Ceramic Microwave Absorbers
Development of Complex Nanotechnology for Production of Ceramic Microwave Absorbers on the Base of Beryllium Oxide
Tech Area / Field
3 Approved without Funding
East-Kazakhstan Technical University, Kazakstan, Ust Kamenogorsk
- Kazakh National University / Research Institute of Mathematics and Mechanics, Kazakstan, Almaty\nCompany limited liability Altrade, Kazakstan, Ust Kamenogorsk
- University of Notre Dame / Department of Chemical and Biomolecular Engineering, USA, IN, Notre Dame\nPolytechnic University of Valencia / Institute of Pure and Applied Mathematics, Spain, Valencia\nCranfield University, UK, Swindon
Project summaryAt present, machine building, power and electronic engineering, and radio-electronics industries are more and more in need of highly efficient absorbers of microwave radiation. Production of highly efficient microwave absorbing materials is a high priority for developing up-to-date equipment and installations such as traveling-wave tubes (TWT), klystron tubes, etc., and for absorbing intensive and hazardous microwave fields that can penetrate beyond the boundaries of research units and commercial plants.
Besides, microwave absorbing materials can be applied as heat converters for improving heat exchange in the microwave field. In the future, heat converters will be widely applied for volumetric microwave heating of liquid media, for instance while advanced hydrocarbon processing (A.V. Bakhonin, et al., Application of microwave electromagnetic emission for hydrocarbon catalytic dispersion, Petroleum refining and petrochemistry, M., TsNIITEneftekhim, 2002, No 2, pages 19-23.)
Technical literature describes microwave absorbing powdered compositions of tungsten and electrocorundum (Al2O3), and austenitic steels and Al2O3 (Yu.K. Kovernistyi, I.Yu. Lazareva, A.A. Ravayev, Microwave absorbing materials, М.: Nauka, 1982, 164 pages, illustrated). Some experience is accumulated in the area of applying microwave absorbing ceramics made of aluminium oxide and titanium dioxide. (V.N. Batygin, N.D. Yefremova, et al., Volumetric absorbers for high power TWTs, Elektrotekhnika, 1970, Issue 11, Microwave Electronics, pages 95-102).
These Al2O3-based materials are defined by low thermal conductivity (10-15 W/m·K), and under excessive heat loads, the elements run hot, which results in degradation of basic electromagnetic properties: the attenuation factor and the standing-wave factor.
Application of beryllium oxide (berlox) with thermal conductivity exceeding 250 W/m·K instead of aluminium oxide with thermal conductivity of 20 W/m·K will promote production of composite materials made of ВеО + TiO2, ВеО + SiC, etc. (with thermal conductivity exceeding 60 W/m·K) and will ensure significant increase in quality and reliability of microwave absorbers. Properties of berlox-based ceramic materials have been enhanced during team-work of the East Kazakhstan State Technical University (EKSTU) and ISTC on the Project of Developing Technology for Beryllium Oxide Based Ceramic Production by Ultrasonic Casting Method (Project K–505, executed in 2003-2006). Therefore the proposed research should be considered as continuation of ISTC’s K–505 Research Project (see the Summary Report attached).
The objectives of this project are as follows: to study formation of composite makeup of ВеО + ТiO2, and ВеО + SiC under conditions of sintering in the controlled atmosphere; to study effects of components preliminary preparation, molding methods (semidry molding, thermoplastic ceramic slurry casting, and ultrasonic activation), and sintering methods (pressureless or pressure assisted); to develop and implement the integrated nanotechnology; and to manufacture and test pilot batches.
Technology processes, equipment, accessories, and implements developed for manufacturing ceramic microwave absorbers will promote decrease in processing deficiencies during inpidual process stages and increase in yield of non-defective from 60-60% to 85-95%. Manufactured products will be defined by high stability of absorbing properties within a range of operating temperatures, by the attenuation factor over 10 decibel (dB) and by the maximum standing wave factor of 2.0. This will result in reducing production costs of metallized products and increasing their competitiveness in the world market.
Intellectual property will be protected by patents and license agreements.
The Serikbayev East Kazakhstan State Technical University (EKSTU), “Altreid” LLC and the Research Institute of Mathematics and Mechanics at the Kazakh National University (RIMM KazNU) have 25-year experience in working with fine engineering special-purpose ceramics made of aluminum, calcium, magnesium, silicon, beryllium, and zirconium oxides; as well as experience in computation and theoretical research in thermal physics, liquid, gas and plasma mechanics, taking account of physico-chemical transformations. These institutions have own production laboratories and industrial sites equipped to perform a complete cycle of manufacturing sophisticated ВеО-based ceramic products and their metallization by screen printing, pasting, vacuum deposition, and spraying methods; and to create any patterns by photolithography methods. Key developers have an experience of 10 to 30 years.
