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Contents of the issue
UDK 621.791:629.621.791:629.76 (2000) Space: Technologies, Materials Science, Structures.Collection of scientific papers. Ed. by B.E. Paton.
Kiev: E.O. Paton Electric Welding Institute, NAS of Ukraine, 528 p. and 24 ins.p. ISBN 966-95847-0-1 The collection presents the results of investigations based on the data of the experiments conducted in various manned and unmanned space vehicles. A broad range of practical issues are considered related to operation and repair of vehicles in space, construction and mounting of extended large-sized structures, making permanent joints by welding and brazing, application of various coatings by thermal evaporation. Particular attention is given to development of the hardware and instrumentation designed for operation in the severe space environment. All the presented papers were published earlier. Collected in one book, however, they allow tracing the emergence of space technologies and outlining the path of their further development. The collection is intended for scientific, engineering and technical workers involved with the aerospace industry and can be useful for students specialising in the respective fields. Compiled by A. A. Zagrebelny, E. S. Mikhailovskaya, V. F. Shulym
Publishing project A. T. Zelnichenko
Editors B. V. Khitrovskaya, V. I. Kotlyar
Design I. V. Petushkov
CRC preparation T. Yu. Snegireva, I. S. Batasheva, N. N. Prijmachenko
Translations I. N. Kutianova, M. I. Zikova (Engl., Germ.)
The collection was prepared with the participation of A. R. Bulatsev, S. S. Gavrich,O. V. Galich, T. S. Zharova, I. V. Krivtsun, L. A. Likhoded, I. S. Malashenko, S. V. Pavlova
Photos are provided by the Department of Space Technologies of the E. O. Paton Institute, as well as by V. N. Bernadsky, S. S. Gavrish, A. A. Zagrebelny, and Yu. N. Lankin from their personal archives
Chapter 1. SPACE TECHNOLOGIES ARE A REALITY
Welding in space 17
Problems of space technology 18
Ten years of space technology development 24
Tested in orbit 29
Chapter 2. SPACE AS A PROCESSING ENVIRONMENT
Technological aspects of welding in space 45
Space features and further progress of welding in space 52
Formation of electron beams for technological and research workin space 59
Some results of space technology work performed by Soviet scientists 64
Mathematical modelling and experimental investigationsof the processes of alloy evaporation under microgravity 70
On new problems of technological processes control in space 78
Forecasting the life of structural materials and their joints duringlong-term exposure to space environment 86
Welding application for repair of space vehicles 90
Diagnostic of space vehicles by the acoustic emission method 93
Features of the equipment for processing operations in space 95
Experience of design of process equipment for performance of workin space vehicles 100
Instrumentation for control of on-board process equipment 115
Chapter 3. PROCESSING EXPERIMENTS UNDER MICROGRAVITY
Special features of training cosmonaut-operators to performprocessing operations 129
Testing facility for studying technological processes under spacesimulation conditions 136
Ergonomic aspects of welding operations performance in space 140
Influence of zero-gravity and gear on cosmonaut-welder labouractivity 147
Training facility for simulation of welding operations performancein space 156
WELDING, CUTTING AND BRAZING OF METALS
Experiment on metals welding in space 159
Features of the hardware and processes of electron beam weldingand cutting in space 165
Investigation of electrode metal melting and transfer in welding underthe conditions of variable gravity 173
On the feasibility of manual electron beam welding in space 179
Testing of a manual electron beam tool in raw space 183
Manual electron beam processing operations in space 191
Some features of brazed joints formation at radiant heating undergravity and weightlessness 216
Welding of aluminium alloy 1201 by the radiant energy of the Sun 221
Features of chemical elements migration in subsurface layers of metalsand alloys during thermal cycling 224
Design taking into account EBW application under extremeconditions 232
Investigation of the properties and structure of 1201 alloy weldedjoints made with the electron beam at different levelsof gravity and low temperatures 236
