Dissertation > Excellent graduate degree dissertation topics show

Area of ??grains of the polycrystalline ceramic material - perimeter relationship

Author: SongHongYan
Tutor: WanYun
School: Northwestern University
Course: Condensed Matter Physics
Keywords: Grain size The coefficient of variation Confidence Confidence interval Sintering Activation energy
CLC: TQ171.1
Type: Master's thesis
Year: 2010
Downloads: 35
Quote: 0
Read: Download Dissertation

Abstract

Study on the relationship between mechanical properties and microstructure of polycrystalline ceramic, the average grain size is often as a key microstructure parameters scholars of universal attention;, the average grain size in the field of functional ceramic materials often used to study grain boundary effect on the performance parameters affect the law is an important parameter. However, it must be noted that, in a polycrystalline ceramic samples of different grain size difference is large, the size difference in the size between the grains is often in an even several orders of magnitude more. In all relevant reports, the grain size but had only uses an average, while ignoring the effects of the statistical distribution of the grain size of the material actually exists. In addition, so far the polycrystalline ceramic sintering process generally are based on the observed average grain size variation basis, research reports on the grain shape changes in the sintering process is extremely rare. The other hand, from many reports sintered dense polycrystalline ceramic grain morphology photograph, the ideal regular hexagonal grains is also very rare. Therefore, to explore a new microstructure parameters of ceramic materials structure and property relationships, the establishment of a technical characterization of grain shape and applied to the ceramic sintering research has a strong theoretical significance and practical value. BaTiO3 PTCR material cubic ZrO2 system and lead-free ceramic three different sintering temperature insulation at different times under the conditions of the grain growth process and surface grain morphology was observed. Confirmed from a statistical point of view, for a given material under the same sintering system, its surface grains of the perimeter (P) and the area (A) of the square root of the ratio P/A0.5 value compared with the grain size discrete small be more accurate and reliable description of the grain morphology. Confirm this the sintered dense single phase polycrystalline ceramic material on the surface of the grain having a substantially constant P/A0.5 value. Secondly, on the basis of the above observations, the grains P/A0.5 values ??as a characterization parameter of the grain shape. By analyzing the process of grain P/A0.5 value change shape changes, the preliminary investigation of the sintering behavior of the parameter study materials especially the role played by the grain growth process. Finally, the measurement the the cubic ZrO2 ceramic crystal sector conductance activation energy Egb of. Results: the grain P/A0.5 and Egb two parameters showed the opposite trend. The corresponding relationship exists between these two parameters seem to indicate the change of the grain shape parameter can reflect to cause material changes in the electrical properties of the grain boundary the microstructure characteristics. Study grain boundary effects laws of P/0.5 value change is expected to reveal the influence of material microstructure of the material properties.

Related Dissertations

CLC: > Industrial Technology > Chemical Industry > Silicate > Glass Industry > Basic theory
© 2012 www.DissertationTopic.Net Mobile