应用MgS基固体电解质硫浓差电池测定铁液中硫含量的试验研究

用自制的 MgS、TiS_2和 MoS_2所组成的 Mo|[S]_(Fe)||MgS+TiS_2||Mo+MoS_2|Mo 浓差电池,并在1375℃无保护气氛下,测定了铁液硫含量;硫浓差电池电势与铁液硫含量有1g〔%S〕=-0.3694-0.0077E(mV)的关系。还在1375℃温度条件下,测定了Cu-Cu_2S 系的硫位,推导出 MgS+TiS_2固体电解质的特征分压—P’_e=6×10~(-9)atm。     

铁液中硫活度的测定方法探讨

以CaS(1%Y2S3)作固体电解质,W/WS2为参比电极组成化学传感器,对碳饱和铁液中硫的活度进行了测定,实验证明:CaS(1%Y2S3)固体电解质作为定硫传感器是可行的.     

用CaS(TiS_2)固体电解质硫浓差电池测定铁液中硫活度的实验研究

在实验室条件下,用自制的CaS(1～1.5wt％TiS_2)固体电解质硫浓差电池测定了1400℃碳饱和铁液和液态生铁中的硫活度。实验所用的电池可以表示为 (+)Mo,W+WS_2|CaS(TiS_2)|[S],Mo金属陶瓷(一) 实验结果表明:在实验条件下,CaS(TiS_2)主要表现为离子导电,其化学性能稳定并具有较高的抗热震性,能满足含碳铁液测硫活度的要求。实验所测得的电动势与硫含量之间的关系为液态生铁1g[S％]=1.118-6.034E(V) (0.03～0.6％S) 碳饱和铁液1g[S％]=3.393-12.375E(V) (0.005～0.15％S) 文章对CaS基固体电解质在1400℃液态生铁和1600℃钢液中的热力学稳定性也分别进行了讨论。     

用ZrO_2固体电解质电动势法测定1600℃时液态Fe-Nb-O合金的热力学性质

用氧化钙稳定的片状氧化锆固体电解质定氧测头测定了1600℃时Fe-Nb-O合金的热力学性质。试验中采用了下列氧浓差电池Mo|Cr Cr_2O_3|ZrO2(4％CaO)|Fe-Nb-O|Mo,测得的热力学性质如下: 用X射线衍射法检定的反应产物为NbO_2(当Nb>0.4％)。     

定硫电化学传感器可行性的理论分析和实验探索

本文回顾了定硫电化学传感器的开发研究现状。对硫化物固体电解质的导性质及在铁液中的化学稳定性作了文献回顾和理论计算，指出了采用硫化物固体电解质直接定硫传感器存在的主要问题。提出了几种用非硫化物固体电解质加辅助电极的间接定硫传感器，并进行了探索性实验，取得了较好的结果。     

铁液中[La]-[S]-[O]平衡的研究

本文采用铁液与镧的脱硫产物直接平衡法研究了铁液中镧的脱硫能力。采用ZrO_2(MgO)固体电解质定氧探头直接测定铁液中的氧活度,CaS(TiS_2)固体电解质定硫探头直接测定铁液中的硫活度,并在低温无水电解操作条件下,分离了固体平衡试样中的平衡产物,测得了溶解状态的镧含量,由实验所得的数据,并选择了有关的热力学数据,通过计算得到了1600℃铁液中[La]-[S]-[O]平衡图和等硫(a_(La)-a_0)、等氧(a_(La)-a_0)平衡图,为理论上预测夹杂物生成的顺序和类型提供了依据。给出了铁液中La的一系列有关热力学参数,并给出了铁液中La加入量和控制夹杂物形态的公式,对La在铁液中的有关行为进行了热力学分析和讨论。     