The project is targeted at the following:
- Providing equipment, accessories and tools for experiments and samples testing;
- Recording results of experiments and testing of pilot samples at all stages;
- Developing rheological model of initial components quantitative and granulation proportion;
- Recording calculation results of dispersion and agitation by ultrasonic activation;
- Carrying out production of a pilot batch and obtaining results of its testing;
- Developing the integrated nanotechnology for manufacturing ВеО-based microwave absorbers.
In accordance with the technological approach to the procedure, comprehensive analysis will be conducted to study specific features of preparation of initial components, molding compositions (molding material and ceramic slurry), effects of ultrasonic (US) activation on dispersion and agitation, pressureless sintering and hot molding, application of metal-sprayed coating by vacuum magnetron deposition, mechanical treatment by abrasive diamond tools – all aimed at enhancing reliability, achieving stable results and improving necessary understanding of basic regularities of the process as a whole.
Generalization of research results will promote application of the developed technology for manufacturing not only berlox-based metal coated ceramic products but also products made of aluminum oxide, zirconium, etc., as well as for manufacturing carbide-based and nitride-based ceramic materials.
The scope of activities consists of three stages covering the whole process.
The first stage includes:
Development of technology to produce initial oxide and carbide powders in accordance with specifications. Analysis of effects produced by granulation composition and preliminary synthesis of mixture components on product structure and phase composition. Practical and theoretical determination of the optimum component proportion.
The second stage includes:
Analysis of molding mixture preparation methods; effects of US activation on components dispersion and agitation; effects of sintering technology on properties of products manufactured by semidry molding, thermoplastic ceramic slurry casting (with and without US activation), and hot molding. Determination of structure, phase composition and absorbing properties.
The third stage includes:
Development and implementation of nanotechnology and equipment for manufacturing ceramic microwave absorbers; mechanical treatment technology; and metallization technology. Production and testing of a pilot batch.
All stages are interconnected and aimed at obtaining high efficient and stable properties of products manufactured in accordance with the new technology proposed.
Comprehensive research will be conducted to develop the nanotechnology for manufacturing microwave absorbers made of berlox, titanium dioxide, etc. Physical experiments applying advanced technologies for synthesis, ultrasonic activation and hot molding combined with theoretical research of hydrodynamic and heat-mass-exchange phenomena will promote determining the optimum conditions for processes of preparation of initial components, molding, sintering, and finishing treatment of products. It will also promote understanding of these phenomena regularities for elaboration and control of all technology stages during pilot testing. Comprehensive research will result in developing efficient technical solutions.
Mathematical models will be developed for hydrodynamics and heat-mass-exchange of dispersed medium taking account of physical and chemical activation. This approach will be developed after heat-mass-exchange analysis during synthesis, cross-linking and crystallization. Theoretical results will be applied for the process control in order to obtain required physical, chemical, mechanical, and electrophysical properties of ceramics.
The obtained results will be discussed with collaborators, research papers will published and reported in the international seminars, symposiums and conferences. Business trips to FSU countries and abroad are also planned.
Foreign Collaborators/Partners’ Role
Collaborators of the given project will be Dr. M.R. Edwards, Cranfield University, GB, Prof. A. Mukasyan, University of Notre Dame, Department Chemical and Biomolecular Engineering.
Dr. M.R. Edwards, Prof. A. Mukasyan: Scientific-technical consultations in experimental research and industrial tests, as well as in the characterization of the beryllium produced.
We'll discuss with collaborators M. Edwards, A. Mukasyan the results of calculations and experiments under the Project. The collaborators will give us methodical recommendations on the results analysis, as well as on using the technology of metal-ceramic materials production.
Planning frames of collaboration:
- information exchange during Project implementation;
- submitting comments to technical reports (annual, final);
- assistance Project participants in participation at international conferences and symposiums;
- holding joint work seminars.
Research studies on collaborators’ devices are not planned.
The International Science and Technology Center (ISTC) is an intergovernmental organization connecting scientists from Kazakhstan, Armenia, Tajikistan, Kyrgyzstan, and Georgia with their peers and research organizations in the EU, Japan, Republic of Korea, Norway and the United States.
ISTC facilitates international science projects and assists the global scientific and business community to source and engage with CIS and Georgian institutes that develop or possess an excellence of scientific know-how.