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A high-temperature in situ route has been employed for the synthesis of carbon nitride supported manganese sulfide nanoparticles (CNMS). The hybrid material was characterized using different analyt...

Photocatalytic hydrogen production from hydrogen sulfide (H2S) splitting has been considered as an appealing and sustainable approach to resolve both energy crisis and environment problem. It remains challenging to quest suitable photocatalysts for highly efficient H2S splitting. Herein, a series of graphene oxide (GO)/MnS-Mn3O4 composites were successfully prepared via a mild method. The results demonstrated that the GO plays three roles in enhancing the photocatalytic H2S splitting performance (i) enhancing sunlight response, (ii) promoting electrons transfer, (iii) inducing manganese oxide specie (Mn3O4) in-situ produced for hole trapping. As a result, the GO/MnS-Mn3O4 composites exhibit enhanced visible-light photocatalytic H2S splitting activity, which is 6 folds higher than that of bare MnS. Finally, the photocatalytic mechanism is proposed over GO/MnS-Mn3O4 composites. This work provides a facile strategy for fabricating double cocatalyst on metal sulfides to realize improved photocatalytic H2S splitting activity.

Manganese sulfide (MnS) has triggered great interest as an anode material for rechargeable Li-ion/Na-ion batteries (LIBs/SIBs) because of its low cost, high electrochemical activity, and theoretical capacity. Nevertheless, the practical application is greatly hindered by its rapid capacity decay lead by inevitable active dissolutions and volume expansions in charge/discharge cycles. To resolve the above issues in LIBs/SIBs, we herein put forward the smart construction of MnS nanowires embedded in carbon nanoreactors (MnS@C NWs) via a facile solution method followed by a scalable in situ sulfuration treatment. This engineering protocol toward electrode architectures/configurations endows integrated MnS@C NWs anodes with large specific capacity (with a maximum value of 847 mA h g–1 in LIBs and 720 mA h g–1 in SIBs), good operation stability, excellent rate capabilities, and prolonged cyclic life span. To prove their potential real applications, we have established the full cells (for LIBs, MnS@C//LiFePO4; f...

The effects of the centerline segregation of Cr carbides and nonmetallic inclusions (NMIs) on the pitting corrosion of an Fe-13Cr-0.3C stainless steel (SS) plate produced by a continuous casting (CC) process were examined and compared with the effects on a plate produced by a strip casting (SC) process. For the CC plate annealed at 820°C, Cr carbides and NMIs were segregated in the centerline region, whereas they were uniformly and finely distributed throughout the SC plate. The resistance to pitting corrosion of the CC plate was much lower than that of the SC plate due primarily to the centerline segregation of Cr carbides and/or NMIs irrespective of whether annealing took place at 820°C or 1050°C. A micro-droplet cell test on CC samples revealed that the most dangerous site for pitting corrosion is the manganese sulfide (MnS) inclusion, followed by the centerline segregation of the Cr carbide. The oxide-type NMIs were not significant as sites at which pitting corrosion was initiated.

Complex bimetallic inclusions formed in billets from steels 09G2S and K52 during heating for rolling are studied by methods of electron microscopy and local x-ray spectrum analysis. To check the established evolution of oxide inclusions based on aluminomagnesium spinel and other oxide compositions, individual inclusions of manganese sulfide and complex oxide-sulfide inclusions, a method developed by the Severstal’Company and the Karpov NIFKhI for determining the content of corrosion-active nonmetallic inclusions (CANI) as a function of the heating mode is applied to the steels studied. It is recommended to increase the temperature and duration of heating of billets for hot rolling in order to lower the content of CANI and to raise the resistance of the steels to local corrosion.

Manganese-based nanomaterials have piqued great interest in cancer nanotheranostics, owing to their excellent physicochemical properties. Here we report a facile wet-chemical synthesis of size-controllable, biodegradable, and metastable γ-phase manganese sulfide nanotheranostics, which is employed for tumor pH-responsive traceable gas therapy primed chemodynamic therapy (CDT), using bovine serum albumin (BSA) as a biological template (The final product was denoted as MnS@BSA). The as-prepared MnS@BSA can be degraded in response to the mildly acidic tumor microenvironment, releasing hydrogen sulfide (H2S) for gas therapy and manganese ions for magnetic resonance imaging (MRI) and CDT. In vitro experiments validated the pH-responsiveness of MnS@BSA at pH 6.8 and both H2S gas and •OH radicals were detected during its degradation. In vivo experiments showed efficiently tumor turn-on T1-weighted MRI, significantly suppressed tumor growth and greatly prolonged survival of tumor-bearing mice following intravenous administration of MnS@BSA. Our findings indicated that MnS@BSA nanotheranostics hold great potential for traceable H2S gas therapy primed CDT of cancer.

