Abstract. The mineral and elemental composition, crystal structure and particle size distribution of kaolin clays have been determined to ascertain its industrial significance. The mineral composition is evaluated by X-Ray Fluorescence (XRF), crystalline structure by X-Ray Diffraction (XRD) and particle size distribution using low angle laser light scattering (LALLS) technique. The results shows the presence of eight elements expressed in percentages in form of their oxides as: SiO 2, Al 2 O 3, Fe 2 O 3, MgO, CaO, K 2 O, TiO 2 and P 2 O 5. Five crystalline structures are revealed by XRD result. The particle size distribution shows that kaolin particles are mainly in the range of 25-35 µm, while few particles have size distribution varied between 0.4-0.75 μm. The report is found to be in agreement with other researchers.

A series of electroplating works have been conducted to investigate the best condition for the coelectrodeposition of nickel-alumina (Ni/α-Al 2 O 3 ) composite coating. Co-electrodeposition was done onto mild steel as cathode at ambient temperature (27°C) with current density of 30 mA/cm 2 under α-Al 2 O 3 concentration of 2 g/l and various agitation speeds of 50, 100, 150, 200, and 250 rpms. The cross-section of the composite coatings portrayed α-Al 2 O 3 particles was co-deposited. Under field emission scanning electron microscopy analysis, the coating shows a coarse surface morphology, while cross-sectional microstructures shows a compact embedding of α-Al 2 O 3 particle in the Ni matrix. Elemental analysis by EDX detected the presence of Ni and α-Al 2 O 3 . Vickers microhardness testing shows that the coating hardness increases almost 60% at the highest agitation speed, i.e., 250 rpm.

Abstract-ThisI. INTRODUCTION The up surge application and request for refractory bricks had motivated this research to investigate the raw clay materials used for production of refractory bricks. The raw clay materials were subjected to standard refractory fireclay brick tests requirement through the tests procedures for chemical, thermal, physical and mechanical properties [1]. Clay as a raw material varied considerably in terms of workability, structure, particle-size distribution, plasticity and mineralogical composition. These differences paved way for clays being categorized or classified into plastic clays, flint clays, kaolin clays, fireclays and ball clays [2]. In the refractory industries, they are grouped and referred to as illite, Montmorillonite and kaolinite [3]. Refractories are clay materials that are generally capable of enduring very high temperatures without deformation, structural changes or softening [4]. The type of refractories is determined by the type of refractory requirement for a specific purpose. The types are classified as acid, basic and neutral refractories [5]. Traditionally these clay materials containAl 2 O 3 .SiO 2 .H 2 O to produce alumino-silicates refractory fireclay bricks. They are further classified by temperature. When the temperature is between 1500-1700 0 C, it is branded as refractory e.g. fireclay.The temperaturebetween 1700-2000 0 Cis recognized as high refractory e.g. chromite. When thetemperature is 2000 0 C, it is referred to as super refractory e.g. zircon [5].The applications of refractories are employed in the construction of furnaceslinings, ladles, reactors, ovens and kiln [6]. This disposition proved that the raw clay material is a fireclay and belongs to the alumino-silicate subgroup. The uses for fireclay refractory brick comprise of porous refractory insulation behind furnace linings, refractory fireclay bricks and ladles [7].Refractories are frequently consumed basically in the iron and steel industries [8]. Contamination of refractories clays are usually with limited amount of impurity as contained in the oxides which are CaO, MgO, TiO 2 , Fe 2 O 3 , Mn, SO 3 , ZnO, Cl, K 2 O, P 2 O 5 , Cr 2 O 3 and alkali oxides that acts as fluxing mediator at very high temperature [9]. In the process ofiron and steel production, the use of basic oxygen furnace (BOF) for the molten iron that comes from the blast furnace is decontaminated from the scums.Refractories belonging to silica-alumina have heterogeneous microstructure with bulky grain size and reasonable rate of porosity [10]. In Nigeria, previous investigation work has been done on the characterization of the native refractory raw clay materials for the making of quality refractory fireclay bricks for furnace lining, ladles, ovens and kilns [11]. In many cases, the outcome and results of such previous work were inconclusive and not comprehensive enough to be used or adopted for industrial uses. They were not subjected to standard test requirement for refractory bricks production.The researches for an alterna...

Abstract. In this work, the consolidation of different alumina particles via sintering process was conducted to the compacted alumina pellets. This consolidation was also assisted with the sintering aid, MgO to densify the final ceramic structure. Comparison between the influence of additive to the different particles size of compacted alumina by observing the microstructure and physical properties was conducted. The value physical properties and microstructure clearly show that for both particle size of alumina, MgO additive can increase the density value and improve microstructure properties.

A series of electroplating works were conducted to investigate the best conditions for the electrodeposition of nickel on a mild steel substrate. The electrodeposition was done at ambient electrolyte temperature with mild agitation and under current density ranging from 10 to 50 mA/cm 2 . X-ray diffraction analysis (2h for first three peaks = 44.6, 51.9, and 76.8) and Energy Dispersive Spectrometer verified the presence of a pure nickel coating. Under field emission scanning electron microscopy analysis, the coating shows a typical nodular surface morphology, while cross-sectional microstructures show a compact nickel layer. Vickers hardness testing shows that the coating hardness gave the highest value of 293 HV at 30 mA/ cm 2 current density.