Papers by Keyword: MnS

Abstract: Thin films of pure and iron doped MnS, have been deposited on glass substrates using a straightforward and cost-effective technique named Chemical Bath Deposition (CBD). The temperature of the heating water bath was maintained at 90°C for three hours of deposition. Deposition is done by varying the doping concentration of Fe from 0 to 10%. Manganese chloride, iron chloride tetrahydrate, urea, and thioacetamide were the precursors employed in this work. The X-ray diffraction method was used to ascertain the thin film's structural properties. Using the Scherrer formula, the average crystallite size for an undoped MnS thin film was observed to be 30.28 nm and is decreased to 24.02 nm for 4% of Fe doping. For an undoped MnS thin film, the values of dislocation density and material strain were 1.09× 10⁻³(𝑛𝑚)⁻² and 3.418× 10⁻³, respectively. These values were increased to 1.73× 10⁻³(𝑛𝑚)⁻² and 4.65× 10⁻³, respectively due to decrement in the crystallite size. Grain size and morphology were examined using Scanning Electron Microscopy (SEM). Micrographs of samples were obtained at different magnifications and their values were noted as 0.9 μm for pure and 4.69 μm for 4% Fe doped thin films. Optical properties were determined using DRS method. The energy band gap was found as 2.21 eV for pure samples and it was decreased to 2.14, 2.09, 1.98, 1.96 and 1.93 eV for 2, 4, 6, 8 and 10% iron doping, respectively. Solar cells, solar selective coatings, sensors, optical mass memory, and anti-reflection coatings have all made substantial use of MnS thin films.

Abstract: The recrystallization behaviors of 60% rolled Fe-wt.3%Si and Fe- wt.3%Si-Mn-S alloys containing coarsen MnS particles were observed in temperature range 600°C~1000°C. The activation energy for recrystallization was determined according to an Arrhenius type of relationship. It was found that the activation energy in the temperature range 600°C~750°C was much higher than that in the temperature range 850°C~1000°C. Thermo-mechanical calculation indicates that there are hardly precipitation behaviors of MnS particles in 600°C~1000°C. Fe₃C will precipitate below 650°C and Cottrell atmosphere will form just above 650°C, which induces dragging effect against the boundary migration during recrystallization and increase the activation energy. The activation energy determined was about 99kJ/mol or 217kJ/mol in Fe-3%Si alloy and 91kJ/mol or 220kJ/mol in Fe-3%Si-Mn-S alloy for the recrystallization in high temperature range of 850°C~1000°C or low temperature range of 600°C~750°C respectively.

Abstract: In the this paper, the compositions design with low carbon and addition of sulfur and manganese which can enhance fish-scale resistance by MnS as hydrogen trap was adopted to produce DC03EK cold-rolled enamel steel. The effect of sulfur and manganese contents on formability and fish-scale resistance of DC03EK cold-rolled enamel steel was investigated. Results show that yield strength, ultimate tensile strength, elongation, work hardening exponent and average plastic strain ratio of the steel with sulfur content of 0.024wt% and manganese content of 0.22wt% is 133 MPa, 310 MPa, 36.8%, 0.22 and 1.46, respectively, showing the well formability. And its hydrogen penetration time and diffusion coefficient is higher than 12 min and lower than 9.26×10^-7 cm²/s, respectively, showing excellent fish-scale resistance. However, for the steel with sulfur content of 0.012wt% and manganese content of 0.12wt%, even though better formability is obtained, the fish-scale resistance is poor with hydrogen penetration time of 4.7 min and hydrogen diffusion coefficient of 2.36×10^-6 cm²/s which is far from the expectation of steel for enamel.

