Spray Forming Solidification Phenomenon and Numerical Simulation Analysis
| Autor: | Hai Ping Liu, 劉海平 |
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| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 This study contains two parts, i.e. solidification experiments and computer simulations. By comparing these two parts of results, a detailed understanding of the solidification mechanism of spray forming process can be achieved. Three types of materials with different melting temperatures, e.g. low melting Pb-50%Sn alloy, middle melting temperature Al, high melting temperature Fe and AISI630 stainless steel, were used in this study. In solidification experiment: The Pb-50%Sn alloy and AISI630 stainless steel were used for solidification experimental observations. By varying two processing parameters, e.g. particle flying distance and quenching liquids (i.e. water and liquid nitrogen with different quenched speed), the solidification mechanisms of the flying particles were studied. The optical microscope (OM) and scanning electron microscope (SEM) were used to observe the microstructure evolution. The EDS and XRD were used to determine the phase structures and chemical composition distributions. The experimental results show that the distance from the spraying nozzle to quenched liquid as well as the type of quenching liquid play an important role on the final microstructure evolution. The solid fraction of the flying droplets was studied. In computer simulation: A numerical simulation program has been built and tested. The parameters of droplet size, grain size, and solid fraction obtained from the solidification experiments were used to compare with the computer simulated results. The comparison provides the information to construct a consistent rapid solidification mechanism of spray forming process. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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