Influence of gravity forces, dissolved hydrogen and initialtemperature on the properties and tightness of joints in electronbeam welding of light structural alloys 243
Investigation of the structure and element distribution in weldedjoints made with the electron beam on alloys 1201 and AMg6 underweightlessness 247
Calculation of heating of a multilayer tubular assembly for brazing 252
Analysis of permanent joints on tubular elements of braze-weldingand brazing type made with the versatile manual tool 257
Technology of vacuum soldering of components of latticed trussstructures of aluminium alloys 263
Features of formation of brazed joints of thin-walled structuresin space 266
Some problems of welding sheet metal in space 277
Analysis of the results of experiments performed with the versatile manual tool in space 283
Manual electron beam welding of sheet metal in raw space 290
Development of the technique of applying thin-film coatings in space 298
Equipment for coating deposition by the method of electron beamevaporation under microgravity 301
Comparative analysis of the structure of pure metal films condensedunder the space and ground conditions 312
Some results of analysis of samples of coatings produced in space 317
Investigation of the influence of gravity on the compositionof coatings from binary AgACu alloys 321
Some features of formation of silver coatings under various gravityconditions 327
Features of formation of the structure and composition of binary alloys in evaporation under microgravity 332
Segregation effects in Ag-Cu coatings deposited in space andon the ground 339
Volume-structural and phase microinhomogeneities of electrondensity in metal films condensed under the flight and groundconditions 348
Coatings produced in near-earth orbit and prospects for their application in microelectronics 357
Possibility of coating restoration under the actual space conditions 363
MELTING AND SOLIDIFICATION
Study of the features of melt solidification in weightlessness onoptically transparent models 372
Experience of the use of an electron beam unit for material remeltingin space 376
Experiments on aluminium melt solidification in «Isparitel-M» unit 379
Crucibleless zonal melting of silicon single-crystals by the electronbeam 385
Chapter 4. STUDY OF THE MAGNETOSPHERE OF THE EARTH
Active experiments in the circumterrestrial space 391
ARAKS – controllable or puzzling experiment? 400
Powerful small-sized electron beam unit for processing operationsand physical experiments under the space conditions 407
Chapter 5. LARGE-SIZED STRUCTURES IN SPACE
On application of transformable welded structures for space systemsand constructions 417
Development of a transformable structure of the docking moduleand technology of its fabrication 424
Transformable all-welded metal structures 428
Experimental investigation of deployment, transformation, rigidityand dynamic characteristics of circular frame structures mountedon «Progress-40» cargo ship 434
Features of welding processes application in fabrication and repairof large-sized structures in space 440
Assembly and welding of large-sized structures in space 448
Truss structures in orbital complexes 457
Reusable transformable space solar batteries 467
Chapter 6. FUTURE OF SPACE TECHNOLOGIES
Welding and allied technologies in Space and the Ocean. Their masteringin XXI century 487
Space technologies on the threshold of the third millennium 490
Additional sources 495
Terms and expressions 507
Name index 513
In the entire spectrum of intensively and successfully developing theoretical and applied space research, advanced material processing technologies are steadily gaining in importance. Their emergence at the dawn of the space era (1969), was marked by the experiment on welding and cutting of metals in «Vulcan» unit. The issues of fast industrialisation of space which was S.P. Korolev's dream, should certainly be addressed allowing for the features of this working environment. This is primarily necessary for the reason that many physical phenomena proceeding on the molecular level (surface tension, adhesion, wetting, capillary pressure, etc.) manifest themselves more actively in space environment that on Earth.
Successful performance in orbit of such complex technological processes as welding, brazing, coating deposition, etc., where liquid metal is present, required a broad range of experts in theory and practical application to become involved in the investigations. They laid down the foundations of the new field of science–space technology.
