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摘要:高铝钢用新型CaO-Al2O3基连铸结晶器保护渣结晶性能较强,在连续浇铸过程中易出现润滑与传热功能协调不均的问题。基于此,针对新型CaO-Al2O3基保护渣,考察了典型助熔剂Li2O对保护渣析晶温度、析晶物相等性能的影响,并进行了相关结晶动力学分析。结果表明,提高Li2O含量可使保护渣的临界冷却速率和初始结晶温度呈现先降低后升高的趋势,当Li2O质量分数为4%时,保护渣结晶倾向最弱。随Li2O质量分数从0增至6%,保护渣的结晶孕育时间先延长后缩短。析晶物相由CaAl4O7+CaF2转变为CaAl4O7+CaF2+LiAlO2,Li2O的加入及其含量的提高促进了LiAlO2的析出。此外,随Li2O质量分数从0增至6%,保护渣结晶活化能先增大后减小,析晶过程受到的阻力先增强后减弱,与结晶性能的变化规律相吻合。 相似文献
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用B2O3作为含氟渣中CaF2的替代熔剂,在保证两结晶器保护渣具有相近粘度和熔化温度的基础上,研究了成分为(%):31.1~35.5CaO、33.9~38.5SiO2、12Al2O3、3MgO、5Na2O、6~15CaF2的含氟结晶器保护渣和(%):33.5~35.5CaO、36.5~39.5SiO2、4Al2O3、5MgO、8~15Na2O、2Li2O、2~6B2O3的无氟结晶器保护渣的结晶温度、结晶能力以及对结晶器控制传热的影响。结果表明,8Na2O-6B2O3无氟渣与5Na2O-15CaF2的含氟渣有相近的粘度和熔化温度,并对结晶器控制传热有相似的作用。 相似文献
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高铝钢连铸过程中,为了避免或减轻钢液中Al与保护渣中SiO2发生反应,设计了低SiO2、高Al2O3含量的高铝钢连铸保护渣,通过添加适量的酸性氧化物B2O3协调熔渣酸碱性,利用实验分析了B2O3含量对高铝钢保护渣熔融特性、黏度特性及渣膜传热特性的影响.结果表明,B2O3含量在4%~10%时,随着B2O3含量增加,保护渣熔化温度、黏度、黏流活化能均降低,渣膜热流密度增加;保护渣的等温转变曲线(TTT曲线)向孕育时间增加的方向移动,晶体生长速率降低;实验条件下,增加B2O3含量可抑制保护渣中CaF2的析出. 相似文献
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对≤1.3 m/min常规拉速(TCaO/SiO2=1.19)和≥1.5 m/min高拉速(TCaO/SiO2=1.40)0.07~0.10C亚包晶钢板坯用两种保护渣(%:2.54~3.0Al2O3、7.34~8.35Na2O、8.83~8.87F、0.79~3.00Li2O)降温凝固过程中结晶特性以及结晶对熔渣粘度的影响进行了研究,得出高拉速保护渣在凝固之前有明显的结晶行为,结晶矿相主要为枪晶石(3CaO·2SiO2·CaF2);常规拉速保护渣在凝固温度以上时,没有明显的结晶现象。与常规拉速保护渣相比,高拉速保护渣完全凝固后晶粒粗大,组织中有大量空隙,有利于增加渣膜热阻,减缓结晶器传热。TCaO/SiO2=1.40保护渣在结晶温度以上时,具有较低的粘度,有利于结晶器润滑;结晶温度以下时,粘度迅速增加,有利于增加固渣膜厚度,减缓结晶器传热。 相似文献
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CSP结晶器保护渣固态渣膜结构和矿相的分析 总被引:4,自引:0,他引:4
通过光学显微镜、扫描电镜及X射线衍射分析,研究了1537 mm×67 mm CSP连铸结晶器保护(%:34.6CaO,28.6SiO₂,8.8C,8.5F,8.6Na₂O)固态渣膜的结构、矿相组成和析晶率,分析结果表明,绝大多数固 态渣膜厚0.6~1.3mm, 呈三层结构:结晶层-玻璃层-结晶层,靠结晶器壁侧为0.10~0.14mm 厚的结晶层;CSP 固态渣膜的析晶率为40%~80%,结晶矿相主要为枪晶石(3CaO ·2SiO₂ ·CaF₂)和矿物Na₂O ·Al₂O₃ ·SiQ₂。通过 调整固态渣膜的厚度及枪晶石等矿物的析晶率,可达到控制渣膜传热,提高连铸坯表面质量的目的 相似文献
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利用Factsage软件计算了Al2O3含量对CaO-SiO2-Al2O3-Fe2O3四元渣系熔点和黏度的影响,并通过实验研究了在1 400℃时,CaO-SiO2-Al2O3-Fe2O3四元渣系对高磷铁水脱磷行为的影响.结果表明:渣中Al2O3的质量分数在3%~6%之间时,随着A12O3含量的增加,渣系的熔化温度迅速降低,进一步增加渣中的A12O3含量,渣系的熔化温度逐渐增加;Al2O3对CaO-SiO2-Al2O3-Fe2O3渣系的黏度影响不大;渣中Al2O3的质量分数在3%~6%之间变化时,渣系脱磷能力变化不是很大,脱磷率维持在91%左右,进一步增加渣系中A12O3的量,脱磷率逐渐下降;Al2O3对脱磷率产生影响可能是其改变了炉渣中液相所占比例,进而影响磷从铁水中向液相渣的传质过程. 相似文献
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针对唐钢中厚板材有限公司低合金钢Q345B连铸过程中出现的铸坯质量问题,系统研究了现场结晶器内渣膜的结构、矿相组成和结晶率;并结合现场铸坯质量,分析渣膜的润滑与传热性能,确定了适用于低合金钢Q345B板坯连铸生产较合理的矿相结构特征.结果表明,低合金钢Q345B的渣膜应为两层结构或多层结构,结晶层和玻璃层交替出现;主要结晶矿物为枪晶石和黄长石,在结晶过程中没有偏向性析出;有较多的玻璃相生成,结晶率相对较低,在35 %~65%.为更好地保证铸坯质量,针对唐钢中厚板坯Q345B的连铸生产,建议在现用的保护渣原渣中适当提高Fe2O和MgO的含量,同时还要调整好现场的浇铸工艺和操作条件. 相似文献
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The solubility of carbon in molten CaO-B2O3 and BaO-B2O3 slags at high temperatures was measured to understand the dissolution mechanism of carbon into the slags. The B2O3-bearing slags, which have a wide range of liquids, at the temperature of interest have been applied to investigate the effect
of basicity on the solubility of carbon from the saturation of acidic or basic components. The solubility of carbon, as a
function of the composition of slags, shows a minimum value, and it is suggested that carbon dissolves by different mechanisms
