The yield properties of gels of aggregated particles are of great economic significance in the ceramics manufacturing, chemical processing, and mining industries, yet remain very poorly understood. Progress has been hampered by the lack of experimental techniques to directly examine the deformation properties of particle aggregates and gels. This Faculty Early CAREER Development project utilizes newly developed digital video microscopy and micromechanical testing techniques to gain a quantitative understanding of the mechanisms, frequencies, and forces required for particles to rearrange during shear and compression. Particulate gel deformation will be observed in-situ to determine the different rearrangement modes which occur, as well as their frequency. Micromechanical testing will directly measure the forces required for particle rearrangement. The micromechanical testing methods have great potential in the study of colloids - with further development, these methods may be able to rival the force resolution of colloidal probe atomic force microscopy. The experiments will be conducted using a variety of model and technically relevant colloids, systematically varying particle size, particle volume fraction, and interparticle potential. It is anticipated that this work will serve as the experimental basis needed to guide the theoretical modeling of particulate gel rheological behavior. Continuing development of undergraduate and graduate level courses will be a major educational goal. Specific projects include the implementation of web-based three dimensional crystal structure models for a structure of materials class, development of a graduate lecture/-laboratory class in ceramics processing, and implementation of new course assessment techniques. Outreach activities will focus upon development of a professional enhancement course for high school science teachers, emphasizing the use of examples from materials science and engineering in standards-based education. The course will be offered in two forms: a lecture/-discussion format to be taught at the Colorado School of Mines, and a web-based distance learning format. It is anticipated that the latter effort will be especially attractive to teachers in rural and disadvantaged areas.
The proposed research utilizes new developed digital video microscopy and micromechanical testing techniques to quantitatively examine the deformation modes of particulate gels. The educational component of the plan includes mentoring of freshmen and undergraduate researchers, teaching at all student levels, and course development. The outreach activities are focused upon developing and teaching professional development courses for high school science teachers. The use of visualization techniques to enhance understanding is a theme running throughout the proposed activities.