铁液中〔Y〕—〔S〕—〔O〕的热力学研究

由直接平衡法研究了1575—1625℃铁液中钇的脱硫氧平衡,固体电解质定氧探头测定了熔池中的氧活度,低温无水电解液电解法测定了溶解状态的钇含量。实验测得钇在铁液中的脱硫氧常数与温度的关系:LgK_(Y_2O_2S)=-(79487)/T+28.03,钇的硫氧化物在铁液中的标准生成自由能与温度的关系:2[Y]+2[O]+[S]+Y_2O_2S(s)△G~0=-363650+128.24T(Cal/mole)=-1521520+536.55T(J/mole)。由热力学分析进一步计算得到:1600℃铁液中[Y]-[S]-[O]平衡立体图、a_O-a_S平衡图及钇的氧化物、硫化物和硫氧化物稳定形成的条件,为理论上预测夹杂物,生成的先后次序及类型提供了依据。并给出了铁液中钇加入量计算公式:[%Y]=(88.9/32)·([%O]+[%S]及控制夹杂物形态的计算公式:[%Y]/[%S]=2.78(1+[%O]/[%S])     

固体电化学定硫传感器在熔融金属中的应用

硫是钢铁生产中的有害元素之一,精确测定和在线检测熔融金属中的硫含量是钢铁冶金过程中一项至关重要的任务。固体电化学原理是一种测量熔融金属中硫含量的精确方法。然而,到目前为止,还没有找到一种化学性质稳定和离子电导率高的硫化物固体电解质材料,因此,人们将常用的固体电解质材料(如ZrO2基固体电解质和β-Al2O3等)与化学性质相对稳定的硫化物辅助电极相结合进行间接测硫。在一些情况下,无需将固体电解质材料与辅助电极结合,而直接使用β-Al2O3也可用于测硫,辅助电极是在测硫过程中在固体电解质与辅助电极界面原位生成的。本文简要回顾了这些固体电化学间接测硫所使用的方法和材料。     

Sr_(0.69)La(0.31)F(2.31)+SrS型高温定硫传感器的研制及铜液中硫活度的测定

用SrF_2和LaF_3按0.69:0.31比例的共沉淀粉料混入SrS粉作原料,按优化的最佳条件制备出固体电解质管,并构成以下电池:W│W,WS_2│Sr_(0.69)La_(0.31)F_(2.31)+SrS│[S]_Cu│W 测定铜液中的硫活度。结果表明,可得到稳定的电动势,电池是可逆的。测量结果显示铜中的硫活度呈负偏差,和文献的实验数据相吻合,表明Sr_(0.69)La_(0.31)F_(2.31)+SrS可以作为高温定硫的电化学传感器材料。     

Fe-C-Sb,Fe-C-Sb-Ce,Fe-C-Sb-Y Fe-Nb-Ce溶液的热力学和稀土、镁与锑在球墨铸铁中行为的研究

本文用溶解度法、化学平衡法、固体电解质浓差定氧法等不同的方法研究了Fe-C-Sb,Fe-C-Sb-Ce,Fe-C-Sb-Y,He-Nb-Ce溶液在钢铁冶炼温度范围内(1300～1700℃)的热力学性质,得到铁液中相互作用系数与温度的关系式;1600℃时铁液中相互作用系数;金属间化合物CeSb、YSb的标准生成自由能与温度的关系;1600℃时反应Ce_2O_2S=2[Ce]+2[O]+[S]的平衡常数。用金相显微镜、扫描电镜、电子探针等方法研究了稀土、镁及锑对稀土镁球铁中石墨形貌的影响,球墨铸铁中锑与硫含量的关系,铈、镁,硫等元素的分布及铈降低铸铁中锑的危害性机理。     

Catalytic Decomposition of CFC-12 over Solid Superacid Mo2O3/ZrO2

Catalytic decomposition of dichlorodifluoromethane (CFC-12) in the presence of water vapor and oxygen was studied over a series of solid superacids, Mo2O3/ZrO2, that had different ZrO2 content by using a fixed-bed reactor. CO2 and CClF3 were the main products and no CO was detected as by-product. The decomposition activity of solid superacid largely depended on the content of ZrO2 and the calcination temperatures of Mo2O3/ZrO2. The optimal calcination temperature and content of ZrO2 for preparing Mo2O3/ZrO2 with the highest activity for catalytic decomposition of CFC-12 were 450°C and 20–40% by weight, respectively. Adopting a low concentration of oxygen and CFC-12 together with a high concentration of water vapor was preferable for having the high conversion efficiency of CFC-12 and the selectivity for CO2. The catalytic activity of Mo2O3/ZrO2 remained steady for 100?h in continuous operation.     

