This goal will be achieved by a unique combination of advanced characterization techniques such as high-resolution and analytical transmission electron microscopy and micro-Raman analysis, combined with scanning microscopy, X-ray diffraction, thermogravimetry and other methods. The combination of these characterization methods, including advanced techniques for sample preparation, will allow us to relate the information on the oxide scales microstructure on the meso- and nanoscopic levels to that of the material and to the exact processing conditions.
The co-operation between partners drawn from companies developing new process technology (ESK, Germany; MRC, Ukraine and ISSPS, Belarus), research institutes specializing in oxidation of ceramics (University of Tuebingen), microstructural characterization (CNRS, France), mathematical modelling (IPMS, Ukraine) and end-users (ABB, Germany) will definitely bring the project to success.
Ceramics are the only materials to allow component temperatures up to 1500°C in oxidizing environments, which are considered necessary for furnace linings and rollers in fast firing of porcelain and new generations of stationary gas turbines with a higher efficiency. Current linings with traditional SiC-based materials are known to have problems because of low life time. The life time limitation is due to the oxidation/corrosion damage of the materials. Such materials can not be considered for gas turbines because only extremely long lasting materials (operation times >10.000 hrs) with high reliability could be used.
An improvement in fumace parts in a new generation of firing fumaces will allow more economic manufacturing of porcelain due to a shorter firing duration, less time for component changes and thus improve the competitiveness of the European ceramic industry. Use of ceramic combustion chambers in stationary gas turbines will increase their working temperature, thus resulting in a higher efficiency, cheaper electrical energy and decrease of the contamination of environment with exhaust gases. The expected consumption of ceramics for lining of combustion chambers of turbines is about 40 t/year and for components of firing furnaces it exceeds 100 t/year. For both applications only advanced Si-based ceramics (SSiC, Si3N4) possess reasonable chances to allow the improvements envisaged above. However, corrosion of the majority of commercial advanced ceramics results in degradation of properties of silicon nitride and silicon carbide based ceramics at ~1400°C or even lower temperatures, in particular in H2O-bearing environments. Therefore, corrosion protection is a vital part of the development of new materials with improved performance and reliability.
The ceramics envisaged to serve in the applications above will have low porosity, low additive content and a designed protective scale. Thus some of the partners and contractors (ESK, Germany; MRC, Ukraine and ISSPS, Belarus) will contribute the materials and optimize it for low porosity and additive content. The others will focus on the development of the scale as the most cost-effective method.
The main objective of the proposed project is therefore to gain fundamental control of the microstructure and growth mechanisms of oxide scales on silicon carbide and silicon nitride ceramics. We will develop predictive tools for scale development and component life time prediction by mathematical modelling of complex kinetics with a direct feed-back to the material designers (ESK, MRC), which develop ceramics with an improved oxidation resistance at temperatures ~1500°C and to endusers to optimize the working regimes of ceramic parts. Protection of ceramics by in-situ formed oxide scales can lead to a major breakthrough of silicon-based ceramics in high-temperature applications.
Funding SchemeCSC - Cost-sharing contracts
94407 Vitry Sur Seine