceramic Microreactors

For high-temperature applications of a microreactor system the precise temperature control inside the reactor is important to optimize the yield of chemical reactions. If a microreactor system is operated inside a tube furnace, at best a homogeneous temperature distribution will be achieved inside the reactor. Heating elements that are integrated in the reactor have the potential to realize localized heating. Moreover, integrated heaters offer an efficient heating and a more convenient handling. Ohmic resistance heating for a modular ceramic microreactor system was investigated by direct connection and induction heating. The ceramic reactor system was modeled with FEM methods. Heat transfer and stress were calculated and compared with measurements taken.

RP process chains for ceramic microcomponents

Conventional shaping processes for ceramics are mostly based on a powder‐technological molding process using a negative mold and subsequent thermal compaction. Especially for prototypes and small lot series of microcomponents the outlay for molds are the major costing factor. Consequently the use of rapid prototyping (RP) processes can decisively reduce the costs and time in product development of ceramic microcomponents. In spite of the fact, that a large number of freeform fabrication techniques for different materials were developed in recent years, most generative techniques of ceramics still have different drawbacks for the fabrication of prototypes and often exhibit limited resolution compared to those of polymers. The combination of RP techniques such as micro stereolithography and ceramic injection molding in a RP process chain can fill in the gap between the limited applicability of solid freeform fabrication of ceramics and the restricted material properties of polymers.

Overview of the HCPB Research Activities in EUROfusion

In the framework of the EUROfusion’s Power Plant Physics and Technology, the working package breeding blanket (BB) aims at investigating four different BB concepts for an EU demonstration fusion reactor (DEMO). One of these concepts is the helium-cooled pebble bed (HCPB) BB, which is based on the use of pebble beds of lithiated ternary compounds and Be or beryllides as tritium breeder and multiplier materials, respectively, EUROFER97 as structural steel and He as coolant. This paper aims at giving an overview of the EU HCPB BB Research and Development (R&D) being developed at KIT, in collaboration with Wigner-RCP, BUTE-INT, and CIEMAT. The paper gives an outline of the HCPB BB design evolution, state-of-the-art basic functionalities, requirements and performances, and the associated R&D activities in the areas of design, functional materials, manufacturing, and testing. In addition, attention is given also to the activities dedicated to the development of heat transfer augmentation techniques for the first wall and the corresponding testing. Due to their nature as design drivers, a brief overview in the R&D of key HCPB interfacing areas is given as well, namely, the tritium extraction and recovery system, the primary heat transfer and power conversion systems, and safety topics, as well as some specific activities regarding the integration of in-vessel systems through the BB. As concluding remarks, an outline of the standing challenges and future R&D plans is summarized.

Kristallisation von überstöchiometrischem Lithiumorthosilikat

Aus der verwendeten Kugelcharge mit einer Zusammensetzung von 65,4 mol% L i​2 O und 34,6 mol% Si O​2 wurden Kugeln mit einem Durchmesser von <50 μm ausgesiebt und für die Versuche verwendet. Thermoanalytische Untersuchungen erfolgten mit einer TG/DSC (STA 449 C Jupiter, Netzsch) unter Luft mit einer Heizrate von 5 K/min bis 900 °C. Röntgenographische Heizaufnahmen wurden mit einem ortsempfindlichen Detektor und einer Heizrate von ebenfalls 5 K/min bis 800 °C durchgeführt (Panalytical XPert Pro, Philips). Zusätzlich wurden bei RT RöntgenbeuKristallisation von überstöchiometrischem Lithiumorthosilikat