Ceramics Processing with SHF Fields
The Investigation of Physical and Chemical Regularities of Syntheses and Sintering of Ceramic Materials by SHF Fields and Development of the Base of Burning Technology of Ceramic Products
Tech Area / Field
- MAT-SYN/Materials Synthesis and Processing/Materials
- PHY-SSP/Solid State Physics/Physics
3 Approved without Funding
National Academy of Sciences of the Republic of Belarus / Institute of Technical Acoustics, Belarus, Vitebsk
- Oakland University, USA, NY, Rochester
Project summaryThe main objective of the project is the development of base technology of sintering of ceramic products SHF fields on the base of carring out the fundamental investigations on the interaction of concentrating flows of electromagnetic energy of HF and SHF of the region on ceramic materials in processes of syntheses and sintering.
At present the main way of getting the products from ceramic materials of different purpose is thermal. The significant duration of the process, high specific consumption of electric power and the using of refractory materials for the lining of the stoves are the essential defects of the high mentioned method. Besides, in the process of thermal burning the breach of stoichiometry of composition of ceramic materials often occurs and this fact is critical for variety of broadly used in industry and electronics products. For example, the getting of stable posistor, piezoelectric elements for radiotechnics is pushed with the problem of flight of lead the basic component of such ceramics materials. There for the problem of the development of new, not traditional ways of syntheses and sintering of ceramic materials becomes actual. In this connection the development of syntheses and sintering of ceramic materials by variable fields SHF region is actual too. This method is very promising as it allows to essentially increase the efficiency of burning of ceramic products. This is bound in the first place with the following fact: under the SHF burning the led energy disperses just on sintering of ceramic samples, avoiding intermediate stages (the heating up of heating elements, the lining of stoves). The duration of burning SHF fields of ceramic materials is on the order less than under thermal sintering that allows to sinter materials with flying and metastable components and joints. The last is presented as the most essential particularity SHF of sintering so as the last time in such joints the number of unique characteristics of ceramic products have been obtained.
Last time the number of countries the investigations of influence SHF radiating on ceramic materials for the reason of development of speed sintering technology of ceramic products have been widely conducted. The number of international conferences denoted specially this problem was conducted. (M. Willert - Porada. In “ Powder metallurgy world congress & exhibition”. Granada. Spain. 1998). In publications absolutely are not considered questions of syntheses by SHF fields of materials of given stoichiometry (1. J. G. P Binner, J. A Fernie, P. A Whitaker. Journal of Materials Science 1998. Volume 33, Issue 12. P. 3009-3015. 2. J. G. P Binner, J. A Fernie, P. A Whitaker. T. E Cross. Journal of Materials Science 1998. Volume 33, Issue 12. p. 3017-3029). Our earlier works have shown that SHF fields allow to synthesise the ceramic materials, including with flying and metastable components, for more short time that with the help of traditional thermal method. So, as the demonstration of possibilities of SHF syntheses and sintering, we synthesised flaky ferroelectrics with the high temperature Curie (type Ca2Nb2O7), which present heating elements with the positive warm-up resistance factor and not containing lead.
As a result of carring out the project the following will be obtained:
- the strategy of studying of processes of syntheses and sintering by SHF fields of ceramic materials (ferroelectrics, ferrite’s, high-temperature superconductors) in irregular conditions was designed and the necessary equipment for studying the mechanisms of interaction of materials components was created;
- the mechanism’s investigations were conducted, defining different stages of syntheses and sintering of ceramic materials, possessing nonlinear physical characteristics (ferroelectrics, ferrite’s, high-temperature superconductors), in irregular conditions and the mathematical syntheses and sintering model of ceramic materials by SHF fields was built;
- the basic technologies and the experienced installation for SHF syntheses and sintering of ceramic materials were created for the reason of demonstration of potential possibilities of proposed method.
The author’s group of the project possesses a high qualification for solving as fundamental problems of the materials studying so the problem of using the obtained results of technology development. It consists of two professors – the doctors of technical sciences, possessing enormous experience in organization and conducting of scientific and technological works, 3 candidate of physicist-mathematical sciences, conducting studies just connecting with the themes of project. The group possesses an experience on special purpose development. The guideline of their activity in last was a development of elements of making and displaying of the information for systems of delivery of weapon, steadfast to the action of penetrating of radiation’s. In a laboratory physics of dielectrics of Institute of technical acoustics NAS of Belarus the works on HF and SHF fields interaction with the ceramic materials are conducted for a long time and for today’s the certain experience of work have been accumulated and some interesting results were obtained. So it was studied that in the process of syntheses by HF fields of some ceramic materials (ferroelectrics, ferrites, high-temperature superconductors) the essential changing of kinetics of solid-phase syntheses takes place. The obtained results point that the kinetics syntheses in SHF field is not described by equation of formal kinetics of type Yander and others. The growing of foetuses of new phase can’t be presented as purely diffusion process.
The proposed project must the requirement of ISTC:
- The carring out the project will allow a group of executors, previously studying the development of special materials; the technologies of their fabrication and devices on their base, to concentrate their own efforts on fundamental problems of the material studying.
- The project corresponds the laws of Belarus and the international rule; so as it implies an open publishing of results of work which have purely scientific value.
