ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The sintering behaviour of boehmitic alumina gels during the transformation to the stableα phase has been studied using dilatometry, transmission electron microscopy, X-ray analysis and differential thermal analysis. The specimens for transmission electron microscopy were prepared from gel specimens, sintered to various predetermined temperatures, using an ion-beam thinning technique. The transmission electron microscope study and X-ray analysis have revealed a characteristic sintering behaviour which is associated with theθ toα phase transition. The transformation to theα phase occurs by a nucleation and growth process. During the growth process considerable redistribution of the fine porosity existing within the transition alumina matrix occurs, in the form of large elongated interconnected pores trapped within the nucleatingα grains. These pores grow rapidly to a size approximately one hundred times that of theθ grains. This process results in a rapid fall-off in sintering rate at the end of the transformation. A study of theθ/α interphase interface by transmission electron microscopy has led to the development of a model that accounts satisfactorily for the redistribution of the porosity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00708257
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