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采用CaO -SiO2 -Na2 O -CaF2 -Al2 O3-MgO渣系 ,通过测定熔渣的粘度和Al2 O3吸收速率 ,研究连铸保护渣的Al2 O3吸收速率与粘度及化学成分之间的关系。在一定条件下 ,当CaO SiO2 为1 .2左右时 ,粘度达到最小值 ,Al2 O3吸收速率达到最大值 ,分别为 0 .1 0Pa·s、8.4 0 3× 1 0 - 4 kg·m- 2 ·s- 1 。随着渣中Na2 CO3含量、CaF2 含量和MgO含量的增加 ,粘度减小 ,Al2 O3吸收速率增大。随着渣中Al2 O3含量的增加 ,粘度增大 ,Al2 O3吸收速率减小。粘度为Al2 O3吸收速率的主要控制因素。随着熔渣粘度的增加 ,连铸保护渣的Al2 O3吸收速率逐渐减小。 相似文献
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《Scripta Metallurgica et Materialia》1991,25(5):1065-1069
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2'-Azido-2'-deoxyuridine and 2'-azido-2'-deoxycytidine were evaluated for their inhibitory activity against ribonucleotide reductase and for subsequent cell growth inhibition. Their mono- and di-phosphates were synthesized and their inhibitory activities against the reductase were also determined in a permeabilized cell system, along with the two nucleosides. The results of the present study identify the first phosphorylation step involved in the conversion of the two azidonucleosides to the corresponding diphosphates to be rate-limiting in the overall activation. 相似文献
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The Gibbs energy changes for the syntheses of the interceramic compounds of BaCuO2 and BaCu2O2 were investigated as a basic study in the Y-Ba-Cu-O system that includes a superconductor, YBa2Cu3O6.5+x
. For the compound BaCuO2, thermogravimetry with CO2-O2-N2 gas mixtures was employed, and equilibrium temperatures were determined at which CO2 partial pressures in the gas mixtures were equilibrated with mixed powder of BaCuO2, CuO, and BaCO3. The Gibbs energy change for the reaction of BaCO3 + CuO = BaCuO2 + CO2 was determined from the relation between CO2 partial pressure and equilibrium temperature, taking into consideration the effect of CO2 dissolution in BaCuO2. For the study on BaCu2O2, electromotive force (emf) measurement using yttria-stabilized zirconia solid electrolyte was conducted. A technique using
two cells was applied to the emf measurement for minimizing the effect of dispersion of oxygen from samples, and the Gibbs
energy change for the reaction of BaCuO2 + CuO = BaCu2O2 + 1/2O2 was decided from the measured O2 partial pressure. 相似文献
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Myung-Duk Seo Cheng-Bin Shi Jung-Wook Cho Seon-Hyo Kim 《Metallurgical and Materials Transactions B》2014,45(5):1874-1886
The effects of basicity (CaO/SiO2), B2O3, and Li2O addition on the crystallization behaviors of lime-silica-based mold fluxes have been investigated by non-isothermal differential scanning calorimetry (DSC), field emission scanning electron microscopy, X-ray diffraction (XRD), and single hot thermocouple technique. It was found that the crystallization temperature of cuspidine increased with increasing the basicity of mold fluxes. The crystallization of wollastonite was suppressed with increasing the mold flux basicity due to the enhancement of cuspidine crystallization. The addition of B2O3 suppresses the crystallization of mold flux. The crystallization temperature of mold flux decreases with Li2O addition. The size of cuspidine increases, while the number of cuspidine decreases with increasing mold flux basicity. The morphology of cuspidine in mold fluxes with lower basicity is largely dendritic. The dendritic cuspidine in mold fluxes is composed of many fine cuspidine crystals. On the contrary, in mold fluxes with higher basicity, the cuspidine crystals are larger in size with mainly faceted morphology. The crystalline phase evolution was also calculated using a thermodynamic database, and compared with the experimental results determined by DSC and XRD. The results of thermodynamic calculation of crystalline phase formation are in accordance with the results determined by DSC and XRD. 相似文献
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CaO-SiO2-Na2O-CaF2-Al2O3-MgO渣系的粘性活化能 总被引:1,自引:1,他引:0
采用CaO-Si02-Na20-CaF2-Al2O3-MgO渣系,通过测定粘度和粘性活化能,建立二次回归正交设计模型,借此研究了粘性特征与碱度、Na20含量、CaF2含量、Al2O3含量及MgO含量之间的关系,为设计开发连铸保护渣提供了理论依据。研究结果表明,粘性活化能随着渣中碱度、Na2C03含量和CaF2含量的增加而减小;Al2O3和MgO对粘性活化能的影响与碱度密切相关。连铸保护渣的粘度和粘性活化能具有相似的变化规律。 相似文献
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Atsuko Tagaya Hiroyuki Chiba Fumitaka Tsukihashi Nobuo Sano 《Metallurgical and Materials Transactions B》1991,22(4):499-502
In order to understand the thermodynamic behavior of phosphorus, such as the polymerization of phosphate ions in slag melts,
the influence of phosphorus content of slag melts on the partition of phosphorus between slags and carbon-saturated iron or
silver was investigated for the CaO-CaF2-SiO2 and CaO-Na2O-SiO2 systems at 1573 and 1473 K, respectively. The predominant species changes from PO
4
3
to P2O7
4-approximately at 2 mass pct of phosphorus in slag melts, which is defined as the critical phosphorus content, for the CaO-CaF2-SiO2 system which is doubly saturated with CaO and 3CaO · SiO2. The critical phosphorus content was found to be about 1 mass pct for the CaO-CaF2-SiO2 melts saturated with 2CaO · SiO2. On the other hand, in the case of the 20CaO-35Na2O-45SiO2 system, PO4/3- is the predominant species until the slag becomes saturated with Ca3(PO4)2. No effect of sulfur on the phosphorus partition ratio was observed for the CaO-CaF2-SiO2 system.
Formerly Undergraduate Student, Department of Metallurgy, The University of Tokyo. 相似文献