in the acidic and basic slags, respectively. From the infrared spectra measurements, the wave number indicating the B-C bond
was found to be about 1150 cm−1 in the acidic region of slags; hence, the incorporation of carbon into the borate network was confirmed qualitatively. The
carbide capacity was compared to the nitride capacity, showing that the dissolutions of carbon and nitrogen into the slags
are similar. 相似文献
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CaO-La2O3-B2O3-Eu2O3转光玻璃的合成及荧光性质 总被引:1,自引:1,他引:1
《稀土》2004,25(4):1-5
X射线衍射研究表明CaO-La2O3-B2O3-Eu2O3体系的玻璃化温度在1025℃附近.荧光光谱和ESR谱研究表明,在CaO-La2O3-B2O3-Eu2O3玻璃体系中存在着Eu2+和Eu3+两种价态离子.
316, 360, 379, 394, 413, 462和532nm锐线激发峰和592,616和650红区发射峰分别对应Eu3+的f-f激发跃迁和5D0-7FJ
(J=1,2,3)跃迁发射;351nm和427nm宽带激发峰和蓝区发射分别对应Eu2+的5d-4f激发跃迁和发射. 相似文献
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钒钛磁铁矿是烧结矿重要的原料之一,Ca3TiFe2O8作为钒钛烧结矿中矿物被发现之后,其生成机理尚不明确.本文采用X射线衍射分析、元素能谱分析和TG-DSC分析相结合的方法,研究了Ca3TiFe2O8的生成机理以及不同温度、CaO与TiO2含量下Ca3TiFe2O8的生成规律.实验结果表明,Ca3TiFe2O8由Ca2 Fe2O5和CaTiO3反应生成,即CaO和Fe2O3反应生成Ca2 Fe2O5;其后,与CaTiO3反应生成Ca3TiFe2O8.反应时间越长,Ca3TiFe2O8的生成量越大,但反应温度对Ca3TiFe2O8生成的影响并不明显.另外,还发现CaO含量越高,Ca3TiFe2O8越易于生成,而且等摩尔Fe2O3和CaO下只要存在TiO2,就会有Ca3TiFe2O8生成. 相似文献
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采用喷射沉积和内氧化法制备出Al2O3La2O3Y2O3/Cu复合材料,研究该材料在直流20 V/20 A的工作条件下触点的电弧侵蚀特性,并与Al2O3/Cu材料进行了对比分析.利用电子天平、扫描电镜等方法分析电弧侵蚀后触点的质量变化和表面微观结构.结果表明,通过添加Y2O3、La2O3稀土氧化物颗粒,可有效降低触头材料的材料转移量.Al2O3La2O3Y2O3/Cu材料的抗熔焊性和抗烧损性优于Al2O3/Cu材料的性能.在直流阻性负载条件下Al2O3La2O3Y2O3/Cu阳极触头表面形成凹坑,阴极触头表面形成凸起,触点表面显示出浆糊状凝固物和喷发坑等电弧侵蚀形貌特征. 相似文献
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在Fe-Cr-Al合金中添加微量的稀土元素可显著改善合金的使用性能, 文中以电渣重熔生产Fe-Cr-Al合金所用稀土渣为研究对象, 根据离子-分子共存理论(IMCT)建立了1 823 K时CaF2-Al2O3-CaO-Ce2O3四元渣系热力学质量作用浓度模型.结果表明:当渣系中CaO和Al2O3的质量百分数之比维持在1:1, 即wCaO /wAl2O3=1时, 随着Ce2O3含量增加, 渣中铈铝酸盐Ce2O3·Al2O3质量作用浓度(活度)显著增加, 但炉渣物相种类没有变化.渣系中Ce2O3含量分别在10 %, 20 %, 30 %, 40 %时, wCaO /wAl2O3值对组元活度的影响各不相同但有共同特征, 表现在处于约1.0~1.8时, CaO活度增加最迅速, Ce2O3活度增加, Ce2O3·Al2O3活度下降, 说明渣中CaO含量增加促进了Ce2O3·Al2O3分解而导致Ce2O3活度增加, 选取渣系进行熔融和X射线衍射实验, 用jade 5.0软件分析物相, 实验结果与计算一致. 相似文献
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Research on Y2O3:Eu Phosphor Coated with In2O3 总被引:2,自引:1,他引:1
Y2O3:Eu red phosphor for FED application was prepared by high temperature solid-state reaction. The In2O3 coating by precipitation method to the phosphor was applied and the analyses of XRD, Zeta potential, SEM, EDS and low voltage cathodoluminescence (CL) were conducted for investigating the coating effect. The results showed that In2O3 coating promoted the low voltage CL of the phosphor efficiently. The promotion was possibly due to the enhancement of the surface conductivity of the phosphor grains. 相似文献
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Ce0.67Zr0.33O2-Al2O3 solid solution was prepared by the co-precipitation method. Fe2O3-based catalysts supported on the solid solution were obtained by the impregnation method. The article revealed that the optimal loading amount of Fe2O3 on Ce0.67Zr0.33 O2-Al2O3 in our experimental condition for catalytic combustion of methane was 8% ( mass fraction). The prepared catalysts were characterized by BET, TPR, XRD analyses, and their catalytic activity was investigated after being calcined at 873 K and after being aged in water gas at 1273 