Thermodynamic Behavior of Manganese and Phosphorus between Liquid Iron and CaO-MgO-SiO2-Al2O3-FetO-MnO-P2O5 Slags

The thermodynamic behavior of manganese and phosphorus between liquid iron and CaO-MgO-SiO2-A12O3-Fe,O- MnO-P2O5 ladle slag system was addressed by investigating the thermodynamic equilibria between liquid iron containing Mn and P and the ladle slag at 1 873 K. The Mn distribution ratio Lmn increases with increasing FetO content and decreasing the basicity (%CaO + %MgO)/ (%SiO2 + %Al2O3 + %P2O5) in slag, while the P distribution ratio Lp seems to be increased as FetO content and the basicity increases. The values of LM, and Lmn decrease by the addition of A12O3 into slag. The expression of the dependence of Lmn. and Lp on the basicity and FetO content in slag was obtained.     

CaO-SiO_2-MgO脱硅渣起泡性能的研究

分析了铁水脱硅预处理后炉渣起泡原因及机理,通过实验验证并提出了抑制炉渣发泡的措施.研究表明：将氧化剂连续、分散加入铁液,可减少单位时间内发泡气体的产生量,有利于抑制炉渣发泡.1450℃条件下,当碱度为0.6～0.8,w（MgO）为10%～20%时,碱度升高或w（MgO）增加,炉渣黏度呈降低趋势,密度变化不大,而发泡高度和发泡指数明显减小.随着w（MgO）增加,炉渣表面张力增大.炉渣碱度为0.8、w（MgO）为20%时,发泡性能最弱.向脱硅渣中加入适量CaO或MgO,可改变炉渣的物理化学性质,抑制炉渣发泡.     

Si和Al对机械合金化合成Ti3SiC2的影响

采用3Ti／Si／2C单质粉体为原料,进行机械合金化,以合成Ti3SiC2粉体。研究了Al和过量Si对机械合金化合成Ti3SiC2的影响。研究结果表明,机械合金化单质混合粉体,会诱发自蔓延反应。反应后产生大量坚硬的颗粒状产物。机械合金化3Ti／Si／2C粉体,会产生组成相为TiC、Ti3SiC2、TiSi2和Ti5Si3的粉体与颗粒产物。添过量Si并不会促进机械合金化反应合成Ti3SiC2。添适量Al可消除硅化物,明显促进反应合成Ti3SiC2。采用3Ti／Si／2C／0．15Al粉体作原料时,颗粒产物中Ti3SiC2含量最高,为92．8wt％;而采用3Ti／Si／2C／0．20Al粉体作原料时,粉体产物中Ti3SiC2含量最高,为61．9wt％。     

白云鄂博铌精矿碳还原直接合金化热力学研究

本文针对使用铌精矿代替铌铁合金在精炼炉的环境下进行直接合金化炼钢的过程,使用FactSage软件进行还原剂为C时,不同Nb2O5活度系数、温度、碱度、渣成分下[Nb]/Nb2O5值进行热力学平衡计算.综合分析结果表明,Nb2O5活度系数成为影响其还原进入钢液的重要因素之一;C作为还原剂时的有利条件为高温、低碱度、低（FeO）;（TiO2）对于[Nb]/Nb2O5的影响较小.使用《矿物炼钢》中类似体系的共存模型结果计算了C还原Nb2O5反应的吉布斯自由能随温度和碱度的变化.结果表明C还原Nb2O5反应的AG随碱度升高而增大,随温度的升高而降低.LNb随碱度升高而降低,随温度的升高而升高.     

石灰石在转炉中与铁水相互作用研究

根据热力学基础理论研究了CO2-CO气体与Fe—C—Si—Mn体系之间反应以及铁水中[C]对Ca-CO3分解温度的影响．结果表明,在气氛组成变化很宽的范围内,CO2与[C]、[Si]、[Mn]、Fe（1）反应的AG小于零,石灰石分解产生的部分CO：可以替代氧气参与熔池的氧化．气氛组成影响CO：对铁水中元素的氧化顺序．CO：浓度高CO浓度低时,CO2优先氧化[C];CO2浓度低CO浓度高时,CO2优先氧化[Si]．在w[C]=2％～4．5％的范围内,石灰石分解温度T与w[C]％的关系为T=2．40w[C]2%-35．91w[C]%＋1129．1．将石灰石煅烧过程从传统石灰窑中转移到转炉可显著降低石灰石分解温度．CaCO3的分解反应和CO2对熔池的氧化反应互相促进,有利于石灰石的分解和铁水中杂质元素的氧化去除．     

Optimum Slag Basicity for Deoxidation DuringSecondary Refining Process

According to the coexistence theory of slag structures, the calculating model of the oxidizing capabilityfor CaO-MgO-FeO-Al2O3-SiO2 refining slag system has been deduced. Based on this model, the concept and thecalculating method of the optimum slag basicity are put forward. The results have proved that at this basicity,steel with lower oxygen content can be obtained and non-metallic indigenous globular inclusions can be avoidedmore effectively than at other basicity.     

