Microwave Melting of Materials
Use of High Pulsed Microwaves in Material Processing
Tech Area / Field
- MAT-SYN/Materials Synthesis and Processing/Materials
8 Project completed
Senior Project Manager
Institute of General Physics named after A.M. Prokhorov RAS, Russia, Moscow
- VNIIEF, Russia, N. Novgorod reg., Sarov
- Boeing Northamerican / Rocketdyne Division, USA, CA, Canoga Park
Project summaryObjectives of the project:
The aim of the present project is the development of methods for the pulsed melting down of fine-dispersed metal and semiconductor powders by means of powerful microwave beams in order to use these melts for connection of dielectric materials.
Experimental and theoretical studies will be carried out in two directions:
1. The study of microwave absorption in various materials and compounds.
Experimental and theoretical investigations on nonlinear processes of energy localization in plasma of microwave discharge induced near the metal-dielectric boundary.
2. Theoretical studies and experiments will be carried out on melting down, the deposition of metal coatings, and the welding of various materials and elements in order to determine the possibility for industrial applications of the microwave methods of material processing.
The project is intended to develop new unique methods of material processing by means of powerful sources of millimeter and centimeter waves (gyrotrons, etc.) constructed in Russia and with the help of highly skilled Russian scientists and engineers.
In this Project the possibility of microwave melting application for metallization and connection of dielectric details in a specific conditions of energy localization is suggested. The seats of connection (transparent for low power microwave radiation) are perceived to be prepared with the help of metallic or semiconductor powder.
As It appears iron GPI's investigations in the case that microwave power exceed a certain threshold value strong nonlinear processes near the boundary of dielectric base and conducting powder particles develop leading to the significant change of microwave absorption character. The most obvious mechanism of such a nonlinearity is the sublimation of dielectric material near its boundary with the metal particle, ionization of the vapor and plasma initiation near the contacts in the end.
With the reaching of such a nonlinearity one would expect a localization of microwave energy release with a high efficiency in the volume occupied by plasma. As a result in the pulse-periodical regime one may expect achievement of an effective local heating of metal powder accompanied by its melting.
Thus we propose to use for such an application as a welding of a dielectric materials effect of nonlinear microwave energy release localization discovered in GPI and reported in J.Phys.D: Appl.Phys., 29, 1996, p. 1641-1648 (G.M.Batanov, E.F.Bol'shakov et al.)
The physical model of the phenomena of nonlinear microwave energy localization in the contact region between small metal (or semiconductor) particles and dielectric base has to be constructed as a result of theoretical research and the realization of planned experiments.
The implementation of this Project will make it possible to obtain data on the irradiation regimes and the methods for melting of various powder materials; to investigate the influence of the grain sizes, the proportions of ingredients, the relation between the densities and thickness of samples; and to study vacuum conditions. It will allow us to realize microwave melting of conducting powder and to study the possibility of welding them with various dielectric materials (including ceramic ones).
The study will be completed within two years, and the results will be analyzed and reported.
Engineering Approach and Methodology:
Experimental part of this work will be performed by the Department of Plasma Physics of the Institute of General Physics (GPI, Moscow). GPI will provide experimental devices, engineering equipment, and powerful gyrotron, klystron and magnetron generators. Microwave generators of GPI which are targeted for the application in the project, overlap extremely wide waveband (0.4-16 cm), pulse durations (10ns-300mcs), peak power (20kW-lMW), and the frequency of pulse repetitions (1-1000 Hz). It will be applicated in the experiments GPI-used scheme of convergent microwave beams formation and input them into vacuum chambers. These generators and experimental setups have been applied previously in the defense subject area of investigations.
The main body of theoretical research will be carried out at the Russian Federal Nuclear Center-All-Russia Scientific-Research Institute of Experimental Physics (RFNC-VNIIEF, Arsamas-16, Nizhegorodskaya Obl.), which own some staff of theoretical physicists and programmers and have powerful park of computer utility.
Potential Role of Foreign Collaborators:
It is possible to perform in future the joint works for studying the possibility of melting, metallization and some aspects of mutual joint of various materials with the next foreign partners:
1. Rocketdyne Division - Rockwell International Corporation (USA)
2. JINRO Plasma Technology Inc., South Korea.