NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.
This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine.
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences.
The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Robert M. White is president of the National Academy of Engineering.
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The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. Robert M. White are chairman and vice chairman, respectively, of the National Research Council.
This study by the National Materials Advisory Board was conducted under Contract No. MDA 972-92-C-0028 with the Department of Defense and the National Aeronautics and Space Administration.
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This report is dedicated to the memory of Joe Pentecost. Joe served as a member of the National Materials Advisory Board from 1988 until his death in 1992. This study was initiated by his efforts, and he was to have been a member of the study committee. We miss him as a person, always gracious and optimistic; as a technical leader with a vision of the future; and as a worker who always did more than his fair share.
Our lives take their meaning from their interlacing with other lives, and when one life is ended those into which it was woven are also carried into darkness. Neither you nor 1, but only the hand of time, slow-moving, yet sure and steady, can lift that blanket of blackness. Adlai Stevenson
COMMITTEE ON MICROWAVE PROCESSING OF MATERIALS: AN EMERGING INDUSTRIAL TECHNOLOGY
DALE F. STEIN Chairman,
Michigan Technological University, Houghton
RICHARD H. EDGAR,
Amana Refrigeration, Inc., Amana, Iowa
MAGDY F. ISKANDER,
University of Utah, Salt Lake City, Utah
D. LYNN JOHNSON,
Northwestern University, Evanston, Illinois
SYLVIA M. JOHNSON,
SRI International, Menlo Park, California
CHESTER G. LOB,
Varian Associates, Inc., Palo Alto, California
JANE M. SHAW, IBM-T.J.
Watson Research Center, Yorktown Heights, New York
WILLARD H. SUTTON,
United Technologies Research Center, East Hartford, Connecticut
PING K. TIEN,
AT&T Bell Laboratories, Holmdel, New Jersey
Government Liaison Representatives
Advanced Research Projects Agency, Arlington, Virginia
Department of Energy, Washington, D.C.
National Aeronautics and Space Administration, Cleveland, Ohio
Air Force Office of Scientific Research, Bolling Air Force Base, Washington, D.C.
Naval Surface Warfare Center, Silver Spring, Maryland
JOHN W. WALKIEWICZ,
U.S. Bureau of Mines, Reno, Nevada
Army Materials Technology Laboratory, Watertown, Massachusetts
National Materials Advisory Board Staff
THOMAS E. MUNNS, Senior Program Officer
AIDA C. NEEL, Senior Project Assistant
The committee is most grateful to the many individuals who took the time to make very informative and useful presentations to the committee.
Speakers at the August 12, 1992 meeting included:
Dr. Mark Janney, Oak Ridge National Laboratory, processing of ceramics and decontamination of concrete
Dr. Joel Katz, Los Alamos National Laboratory, processing of ceramics and hazardous waste processing
Dr. Jes Asmussen, Michigan Sate University, electrical engineering considerations related to microwave processing
Dr. Martin Hawley, Michigan State University, application of microwave processing to polymers and polymer composites
Dr. Raymond Decker, University Science Partners, utilizing microwaves in the former Soviet Union and the application of microwave processing to a number of problems
Dr. Leonard Dauerman, New Jersey Institute of Technology, using microwaves to treat hazardous waste
Mr. Edward Daniels, Argonne National Laboratory, dissociation of hydrogen sulfide, using microwave energy
Speakers at the December 14, 1992 meeting included:
Dr. Ed Neas, The Rubbright Group, use of microwave heating in chemistry, with a special emphasis on analytical laboratory applications
Mr. Hal Kimrey, Oak Ridge National Laboratory, process scaling, technology transfer, and temperature measurement techniques used at the Oak Ridge National Laboratory
Special thanks to Arthur C. Lind of McDonnell Douglas Research Laboratories who provided valuable information on microwave processing of polymeric composites.
