Study on the apparent sintering activation energy and phase transformation of nanocrystalline Titania
Date Issued
2007
Date
2007
Author(s)
Chang, Yu-Wei
DOI
zh-TW
Abstract
Abstract
Master Sintering Curve (MSC) model, which can predict the sintering behaviors of ceramic sintering, has been widely used in sintering during the past few years. Based on the inherited assumptions from the combined stage sintering model, from which the MSC was derived, MSC should not work in the sintering of nanocrystalline ceramic, but as we have proved in our earlier work that it does work. Though we still don’t know the physical meaning of the only parameter of MSC, i.e., the apparent activation energy Qa, it must have something to do with the excellent applicability of the model. This research experimenting on the sintering of nanocrystalline titania samples with various average initial diameters and relative density, explores the variations of Qa and helps increase our understandings of the parameter.
Sintering experiments were conducted using both 35 nm diameter titania samples with initial relative densities of 44%, 41% and 36%, and 80 nm diameter titania samples with initial relative densities of 43%, 41% and 35%. Each set of samples were sintered at 3oC/min, 5oC/min and 10oC/min.
One of the great discoveries of the study is that the MSC can be used to analyze and describe the complex reactions that both phase transformation and sintering happened at same time. In addition, using both our five-parameter S-curve fitting and German’s three-parameter curve fitting lead to very similar results and values of Qa. Most importantly, we cannot find satisfactory data to support the hypothesis that Qa varies linearly either with particle diameter or with initial porosity of the samples.
Subjects
主導燒結曲線模型
視燒結活化能
相變
Master Sintering Curve Model
apparent sintering activation energy
phase transformation
Type
thesis
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