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Multi-Phasic Ceramic Composites made by Sol-Gel Technique

Published online by Cambridge University Press:  15 February 2011

Rustum Roy ,
S. Komarneni  and
D.M. Roy
Rustum Roy
Affiliation:
Materials Research Laboratory, The Pennsylvania State University, University Park, PA 16802
S. Komarneni
Affiliation:
Materials Research Laboratory, The Pennsylvania State University, University Park, PA 16802
D.M. Roy
Affiliation:
Materials Research Laboratory, The Pennsylvania State University, University Park, PA 16802
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Abstract

Instead of aiming to prepare homogeneous gels and xerogels, this paper reports on work done to prepare deliberately diphasic materials. This has been achieved by three different paths: (1) mixing 2 sols; (2) mixing 1 sol with 1 solution; and (3) post formation diffusion of either one or two solutions.

By the last named process we have made SiO2, mullite and alumina based composites, with silver halides, BaSO4, CdS, etc., as the dispersed phase. The crystal size can be confined to the initial pores by rapid diffusion giving rise to extremely fine second phases in the submicron range. Subsequent reduction of appropriate metallic salts can be used to give finely dispersed metals (e.g. Cu, Ni) in essentially any xerogel matrix. The open porosity makes these metal atoms very accessible.

By the first two processes we have made both single phase and di-phasic gels of the same composition (prototype: mullite) and shown that though they cannot be distinguished by XRD, SEM, and TEM, by DTA and thermal processing, they are radically different. Such di-phasic gels store more metastable energy than any other solids.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 32: Symposium B – Better Ceramics Through Chemistry I , 1984 , 347
Copyright
Copyright © Materials Research Society 1984

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References

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