One of the important issues in the field of thermal treatment of materials is correct selection of the method of their heating. In the 1960ties, when the first space technology experiment was prepared, the method of direct and indirect electron beam heating was recognised to be the most advantageous. The process flexibility and power efficiency allows one and the same all-purpose equipment to be used to perform in space a sequence of various technological operations in different modes. «Universal» unit developed in 1991, which consists of four manual electron beam tools has successfully passed ground-based testing and is ready for use as part of the long-term space systems of the future. The versatility and advantages of electron beam utilisation in space are further illustrated also by the ability to apply an injected flow of accelerated electrons to study the magnetosphere of the Earth, which was theoretically predicted and experimentally confirmed. Use of electron beam heating for a number of processing operations in orbit, does not, however, eliminate the application of other heat sources, for instance, the radiant energy of the Sun, etc., which can still be justified in some cases. Creation of long-term orbital systems gave an impetus to performance of systematic research in the priority areas of space technology.
Experiment optimisation on the ground is preceded by verification of various hypotheses and theoretical development, in particular mathematical simulation of various processes. Solving applied problems of space technology will require knowledge of the laws of behaviour of multiphase systems (solid body–liquid, liquid with solid and gas inclusions, etc.). The processes running in such multiphase systems can be intensified and controlled by external impact (vibration, ultrasound, etc.). So, for instance, the vibration effect of resonance stirring of liquid immiscible media and formation of stable periodical structures can be used in fabrication of unique materials (foam materials, composite materials, etc.), and the effect of localising and controlled displacement of gas bubbles in oscillating media can be applied in degassing of liquids and liquid metals. It is intended to conduct theoretical development in the field of forecasting the service life of structural materials and their joints under the integrated impact of space factors by physical simulation on scaled thin-walled models, allowing both the surface and three-dimensional processes of material degradation to be studied with relatively short exposure times.
Prolongation of operational life of long-term space vehicles is closely related to application of welding processes in orbit for repair of large-sized structures, as well as non-destructive testing of metal structures, including the acoustic emission method, in difficult-of-access places.
Impetuous mastering of space at the start of the 1970s with a simultaneous increase in the scope of work and experiments performed in raw space, led to a radical change in the operator activity, due to the fact that performance of a number of technological processes in orbit raises problems related both to the specific conditions of space and substantial professional training of operators. The ability to perform precise co-ordinated motion steps under microgravity and conduct EVA in the space-suit should form the basis for qualification training of operators.
Performance of space experiments is always preceded by their optimisation on the ground under the conditions simulating those of space (microgravity, vacuum, variable lighting, temperature gradient, ultraviolet radiation, etc.). Used on the ground with this purpose are various simulation facilities (thermal, altitude simulation, echo and other chambers, flying laboratories or «weightlessness towers», providing short-time microgravity; various test rigs reproducing certain factors of the space environment, etc.). Such a retrofitting, while being costly, is still worthwhile as it confirms the ability to perform the defined task, allows correction of the procedure of conducting the planned experiment or considering the possibility of an emergency situation arising during its performance in space.
For ground-based retrofitting of the manual processing operations under the conditions simulating the space environment, E.O. Paton Electric Welding Institute developed special testing facilities which have been used for more than 25 years now and became an indispensable tool in training operators to use sophisticated engineering hardware functioning outside the space vehicle.
Thorough retrofitting on the ground and testing in the flying laboratory which allowed determination of the optimal process parameters of the «Vulcan» unit, were followed by numerous process experiments in orbit, which were the basis for development of all-purpose equipment for performance of repair and erection work directly in orbit, which has been successfully tested in raw space.
The many years of E.O. Paton Institute experience on development and improvement of the hardware for conducting processing operations in space, which meets the requirements of safe operation in a space vehicle, high operational reliability, compatibility with the space vehicle systems and capabilities of its crew, are the pledge of successful development of control and information systems of a new generation designed for operation on board the International Space Station which is under construction now.
Manned missions in orbital stations demonstrated that during long-term operation in the raw space environment, the surface of the space vehicles is degraded to the depth of up to 10mm, this impairing the functional (optical, electrophysical, physicomechanical, etc.) properties of structural materials. Therefore, deposition of coatings for various purposes in space is one of the most important practical problems in terms of the ability to perform repair-restoration operations directly in orbit.
