Transport phenomena in microelectronics & metals processing

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Under the general theme of transport phenomena in microelectronics and metals processing, the applicant wishes to carry out fundamental research in two areas of direct industrial importance. These are concerned with: (a) Mathematical and physical modeling of co-deposition of SiO2 and GeO2 in Modified Chemical Vapor Deposition (MCVD) reactors, and (b) ultrasonic de-agglomeration and dispersion of particles in liquid metals and fluids. (a) MCVD reactors are used to commercially manufacture high quality optical fibers. A MCVD reactor consists of a slowly rotating, fire polished, heated silica tube wherein a mixture of gaseous silicon tetrachloride (SiCl4), germanium tetrachloride (GeCl4) and oxygen is introduced. The reaction products of interest are fine particles of SiO2 and GeO2 which deposit onto the inner surface of the tube. After a sufficient number of layers are deposited, the tube is collapsed into a solid preform rod and then drawn into a long thin fiber. The first objective of this work is to develop a transient 3D transport model which will provide temperature, velocity and concentration profiles as well as deposition rates of SiO2 and GeO2 inside the reactor. The second objective is to perform MCVD experiments in an arranged experimental research facility in China. Experimental results will be used to verify modeling results and the model will be appropriately tuned and/or modify to provide satisfactory results. (b) Dispersion and de-agglomeration of powders are required in many processes in the metals, pharmaceutical, chemical, paint and ink industries. Powder of any particle size tends to form agglomerates when being mixed into a liquid. Therefore, effective means of de-agglomerating and dispersing are required to overcome the bonding forces after wetting the micron- or nano-powders. Mathematical and physical models will be developed to explain the ultrasonic dispersion phenomenon of fine particles in fluids. An ultrasonic device will also be developed to measure bubbles' particles loading characteristics to make efficient flotation columns for industry