Date of Award
Master of Science
AN ABSTRACT OF THE THESIS OF James A. Rhodes, for the Master of Science degree in Mechanical Engineering, presented November 3, 2008, at Southern Illinois University Carbondale. TITLE: PROCESSING PARAMETERS AND MICROSTRUCTURE OF INTERMETALLIC BONDED DIAMOND COMPOSITE MATERIALS MAJOR PROFESSORS: Drs. Dale E. Wittmer and Peter J. Filip The general purpose of this research was to produce a material that can outperform conventional materials used in high wear applications such as mining, drilling, and sawing. These types of applications are well suited for diamond materials because of the hardness and wear resistance of diamonds, yet the material must also show an ability to withstand impact loading, and perform at high temperatures. Research in the area of intermetallic bonded diamond (IBD) composites is on-going with the goal of achieving a set of processing parameters which can reliably and repeatedly produce IBD materials with high density and low porosity. The material investigated was composite of nickel aluminide, with a molybdenum dopant, tungsten carbide, and diamond. Experimentation has shown that hot pressing, at appropriate pressures in the range of 1350 - 1450 ° C, can yield results near 100% theoretical density. These experiments have also yielded apparent porosities below 1%. Still, much care must be taken to control time, temperature, and pressure in order to avoid unwanted metal leakage and diamond degradation, and to yield the proper phase formation. In this research, the parameters investigated for specific IBD composites included a range of hot-pressing temperatures and pressures, and the properties measured were porosity, density, and impact resistance. Also included were material analysis done by means of X-ray analysis and SEM with EDS inspection. From the research it was concluded that the ideal set of parameters for processing the intermetallic bonded diamond composite material in a hot press operation lie between 1350 and 1375 °C, and a pressure of between 26.3 and 52.7 MPa. It should also be noted that the process requires strict control on the cycle's heat ramp-up, pressure application, pressure reduction, and cool down cycle. As with most material processing, failure can result from sloppy handling of the die set, and material contamination.
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