搜索到271篇“ REOXIDATION“的相关文章
Numerical simulation on the multiphase flow and reoxidation of the molten steel in a two-strand tundish during ladle change
2024年
A 3D mathematical model was proposed to investigate the molten steel–slag–air multiphase flow in a two-strand slab continuous casting(CC)tundish during ladle change.The study focused on the exposure of the molten steel and the subsequent reoxidation occurrence.The exposure of the molten steel was calculated using the coupled realizable k–εmodel and volume of fluid(VOF)model.The diffusion of dissolved oxygen was determined by solving the user-defined scalar(UDS)equation.Moreover,the user-defined function(UDF)was used to describe the source term in the UDS equation and determine the oxidation rate and oxidation position.The effect of the refilling speed on the molten steel exposure and dissolved oxygen content was also discussed.Increasing the refilling speed during ladle change reduced the refilling time and the exposure duration of the molten steel.However,the elevated refilling speed enlarged the slag eyes and increased the average dissolved oxygen content within the tundish,thereby exacerbating the reoxidation phenomenon.In addition,the time required for the molten steel with a high dissolved oxygen content to exit the tundish varied with the refilling speed.When the inlet speed was 3.0 m·s^(-1)during ladle change,the molten steel with a high dissolved oxygen content exited the outlet in a short period,reaching a maximum dissolved oxygen content of 0.000525wt%.Conversely,when the inlet speed was 1.8 m·s^(-1),the maximum dissolved oxygen content was 0.000382wt%.The refilling speed during the ladle change process must be appropriately decreased to minimize reoxidation effects and enhance the steel product quality.
Jingcheng WangZhentong LiuWei ChenHongliang ChenLifeng Zhang
关键词:TUNDISHREOXIDATION
Reoxidation of liquid steel and evolution of inclusions during protective atmosphere electroslag remelting of Ce-containing heat-resistant stainless steel
2024年
The evolution of Ce-containing inclusions and its correlation with the reoxidation of liquid steel during protective atmosphere electroslag remelting(ESR)of heat-resistant steel were studied.The reoxidation of liquid steel took place during the ESR,resulting in the oxygen pickup from 0.0014 to 0.0053 wt.%.The inclusions in the consumable electrode,liquid metal pool and remelted ingot are Ce_(2)O_(2)S and Ce_(2)O,inclusions invariably.The inclusions in the remelted ingot are originated from three ways:(I)the original inclusions from the electrode;(Il)the newly formed Ce_(2)O_(2)S and Ce_(2)O_(3) inclusions in the liquid metal pool by reoxidation remaining still in remelted ingot;(IlI)the newly generated Ce2O2S and Ce_(2)O_(3) inclusions during cooling and solidification of liquid steel.The relative proportions of Ce_(2)O_(3) inclusions in liquid metal pool and remelted ingot are 41% and 76.5%,respectively.The inclusions ranging from 2 to 5μm in the remelted ingot take up 55%,followed by the inclusions smaller than 2μm(43%of total inclusions).The number proportion of the Ce_(2)0,inclusions in the liquid metal pool which were removed by floating up into slag is 1.96×10-5%.
Yu ZhaoCheng-bin ShiShijun WangPeng RenJing Li
关键词:REOXIDATION
中间包内钢液流动和二次氧化的数值模拟被引量:6
2023年
由于目前关于铸锭中间包内钢液二次氧化过程仍然缺乏深入研究,对某厂实际生产303 t铸锭过程中真空脱气精炼(Vacuum Degassing Refining, VD)过程以及中间包内钢液进行取样,分析了钢中总氧(TO)和总氮(TN)含量的变化以及夹杂物成分、数量和尺寸的变化。结果表明,由于大铸锭浇注过程没有进行保护浇注,导致中间包内钢液的TO和TN质量分数较精炼结束分别增加了5.59×10^(-6)和9.08×10^(-6)。二次氧化后,夹杂物的数密度增加了近4倍,夹杂物也由液态的钙铝酸盐向Al2O3转变,降低了钙处理效果。数值模拟得到浇注时中间包钢液面卷入空气的平均速率为4.2×10^(-5)kg/s,圆形中间包较深的液位导致中间包进出口温差达到3.9 K。二次氧化后,在注流区的TO质量分数较高,而在右侧循环流区域和靠近底部区域质量分数较低,TO的平均质量分数和最大质量分数分别为28.6×10^(-6)和45.3×10^(-6);CaO和Al2O3的平均质量分数分别为20.9×10^(-6)和32.3×10^(-6)。研究结果为优化中间包浇注过程中钢液二次氧化问题提供理论指导。
陈宏亮刘珍童周秋月巴钧涛陈威张立峰
关键词:多相流
开浇过程二次氧化对铝脱氧不锈钢中夹杂物的影响被引量:3
2023年
