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Assessment of ceramic raw materials in Uganda for electrical porcelain
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Clay, quartz and feldspar are widely available in Uganda. The location and properties of various clay deposits are reported in the literature, but little is reported on feldspar and quartz deposits. In this work an extended literature on ceramics and porcelains in particular, is documented. Samples from two deposits of feldspar and two deposits of quartz are characterised and found to possess requisite properties for making porcelain insulators. Sample porcelain bodies are made from materials collected from selected deposits using different mixing proportions of clay, feldspar and quartz. Their properties in relation to workability, firing temperature, dielectric and bending strengths are studied. It is found that a mixture consisting of 30% Mutaka kaolin, 15% Mukono ball clay, 30% Mutaka feldspar and 25% Lido beach flint yields a body with highest mechanical strength (72MPa) and dielectric strength (19kV/mm) when fired at 1250°C. The strength (both mechanical and dielectric) is found to decrease with increasing firing temperature. At high firing temperatures, the undissolved quartz in the body decreased, the glass content increases and pores are formed. Mullite content on the other hand does not change at temperatures above 1200°C but there are significant differences in the morphologies of the mullite crystals in the samples. Optimum mechanical and electrical properties are found at maximum virtification and a microstructure showing small closely packed mullite needles.

Place, publisher, year, edition, pages
Stockholm: KTH , 2006. , ii, 20 p.
Series
KTH/MSE--06/45--SE+MEK/AVH
Keyword [en]
porcelain, characterisation, bending strength, dielectric strength, Uganda
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-4013ISBN: 91-7178-408-X (print)OAI: oai:DiVA.org:kth-4013DiVA: diva2:10389
Presentation
2006-06-02, Konferensrum K408, KTH, Brinellvägen 23, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101122Available from: 2006-05-31 Created: 2006-05-31 Last updated: 2010-11-22Bibliographically approved
List of papers
1. State of the art paper on development of electric porcelain insulators from Ugandan raw materials
Open this publication in new window or tab >>State of the art paper on development of electric porcelain insulators from Ugandan raw materials
(English)Manuscript (preprint) (Other academic)
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-5865 (URN)
Note
QC20100706Available from: 2006-05-31 Created: 2006-05-31 Last updated: 2010-11-22Bibliographically approved
2. Characterization of feldspar and quartz raw materials in Uganda for manufacture of electrical porcelains
Open this publication in new window or tab >>Characterization of feldspar and quartz raw materials in Uganda for manufacture of electrical porcelains
2006 (English)In: Journal of the Australasian Ceramic Society, ISSN 1018-6689, Vol. 42, no 1, 29-35 p.Article in journal (Refereed) Published
Abstract [en]

Electric porcelains are widely used for insulation purposes. The aim of this study is to characterize feldspar and quartz raw materials in Uganda for use in manufacture of electric porcelains. Samples from two deposits of each feldspar and silica are investigated to assess their potential as raw materials in the manufacture of electric porcelains. Raw samples ground to powder form are investigated by means of X-ray diffraction, thermal analysis, and scanning electron microscopy. In addition, the chemical composition, particle size distribution and density of the powders are determined. The study reveals one of the feldspar deposits to consist of purely ordered microcline, while the other has ordered microcline, quartz and albite. The silica deposits are purely of quartz mineral. The materials investigated, are suitable for use in porcelain production.

Keyword
Engineering controlled terms: Characterization; Composition; Deposits; Feldspar; Manufacture; Particle size analysis; Powders; Quartz; Raw materials; Silica; Thermoanalysis; X ray diffraction analysis
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-5866 (URN)2-s2.0-33645638858 (Scopus ID)
Note

QC 20100706

Available from: 2006-05-31 Created: 2006-05-31 Last updated: 2016-12-13Bibliographically approved
3. Effects of mixing proportions and firing temperature on properties of electric porcelain from Ugandan minerals
Open this publication in new window or tab >>Effects of mixing proportions and firing temperature on properties of electric porcelain from Ugandan minerals
2008 (English)In: Industrial ceramics, ISSN 1121-7588, Vol. 28, no 1, 1-10 p.Article in journal (Refereed) Published
Abstract [en]

Five sample mixtures of Ugandan kaolin, ball clay, feldspar and flint were formulated and porcelain samples fabricated by extrusion through a vacuum pugmill. Samples were evaluated for formability. The degree of densification of sintered specimens fired at 1200 to 1350 degrees C was evaluated by measuring the firing shrinkage, bulk density, water absorption and bending strength. Crystalline phases and mullite morphology were studied using XRD and SEM respectively. Dielectric strength measurements were carried out on disc specimens. Dielectric and bending strength properties deteriorated at high temperatures because of pore formation and decreasing amount of undissolved quartz in the crystalline phase. An optimum composition of 30% kaolin, 15% ball clay, 30% feldspar and 25% quartz yielded an unglazed body with highest bending strength of 72MPa and dielectric strength of 19MVm(-1) after firing at 1250 degrees C. The body consisted of small, closely packed mullite needles and undissolved quartz crystals embedded in a glass matrix.

Keyword
rice husk ash, whiteware compositions, bending strength, mechanical-behavior, raw-materials, silica fume, fly-ash, quartz, substitution, constitution
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-17593 (URN)000256573400001 ()2-s2.0-45749156420 (Scopus ID)
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2010-11-22Bibliographically approved

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