Department of Physics

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Browsing Department of Physics by Subject "Clay minerals"

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    Structural and mechanical properties of non-glazed ceramic tiles developed from selected mineral deposits in Uganda
    (Nano-Horizons: Journal of Nanosciences and Nanotechnologies, 2023-07) George, William Mukwaya; Ben, Enjiku; Emma, Panzi Mukhokosi
    Uganda is well endowed with clay resources; however, comprehensive knowledge about the composition, structure and suitability of these clays for ceramic tile production is lacking. In this study, we provide a comprehensive characterisation of locally sourced clays in Uganda and their suitability for ceramic tile production. In the study, we developed ceramic tiles using feldspar, kaolin, ball clay and sand from four different sites in Uganda. We focused on analysing the surface morphology, crystallographic structure and mineralogical composition of the raw materials. In addition, we examined the mechanical properties of the developed tiles with the different mixture ratios of the clay types. The surface morphology of the raw materials was analysed by using a scanning electron microscope. The structural analysis of the raw clay materials was done using X-ray diffraction. The mineralogical composition of the raw materials was investigated using energy dispersive X-ray spectroscopy and X- ray fluorescence spectroscopy. The results indicated that the strength and rapture modulus are influenced by the composition of kaolin and feldspar. We concluded that the selected mineral deposits can be used in the production of ceramic tiles in Uganda.
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    A study of electrical insulation materials developed using selected clay minerals in Uganda
    (Kyambogo University [unpublished work], 2012-06) Nasejje, Stella
    This study was to investigate appropriate mixtures of different ceramic mineral ingredients needed to make electrical porcelain insulators and to determine the best method of developing the electrical insulator of slip casting, dry pressing, and wet pressing. The mixing of the clay minerals was done using percentage ratios of ball clay. kaolin, feldspar and flint of which the quantity of flint was kept constant at 20% in all compositions and that of ball clay to kaolin changed through a range of 1:1.75 , 1:2 and 1: 2.5, well as that of feldspar took up any remaining percentage. These samples were formed by slip casting. Wet, and dry pressing and then tired at a constant heating rate to a temperature of l 250°C. Then the dielectric strength was tested using the oil test set, Avo Megger foster OTS100A F/2. The mixtures of the clay minerals with a ratio of ball clay to kaolin of 1:2 showed good formability in all forming methods, but those with a ratio of 1:1.75 and 1:2.5 could not easily form good casted and wet pressed samples. The best formulation was that with 55% clay, where the ratio of ball clay to kaolin was 1:2. The sample compositions of the various, minerals were found to affect both voltage breakdown and dielectric strength. The voltage break clown. V was found to be proportional to the thickness. t of the samples according to the expression V= at + b: where a and b are constants of testing conditions like room temperature and frequency. Conversely, the values of dielectric strength; U was found to be inversely proportional to the thickness, d of the samples according to the expression; D = VB over d where VB is the breakdown voltage and d is the thickness of the sample. Values of both the voltage breakdown and dielectric strength of samples tested in air were much lower than those of samples tested in transformer oil due to generated carbon around them when in air as a result of corona discharge. The samples tested in transformer oil had values above 10kV/mm. Thus, the electrical insulation properties of the formulation of the samples developed in this study were found to match that required for international standards.