Research on the trajectory of non-metal inclusions with the flow in the mold during the solidification of continuous casting slabs

By means of the numerical simulation method,the mathematical model of inclusions movement in the mold is established under the condition of austenitic and ferritic stainless steel slab production.According to the simulation results,the main zones for inclusion particles accumulation were found and many factors that affected floating-up probability of inclusion particles were identified.These factors include the inclusion particle size,the casting speed and the slab width,etc.It is believed that the inclusion particle size is the key one among these factors.     

Microstructure and micro-hardness of the Inconel 718 superalloy coating prepared by cold gas dynamic spraying

Inconel 718 superalloy coating was prepared on a martensitic steel substrate by cold gas dynamic spraying (CGDS).Microstructure and micro-hardness of the coating were characterized by means of scanning electronic microscope (SEM),energy dispersive spectrometer (EDS),and micro-hardness and nano-indentation tests.The results have indicated that the coating’s thickness can reach more than 300 μm,and there exists a good interfacial cohesion between the coating and the substrate.The quantity and size of the defects at the bottom,middle and top areas increase gradually.There is no significant change to the original microstructure of the Inconel 718 superalloy particle after the process of CGDS;and an obvious torsional deformation on the particle’s profile is produced while little deformation at the center part occurs.The micro-hardness of the coating at the bottom,middle and top areas decreases in turn.Compared with the bottom area,the micro-hardness of the middle and top areas decreases by about 10% and 21%,respectively.The nano-hardness of the coating is much lower than the original particle,which decreases by about 13.5% at the bottom area and 28% at the top area,respectively.The distribution of micro-defects is an important factor to the micro-hardness of the coating.     

Gas-particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans in the sintering process

The distribution of seventeen gaseous and particle-bound 2,3,7,8-substituted chlorinated PCDD/Fs in the flue gas of different windboxes of the sintering machine was analyzed.The influence of temperature change on the PCDD/Fs emission from the sintering process and the formation mechanism of PCDD/Fs were discussed.The result has shown that among the seventeen gaseous and particle-bound PCDD/Fs in the flue gas of different windboxes,furans occupied the major place.The proportion of the gaseous PCDD/Fs in most windboxes is from 40% to 60%.The change tendencies of the concentration of both the gaseous and particle-bound PCDD/Fs were similar,with a higher level at the end of the sintering bed.The PCDD/Fs concentration’s change tendency in the windbox was very consistent with the change of temperature of the flue gas in the windboxes.More than 60% PCDD/Fs of the total PCDD/Fs emission amount was emitted at the end of the sintering bed.Only this part of the waste gas accounted for 12% of the total waste gas volume.     

从铸铁机的优化改造实践看今后铸铁机的设计

本文描述了八钢铸铁机的优化改造和具体实施过程,铸铁生产工艺和生环境得到改善。     

Numerical simulation of tube profile growth during spray forming process

Spray forming is a new type of metal material forming process,which can produce metal blanks such as billet,tube,plate etc.A mathematical model has been developed to forecast the shape evolution of tube billets during the spray forming process.The atomizer mass flux as,radial distribution coefficient bs,draw velocity and diameter of mandrel were considered in this model and the influence of different parameters such as metal flowrate,draw velocity of mandrel,diameter of mandrel on the tube’s shape change were simulated and analyzed in this paper.The simulation results obtained from this model can be provided to engineers as reference.     

钕元素对葡萄试管苗生长的影响

以克瑞森葡萄(Vitis vinifera L.Crimson)试管苗茎段为外植体,经NdCl3溶液处理,研究不同浓度NdCl3对其生长的影响。结果表明,浓度为20～40 mg/L的NdCl3能显著提高克瑞森试管苗的生长(包括根长、根数、株高、叶数),促进植株干重增加和叶绿素含量提高。而高浓度NdCl3(>100 mg/L)处理则显著抑制葡萄试管苗的生长。     

Thermal analytical investigation of biopolymers and humic- and carbonaceous-based soil and sediment organic matter

Improved understanding of the physical, chemical, and thermodynamic properties of soil and sediment organic matter (SOM) is crucial in elucidating sorption mechanisms of hydrophobic organic compounds (HOCs) in soils and sediments. In this study, several thermoanalytical techniques, including thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), temperature-modulated differential scanning calorimetry (TMDSC), and thermal mechanical analysis (TMA) were applied to 13 different organic materials (three woods, two humic acids, three kerogens, and five black carbons) representing a spectrum of diagenetic and/or thermal histories. Second-order thermal transition temperatures (T(t)) were identified in most materials, where the highest observed T(t) values (typically characterized as glass transition temperatures (T(g were shown to closely relate to chemical characteristics of the organic samples as influenced by diagenetic or thermal alteration. Results further suggest a positive correlation between glass transition temperature and a defined diagenetic/thermal index, where humic-based SOM (e.g., humic and fulvic acids) possess lowertransition temperatures than more "mature" carbonaceous-based SOM (i.e., kerogens and black carbons). The observed higher thermal transition temperature of aliphatic-rich Green River shale kerogen (approximately 120 degrees C) relative to that of aromatic-rich humic acids suggests that a sole correlation of aromaticity to thermal transition temperature may be inappropriate.     

泡沫压裂液稳定性及衰变机理研究

针对泡沫压裂液的在水流中稳定性能差的问题,通过对6种不同稳泡剂的泡沫压裂液的泡沫高度、泡沫排液量随时间的变化以及泡沫稳定系数(FSI)来评价不同类型稳泡剂的泡沫压裂液的稳定性,得到AEO-X2/C12醇复合稳泡剂(0.057%)和PAM(0.02%)的较好。利用电子显微镜观察泡沫形态随时间的变化研究了泡沫衰变的机理。     

流体机械非定常流动的涡方法数值模拟

本文描述了一种建立在拉格朗日框架下涡方法的具体算法,主要包括：涡量边界条件的给定,涡量输送方程中拉伸项及粘性扩散项的数值处理,以及根据流场中离散涡元的分布计算流场压力的积分方法。利用该方法对有代表性的流体机械非定常流动现象进行了数值模拟,结果表明基于涡方法基础上的数值模拟法是非常适合于数值模拟流体机械非定常流动。     

自并励静止励磁系统在发电厂励磁系统改造中的应用

结合鞍钢第二发电厂机组励磁系统的改造,采用自并励磁方式,用静止励磁变压器替代旋转励磁发电机,通过介绍发电机自并励静止励磁系统及其特点,说明该励磁方式与过去的励磁方式相比有较大的优越性.