Abstract: The manganese sulfide, MnS, is a wide bandgap (Eg = 3.1eV) diluted magnetic semiconductor belonging to the VIIB-VIA family with outstanding magneto-optical properties. The authors report the synthesis and characterization of MnS nanoparticles. The MnS nanoparticles were synthesized by simple wet chemical method at ambient temperature. Manganese acetate (C4H6MnO4.4H2O) was used as source for Mn+2 ions and thioacetamide (C2H5NS) was used as source for S-2 ions. The energy dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD) were used for stoichiometric and structural characterization of the synthesized nanoparticles respectively. The crystallite size calculated from XRD using Scherrer’s formula and Hall-Williamson relation came out to be of 6.81 nm and 5.27 nm respectively. The optical absorption spectra showed absorption edge at 325 nm corresponding to energy of 3.82 eV, which acknowledged the occurrence of blue shift. The photoluminescence spectra recorded for five different excitation wavelengths viz 250, 275, 280, 300 and 325 nm showed three emission peaks at 463 nm, 550 nm and 821 nm. The TEM and SEM analysis of the particles clearly shows the particles are spherical in shape. The selected area electron diffraction (SAED) pattern showed ring pattern, stating the nanoparticles to be polycrystalline. The obtained results are discussed in details.

Abstract: Mixed solvent of ethylenediamine (EDA) and ethylene glycol (EG) using MnCl4H₂O, and (NH₂)₂CS as precursors was used to synthesize α-MnS micronsized architectures. Optimal α-MnS crystals were successfully grown from a mixed solvent of EDA:EG with a volume ratio of 1:1, reaction temperature of 140-180 °C and maintained for 6h. X-ray diffraction (XRD), scanning electron microscopy (SEM) was employed to characterize the structure and morphology of the product. The results show that the morphologies of α-MnS are found to be temperature dependent.

Abstract: Three studies on the oxidation behaviour of austenitic stainless steels were described in the present paper. (1) High temperature oxidation behaviour and its mechanism in austenitic stainless steels with high silicon: Sulfur contained as impurity in steel showed a harmful influence to the oxidation resistance of 19Cr-13Ni-3.5Si stainless steels. It was found that the abnormal oxidation was caused from the surroundings of MnS inclusions. (2) Effect of a small addition of yttrium on high temperature oxidation resistance of Si-containing austenitic stain less steels: The oxidation resistance of 19Cr-10Ni-1.5Si steels was improved remarkably even with only 0.01%Y addition, which is the same concentration as added for de-oxygenation. Y was enriched at the grain boundary of oxide scale and metal-oxide interface. It was suggested that Y-containing steels shoed good oxidation resistance, because the enriched Y at the grain boundary and metal-oxide interface prevented the diffusion of iron and oxygen ions through the oxide scale. (3) Effect of grain size on the oxidation behaviour of austenitic stainless steels: Type 304, 316 and 310 steels with finer grain size showed better oxidation resistance than those with coarser grain size at 850°C. The oxide scale of steels with coarser grain size easily spalled during the cooling process.

Abstract: Hot deformation was applied on Fe-3%Si by the Gleeble-1500 thermo-mechanical system, and the effect of solute depleted area around the primary MnS particles precipitated prior to hot deformation on the distribution of strain-induced MnS particles was investigated. The obtained results showed that the depleted area around primary MnS particles affects significantly the distribution of strain-induced MnS particles, and the involved parameters were discussed.

Abstract: H beam welds along rolling and transverse direction were investigated with nondestructive testing, mechanical testing and microstructural analysis. Crack and fracture occurred, during guided bend testing, in the specimens welded along rolling direction between flanges of the H beams with higher S content although no defect was detected prior to the bend test. The fracture seemed to be lamellar tearing because of step-like fracture propagation and terrace and wall fracture appearance of the ruptured bend test specimen. On top of this, lamellar tear was already created in the base metal area near the HAZ before the bend test in microstructural analysis on the welds. It seems that lamellar tearing occurred in the specimens welded along rolling direction between flanges of the H beams with higher S content as cracks were formed and propagated into a ferrite phase region in α-γ band structure in combination with low ductility in transverse direction due to MnS inclusions elongated along rolling direction.