Starting from 1979, E.O. Paton Institute has conducted development of special hardware for coating deposition in space. Over this period not only the stationary «Isparitel», «Isparitel-M», «Yantar» laboratory units, but also the all-purpose manual hardware have been successfully tested in «Salyut-7» and «Mir» orbital stations. Investigation of the properties of the produced coatings from pure metals (silver, gold, copper) demonstrated that their functional properties (adhesion, residual internal stresses, morphology, internal structure, optical and radiation characteristics) are not inferior to those of their analogs produced on the ground, and are on the level of the requirements of industrial standards. The ability to produce various coatings, in particular, of binary alloys in space, opens up wide possibilities for their application in industry.
Over the years of manned cosmonautics development, the greatest number of process experiments in various space vehicles have been conducted in the field of space materials science. And it is no coincidence. Absence of gravity really enables production of materials with a high «structural purity», a specified distribution of impurties, as well as implementation of containerless technology, etc.
The multi-faceted utilisation of space for fulfilment of research programs necessitated a considerable increase in the overall dimensions of the space vehicles and development of their infrastructure in service. Thus, the construction of the currently orbiting «Mir» station features a multitude of all kinds of various-purpose superstructures and truss structures located on its outer surface. In addition, over the 15 years of the «Mir» station functioning, a great number of large-sized structures or their elements and components have been delivered on board the station for further fitting of its service systems, as well as experimental retrofitting of the promising structures or procedures of their construction directly in orbit.
Brazing is an attractive technology for mounting of the truss structure elements. Therefore, the issues related to this technology, are being continuously followed by specialists, starting with theoretical calculations of the process parameters and ground retrofitting in the space simulation test chamber up to testing of brazed joints in raw space. The issues of construction of extended large-sized structures should be addressed allowing for the specifics of their operation in space, namely costly delivery to orbit, limitations on the weight of the delivered structure, service life, simple assembly and repairability during service. Several basic principles have been proposed for construction of large-sized structures in space.
As far back as in 1970ties, development of various kinds of transformable structures, also pressurised, was looked upon as one of the most promising areas, allowing working, storage, and docking modules, aerials, etc. to be erected in orbit. A number of interesting approaches were elaborated to fabrication of convenient easy-to-transport structures (metallic trans-formable shells). A transformable structure of a docking module of the orbital station can serve as an illustration of such a development.
Another area of research which still goes on now, is development of deployable frame structures allowing deployment of large aerial systems in orbit, mounting «power fields», etc. Creation of this kind of structures and the related issues of their rigidity, and dynamic stability, required not only theoretical calculations, but also extensive ground-based and flight testing.
This collection, including about 70 of the earlier published papers with indication of their source, certainly cannot cover all the aspects of space technology. The editors tried to sum up the many-year cooperation of specialists of E.O. Paton Institute and other organisations in this, barely emerging field of science, in order to trace the evolution of some, in our opinion, of its priority areas, and share the gained (although not always positive) experience of staging various experiments in orbit, and analysis of their results. Moreover, the collection provides abundant photos that not only recreate the episodes of the major events, but also pay tribute to those who are no longer with us. The specialists who performed this work, are real enthusiasts of their cause. The importance of their efforts aimed at the practical implementation of the space programs, can scarcely be exaggerated.
The XX century, the era of great discoveries and deeds, is slipping away. One of its greatest achievements is the man's breaking beyond the bounds of the Earth into the infinite space. Analysing the traversed path, it can be stated that significant progress has been made. The space missions, no longer causing a sensation, have moved into the sphere of routine scheduled activities. Nonetheless, a lot is still to be accomplished.
Looking into the future, one can anticipate that the progren of science and technology, just as the already started global information revolution, will be closely connected with further space exploration. In this context the advanced high technologies of processing and production of materials in space, biological and agricultural technologies, etc., have a special, probably, even primary role. Their priority is confirmed by the continuously growing pace of their development. Close is the day when large-scale productions vitally important for mankind, will be deployed in the near-earth orbits.