Catalytic Decomposition of CFC-12 over Solid Super Acid Mo2O3/ZrO2

Catalytic decomposition of dichlorodifluoromethane (CFC-12) in the presence of water vapor and oxygen was studied over a series of solid super acids Mo2O3/ZrO2 that had different ZrO2 content by using a fixed-bed reactor. CO2 and CClF3 were the main products and no CO was detected as by-product. The decomposition activity of solid super acid largely depended on the content of ZrO2 and the calcination temperatures of Mo2O3/ZrO2. The optimal calcination temperature and content of ZrO2 for preparing Mo2O3/ZrO2 with the highest activity for catalytic decomposition of CFC-12 were 450°C and 20–40 wt?%, respectively. Adopting a low concentration of oxygen and CFC-12 together with a high concentration of water vapor was preferable for having the high conversion efficiency of CFC-12 and the selectivity for CO2. The catalytic activity of Mo2O3/ZrO2 remained steady for 100 h in continuous operation.     

Transformation Behavior and Mechanical Properties of Al2O3/ZrO2(2Y) Ceramic Composites

The content of zirconia has a remarkable influerce on transformation behavior and mechanical properties of Al2O3/ZrO2 (2Y) composites. When 15% and 20% ZrO2(2Y) was added to Al2O3, the bending strength and fracture of the content of ZrO2 (2Y) on transformation and mechanical properties was investigated. The changes of m-ZrO2 and t-ZrO2 phases content before and after fracture were measured by X-ray diffraction quantitative phase analysis, It is shown that improvement in bending strength and fracture toughness of the Al2O3/ ZrO2 (2Y) composites is due to the phase transformation toughening mechanism of ZrO2 (2Y) and thermal expansion mismatch.     

A Coupled Thermodynamic Model for Prediction of Inclusions Precipitation during Solidification of Heat-resistant Steel Containing Cerium

A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microsegregation of solute elements during solidification of heat-resistant steel containing cerium was established.Then the model was validated by the SEM analysis of the industrial products.The type and amount of inclusions in solidification structure of 253 MA heat-resistant steel were predicted by the model,and the valuable results for the inclusions controlling in 253 MA steel were obtained.When the cerium addition increases,the types of inclusions transform from SiO2 and MnS to Ce2O3 and Ce2O2S in 253 MA steel and the precipitation temperature of SiO2 and MnS decreases.The inclusions CeS and CeN convert to Ce2O3 and Ce2O2S as the oxygen content increases and Ce2O3 and CeN convert to Ce2O2 S,Ce3S4,and MnS as the sulfur content increases.The formation temperature of SiO2 increases when the oxygen content increases and the MnS precipitation temperature increases when the sulfur content increases.There is only a small quantity of inclusions containing cerium in 253 MA steel with high cleanliness,i.e.,low oxygen and sulfur contents.By contrast,a mass of SiO2,MnS and Ce2O2 S are formed in steel when the oxygen and sulfur contents are high enough.The condition that MnS precipitates in 253 MA steel is 1.2 w[O]+w[S]0.01%and SiO2 precipitates when 2 w[O]+w[S]0.017%(w[S]0.005%)and w[O]0.006%(w[S]0.005%).     

添加Y2O3的ZrO2增韧Al2O3陶瓷抗钢液腐蚀性能的研究

采用工业ZrO2和AlO3为原料,以Y2O3作为稳定剂,通过适当工艺制备出ZrO2增韧Al2O3(ZTA)陶瓷.主要研究了ZrO2和Y2O3稳定剂对ZTA陶瓷烧结性和抗钢液腐蚀性能的影响.实验结果表明:机械混合法引入的Y2O3在改善ZTA陶瓷的烧结性的同时,可以提高材料的抗钢液腐蚀性能;随ZrO2含量的增加,ZTA陶瓷的抗钢液腐蚀性能增强;材料中大量微裂纹的存在可以提高材料的韧性,但抗钢液腐蚀性能有所下降.     