Manganese sulfide (MnS) inclusion in steel is related to the machinability of steel. Controlling the type and shape of MnS inclusion has been a problem for the steelmaking process for a long time. The effect of tellurium (Te) treatment on the control of MnS inclusion is studied with experiments and discussion of sequential solidification. The result shows that Te addition to the high- and low-sulfur steel dominantly changes the size and shape of MnS inclusions in steel. The aspect ratio of inclusions in cast steel changes with Te/S ranges from 0 to 1.9, which offers an effective way to control the MnS type and thus to improve the machinability and mechanical properties of steel. With an excessive Te addition, no further improvement could be observed by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS).

The article is devoted to finding new production methods making it possible to prepare rolled product of carbon or low-alloy steels with a fine-grained structure, and this means greater strength with limitation or exclusion of expensive alloying with niobium. The possibility is considered of retarding recrystallization during hot rolling as a result of reprecipitation of manganese sulfide particles previously dissolved on heating for rolling. Laboratory tests are performed with the aim of determining the optimum heating temperature for rolling in order to implement the mechanism described.

Spherical micron-sized MnS–C and MnO–C composite powders are successfully prepared by post-treating the spray-dried precursor powders. Dextrin, which is used as the carbon source material, plays a key role in the preparation of the composite powders with regular morphologies; the bare MnS and MnO powders prepared from the spray solution without dextrin have irregular morphologies. The MnS–C composite powders prepared from the spray solution containing 17 g L−1 of dextrin have mixed crystal structures of α- and γ-MnS phases. These powders exhibit superior electrochemical properties compared with those of their MnS and MnO–C counterparts. For example, at a current density of 0.5 A g−1, the MnO–C powders have a 100th-cycle discharge capacity of 321 mA h g−1; the corresponding discharge capacities of the MnS powders prepared from spray solutions containing 0, 17, and 50 g L−1 of dextrin are 501, 786, and 636 mA h g−1, respectively.

Copper is difficult to separate from nickel electrolyte due to low concentration of copper (0.53 g/L) with high concentration of nickel (75 g/L). Manganese sulfide (MnS) was used to deeply remove copper from the electrolyte. Experimental results show that the concentration of copper ( ρ (Cu)) decreases from 530 to 3 mg/L and the mass ratio of copper to nickel ( R Cu/Ni ) in the residue reaches above 15 when the MnS dosage is 1.4 times the theoretical value D t,MnS ( D t,MnS =0.74 g) and the pH value of electrolyte is 4–5 with reaction time more than 60 min at temperatures above 60 °C. The concentration of newly generated Mn 2+ ( ρ (Mn)) in the solution is also reduced to 3 mg/L by the oxidation reaction. The values of ρ (Cu), ρ (Mn) and R Cu/Ni meet the requirements of copper removal from the electrolyte. It is shown that MnS can be considered a highly effective decoppering reagent.

Acrystal geometry mechanism of intergrowth of crystals of MgAl2O4 spinel and MnS manganese sulfide into a single complex inclusion with anion fcc skeleton is suggested. The deformation of the edges of the polyhedrons during the intergrowth is limited to 10%. The structure of the intermediate layer is shown to be represented by a face union of triangulated polyhedrons the vertexes of which are occupied with oxygen and sulfur ions.

Existing standards for the characterization of the size, morphology, chemistry, and distribution of inclusions in steels using different techniques are briefly reviewed in this work. Strengths and shortfalls of different methods are discussed, and a combination of different criteria is used to quantitatively characterize the inclusions in a continuously cast high-carbon steel. It is shown that the main elements in the inclusions for the studied steel were Mn, S, Ti, Al, and oxygen and that alongside MnS and some Al2O3 inclusions many non-metallic inclusions appeared in complex forms, consisting of silicates, sulfides, and different types of oxides. Duplex inclusions, mainly cores of Al2O3, or SiO2 surrounded by MnS were the most common complex multiphase inclusions in this steel. An industrial approach was used to classify the inclusions into thirteen different oxide types. Based upon this approach, data are presented according to the chemistry of inclusions using diagrams featuring different quantitative parameters. Furthermore, it is shown that the number of oxides per unit area and the size of oxides, respectively, decreased and increased with increasing distance from the surface of the bloom which had solidified at the highest cooling rate.

