Transport phenomena in microelectronics & metals processing

在微电子和金属加工中的输运现象这一主题下，申请人希望在两个具有直接工业重要性的领域开展基础研究。这些研究涉及：(a) SiO2和GeO2在改性化学气相沉积（MCVD）反应器中共沉积的数学和物理模型，以及(b)液体金属和流体中颗粒的超声波脱团聚和分散。(a) MCVD反应器用于商业生产高质量的光纤。MCVD反应器由一个缓慢旋转、火抛光、加热的硅管组成，其中引入了气态四氯化硅（SiCl4）、四氯化锗（GeCl4）和氧气的混合物。感兴趣的反应产物是沉积在管内表面的SiO2和GeO2的细颗粒。在沉积了足够数量的层之后，管被压缩成一个固体预制棒，然后被拉成一根又长又细的纤维。这项工作的第一个目标是开发一个瞬态3D传输模型，该模型将提供反应器内SiO2和GeO2的温度、速度和浓度分布以及沉积速率。第二个目标是在中国安排的实验研究设施中进行MCVD实验。实验结果将用于验证建模结果，模型将适当调整和/或修改以提供满意的结果。(b)金属、医药、化学、油漆和油墨工业的许多工序都需要粉末的分散和去团聚。任何颗粒大小的粉末混合到液体中都容易形成结块。因此，需要有效的脱团聚和分散手段来克服微米或纳米粉末湿润后的结合力。将建立数学和物理模型来解释流体中细颗粒的超声分散现象。还将研制一种超声波装置来测量气泡颗粒的负载特性，为工业生产提供高效的浮选柱

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