Development of electrochemical silicon sensors for iron and steel melts

Based on the commonly used oxygen sensors with O^2- ion-conducting ZrO₂ electrolytes and solid metal-metal oxide references, new sensors have been developed for direct measurements of Si content in iron and steel melts. The sensors are designed in such a way that local chemical equilibrium of the reaction ZrO₂ + [Si] + 2[O] = ZrSiO₄ is established at the surface of the ZrO₂ electrolyte tube or inside a cavity adjacent to the ZrO₂ electrolyte sensor tip using a saturating ZrO₂-ZrSiO₄ mixture. Concepts and dimensions of the sensors were optimized in view of a fast EMF response upon immersion and the maintenance of a stable EMF recording over extended periods. Reliable measurements were performed in Fe-Si melts at 0.05 to 5 wt.-% Si.     

Mechanical Behaviors of ZrO2-Al2O3 Ceramic Composites with Y2O3 as Stabilizer

Forlongthebrittlenessofceramicmaterialshasstoodinthewayofindustrialapplicationanddevelop ment.However ,inrecentyears ,suchprogressasthephasetransformationtougheningofzirconia ,thedis persionofparticletougheningandthefiberorwhiskertougheninghavewellimprove…     

Physicochemical Processes of Fabricating Ceramic Materials Based on Nanopowders of Zirconium,Yttrium, Cerium,and Aluminum Oxides

When studying nanoceramics, it is necessary to constantly keep in mind the closest interrelation of their fabrication method, structure, and properties. Nanoceramic materials are used in various branches of technology as structural and functional materials. Nanoceramics are also widely used in medicine. They are harmless, stable, and have great affinity to living organisms. ZrO2-based nanoceramics have a lower elastic modulus than other oxide materials. The specificity of their application lies in their high rupture strength, thermal shock resistance, and chemical stability at high temperatures. However, it is necessary to solve the problem of increasing the fracture toughness of ZrO2-based ceramic materials. The complex alloying of ZrO2 with yttrium and cerium oxides and the use of the Al2O3 additive leads to an increase in the fracture toughness and lowering of the negative effect of materials in the biological medium. In this work, the physicochemical properties of ceramic powders and materials of the ZrO2–2Y2O3–4CeO2–Al2O3 system synthesized by the chemical deposition of inorganic precursors when applying the sol-gel technology are considered based on scientific data and experimental studies. Alloying pure zirconium oxide by stabilizing Y2O3 and CeO2 oxides and thermal hardening of Al2O3 ensure the conservation of the tetragonal structure at room temperature, which makes it possible to retard and control the crack resistance of the material under the load. Investigations into the influence of the sintering temperature and aluminum oxide content on the microstructure and grain size, as well as physicomechanical properties of ceramic materials of compositions ZrO2–2Y2O3–4CeO2 + 1 wt % Al2O3 and ZrO2–2Y2O3–4CeO2 + 3 wt % Al2O3, are carried out.     

Thermodynamics of nozzle blockage in continuous casting of calcium-containing steels

Calcium-bearing material is added commercially to remove sulfur and to control sulfide shape. Few steelmakers, however, have used calcium additions to cast aluminum-killed steels successfully through metering nozzles. In a development program to cast aluminum-killed steels at Inland's No. 1 Electric Furnace and Billet Caster Shop, calcium-silicide injection at first resulted in nozzle blockage in both aluminum-killed and silicon-killed steels. This paper discusses the thermodynamics of iron containing silicon, aluminum, calcium, oxygen, and sulfur, as well as analyses of the nozzle deposits. The thermodynamic calculations show that, in iron containing aluminum, the calcium content can be too high, so that solid calcium sulfides form. In iron containing silicon without aluminum, with similar calcium contents, solid calcium silicates and calcium sulfides can form. The results of the analyses from plugged nozzles were in agreement with these thermodynamic predictions.