K. When the loading amount of Fe203 was 8% ( mass fraction), the catalyst held the highest activity, and the best temperature speciality and thermal stability. The complete-conversion temperature of methane for fresh and aged sample was 788 and 838 K, respectively. The range between the light-off temperature and the complete-conversion temperature was only 15 K. The characterization results of XRD indicated that Fe2O3 was well dispersed on the Ce0.67Zr0.33O2-Al2O3 matrix. The results of BET and TPR were in good harmony with the catalytic activity results. 相似文献
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Employing Dy2O3, Al2O3, and SiO2 as starting materials, several series of Dy2O3-Al2O3-SiO2 sealing glass were prepared. The relationship between their coefficients of thermal expansion and the contents of Dy2O3, Al2O3, and SiO2 were studied respectively. Experimental results showed that Dy2O3 and Al2O3 had a positive effect on the coefficient of thermal expansion of glass, whereas, SiO2 had a negative effect. The coefficient of thermal expansion of glass showed an apparent linear relation to the contents of these three raw materials, from which an estimation model was built, to calculate the coefficient of thermal expansion of sealing glass. Relative errors of the calculating results to testing results were no more than 2%, which suggested that the estimation model was reasonable. This study provides a good theory reference for the practical utilizing of this sealing material, through which a proper glass composition for good sealing could be easily found. 相似文献
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Al2O3/TiCN composites were synthesized by hot pressing.The influences of components and HP temperature on mechanical properties,such as bending strength,breaking tenacity and Vickers hardness were investigated.The results showed that the mechanical properties of Al2O3/TiCN composite increased with temperature when hot pressing temperature is below 1650 ℃.The mechanical properties reached their maximums when the composites were sintered at 1650 ℃ for 30 min under hot pressing pressure of 35 MPa,the value of bending strength,breaking tenacity and Vickers hardness was 1015 MPa,6.89 MPa·m1/2,and 20.82 MPa,respectively.When hot pressing temperature was above 1650 ℃,density decreased because of decomposition with increased temperature,and mechanical properties dropped because of rapid growth of grains in size at high temperature.Microstructure analysis showed that the addition of Y2O3 led to the formation of YAG phase so as to inhibit the growth of crystals.This helped to improve breaking tenacity of the composites.TiCN particles with diameters of 1 μm dispersed at Al2O3 grain boundaries,inhibited grain growth and enhanced mechanical properties of the composites.SEM study of the propagation of indentation cracks showed that the bridge linking behavior between matrix and strengthening phase might lead to the formation of the coexisted field of crack deflection,branching and bridge linking.The mechanism of this phenomenon was that the addition of Y2O3 improved the dispersion of TiCN particles so as to enhance the tenacity of the composites.The breaking tenacity was changed from 5.94 to 6.89 MPa·m1/2. 相似文献