Government liaison representatives briefed the committee on the programs and needs of their respective agencies:
Mr. John Walkiewicz, Bureau of Mines' Reno Research Center, the use of microwaves for drying, comminution, and fragmentation
Dr. Alan Dragoo, Department of Energy Basic Sciences Office, microwave programs at Oak Ridge and Los Alamos National Laboratory
Dr. Walter Zukas, Army Materials Laboratory, microwave processing of polymers, ceramics, and thick section polymeric composites
Dr. William Messick, Office of Naval Technology, Materials processing needs of the Navy
Dr. Sunil Dutta, National Aeronautics and Space Administration, Lewis Research Center, needs in ceramics, ceramic composites and composites
Dr. William Coblenz, Advanced Research Project Agency, Defense Science Office, microwave processing of structural ceramics, CVD of ceramics and diamond, and curing of conducting polymer adhesives and polymeric composites
The committee is grateful for their contribution to defining the scope of the study and their active participation in the work of the committee.
The Chair thanks the members of the committee for their efforts. Many made in-depth presentations on special topics, and all contributed to the writing and rewriting of the report. Through it all they remained congenial, hard working, and committed to a balanced and objective report. A Chair could not ask for a better group of people.
Special thanks go to Aida Neel, who made the many arrangements necessary for productive and pleasant meetings, and Tom Munns, the National Materials Advisory Board program officer; whose dedication, good humor, and steady prodding kept the report on schedule.
The use of microwaves in industrial materials processing can provide a versatile tool to process many types of materials under a wide range of conditions. Microwave processing is complex and multidisciplinary in nature and involves a wide range of electromagnetic equipment design and materials variables, many of which change significantly with temperature. A high degree of technical and other (e.g., economic) knowledge is required in determining how, when, and where to use microwaves most effectively, and when not to use them.
The committee conducted an assessment of the potential of microwave technology for industrial applications. This assessment included a review of microwave technology, equipment, processing methods, and applications. Barriers to industrial applications and gaps in understanding of microwave processing technology were identified, as were promising applications and development opportunities that take advantage of unique performance characteristics of microwaves.
The microwave processing of materials is a relatively new technology that provides new approaches to improve the physical properties of materials; provides alternatives for processing materials that are hard to process; reduces the environmental impact of materials processing; provides economic advantages through the saving of energy, space, and time; and provides an opportunity to produce new materials and microstructures that cannot be achieved by other methods.
Microwave processing is an unusual technology. It is widely used (more than 60 million home units are used to cook food) in an environment in which the user understands little of the technology. Yet, the difficulty in applying the technique in industrial processing has often lead to frustration of technically competent materials processors.
Some of the mystery of microwave processing is associated with this dichotomy. If it is so easy to "nuke" a meal, it must certainly be as easy to sinter a ceramic or cross-link a polymer. The apparent ease in using microwaves in food processing is a tribute to the equipment manufacturers for their success in making a "user friendly" oven, but these ovens also have the advantage of having a molecule widely distributed in the food, the water molecule, that easily "couples" to microwaves. In materials processing coupling of microwave energy must be to atoms or atomic groups other than water, at much greater technical complexity.
The purpose of this report is to:
Introduce the reader to the use of microwaves for processing materials. The basic interactions will be described, along with the basic equipment required to process materials. Examples of successful applications will be presented, as will an evaluation of the conditions or parameters needed for the successful application of microwaves to the processing of materials.
Provide an assessment of the state-of-the-art of microwave processing as an industrial technology.
Identify gaps, limitations, or weaknesses in the understanding of the use of microwaves in materials processing, and suggest research and development to address these issues.
The committee approached its responsibility to evaluate the potential of microwave processing of materials in a critical and objective way. To some the report may seem overly cautious and to others it may seem overly critical. It is very clear that the microwave processing of materials has had some major advantages and major successes. But it is equally clear that potential users should take the time to become knowledgeable about microwaves and their interaction with materials before embarking on a program of using microwaves to process