Browsing by Author "Kanagaratnam, J.N."

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    Establishing a Relationship between Silica/ Feldspar/ Ball Clay Content and Shrinkage Properties in Wall Tile Manufacturing
    (Uva Wellassa University of Sri Lanka, 2016) Kanagaratnam, J.N.
    The manufacturing of a walltiles contains the raw materials such as silica, feldspar, ball clay calcite, kaolin and tile grog. Silica content in ball Clay may vary from location to location. This variation may cause shrinkage problems while firing the tile body. Since ball clay is a plastic material and silica is not, higher the silica, lower the shrinkage will be. Yet the extent of the effect of silica content on shrinkage properties is unknown. The objective of this study was to establish a relationship between Silica/ Feldspar/ Ball Clay content and shrinkage properties of wall tiles. Homogenized master batch of raw materials were made by collecting the raw materials from the storage bins. They were dried in the oven to reduce the moisture. The indirect silica content of ball clay was measured by checking the residue. Different formulas containing different percentage of silica were prepared. The powder was then prepared by adding 6% of moisture. Two tiles from each formulae were pressed in the lab scale press (6 x 6"). The green tile size was measured using a Vernier caliper. The tiles were then fired in the biscuit kiln and the final size of the fired tiles were measured. Using the data collected from the above procedure, a formulae for shrinkage and silica/ feldspar/ ball clay content was derived. The standards and limitations were established. Keywords: Wall tile, Silica content, Ball clay, Shrinkage
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    Synthesis of Expanded Graphite using Sri Lankan Vein Graphite via Ultrasonication
    (Uva Wellassa University of Sri Lanka, 2018) Senavirathne, M.M.K.R.N.D.; Kanagaratnam, J.N.; Amaraweera, T.H.N.G.; Wijayasinghe, A.
    Sri Lankan vein graphite, which is found in highly crystallized form with high purity (95 - 99 % carbon), have already been successfully developed for the anode of the lithium ion rechargeable battery. However, for their use in future energy storage applications, such as in sodium ion batteries, modification of the vein graphite structure is essential. Hence, this study focuses on structural modification of purified vein graphite by converting into expanded graphite via solvent assistant ultrasonication. Graphite oxide was synthesized from purified vein graphite by employing improved Hummer's method and then sonicated with propylene carbonate. The dried product was heated and again subjected to sonication with the same solvent. Then the solution was centrifuged to remove any non exfolliated graphite. Finally, the solution containing Graphite Oxide (GO) particles in PC were thermally reduced to produce reduced graphite oxide (rGO-PC). X-ray diffraction of crystal phase of the resulted graphite oxide shows the existence of a broad peak at 23.19 ° (20) corresponding to an interlayer spacing of 0.38 nm. The Fourier transform infrared spectrum obtained on the synthesized GO confirm the presence of O -H, C=O, COOH and C-0 oxygen functionalities, which are then, confirm to be partly removed by the successive thermal treatment. Scanning electron microscopic images are evidence for the expanded structure with wrinkles and folded nature in contrast to the opaque and smooth structure observed in the pristine graphite. Altogether, these results confirm the successful formation of expanded graphite by the solvent assisted ultrasonication technique.
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    Synthesis of FeCl3-Graphite Composite from Vein Graphite via Solvothermal Method for Lithium-Ion Rechargeable Battery Applications
    (Uva Wellassa University of Sri Lanka, 2019) Ranasinghe, U.G.K.L.K.S.; Kanagaratnam, J.N.; Amaraweera, T.H.N.G.; Wijayasinghe, H.W.M A.C.
    Natural vein graphite is a good crystalline material with high natural purity and is used for advanced applications. Natural vein graphite has been identified as a cost effective source to produce anode material in Lithium-ion Rechargeable Batteries (LIBs). However, the electrochemical performance of anode material prepared from vein graphite has to improve further for practical LIB applications. This study focuses on synthesizing Ferric Chloride-Graphite Intercalation Compound (FeCl3-GIC) via solvothermal method to enhance the Li-ion intercalation. Anhydrous Ferric chloride was used as an intercalant into graphite layers via solvothermal method at 400 °C for 12 hours by using 50 mL autoclave. The X-Ray Diffraction patterns show the characteristic behavior of the graphite intercalation compound. Moreover, weaker peaks corresponding to the Fe2O3 and FeCl3 could also be observed in the XRD pattern indicating the existence of secondary minor phases of Fe2O3 and FeCl3 in the GICs. Scanning Electron Microscopy images evidenced for the smooth surface morphology of graphite particles after the treatment. Half-cells were assembled using the electrode fabricated from the synthesized material and Li counter electrode in an argon-filled glovebox. It shows a high specific capacity of 378 mA h g-1, which is little higher than the theoretical capacity (372 mA h g-1 for LiC6) during its first discharge. However, there is a high capacity loss after 25 cycles. The fading nature of this assembled battery could be due to the detrimental effect of Fe2O3 and unreacted FeCl3. This could be minimized by carrying out the solvothermal treatment in a vacuum environment by eliminating the O2 present inside the autoclave chamber. By doing this, the formation of Fe2O3 could be minimized and as the chamber pressure increases, the ability of FeCl3 molecules to be intercalated into the graphite layers could be enhanced.