Dephosphorization Kinetics of Hot Metal at Low Slag Basicity and Low Temperature under the Different Fe2O3 Addition Amounts

In this article, the influence of the Fe₂O₃ addition amount on the dephosphorization kinetics of hot metal at the low slag basicity (CaO/SiO₂) of about 1.6 and low temperature of 1623 K is investigated with laboratorial experiments and the kinetic model. Si and P contents in the hot metal during the whole dephosphorization process, and the endpoint FeO content in the slag, show good agreements between the calculated results with the kinetic model and experimental results. The peak value of dephosphorization rate linearly increases from 8.35 × 10⁻⁵ to 4.52 × 10⁻⁴ mass% s⁻¹ when the weight ratio of Fe₂O₃ is increased from 5 to 10/100 g hot metal. With the increase in Fe₂O₃ addition amount, the mass transfer coefficient in the hot metal phase (k_m) and that in the slag phase (k_s) and dephosphorization rate constant (k) all increase. The value of k_m is found to be 4.34 times that of k_s. During the dephosphorization process, the rate-controlling step converts from the mass transfer in slag phase to the mass transfer in hot metal phase in less than 10 min. With the increase in Fe₂O₃ addition amount, the value of interfacial oxygen activity of $a_{\mathrm{O}}^{*}$ increases from 0.0102 to 0.0201.     

热红外遥感在内蒙古多伦县玉米良种适宜积温地块调查中的应用

论证了热红外遥感技术探测种植玉米良种适宜积温地块的物理依据,探讨了实现这一目的的技术途径与方法,以监督彩色密度分割后的热红外辐射温度等级分布图为基础,建立了辐射温度与相应积温的对应关系,并结合多伦县的实际情况利用遥感方法对该区玉米良种适宜地块的分布进行了分析,为多伦县寻找种植玉米良种适宜积温块提供了科学的依据。2000年多伦县推广种植情况表明该技术方法具有良好的应用效果。     

Measurement of the heat of fusion of titanium and a titanium alloy (90Ti-6Al-4V) by a microsecond-resolution transient technique

A microsecond-resolution pulse heating technique was used for the measurement of the heat of fusion of titanium and a titanium alloy (90Ti-6Al-4V). The method is based on rapid (50- to 100-s) resistive self-heating of the specimen by a high-current pulse from a capacitor discharge system and measuring, as functions of time, current through the specimen, voltage across the specimen, and radiance of the specimen. Melting of the specimen is manifested by a plateau in the measured radiance. The time integral of the net power absorbed by the specimen during melting yields the heat of fusion. The values obtained for heat of fusion were 272 J · g^–1 (13.0 kJ · mol^–1) for titanium and 286 J · g^–1 for the alloy 90Ti-6Al-4V, with an estimated maximum uncertainty of ±6% in each value.Paper presented at the Second Workshop on Subsecond Thermophysics, September 20–21, 1990, Torino, Italy.     

Scanning the Melting Curve of Tungsten by a Submicrosecond Wire-Explosion Experiment

Measurements of temperature and density during a wire-explosion experiment at atmospheric pressure are described. The measurements encompass a parameter range from the solid to near the critical point. The influence of a polytetrafluoroethylene coating of the wire, necessary to prevent surface discharges, on the temperature and density measurements is investigated. The melting curve of tungsten up to 4000 K is detemined.     

低温低碳烷烃和氮双元液态混合物密度的推算

将一个饱和液体状态方程(TONG方程)应用于已知的双元液体混合物密度的推算,温度为105K～140K,该混合物的组分是低碳烷烃和氮,它们都是液化天然气(LNG)的主要成分。此模型方程利用纯组分数据来预测液化天然气低温下密度而被检验。本方法的优点是使用简便。     

Effect of elevated temperatures and cooling regimes on normal strength concrete

The compressive strength of normal strength concrete at elevated temperatures up to 700^°C and the effect of cooling regimes were investigated and compared in this study. Thus, two different mixture groups with initial strengths of 20 and 35 MPa were produced by using river sand, normal aggregate and portland cement. Thirteen different temperature values were chosen from 50 to 700^°C. The specimens were heated for 3 h at each temperature. After heating, concretes were cooled to room temperature either in water rapidly or in laboratory conditions gradually. The residual strengths were determined by an axial compressive strength test. Strength and unit weight losses were compared with the initial values. Throughout this study, ASTM and Turkish Standards were used. It was observed that concrete properties deteriorated with the heat; however, a small increase in strength was observed from 50 to 100^°C. Strength loss was more significant on the specimens rapidly cooled in water. Both concrete mixtures lost a significant part of their initial strength when the temperature reached 700^°C. Copyright © 2008 John Wiley & Sons, Ltd.