Helen M. Chan Research
Dr. Chan’s research interests include the application of reactive processing to fabricate unique ceramic/metal structures, and the role of interfacial chemistry in determining the elevated temperature mechanical behavior of ceramics. For example, we have an interdisciplinary project involving faculty members from chemical engineering (H.S. Caram), Mechanical Engineering (J. Grenestedt) and Material Science and Engineering (M.P. Harmer), in which a novel process for fabricating metallic foams has been developed. In this technique, ceramic foams made up of metallic oxides are reduced and converted into the metallic state. As a class of materials, metallic foams exhibit high stiffness and strength at low density, as well as an excellent capability for isotropic absorption of impact energy. They are useful in a wide range of applications, including structural and biomedical. In collaboration with Prof. Vinci, Prof. Chan is also involved with the processing of nano-patterned sapphire substrates (see inset figure). Sapphire substrates are widely used for the growth of LED (light emitting diode) materials. It has been shown that the quality of the grown films can be enhanced by using a patterned substrate, versus a planar one. Because the machining of sapphire can be time-consuming and relatively expensive, the group has pioneered a process which begins with the patterning of a metallic Al film, and subsequent oxidation and heteroepitaxial conversion to sapphire.
Patterned array after AGOG conversion to sapphire. for 24 h at 450 deg C., and 1 h at 1100 deg.C. (Supported by NSF)