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Nzeukou N.A.,Local Material Promotion Authority MIPROMALO | Nzeukou N.A.,University of Yaounde I | Traina K.,Innovative Solutions | Medjo E.R.,University of Yaounde I | And 6 more authors.
InterCeram: International Ceramic Review | Year: 2014

The sintering behavior and mechanical properties of four alluvial clays sampled from the Sanaga River (sampling sites: Nanga-Eboko, Mbandjock, Batschenga, and Ebebda), central region of Cameroon were investigated. Specimens were shaped by cold pressing and fired between 850 and 1100 °C. X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy were used to monitor microstructural modifications and thermal phase transformations. Linear shrinkage, density, open/closed porosity, and water absorption were used to assess the effects of firing cycle on the mechanical properties of the fired compacts. The results showed that between 850 and 1050 °C the mineralogical phases are mainly quartz and feldspar. Mullite, spinel, and cristoballite appear at 1100 °C together with viscous phases. The values of apparent density (2.62-2.76 g/cm3), open porosity, and flexural strength (3-30 MPa) of the brown compacts suggest the possible use of these clays for earthenware ceramics such as building bricks, roof and floor tiles.

Deutou J.G.N.,University of Ngaoundéré | Mohamed H.,Local Material Promotion Authority MIPROMALO | Nzeukou N.A.,Local Material Promotion Authority MIPROMALO | Kamseu E.,Local Material Promotion Authority MIPROMALO | And 4 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2016

Fine particles of kyanite were used as reinforcement in mullite matrix composite. Mix of metakaolin and meta-alumina (calcined bauxite) received different fraction of fine kyanite particles: 37.5, 42.5 and 50 mass%. The objectives were to improve the crystallization of kaolin-based mullite matrix reducing the amorphous content and the grain growth. Packing process and densification were enhanced, leading to the action of kyanite at low temperature (<1250 °C) as phase separator and nucleation sites for the transformation of metakaolin to acicular mullite. At high temperature (>1350 °C), the kyanite particles are decomposed to mullite still without glassy phase and the metastable alumina presented in the mix reacts with amorphous silica to produce additional mullite. The sintering behaviour, the thermal expansion behaviour of ~0.5 % between 200 and 1000 °C and the coefficient of the thermal expansion of 5.92, 5.15 and 6.92 × 10−6/°C for KY3, KY4 and KY5, respectively, between 200 and 1000 °C, and their decrease at higher temperature demonstrated the optimum refractoriness of the mullite matrix composites developed. © 2016 Akadémiai Kiadó, Budapest, Hungary

Nzeugang N.A.,Local Material Promotion Authority MIPROMALO | Nzeugang N.A.,Laboratory of Alterology and Engineering Geology | Eko M.R.,Laboratory of Alterology and Engineering Geology | Fagel N.,Laboratory of Clays | And 5 more authors.
Clay Minerals | Year: 2013

Clayey deposits of Nanga-Eboko (central Cameroon) were studied to assess their potential as building materials. Characterization was performed using XRD, FTIR, XRF, DTA/DTG and firing testing. Clays appear as discontinuous pockets with the same textural characteristics in three villages located on both sides of the Sanaga River. The average thickness of the exploitable layer is about 3m. The estimated tonnage ∼7-17 × 105 m3 can supply a brick industry of great importance. SiO2 (∼70%), Al 2O3 (∼15%) and Fe2O3 (∼4%) are the predominant oxides of the natural clays. Quartz (∼55%), kaolinite (∼33%), illite (∼5%) and K-feldspar (∼4%) are major minerals. Clays are not suitable for building construction due to their fine-grained size and high plasticity properties. Firing properties of bricks (950 and 1050°C) are good despite the high shrinkage values. Therefore the addition of '' degreasers '' is recommended to control shaping and drying. © 2013 Mineralogical Society.

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