Particle Size Analysis and the Use of Particulates in Advanced Materials Processing
Professor Don H. Rasmussen has published extensively in the areas of nucleation and growth of new phases and on techniques to study nucleation and particle growth processes. His research is focused on (1) the study of phase stability in ternary systems using DIT (diffusive interface transport) techniques; (2) characterizing concentrated colloidal systems using fiber optic dynamic light scattering; (3) metal particle nucleation and growth in non-aqueous media; (4) nano-scale ceramic particle nucleation and growth, and in the deposition of thin ceramic films; (5) homogeneous nucleation in aerosols; and finally, the influence of surface properties of polymers and colloidal particles on the chemical-mechanical polishing of metal and nonmetal films. His ongoing experimental projects include: (1) measurement of the dynamic scattered light power spectrum from concentrated colloidal systems using a bifurcated single mode fiber optic probe (being developed to study particle breakdown, aggregation or growth in concentrated systems; the probe reduces the influence of multiple scattered light), (2) determination of the particle size from the shape of the power spectrum and the particle concentration from the integrated power spectral density, (3) nucleation and growth of particles in supersaturated systems (both aerosols in vapors and particles in supersaturated liquors), and (4) the characterization of the hardness and surface properties of CMP polishing pads by surface energy determination and measurement of hardness using nano-indentation resistance. The establishment of a laboratory for the determination of phase equilibrium in ternary surfactant systems is currently a high priority.
CAMP Professor Hayley Shen, of Clarkson University's Department of Civil and Environmental Engineering, is investigating granular flows in terms of constitutive relations, flow rate effects, particle size and shape effects. She is also interested in two-phase flows. Professor Shen is currently funded by a NASA Microgravity Fluid Physics Program to study the behavior of granular flows in different gravitational fields. This project is being conducted in collaboration with researchers from the University of Florida and Cornell University.
Professor Shen has recently been invited to be a long-term participant at the Isaac Newton Institute for Mathematical Sciences in Cambridge, UK. She will present a lecture on "Dry Shear Flows of Granular Materials." Her current topic of research is the transition of granular materials from plastic to non-linear viscous behaviors.
Professor David Morrison and Chair / Professor John Moosbrugger of the Department of Mechanical and Aeronautical Engineering have begun a project on the processing, microstructure and mechanical properties of ultra-fine grain nickel. Sub-micron grain size nickel is being produced by electrodeposition (ED) and the effects of current density, electrolyte composition, temperature, and current pulsing are being examined using a standard Ni sulfanate plating process. Specimens are being produced with sub-micron grain sizes using current pulsing. Sections of electrodeposited material have been successfully electron-beam-welded to standard polycrystal sections to produce "billets" large enough for machining fatigue specimens. Some fatigue tests have been conducted. Metallography has verified grain sizes and material integrity (there is no metallographic evidence of microvoids) and grain morphology. Chemical analyses show no significant contaminants in the bulk. Reverse magnetostriction (rotation of magnetization due to stress reversals and associated magnetostriction strain) in the ED material is also similar to the previously tested fine grain material. The fatigued ED material had very fine, intragranular persistent slip bands. Fatigue cracks that developed in the gage section were intergranular. Stress levels were initially much higher (perhaps a factor of 5) than initial stress levels for conventional fine or coarse grain material tested at similar plastic strain amplitudes.
Research Using Welding Systems
CAMP Professor Daryush (Dary) K. Aidun has designed and built an Automated Dual Torch Arc Welding System (ADTAWS) with the help of selected undergraduate students. The ADTAWS is capable of butt welding two steel plates (2 in. thick, 12 in. long) from both sides simultaneously without any arc interference. In the first trial it took 1.45 hours to perform the welding process. The ADTAWS can reduce fabrication and labor time, and produce welds free of distortion. In addition Mr. Robert Dixon and Mr. Paul Rader (science teachers at Canton Central and Edwards-Knox respectively) are working with Professor Aidun on a RET/NSF grant. Their project is to examine the effect of simulated enhanced buoyancy convection on the weldability of dissimilar metals. They used the Multi-Gravity Research Welding System (MGRWS) to autogenously weld A36 steel to 304 stainless steel at 1g (9.8 m/s2), 4g, and 8g.