Masters Theses

Abstract

"The literature on mullite properties and selected uses is reviewed. Areas of specific interest covered in this review are melting behavior, structure, mullite starting materials, sintering parameters, and influence of impurities on fabrication and properties. Mullite as a bonding phase in refractory and structural ceramics is emphasized.

The development of mullite in situ as a bond phase from alpha-alumina and fumed silica was the central focus in this study. A designed mixture experiment was implemented to aid in characterizing the formation of mullite from a-Al2O3 and fumed silica. Both a ground and super ground alumina most likely contribute alumina to the formation of a mullitic bond phase consequently one of each of these aluminas together with fumed silica were investigated simultaneously. A triaxal scheme allowed the determination of compositional effects on mullite formation and properties.

The determination of mullite formation with temperature and composition are reported. Properties used to characterize the mullite formation are fired density, shrinkage, and porosity, and quantitative mullite yield. Green densities were also measured and correlated. The quantitative analysis uses the most up to date programs for retrieval and interpretation of the data developed by an external standard method. All data is modeled and plotted as contour maps over the compositional triangle by use of response surfaces.

The comparative behavior of A-1000 and A-3000 aluminas in place of A-16 and A-17 aluminas in mixes as mullitic bond formers is also discussed.

Alternate sources of silica were investigated as improvement of mullitic bonds in refractory ceramic materials. The silicas investigated included fumed, ground, precipitated, and colloidal silica.

A wet mixing procedure with pH control was implemented in order to obtain homogeneity before specimens were pressed. The same properties were investigated to determine the effects of the new silica and alumina sources. Sixteen sources of silica and seven alumina sources were evaluated. improved mullite yields Several of the silica sources along with other selected properties enough to warrant further investigation as mullitic bond formers"--Abstract pp. v-vi

Advisor(s)

Robert E. Moore

Committee Member(s)

M. N. Rahaman
Robert Wolf

Department(s)

Materials Science and Engineering

Degree Name

M.S. in Ceramic Engineering

Publisher

University of Missouri--Rolla

Publication Date

Summer 1988

Pagination

xvi, 119 pages

Rights

© 1988 Andrew Jay Skoog, All rights reserved.

Document Type

Thesis - Restricted Access

File Type

text

Language

English

Thesis Number

T 5732

Print OCLC #

18973077

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