This article reports the morphology, size, and distribution evolution of MnS inclusions in non-quenched and tempered steel during heat treatment. The variation of single large-sized MnS inclusions at high temperature was observed in situ using a confocal scanning laser microscope (CSLM). The slender MnS inclusions first changed to pearl-like strings. These small-sized pearls subsequently coalesced and became closer together as the temperature increased. Large-sized MnS inclusions in non-quenched and tempered steel samples with different thermal histories were investigated with respect to the evolution of their morphology, size, and distribution. After 30 min of ovulation at 1573 K, the percentage of MnS inclusions larger than 3 µm decreased from 50.5% to 3.0%. After a 3 h soaking period, Ostwald ripening occurred. Most MnS inclusions moved from the grain boundaries to the interior. The present study demonstrates that heat treatment is an effective method of changing the morphology, size, and distribution of MnS inclusions, especially large-sized ones.

Type 303 austenitic stainless steel has been applied in jewelry production, and its nickel release rate has become a concerned issue in the jewelry industry. In this paper, the commercial type 303 stainless steel was used as the test material, while 304 stainless steel as the contrast material; their nickel release rates and corrosion behaviors in artificial sweat were studied. The results show that the actually measured nickel release rate of 303 stainless steel reaches 2.06μg/cm2/week, nearly 25 times higher than that of 304 stainless steel, which exceeds the threshold specified in nickel release standard EN1811:2011 for jewelries coming into direct and prolonged contact with the skin (0.88μg/cm2/week), and its adjusted value also exceeds the threshold specified in Nickel Directive 2004/96/EC for puncture accessories (0.35μg/cm2/week). The high nickel release rate for 303 stainless steel is mainly caused by its high sulfur content and the inevitable formation of manganese sulfide inclusions, which will cause the pitting and exacerbate the material corrosion. Considering the risk of nickel sensitization of 303 stainless steel, it is not suggested to use 303 stainless steel as the jewelry material, especially for piercing jewelry.

Transition metal sulfides (TMSs) are attracting great attention as cathode catalysts of Li-O2 batteries. In this article, both γ-MnS and α-MnS are successfully synthesized and their performance is comparatively investigated when employed as cathode catalyst of Li-O2 batteries. It reveals that both MnS materials are capable of catalyzing oxygen reduction reaction as well as oxygen evolution reaction, but α-MnS demonstrates higher activity and better reversibility. The batteries fabricated with α-MnS deliver higher discharge capacity, lower charge voltage, improved high-rate discharge ability and superior cycling performance. These results are discussed and analyzed with help of various physicochemical techniques and compared with the performance of other reported TMSs and a widely studied oxide counterpart (MnO2) of MnS.

Tramp elements such as tin are considered harmful to steel because of hot brittleness they induce at high temperatures. Because tramp elements retained in steel scrap will be enriched in new steel due to the difficultly of their removal, studies on the precipitation behavior of tin are essential. In this study, the effects of different inclusions on the precipitation behavior of tin in steel were studied. The results show that the tin-rich phase precipitates at austenite grain boundaries in an Fe-5%Sn alloy without MnS precipitates, whereas Sn precipitates at the boundaries of MnS inclusions in steel that contains MnS precipitates. MnS is more effective than silicon dioxide or aluminum oxide as a nucleation site for the precipitation of the tin phase, which is consistent with the disregistry between the lattice parameters of the tin phase and those of the inclusions.

Failure analysis of a shaft used in a bridge crane has been carried out. The shaft fractured in the keyway with evidence of fatigue. Chemical analysis, micro-structural characterization, fractography, hardness measurements, and finite element simulation were used for the analysis. The microstructure was predominantly tempered martensite; large amounts of oxides, micropores, and manganese sulfide inclusions were found. The geometry of the keyway also promoted the initiation crack because the width and height were erroneously designed. It was concluded that all these factors produced fatigue failure. It is recommended to first guarantee the chemical composition and microstructure of the material. Secondly, use magnesium or calcium additions in the steel casting process to obtain better shape control of inclusions and, finally, accomplish the geometric parameters recommended by the standard to avoid high stress concentration factors.

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The behavior of different precipitates during hot deformation of a low carbon, low manganese, and titanium added steel has been studied. Microstructural and inclusion analyses from the centerline of as-cast slabs revealed the presence of a wide variety of simple and/or complex precipitates with different size and morphologies. These precipitates were mostly deformed along the deformation direction and affected the recrystallization as well as the mechanical properties of the material. However, those effects altered by changing the re-heating temperature and/or deformation rate.