为了研究铝脱氧不锈钢开浇过程中二次氧化对钢水洁净度和夹杂物演变的影响,实现钢中夹杂物的有效控制,分别在LF精炼出站、开浇过程中不同时刻取样,采用扫描电镜、ASPEX自动分析仪、热力学计算等不同方法研究了铝脱氧不锈钢中夹杂物的形貌、成分、数量和尺寸分布,确定了铝脱氧不锈钢开浇过程中夹杂物的演变行为和对应机理。研究结果表明,开浇过程钢中氧氮质量分数、夹杂物数密度变化规律类似,20 min时分别增加至7.4×10^(−5)、0.0674%、17.1 mm^(−2),此后随着浇铸过程进行逐渐降低;LF精炼出站时钙处理改性夹杂物效果较好,其类型主要为CaO−Al_(2)O_(3)−SiO_(2)−MgO,开浇过程中二次氧化降低了钙处理操作的作用效果,20 min时夹杂物类型转变为MnO−Al_(2)O_(3)−SiO_(2)−CaO复合夹杂物,浇铸约60 min时,连铸过程中钢水的洁净度基本达到稳定,此时夹杂物类型重新转变为CaO−Al_(2)O_(3)−SiO_(2)−MgO;二次氧化使得钢液中氧质量分数较高,促进了MnO−Al_(2)O_(3)−SiO_(2)−CaO夹杂物的生成,而钢中大尺寸的CaO−Al_(2)O_(3)−SiO_(2)−MnO−(MgO)夹杂物主要通过夹杂物间的碰撞聚合形成;凝固过程中随着温度的降低,促进了MgO·Al_(2)O_(3)尖晶石相和CaO·2MgO·8Al_(2)O_(3)相的析出,提高了夹杂物中Al_(2)O_(3)组分的含量。
凌海涛吴锦圆常立忠杨树峰仇圣桃
关键词:洁净度凝固过程
Reoxidation process and corrosion behavior of TA15 alloy by laser ablation被引量:2
2021年
The thermal oxide layer formed of TA15 alloy has poor corrosion resistance.In this paper,the changes of the elements and components on the surface after laser ablation with different energy densities(E) were researched.The formation process and corrosion behavior of laser-generated oxide layer were clarified.As E increases,the oxygen content decreases from 8.52% to 5.43% and then increases to 11.89%.The surface oxide layer changes from TiO_(2)(R)(i.e.,rutile) to Ti_(2) O_(3)+TiO_(2)(R) and finally becomes TiO_(2)(R)+TiO_(2)(A)(i.e.,anatase).The TiO_(2)(R) gasification was confirmed by calculating the surface temperature rise.The surface reoxidation process was illustrated by a thermodynamically calculated ΔGT(i.e.,the Gibbs free energy changes with temperature).When E≥17.5 J·cm^(-2),the oxide layer exhibits an agitated morphology,and oxide falls off at the bottom.As E increases,the corrosion rate decreases first and then increases.With energy density of 8.75 J·cm^(-2),the surface corrosion rate was 20.43 times slower than that of the untreated sample.The impedance spectrum and equivalent resistance results also prove the best corrosion resistance at 8.75 J·cm^(-2).The corrosion behavior of the oxide layer is analyzed from the properties of the oxide layer components and the reaction products with the electrolyte.
Bo-Wen LiuGao-Yang MiChun-Ming Wang
二次氧化过程IF钢中间包中夹杂物演变行为被引量:29
2020年
为了研究中间包二次氧化对IF钢洁净度的影响,针对中间包连铸过程不同时刻IF钢钢液成分和夹杂物的性质进行系统的检测分析,结合热力学计算,揭示IF钢二次氧化过程中夹杂物的演变机理。发现开浇过程中的二次氧化主要是由于吸收空气造成的,使得夹杂物中的Al2O3夹杂物质量分数增加。这些增加的Al2O3一部分是均质形核导致钢中生成了更多小尺寸的Al2O3夹杂物;另一部分是非均质形核导致原来的Al2O3-TiOx复合夹杂物表面形成了一层纯的Al2O3层,同时使得夹杂物尺寸变大。
朱坦华周秋月任英段豪剑张立峰
关键词:IF钢中间包
Interplay of transport processes and interfacial chemistry affecting chromium reduction and reoxidation with iron and manganese被引量:3
2020年
Hexavalent chromium(Cr(Ⅵ))is a water-soluble pollutant in soil and groundwater,the mobility,bioavailability,and toxicity of which can be controlled by transforming to less mobile and more environmentally benign Cr(Ⅲ)by ways of reduction.This review focused on recent advances in identifying the reaction pathways,kinetics,and products of iron-based techniques for Cr(Ⅵ)removal.It also examines new information regarding remobilization of Cr(Ⅲ)in the existence of complexing ligands and manganese(Mn)of different oxidation states.A range of iron-based techniques can remove Cr(Ⅵ)from water by adsorption or reduction-coprecipitation processes.However,the success of a chromium treatment or remediation strategy requires the stability of the Cr(Ⅲ)-containing solids with respect to solubilization or reoxidation in the settings they are generated.Manganese is ubiquitous in aquatic and terrestrial environments,and the redox cycling of manganese may greatly influence the fate,transport,and distribution of chromium.Coupling of redox reactions of chromium,iron,and manganese involves reaction pathways not only in the aqueous phase but also at solid-aqueous interfaces.To provide a quantitative understanding of these processes,it is essential to develop mechanistically based kinetic and transport models.Continued research should be made on iron-based treatment of Cr(Ⅵ)-contaminated water and soils and the stability of the subsequently produced Cr(Ⅲ)-containing solids at environmentally relevant conditions,which will support improved predictions of chromium's environmental fate and transport and aid in decision-making for remediation and treatment of Cr contamination.
