Tailoring of structural and magnetic properties by substitution of copper in cobalt chromium ferrites

The simple and cost-effective powder metallurgy method has been employed to prepare a series of copper substituted cobalt chromium ferrites Cu_xCo_1-xCr_0.5Fe₂O₄ (x?=?0, 0.2, 0.4, 0.6, 0.8, 1.0). The calcination of the samples has been carried out at 1100?°C for 24?h. X-Ray Diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR) measurement proves the formation of cubic spinel ferrites. Vibrating Sample Magnetometer (VSM)) analysis revealed that the substitution of copper in the Co-Cr ferrites leads to reduce the magnetic moment that in turns decrease the saturation magnetization and coercivity. The Ultra violet visible spectroscopy (UV–VIS) showed that the band gap energy increases with copper substitution which is due to reduction in crystallite size. The results indicate that the replacement of copper with the cobalt-chromium ferries strongly influences the crystal structure, microstructure, magnetic parameters and band gap energy.     

Study of cavity modes in BOF by analysis of sound

Various cavity modes (i.e. dimpling, splashing and penetrating) are important phenomena in estimating splashing in oxygen steelmaking. Though few studies in the literature have addressed this issue, no investigation can be found focusing on identifying modes by physical means. In the current work, sound produced in a cold air-water model was analysed to distinguish various cavity modes. Wave analysis showed that amplitude of sound increased as the mode changed from one to other. From spectrum analysis, it was found that between a certain range of frequencies, there was considerable difference in the sound level as the mode changed from splashing to penetrating. The presence of a second layer over the bath surface did not affect the general outcomes of the analysis. Present work indicates that it may be possible to identify cavity modes by analysing the sound produced from the bath. This would allow greater control of splashing in oxygen steelmaking and potentially help prevent slopping by controlling operation parameters of the process.     

Soaking–drying frequency effect on gypsum-rich roadbed sand

This article presents the California bearing ratio (CBR) and moisture content behaviour of a gypsum-rich roadbed sand with a gypsum content of about 39% subjected to cyclic soaking and drying. Frequencies of 8-, 14- and 60-day cycle lengths were adopted together with six cycles of soaking and drying for each frequency. Each cycle consisted of two equal time periods of soaking and drying. For each frequency, 13 pairs of CBR samples were prepared and subjected to cyclic soaking and drying in the laboratory under a surcharge load of 45 lb (200 N). The time variation of moisture content during cyclic soaking and drying at the top, middle and bottom of each CBR sample was studied as well. The article reveals that for each cycle, the CBR decreases during soaking and increases during drying for all frequencies.