The Advanced Ceramics Laboratory offers a multi-disciplinary environment with extensive materials processing facilities and thermo-mechanical characterization techniques. Current research activities fall in three main areas: a) Hybrid materials for extreme environments, such as thermo-mechanical protection systems (TPS) for spacecraft (funded by the European Space Agency, ESA), b) functional industrial ceramics, such as heterogeneous catalysts for environmental protection and chemical synthesis and c) Reduction of environmental impact of production processes. In the first area, recent major developments are the “HybridTPS” system which is undergoing feasibility studies as well as the new BioPICA ablator system for ultra high velocity spacecraft. Recently, we succeeded in obtaining RD funding under a FP7/Space project “RASTAS SPEAR” on the further development of an ablating TPS for spacecraft. The lab also has a role in the FP7/Space project HYDRA on TPS development. A new FP7/Space project – PULCHER – has just started on 1 Jan 2013 to develop new rockets for exploration craft. In addition, we recently received an invitation to partake in a project on developing structural units on the Moon using lunar raw materials as well as to carry out SHS experiments under microgravity conditions. In the second area, we have developed very sensitive inorganic catalysts using the SHS method for use in vehicles and to increase chemical synthesis yields. This is the subject of a number of industrial projects. Our Microwave-assisted drying technology is aimed at the heavy ceramics, lignite and waste materials industries in collaboration with the manufacturing SME “AIT SA” of Thessaloniki, reducing substantially energy use and environmental impact. In this respect, end users of the MW heating technology (customers of AIT SA) include large ceramics manufacturers in Greece and Europe as well as the Greek Power Corporation for lignite processing. Finally, we are currently developing a new method, based on MW-assisted decomposition and electrostatic separation, for converting Carbon Dioxide to C, CO and O2, thereby reducing industrial emissions of CO2 from fossil-fuel burning plants.
- Self-Propagating High-Temperature synthesis (SHS) of refractories, catalysts, intermetallics and other materials
- Hybrid engineering materials for spacecraft protection
- Inorganic catalysts for Industrial and environmental applications
- Microwave processing for reduced environmental impact and energy use in industry
- Nanostructured materials for protection against Cosmic Rays
- New spacecraft propulsion systems
- Services on Mechanical and thermal properties
Self-Propagating High-Temperature synthesis (SHS) of refractories, catalysts, intermetallics and other materials
The SHS method exploits highly exothermic solid-state combustion reactions for the synthesis of many engineering materials, many of them unique, with minimal use of externally applied heat. Although the starting temperature may be as low as ambient, the final combustion temperature may reach as high as 3000<oC, depending on the system and conditions. The method offers very significant advantages over traditional furnace-based methods, the most significant being lower overall energy usage and very rapid (seconds) synthesis times. Materials such as carbides, borides, nitrides, oxides, intermetallics, composites are produced at a fraction of the cost of traditional methods. Using SHS, in the Advanced Ceramics Laboratory we have developed a range of very active catalysts, refractories, inorganic pigments, high-temperature refractories and intermetallics. Currently, we are investigating new refractory compositions of MgO/MgAl2O4 (see our ESA-funded activities), new catalytic systems based on MgxCoyAl2O4 for pyrolysis of hydrocarbons, the system NixAlyOz for hydrogenation processes and various mixed oxides as industrial pigments.
Hybrid engineering materials for spacecraft protection
Spacecraft entering a planetary atmosphere at very high speeds experience plasma-level surface temperatures as a result of friction with the atmosphere. The incident heat fluxes depend on the conditions (shape, speed, atmosphere etc) and can reach up to 30MW/m2, giving, over a transit time of up to 20-30 seconds, a total heat load of up to 700MJ/m2. Since no engineering material can sustain such heat fluxes, ablative thermomechanical protection systems (TPS) are used, made of carbon-phenolic composites, sometimes incorporating silicon. But these suffer from ablation-induced irregular surface recession and do not offer any protection against high-speed particulate impact. To address these limitations, we are currently developing 2 new types of TPS, with European Space Agency support. First, a “HybridTPS” composite made of a porous MgO-ceramic (made by SHS) filled with a phenolic ablator, which offers impact protection as well as almost no recession. Proof of concept has been completed and current work centres on enhancing the ablative heat-dissipation properties. A recent system under development, is the “BioPICA”, is a phenolic filled-carbon structure made by Microwave-assisted pyrolysis of wood.
Inorganic catalysts for Industrial and environmental applications
Inorganic catalysts are the back-bone of the chemical industry. Nearly all industrial chemicals are manufactured using catalysts, since catalytic materials increase the reaction kinetics by many orders of magnitude without actually taking part in the reaction. The same advantages are also conferred by catalysts for cleaning of environmental pollutants, e.g. in factory emission scrubbers and car exhaust pipes. Catalyst activity (and selectivity for particular processes) depends on the composition, the open porosity but also crucially on the amount of “active centres” on its surface, usually dictated by a degree of distortion of the atomic lattice. Most catalytic systems are industrial secrets and are specially developed for each process. We are developing new inorganic catalytic systems using the SHS method for a range of industrial and environmental applications, whereby the catalytic activity is enhanced by the creation of a large number of active centres and metastable, often non-stoichiometric compositions. The processes we are studying include ethylene and propylene production, deep oxidation of methane, CO oxidation, hydrogenation of naphtha and diesel and others and SHS catalysts offer significant improvements over existing industrial systems.