Chao PanDaniel Giammar
Klotho通过抑制氧化应激对肾小管上皮细胞低氧/再氧化损伤的影响被引量:2
2020年
目的探讨Klotho蛋白对肾小管上皮细胞低氧/再氧化损伤的保护机制。方法体外培养小鼠近端肾小管上皮细胞(TCMK-1),根据是否给予低氧/再氧化刺激及Klotho蛋白干预分为对照组(无干预),低氧/再氧化损伤组(低氧24 h后再复氧不同时间),低氧/再氧化+Klotho干预组(给予Klotho蛋白预处理1 h后,低氧24 h后再复氧8 h)。Western blot法检测细胞Klotho蛋白的表达;Cyto Tox-ONETM法检测细胞乳酸脱氢酶(LDH)的释放水平,评估细胞损伤程度;DCFH-DA探针检测细胞内活性氧(ROS)水平。结果低氧/再氧化损伤组LDH释放率高于对照组,低氧/再氧化+Klotho治疗组LDH释放率低于低氧/再氧化损伤组(P <0.05)。同时,低氧/再氧化损伤组ROS水平高于对照组,低氧/再氧化+Klotho治疗组ROS水平低于低氧/再氧化损伤组(P <0.05)。结论 Klotho对肾小管上皮细胞低氧/再氧化损伤的保护作用可能与其抗氧化应激的作用机制相关。
邵驾宇应奇素钱盈盈杨秀费晓王鸣
关键词:肾小管上皮细胞KLOTHO氧化应激
H9C2大鼠胚胎心肌细胞缺氧/复氧损伤对端粒酶逆转录酶的表达变化
2020年
目的探讨H9C2大鼠胚胎心肌细胞株不同时间缺氧/复氧损伤对端粒酶逆转录酶的表达变化。方法利用H9C2大鼠胚胎心肌细胞株建立缺氧复氧损伤模型,实验分组及处理;正常对照组,缺氧3 h组,缺氧6 h组,缺氧12 h组。缺氧损伤结束后更换为正常培养基进行复氧培养。复氧3 h后进行相关检测,采用CCK-8法测定细胞活力,测定细胞上清液中乳酸脱氢酶(LDH)的含量,Western blot法检测细胞总蛋白中端粒酶逆转录酶(TERT)的表达量。结果随着缺氧处理3、6和12 h后,与对照组相比细胞株的存活率明显下降(P<0.05),其LDH含量明显升高,各个时点与对照组相比,细胞株的TERT蛋白含量明显增高(P<0.05)。其中在缺氧6 h TERT蛋白含量最高(P<0.05)。结论在缺氧3~6 h期间,随着缺氧时间的延长,心肌细胞TERT表达增高,但随着缺氧时间持续延长到12 h,心肌细胞TERT表达降低,导致心肌损伤增加。
郭海马海平张永强王江
关键词:端粒酶反转录酶心肌细胞
Uranium sequestration in sediment at an iron-rich contaminated site at Oak Ridge, Tennessee via.bioreduction followed by reoxidation被引量:1
2019年
This study evaluated uranium sequestration performance in iron-rich (30 g/kg) sediment via bioreduction followed by reoxidation.Field tests (1383 days) at Oak Ridge,Tennessee demonstrated that uranium contents in sediments increased after bioreduced sediments were re-exposed to nitrate and oxygen in contaminated groundwater.Bioreduction of contaminated sediments (1200 mg/kg U) with ethanol in microcosm reduced aqueous U from 0.37 to 0.023 mg/L.Aliquots of the bioreduced sediment were reoxidized with O2,H2O2,and NaNO3,respectively,over 285 days,resulting in aqueous U of 0.024,1.58 and 14.4 mg/L at pH 6.30,6.63 and 7.62,respectively.The source-and the three reoxidized sediments showed different desorption and adsorption behaviors of U,but all fit a Freundlich model.The adsorption capacities increased sharply at pH 4.5 to 5.5,plateaued at pH 5.5 to 7.0,then decreased sharply as pH increased from 7.0 to 8.0.The O2-reoxidized sediment retained a lower desorption efficiency at pH over 6.0.The NO3--reoxidized sediment exhibited higher adsorption capacity at pH 5.5 to 6.0.The pH-dependent adsorption onto Fe(Ⅲ) oxides and formation of U coated particles and precipitates resulted in U sequestration,and bioreduction followed by reoxidation can enhance the U sequestration in sediment.
Peng-Song LiWei-Min WuDebra H.PhillipsDavid B.WatsonShelly KellyBing LiTonia MehlhornKenneth LoweJennifer EarlesHu-Chun TaoTong ZhangCraig S.Criddle
关键词:URANIUMSEQUESTRATIONBIOREDUCTIONREOXIDATION