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There are abundant manganese mineral resources in Chengkou and Xiushang County, Chongqing City, as well as a phosphorus content that is over the national standard; thus, the mass percent of phosphorous in Si-Mn alloys produced from manganese ores is over 1%. This can easily result in "cold brittleness" and reduce the steel quality when the alloys are used for deoxidation and alloying in steelmaking. Therefore, it is important to research on the dephosphorization of Si-Mn alloy. Dephosphorization of a high-phosphorus Si-Mn alloy was studied under dephosphorizing agents of Si-Ca alloy, rare earth silicon, and Al-based dephosphorizer in a silicon molybdenum furnace of 1400℃. In the experiment, CaO-CaF2 (mass ratio of 25:75) was used as a covering slag, and the ratio of slag-metal is 0.2:1. The phosphorous content in the Si-Mn alloy after dephosphorizatoin was detected by an inductively coupled plasma (ICP) spectrometer, and the phase composition of the slag was analyzed by X-ray diffractometry (XRD). The effects of different dephosphorizing agents and their dephosphorization rates were analyzed. The results show that the dephosphorization rate increases with dephosphorizer content. For Al-based dephosphorizer, the dephosphorization effect is optimum at 8% dephosphorizer content, whereby the phosphorus content in the Si-Mn alloy is reduced to 0.21%, which meets the national standard (≤ 0.25%), and the dephosphorization rate reaches 78%. The efficiency of Si-Ca alloy is lower; the dephosphorization rate is 47% even when the alloy content reaches 10%. The effect of rare earth silicon is the least; the dephosphorization rate is 22% when the content reaches 10%. Thus, the Al-based dephosphorizer is the best dephosphorization agent under the present experimental conditions.

The paper reports on the comprehensive study of properties of nonstoichiometric Si 1− x Mn x alloys slightly enriched in Mn ( x ≈0.51–0.55) as compared to the stoichiometric monosilicide MnSi. Mosaic type Si 1− x Mn x films 55–70 nm in thickness were produced by the pulsed laser deposition (PLD) method onto the single crystalline Al 2 O 3 substrates at 340 °C. The Curie temperature T C in nonstoichiometric Si 1− x Mn x ( x ≈0.52–0.55) films exceeds room temperature, while in their stoichiometric counterpart, MnSi, the T C value does not exceed ≈30 К. The consistent data on anomalous Hall effect and transverse Kerr effect prove the global character of ferromagnetic (FM) order caused by magnetic defect formation rather than the presence of FM clusters. Аt Mn content x ≤0.55, the magnetization data testify to a good homogeneity in the distribution of magnetic defects without their segregation: variations of the saturation magnetization M s do not exceed 6% in the temperature range T =10–100 К and are well described by the Bloch law. It is also revealed that textured high-quality Si 1− x Mn x films with x ≈0.52 and Т С ~300 К could be formed by PLD method in the “shadow” geometry (at lower energy of deposited atoms). [ABSTRACT FROM AUTHOR]

Abstract: Si–Mn composites were prepared by mechanical ball milling for different periods. The microstructure and electrochemical performance of the composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. XRD showed that the materials prepared by ball milling were composites consisting of Si and Mn powders. The particle size was about 1μm from the SEM images. The Si–Mn composites after 60h ball milling showed the best performance, especially when annealed at 300°C for 2h, which had a reversible capacity of 455mAhg−1 and an initial Coulomb efficiency of 52%. Mn acted as an inactive buffer of the Si–Mn composite electrode and enhanced the cyclic performance of the active center (Si). It was also observed that nanosized Si–Mn particles merged together after the insertion/extraction of lithium ions, which decreased the electric contact between the active materials and copper substrate. [Copyright &y& Elsevier]