转炉锰矿直接合金化国内外现状及对策

通过对国内外转炉采用锰矿直接合金化研究现状和实际操作工艺的剖析,分析了转炉渣量、(FeO)、终点[C]含量及炉渣碱度等主要工艺参数对转炉锰矿直接合金化锰收得率的影响规律,形成了提高转炉锰矿直接合金化锰收得率的关键技术思想。并针对目前国内转炉冶炼的实际情况提出了相应对策,即用锰矿自还原压块代替直接加锰矿进行直接合金化。     

Al2O3对3Ti/Si/2C体系自蔓延高温合成Ti3SiC2的影响

以3Ti/Si/2C粉体为原料,通过自蔓延高温合成技术合成了Ti3SiC2材料。研究了Al2O3助剂对自蔓延高温合成Ti3SiC2的影响。研究结果表明,3Ti/Si/2C粉体会发生自蔓延反应,产物的组成相为TiC、Ti3SiC2和Ti5Si3,产物中Ti3SiC2含量约为23%。添加适量的细粒度Al2O3可显著促进反应合成Ti3SiC2,3Ti/Si/2C/0.1Al2O3原料反应后得到的产物中Ti3SiC2含量达64%。     

P2O5对转炉钢渣矿物结构的影响

依据实际转炉钢渣理化特性,以CaO-MgO-SiO2-Fe2O3四元渣系作为基础渣系,向该渣系中加入渣量1%～7%（质量分数）的P元素,使用SEM和EDS对合成渣系矿物结构进行表征与分析。结果表明：合成渣系主要由硅酸二钙、铁酸二钙及方镁石组成,其中磷元素主要以磷酸三钙的形式固溶于硅酸二钙中,在其他相中并未发现磷元素的存在;随着磷含量的增加,磷元素在硅酸二钙矿物中的含量随之增加,并可能出现独立的磷灰石相,这可为转炉钢渣在磷肥工业的应用研究提供参考。同时,由于磷加入量增多,CaO优先与[PO4]4-反应,早先存在的方镁石逐渐消失而溶入基质相。基质相2CaO·Fe2O3向CaO·MgO·Fe2O3发生转变,最后形成2MgO·Fe2O3,表明高磷含量有利于改善转炉钢渣的安定性能。     

电熔再结合镁铬砖的精炼渣浸实验

用试样旋转法在1600℃下实验研究了CaO－SiO2－Al2O3－MgO－CaF2（3％）型精炼渣组成对电熔再结合镁铬砖的侵蚀影响．结合渣浸试样的电镜分析，结果表明，随渣碱度（CaO／SiO2）的增大，试样的侵蚀增加；碱度大于1．8时，试样在冷却过程中粉化．由于尖晶石保护层的生成，渣中Al2O3含量的增加能沽少侵蚀．随渣中MgO含量的增加，试样的侵蚀减少，在此基础上，讨论了对提高镁铬砖炉衬有利的炉外精炼造渣制度．     

不锈钢粉尘内配煤团块高温自还原过程中金属铁的聚集

用不锈钢生产中的高碱度二次粉尘制备内配煤团块,在高温下自还原获得含铬、镍的金属铁粒.研究影响铁粒聚集长大的因素.研究表明：（1）内配煤团块的渣相碱度（w（CaO）/w（SiO2））小于2.8时,还原产物冷却过程中渣相与金属铁粒才能自然分离.碱度越低,渣量越大,越不利于金属铁聚集长大;（2）提高内配碳比,渣相残碳量明显升高,渣中过量的碳阻碍金属相聚集长大;（3）提高还原温度,直接还原铁的海绵状结构解体,逐渐聚集成颗粒状金属铁.还原温度越高,越有利于金属铁的聚集长大     

复吹转炉锰矿直接合金化热力学模型研究

基于某钢厂铁水、废钢和造渣料等的成分得出转炉炼钢的渣量计算模型,根据热力学原理得出锰的收得率和终点锰含量的预报模型。对模型研究结果表明,提高终点出钢温度、渣碱度、锰矿品位和铁水Mn含量,降低终渣含量及渣中FeO含量,可显著提高Mn的收得率和终点Mn含量。     

Wettability and pressureless infiltration mechanism in SiC-Cu systems

The wetting behavior of copper alloys on SiC substrates was studied by a sessile drop technique. The microstructure of SiCp/Cu composites and the pressureless infiltration mechanism were analyzed. The results indicate that Ti and Cr are effective ele-ments to improve the wettability, while Ni, Fe, and AI have minor influence on the improvement of wettability. Non-wetting to wet-ring transition occurs at 1210 and 1190℃ for Cu-3Al-3Ni-9Si and Cu-3Si-2Al-1Ti, respectively. All the copper alloys react with SiC at the interface forming a reaction layer except for Cu-3Al-3Ni-9Si. High Si content favors the suppression of interfacial reaction. The infiltration mechanism during pressureless infiltration is attributed to the decomposition of SiC. The beneficial effect of Fe, Ni, and Al is to favor the dissolution of SiC. The real active element during pressureless infiltration is Si.     