- The project does not put its problem a development of the technologies of military purpose and the passing of corresponding information to third countries. The executors guarantee ISTC in accordance with the article VII agreements on founding ISTC the possibility of checking and auditing of the whole Institute activity, connected with the carring out of the project.
Work execution on the project will bring about essential understanding of processes, occurring at the solid-phase syntheses and sintering of ceramic materials in general. This fact determines its scientific value. This is bound at the first place with the original strategy of studying such processes, allowing to study the concrete mechanisms in irregular conditions. The dynamic working out of get information will allow to use the proposed strategy when studying practically any high-temperature processes in solid bodies. The creation of the experimental installation with the required parameters on velocity of information handling and accuracy of determination of salient features of materials spectrum at syntheses and sintering will ensure the significant increasing of level of conducting investigations. The finish aim of project is the creation of experimental installation for the demonstration of possibility of SHF sintering and it is to be marked that with the help of suggested method it is possible to burn practically any ceramic materials. This will allow, on the completion of the project, to offer the concrete practical using of obtained results. In combination with energy and ecological values of given method the commercial potential of project is presented as high and various. The strategy can serve as a basis for making the instruments, checking the process of sintering in usual thermal conditions. The built mathematical process model will allow to approach to the choice of conditions of getting the ceramic materials more concretely. The concrete products from ceramic materials can be burn on the experimental installation for the evaluation of new technology and, hereafter, create technologies of burning of ceramic products of the most broad fix.
Coming from the foregoing the main works amount on the project will consist in creation of computerizing complex on the base of available installations. Herewith the experimental installation will be created on block principle, in order to shorten the time of transition from scientifically experimental stage to the industrial mastering of technology without the essential expenses. The math working out of experiments results on syntheses and sintering of different on structure and properties ceramic materials will bring about the creation of a consequent model of sintering. Here the essential help can render the collaborators of the project, which role is to expert the obtained results and to independently check the conclusions of a model. Besides, the constant discussing of the achievements and the cooperative choosing of investigated materials will allow quicker to find a concrete practical using of technology of the SHF burning. The participation in symposiums, conferences, conducted abroad will give an opportunity to establish the scientific and other relationships not only with the leading scientific foreign centers but as well as with industry representatives for the revision of practical using of a project.
For the irreversible processes investigations under the sintering by SHF fields of ceramic materials it is supposed to use methods of a velocity optical spectroscopy. This is required to define distinctive physical features of the process, but through them and the mechanisms, defining it in essentially irregular conditions. An optical spectrum of material is such parameters. The radiation of sample in the process of burning is changed, moreover not only its integral features are changed but the spectral too. Their analysis will allow to define factors, rendering the essential influence upon a stage of sintering. Since study of spectrum of sample is conducted under the given temperature in a short time, the spectrum gives an instant mold of condition of material. There by at the study of the process of sintering its dynamic reveals and through it it’s possible to build the kinetic model of sintering as well. It’s necessary to note that known our times methods work with materials, passed the burning stage, even if under different conditions, but investigated under normal temperatures. The suggested strategy will allow to investigate the materials under the high temperatures right in the process of burning. On our glance it will give the essentially greater volume of information on sintering and will allow to create an identical mathematical model fit for using it at the analysis of traditional ways of burning as well. The mathematical model will be based on a description of kinetics of syntheses and sintering on the base of kinetics equations of type Fokker-Plank. Such approach at the present time is well designed for solving other problems. The using of it for the kinetic stages of syntheses and sintering description will allow to suggest the united and consequent approach to the general scientific problem of announcing of materials, in particular ceramic under the high temperatures and in conditions of non-stationary external influence. The technical realization suggests to create an experimental installation under the block principle. This will allow, first, to conduct a modernization with using the last achievements of technicians without essential expenses. So the block for velocity analysis of spectrum of radiating a sample will be created on the base of installation, working on PICTS strategy. Using a computer technology of information handing with inverse connection on active elements management will allow to create a flexible and high-automated experimental installation. The developed at the present time generators of SHF radiation allow to connect a measurement of temperature of sample in the area of burning with management of generator’s power. This presents the additional possibilities on burning process management with the active control of parameters of material. On our glance the making of such installation is the interesting technical problem itself and will be able to find a broad using. The decision of methodological and theoretical problems of the project can be achieved by the way of computer working out the results of the experiment and numerous modeling of a process. Since problems are many-factors and greatly nonlinear, the computer technicians with the sufficient speed corresponding software is required. The proposed approach on the base of equations of Fokker’s-Plank’s will allow to consequently take a number of factors into account (heat and electrical characteristics of components, the presence of external field, non-stationary of the problem and etc) which are usually taken into account or phenomenological either as small parameter. General volume of work takes a development of software of experiment into account and calculation of theoretical models. Experimental installation will allow with the high velocity (for time 5-10 minutes) produce a scan of spectrum of radiating a warming sample and define a degree of conversion at the syntheses of ceramic material. Herewith a spectrum within the range of from infrared (2.4 m) before ultraviolet (0.16 m) range will be scanned. Velocity of information handling by modern computers will allow to take particularities of spectrum account into different temperatures, up to temperatures of sintering (1400 °С).
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