Zn1−xMnxS epilayers were grown on GaAs (1 0 0) substrates by hot-wall epitaxy. X-ray diffraction (XRD) patterns revealed that all the epilayers have a zincblende structure. The optical properties were investigated using spectroscopic ellipsometry at 300 K from 3.0 to 8.5 eV. The obtained data were analyzed for determining the critical points of pseudodielectric function spectra, 〈ɛ(E)〉 = 〈ɛ1(E)〉 + i〈ɛ2(E)〉, such as E0, E0 + Δ0, and E1, and three E2 (Σ, Δ, Γ) structures at a lower Mn composition range. These critical points were determined by analytical line-shapes fitted to numerically calculated derivatives of their pseudodielectric functions. The observation of new peaks, as well as the shifting and broadening of the critical points of Zn1−xMnxS epilayers, were investigated as a function of Mn composition by ellipsometric measurements for the first time. The characteristics of the peaks changed with increasing Mn composition. In particular, four new peaks were observed between 4.0 and 8.0 eV for Zn1−xMnxS epilayers, and their characteristics were investigated in this study.

Quench crack propensity has been investigated for two identical medium carbon steels (50CrMo4) which only differed in sulfur content. The standard variant of the material was affected by manganese sulfide inclusions whereas the low sulfur material was essentially free of sulfides. 80 mm, cylindrical test specimens were used. The test specimens had been cut out of cross rolled steel plates in which the manganese sulfide were flattened to discoid shape. The specimen orientation was in direction of principal deformation where the flattened sulfides were aligned with the test specimen axis. The largest sulfides reached lengths of 150 μm. Both materials were austenitized at 850 °C for 60 minutes, quenched in a salt-bath at 180 °C and immediately annealed at 425 °C for one hour. It turned out that the standard material developed quench cracks which initiated at manganese sulfide. No cracks could be found in the low sulfur material. Thermal and transformational stresses, which develop during quenching, aggravate the stress situation around the manganese sulfide and cause the cracking. The results are interpreted in fracture mechanical terms.

Scanning electron microscopy was used to study the structure of flakes in samples of large 40KhGM-steel forgings obtained under industrial and laboratory conditions. It has been established that manganese sulfide inclusions overwhelmingly serve as the flake nuclei. The data obtained suggest the existence of gaps between the sulfides and the matrix. Such gaps act as "hydrogen traps.". © Nauka/Interperiodica 2007.

The present research deals with the influence of sulfur on gray cast iron machinability. Tupy Fundicoes produced the workpiece materials in usual commercial manufacturing conditions with sulfur levels raging from 0.065 to 0.18%. The influence of different of sulfur contents on gray cast iron machinability was studied for turning operation at 100, 150 and 200 m/min cutting speeds. Uncoated cemented carbide tools were used, and ‘flank wear’ assessment criterion was applied. The sulfur increase from 0.065 to 0.18% did not produce significant alteration on mechanical properties nor on material microstructures. It was verified that for an effective reduction of the adhesive wear during the machining the smallest area occupied by the manganese sulfide must be (18 ± 6) × 10−3%. The machinability of gray cast iron FC25 with 0.12, 0.15 and 0.18% of sulfur does not differ significantly when machined at 150 and 200 m/min. In relation to gray cast iron FC25 with 0.12% of sulfur, the material with 0.065% S presented a tool life reduction of 24, 32 and 38%, for the speeds 100, 150 and 200 m/min, respectively. From this research, important results were obtained, becoming viable the use of a higher sulfur percentage on gray cast iron FC25 production, without the detriment of mechanical properties, microstructure and machinability.

Crystalline ?-MnS thin films were deposited by chemical bath deposition method at 27 °C. The MnS thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy, energy dispersive X-ray analysis (EDAX) and optical absorption spectroscopy. XRD measurements show that the films are crystallized in the wurtzite phase and present a preferential orientation along the c-axis. Only one peak, corresponding to the (002) phase (2? = 28.26°), appears on the diffractograms. The X-ray absorption fine structure spectroscopy calculation of Mn K-edge in MnS is in agreement with the measured result. The deposited MnS thin films on glass substrates consist of nanocrystalline grains. EDAX analysis shows that average ratio of atomic percentage of Mn : S is 1 : 0.82 so one can conclude that the films are in good stoichiometric ratio. The optical band gap of thin film was estimated to be 3.88 eV. © 2005 Elsevier B.V. All rights reserved. FEF2004BAP3 This work was supported by Cukurova University under FEF2004BAP3 project number.

This paper presents results on the quantification of MnS precipitation during solidification of steels with intermediate levels of sulfur (0.05%) using a Confocal Scanning Laser Microscope (CSLM) equipped with a gold image furnace. The precipitation of MnS was observed in the liquid pools remaining in between advancing dendrites at the end of solidification. It was observed that MnS precipitated during cooling on existing mixed-oxide particles of Al, Si and Ca. The rate of precipitation was seen to accelerate at two distinct points, once when the steel was molten and once during solidification.

