Principal Investigator	Darin Zimmerman
Co-principal investigators	Brock Weiss
	Nicholas Miskovsky
Senior Associates	Gary Weisel
	Paul Cutler
Undergraduate researchers	Kelly Martin, Charles Smith
	John Diehl, Chris Lynch, Derek Bailey
Postdoctoral position	JunKun Ma

Funding  RUI-DMR 0406584

NSF (Grant DMR-0406584)	$300K
Penn State University	$74K
Period	July, 2004 - June, 2007

                                             
 

The PSA Microwave Sintering Group has been using this setup to study the microwave heating of various powdered metal samples (pressed into small cylindrical pellets).   The magnetron is on the right side and the TE102 (or TE103) resonant cavity is on the left.  A quartz sample tube is inserted in the cavity and has a pyrometer aimed along it.  Our simple cooling system uses a styrofoam cooler filled with ice.  A blender (powered by a low-voltage source) is used to mix powders.  After heating, we view the surfaces and interiors of our (now partially sintered) samples using scanning electron microscopy. In addition to these heating and SEM investigations, we are using a second resonant cavity and network analyzer to measure the complex permittivities and permeabilities of various powdered samples. We are also modeling the electromagnetics of our cavities and the heating of our samples using the multiphysics package created by Comsol.

 

Project Summary This project investigates systematically the heating and sintering of powdered metal compacts by microwave radiation.  Recent experiments by Roy and co-workers at Penn State UP, confirmed by our preliminary work at Penn State Altoona, demonstrate that metal-powder compacts are heated in both electric and magnetic microwave fields.  Our research addresses two unanswered questions.  First, how are metal-powder compacts heated so efficiently by microwave radiation?  Second, can the experimental results for the first stage of sintering be explained using conventional models or do they require more exotic mechanisms? We address these questions in three ways: a) An empirical study of the complex permittivity and permeability of powder metal compacts as a function of temperature, particle size, particle oxidation, and packing density using resonant-cavity techniques.  b) Identification of the separate contributions of the E and H fields to the heating and subsequent sintering of powder metal compacts using a single-mode microwave system. c) Evaluation of first stages of sintering by direct examination of heated (sintered) samples using scanning and transmission electron microscopy. This project provides new knowledge on the electromagnetic properties and microwave heating and sintering of powdered metals.  In addition to enhancing the professional development of faculty and a postdoctoral researcher, the program also provides a research environment for undergraduate students who are preparing for graduate studies or industry work in the applied sciences and engineering.  Our B.S. degrees in Science, Electromechanical Engineering Technology, and a proposed degree program in material science will benefit from the program.  The students will reap the educational benefits while making a significant contribution to the success of the research.  Their experience will culminate in the dissemination of results with oral and poster presentations at regional or national meetings.  Since our proposed studies will make use of characterization facilities at Materials Research Institute (Penn State UP), our students will have the opportunity to interact with a wide range of students, postdoctoral researchers and faculty.

 

Talks, Posters, and Publications D.T. Zimmerman, E.J. Johnson, J. Ma, K.R. Martin, N.M. Miskovsky, C.T. Smith, G.J. Weisel, and B.L. Weiss, “Microwave Heating and Pre-sintering of Copper Powder Metal Compacts in Separated Electric and Magnetic Fields,” talk given at PM2006: World Congress on Powder Metallurgy, September 24–28, 2006 Busan, South Korea.  J. Ma, C.T. Smith, G.J. Weisel, B.L. Weiss, N.M. Miskovsky, D.T. Zimmerman, “Single Mode Microwave Heating of Copper Powder Metal Compacts, talk given at the COMSOL Users Conference 2006, October 22–24, Cambridge, MA. C.M. Lynch, E.J. Johnson, J. Ma, N.M. Miskovsky, G.J. Weisel, B.L. Weiss, and D.T. Zimmerman, “Complex Permittivity of Powder Metal Compacts by Cavity Perturbation Technique,” poster presented at the 2006 March Meeting of the American Physical Society, March 13–17, Baltimore, MD. K.R. Martin, E.J. Johnson, J. Ma, N.M. Miskovsky, C.T. Smith, G.J. Weisel, B.L. Weiss, and D.T. Zimmerman, “Microwave Heating and Pre-sintering of Copper Powder Metal Compacts in Separated Electric and Magnetic Fields,” poster presented at the 2006 March Meeting of the American Physical Society, March 13–17, Baltimore, MD. J. Ma, J.F. Diehl, E.J. Johnson, K.R. Martin, N.M. Miskovsky, C.T. Smith, G.J. Weisel, B.L. Weiss, and D.T. Zimmerman, “Systematic Study of Microwave Absorption, Heating, and Microstructure Evolution of Porous Copper Powder Metal Compacts,” paper submitted to Journal of Applied Physics.