Synthesis of Ti3SiC2/TiB2 Composite by In-situ Hot Pressing (HP) Method

Ti3SiC2/TiB2 composite was successfully obtained by hot pressing Ti/TiC/Si/B4C power mixtures.Volume fraction of TiB2 in Ti3SiC2/TiB2 composite can not exceed 10%.Incorporation of excessive TiB2 will affect the reactions process.TiC and Ti5Si3 were two important intermediate phases during the whole reactions.The microstructure characteristics of the Ti3SiC2/TiB2 composites were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The experimental results show that the grains of Ti3SiC2/TiB2 composite are structured in a layered form,and the formation of TiB2 particles as reinforcements with elongated or equiaxed shape distributes in Ti3SiC2 matrix.     

含BaO,Na2O渣系渣钢间硫平衡研究

在钼丝炉上进行了含BaO,Na2O精炼渣系渣钢间流平衡实验。研究 结果表明,在传统精炼渣系中加入BaO,能够提高渣系的硫容量,Na2O对渣系的硫容量也有很大的影响,但稳定性不好。     

SiCl4锌还原异相反应机理的研究

通过MP2/6-311G（d,p）方法,计算并得到了SiCl4锌还原各反应通道上各驻点的几何构型、振动频率和能量.根据密度泛函理论,采用广义密度梯度近似和总体能量平面波赝势方法结合周期性平板模型,研究了反应驻点在Si（100）面上的吸附、解离及锌还原过程.结果表明,衬底硅参与SiCl4锌还原反应,SiCl4易在顶位吸附解离成SiCl3和Cl;当硅基表面有Cl自由基吸附时,Zn或ZnCl更倾向于与Cl结合,而不是还原SiCln（1～3）.     

Thermodynamic analysis on the formation mechanism of MgO·Al_2O_3 spinel type inclusions in casing steel

MgO·Al2O3 spinel type inclusions in casing steel were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).The results show that there are three forms.One is pure MgO·Al2O3 spinel,another is the composite oxide of the Mg-Al-Ca-Si-O system,and the third is the complex with oxide as a core covered by sulfide.The formation mechanisms were studied.The influences of slag basicity and vacuum degree on the magnesium content during the vacuum treatment of molten steel and furnace ...     

多晶SiC/多孔硅结构材料的APCVD生长及表征

采用SiH₄-C₃H₈-H₂气体反应体系,通过常压化学气相淀积(APCVD)工艺在电化学腐蚀的多孔硅衬底上进行了多晶3C-SiC薄膜的生长,研究了多孔硅孔隙率对薄膜生长质量的影响．实验结果表明,当多孔硅孔隙率较低时,得到的是含有SiC(111)晶粒的多晶硅薄膜,随着孔隙率的增加,生长薄膜由富碳多孔SiC向多晶SiC薄膜过渡,表面平整度增加,并具有<111>晶向择优生长的特点．     

基于普通纸张的蜂窝陶瓷载体材料的设计与性能研究

以普通纸张为原料,采用凝胶-溶胶技术对纸张进行处理,并通过折叠、粘贴等仿生设计,经低温炭化、高温碳热还原反应及气相渗硅等方式制备出SiC/Si蜂窝陶瓷载体复合材料.采用XRD、SEM、TEM和三点弯曲等分析测试手段对其相组成、微观结构和力学性能进行分析.结果表明,陶瓷纸炭化以后为非晶态的碳;经真空炉烧结后的相组成为β-SiC相、Si相和残留的C相.三点弯曲实验表明,SiC/Si陶瓷复合材料的强度超过200MPa.多孔碳化硅的气孔率随着排硅时间的增加而增加,其强度和韧性随着排硅时间的增加而减小.     

Vaporization behavior of lead from the FeO-CaO-SiO_2-Al_2O_3 slag system

Vaporization behavior (1163-1463 K) of lead in the slag system of FeO-CaO-SiO2-Al2O3 with CaCl2 was examined.A thermodynamic estimation with the principle of Gibbs free energy minimization showed that the major vapor species from the sample of the FeO-CaO-SiO2-AI203 system+PbO+CaCl2 were metallic Pb,PbC1,PbCl2,and FeC12,at the experimental temperature range.The experimental results show that the mole ratio of vaporized CI in lead chlorides to vaporized Pb,simply expressed as CI/Pb,decreases with increasing temperature.The larger CUPb means a larger ratio of gaseous PbCl2,since metallic Pb and PbCI vapors are formed in a similar reduction atmosphere.The evaporation is initially rapid and becomes steady after holding for 10 rain.Gaseous PbCI2 is mainly formed during the heating period,and at the holding stage,it reacts with FeO to produce gaseous FeCI2.With regard to slag composition,FeO content and basicity significantly affect the evaporation of lead.High FeO content and high basicity promotes the formation of metallic Pb and PbCI,whereas,it prohibits PbCl2 evaporation.