Large-scale (∼1 cm2) measurements and immersion tests were conducted on stainless steels (SS) to study the role of Mo content and manganese sulfide (MnS) inclusions on corrosion. Higher S content increased the number of pits and an increase in Mo content produced smaller pits on SS. It was found that the Mo content influenced repassivation of pits and MnS inclusions affected pit initiation. A microelectrochemical cell (d = 100 μm) was used to investigate the corrosion of SS with 6% Mo content (DIN 1.4529 [UNS S31254]) in sodium sulfate (Na2SO4), sodium chloride (NaCl), and lithium chloride (LiCl) solutions of neutral pH at room temperature. It was found that MnS inclusions on DIN 1.4529 dissolved in both NaCl and Na2SO4 after 2 h of potentiostatic experiments. Dissolution of inclusions did not cause observable dissolution of the bulk material around the inclusions in NaCl and Na2SO4 solutions. In large-scale and microelectrochemical experiments, the breakdown of DIN 1.4529 occurred around 0 V vs ...

In this study, the precipitation behavior of MnS was calculated during the solidification process of the medium sulfur, non-quenched and tempered 49 MnVS steel. And the precipitation process was directly observed by a high-temperature confocal laser scanning microscope (HT-CLSM) equipped with a gold-image furnace. Besides, the precipitated particles were proved to be MnS by using the Scanning Electron Microscope-Energy Dispersive spectroscopy (SEM-EDS) analysis. The modified thermodynamic calculation indicated that the MnS precipitated from the residual liquid steel when the product of manganese and sulfur concentrations exceeded the equilibrium value at 1417.0 °C. Meanwhile, the results calculated by FactSage software shown that the beginning precipitation temperature of MnS is about 1411.0 °C. The observation of HT-CLSM demonstrated that the primary solid on the free surface of the liquid steel was visualized at 1485.0 °C during the solidification process (cooled from 1520.0 °C to room temperature with a rate of −30 °C/min). Then, the MnS particles started to form at 1437.0 °C and rapidly grew up into shape on the solid-liquid boundary. And the precipitation of MnS continued to form in a large amount (90% of the total) in the next 10 degrees. The enrichment of Mn and S near the local melt surface may be conducive the MnS formation, which results a higher actual precipitation temperature than the calculated value.

The magnetic properties of non-oriented silicon steel are closely associated the precipitates in steel. To study and analyze the effect of the size, morphology and distribution of sub-micron grade precipitates on the magnetic properties of silicon steel, some experiments has been carried out by using transmission electron microscope (TEM) technique. In addition, the precipitation temperature of precipitates is calculated by using the thermodynamic software Thermo-calc. The results shown that, most of the precipitates are spherical particles, with sizes ranging from 10 nm to 500 nm. Manganese sulfide precipitation temperature is about 1250 °C, the precipitates of different sizes corresponding to different precipitate types, the size of single copper sulfide precipitation is smaller than compound precipitates, The size of copper sulfide and manganese sulfide compound precipitates increases with the content of manganese sulfides, the size of separately precipitated manganese sulfides are larger.

An investigation into the cracking of cross members during forming from E-34 grade steel found that the cracking was a result of the presence of stringers of manganese sulfide inclusions, a high free nitrogen content, and a yield strength that was near the upper limit of the specified yield strength. A decrease in sulfur level and free nitrogen contents and a decrease in the yield strength were recommended as the measures to be taken to prevent such cracking.

Kept cubic: MnS microboxes, which act as an anode material for lithium ion batteries, are synthesized by a simple H(2)S gas sulfidation approach (TEM images show porous and hollow microcubes and a microbox). The formation of the single crystals is aided by the intrinsic cubic crystal structure and the nearly cubic shape of the MnCO(3) precursor.

The effects of hydrogen on ductile fracture were investigated in a spheroidized steel similar to AISI 1520, which contained negligible amounts of P and S. Cylindrical tensile data indicated that hydrogen does not significantly affect void initiation and the early stage of void growth. Instead the effects of hydrogen were observed in the final fracture stages. It was inferred that hydrogen could assist the later stage of void growth by an internal pressure and affect the center crack growth in tension by the enhanced strain localization caused by hydrogen. The fracto-graphic response to hydrogen in spheroidized steels was rationalized by the combination of these two effects, that is, internal pressurization and enhanced strain localization. The critical role of manganese sulfide was manifested by comparison with previous work.