This study characterized the sizes, shape and surface properties of Nigerian cement particles and investigated how the features affect the performance of Electrostatic Precipitator (ESP), a commonly employed particulate control device. Samples of cement powder were collected across existing cement plants in Nigeria and analyzed using standard laboratory methods. The particles have a broad size distribution and the sizes ranged roughly between 10 µm and 100 µm. The mass mean diameter is within 94.8 µm – 95.6 µm indicating that the samples are composed mainly large diameter particles. Regarding shape, the particles of the cement powder have no symmetry but exhibited strong cohesion with one another. The findings of this study have concluded that the physical and structural characteristics of Nigerian cement dust are adaptable to the design and operation of an efficient ESP. Therefore, reasons for the unsatisfactory performance of employed ESP in Nigerian cement manufacturing plants need to be traced to other factors.
A bidentate Schiff base ligand having nitrogen sulphur donor atoms was derived from the condensation of S-benzyldithiocarbazate (SBDTC) with cinnamaldehyde. The ligand was then chelated with Co(II) and Sb(III). Molecular structures of the Schiff base ligand and its complexes were established through elemental analysis, conductivity and magnetic susceptibility measurements as well as spectroscopic data (FT-IR, UV-Vis and ESI-MS). The geometrical structures are tetrahedral and octahedral for the cobalt complex and antimony complex respectively. The biological activities of the ligand and its complexes were investigated against the gram-positive and gram-negative bacteria and the fungus strain. The metal complexes were shown to possess more.
Aims: A comparative study on the thermal behavior of natural rubber (NR) filled with different plant wastes and carbon black was carried out with the aim to evaluate green fillers that can replace carbon black filler in natural rubber vulcanisates for thermal applications.
Study Design: The plant wastes used for this study were carbonized and un carbonized cocoa pod husk, corncob and empty palm fruit bunch. Natural rubber vulcanisates filled with 10 phr carbon black (reference) and the various plant waste materials were prepared.
Methodology: The thermal behaviour of the vulcanisates and the fillers was studied by thermogravimetric analysis (TGA). The glass transition temperature (Tg) for the vulcanisates was determined by differential scanning calorimetry (DSC). The shape of the decomposition curve was obtained from the derivative of the TGA curve (DTGA). The amount of residue remaining at various temperatures for the different samples was calculated from the TGA curve. Activation energies of degradation were calculated using Horowitz–Metzger equation.
Results: The carbonised fillers and carbon black were more thermally stable than the un carbonised fillers and raw rubber. The decomposition behavior of vulcanisates followed a similar trend; with a single main decomposition peak at about 380°C. Samples with un carbonised fillers had higher residues than those filled with carbon black and carbonized plant wastes. From the activation energy values, it was found that vulcanisates, filled with carbonized corncob and carbonized cocoa pod husk were very close in thermal stability to those filled with carbon black and they were more stable than those filled with un carbonised plant wastes. DSC studies revealed that the fillers had non-significant effects on the Tg of the vulcanisates. This was evident from the very close nature of the Tg values for the different vulcanisates. Among the plant wastes studied, carbonised cocoa pod husk and corncob presented very close values of Ea and Tg to carbon black as fillers for raw natural rubber.
The vulcanisates with un carbonised fillers were less thermally stable than vulcanisates filled with carbonized fillers and carbon black.
Aims: The LBL technique is leveraged in this study to perform thin film fabrication using (diallyl dimethylammonium chloride) (PDDA) and copper phthalocyanine-tetrasulfonic acid (CuTsPc). The deposition of PPDA/CuTsPc films over a glass substrate through alternate adsorption is studied in this research. Both manual and automated methods are examined to evaluate the efficiency of the LBL technique.
Study Design: Analysis.
Place and Duration of Study: Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology-Bombay (IIT Bombay), between July 2019 and December 2019.
Methodology: A clean glass substrate is used to perform the Layer by Layer assembly technique for fabricating three thin films of PDDA/CuTsPc. The first sample is prepared manually by immersing the glass substrate in an aqueous solution of polycation for eight minutes, which is followed by washing in deionized water and drying using nitrogen gas. This process is repeated until five bilayers are formed. UV-Vis spectroscopic measurements are used to analyze the absorbance trends. For the second sample, the same process is repeated but with an automated apparatus. An aqueous polyanion solution and an automated apparatus is used for the third sample with the remaining steps being identical to that of the previous samples.
Results: For manually prepared samples, UV-Vis absorption spectra of glass covered with about one to five bilayers of PDDA/CuTsPc for showed that the increase in peaks are directly proportional to increase in the number of bilayers. A similar linear behavior is seen for the samples prepared by automated fabrication. The linear growth of the samples is fairly alike for the monolayers of PDDA and CuTsPc.
Conclusion: An orderly deposition process is observed upon performing Atomic Force Microscopy and UV-Vis spectroscopy. The research findings show a linear behavior in the absorbance curve, which demonstrates the fact that monolayers form at every stage of the film fabrication process. It is also observed that the materials were being absorbed at the same rate for both the automated and manual methods
Fe-Co-2V is a popular metallic alloy used in electromagnetic applications. However, there is a lack of mechanical fatigue characterization of this alloy in the literature. In this work, Fe-Co-2V specimens with rectangular cross-sections were carefully prepared in accordance with standards. They were measured for surface roughness and then subjected to quasi-static monotonic testing, as well as fatigue testing at both 0.5 Hz and 1 Hz frequencies. Both Rockwell hardness and Vickers micro-hardness testing were performed. Additionally, scanning electron microscopy imaging of the fractured surfaces was done. The quasi-static testing revealed a flat yield region characteristic of Lüders bands. The fatigue results did not show significant differences or sensitivity to change in frequency, although the fatigue life was higher on average for the 0.5 Hz. However, the fatigue results differed from published work at 0.33 Hz. The fractography revealed purely brittle fracture, with clear chevron marks and fracture initiation always starting at the surface. Lastly, it was identified that the C, D, and F Rockwell hardness scales were appropriate for testing this material and that the grain size necessitated the use of the upper end of indentation force for Vickers micro-hardness testing.