Preparation and stabilization of γ-La_2S_3 at low temperature

Eu doped γ-La2S3 were synthesized by the sulfurization of their oxide powders using CS2 gas at 700 ℃. During the sulfurizing reaction process, the cubic Eu3S4 crystals of prior formation acted as the nuclei sites of the γ-La2S3 phase to facilitate the nucleation process. The γ-La2S3 transformation occurred at significantly lower temperature by the combined contributions of low transformation enthalpy and induced multiple nuclei. On the other hand, the doped Eu ions could be inserted into the empty tetrahedr...     

Reactions of Fe-Cr and Ni-Cr alloys in CO/CO2 gases at 850 and 950 °C

A series of Fe-Cr and Ni-Cr solid solution alloys was reacted at 850 and 950 °C in CO/CO₂ gas mixtures in which FeO and NiO were unstable. The compctitive tendencies toward the carburization and oxidation of the chromium solute, as compared to a graphical thermodynamic "metastability" criterion, were tested experimentally. Relatively good agreement was found between predictions and experiments for the occurrence of Cr carburization beneath Cr₂O₃ internal oxides or external scales. The chromium contents required for the transition from internal oxidation of Cr to the formation of Cr₂O₃ external scales in CO/CO₂ gas mixtures were established for Fe-Cr and Ni-Cr alloys. The Cr₂O₃ external scales formed on Fe-Cr alloys were found to be relatively impervious to carbon penetration for short (12-hour) experiments. No carburization was observed in the Ni-Cr alloys, but the only alloys that were predicted to carburize were the ones that formed external scales. Formerly Graduate Student, The Ohio State University     

Crystallography of β2 → γ2′ martensitic transformation in Au-47.5 at.% Cd and Au-47.5 at.% CdCu alloys

The crystallography of the β₂ → γ₂′ stress-induced and thermally-induced martensitic transformations in Au-47.5 at.% Cd and Au-47.at.% CdCu alloys were reexamined by simultaneous measurements was essentially {111}γ₂′ Type I twinning, <121>γ₂′ Type II twining was also found in one case. No difference was found in the crystallography of stress-induced and thermally-induced transformations. Two non-equivalent solutions of the phenomenological crystallographic theory, Type I (+) and (−) solutions, were in excellent agreement with experimental observations. The results for the Type I (+) solution were essentially the same as those previously reported by Lieberman et al., but the agreement between theory and experiment was much better than theirs. Furthermore, (−) solution for Type I twinning and (+) solution for Type II twinning were also found for the first time. Both results show that the phenomenological crystallographic theory applies well in all respects to the present alloy system.     

Interactions in the Al2O3 ― ZrO2 ― La2O3 System at 1250 and 1650°C

Triangulation has been determined for the Al₂O₃ ZrO₂ La₂O₃ system, and 1250 and 1650°C isothermal sections of the phase diagram have been constructed. The LaAlO₃ La₂Zr₂O₇ section is quasibinary, while the LaAlO₃ T-ZrO₂ and La₂O₃ ·11Al₂O₃ T-ZrO₂ ones are partially quasibinary. The triangulation of the ternary system is based on ZrO₂ and a phase containing it. No ternary compounds or regions of ternary solid solutions have been identified.     

Thermodynamic activity of Na2O in Na2O-CaO-SiO2, Na2O-MgO-SiO2, and Na2O-CaO-SiO2-Al2O3 melts at 1400°C

A gas phase equilibration technique was used to generate Na₂O isoactivity data at high-silica compositions in the systems Na₂O-CaO-SiO₂, Na₂O-MgO-SiO₂, and Na₂O-CaO-SiO₂-(10 and 20 wt pct) A1₂O₃ at 1400 °. Loga _{Na 2 O} values referenced to pure liquid Na₂O at 1400 ° as standard state ranged from about ?8.0 to ?7.0. Silica activities were calculated in the Na₂O-CaO-SiO₂ system using the Gibbs-Duhem equation. Richardson’s model for ideal mixing of basic oxides in silica was applied to the Na₂O-CaO-SiO₂ system. The model shows best fit when cationic mixing is assumed to occur on divalent sites. The alkali retention in slags has been described using a defined “sodium capacity”. The temperature variation of alkali retention was estimated, and the resulting sodium capacity was used to evaluate alkali stability in blast furnace slags.     

COREX—learnings and innovations at JSW Steel Limited

Ultra pure ferritic stainless steel is a kind of new stainless steel grade with high quality developed in the mid-twentieth century,it is characterized by ultra low Carbon and Nitrogen content and micro-alloying with Ti, Nb,V,Cu etc.,so it overcomes a lot of use shortcomings of the ordinary ferritic stainless steel,such as intergranular corrosion sensitivity,low ductility and toughness under atmosphere temperature,crack inclining at the weld zone etc.,namely,it has better performance than the ordinary fe...     

The Al2O3-ZrO2-Yb2O3 phase diagram. I. Isothermal sections at 1250 and 1650°C

Isothermal sections at 1250 and 1650 °C of the Al₂O₃-ZrO₂-Yb₂O₃ phase diagram are plotted for the first time. Phase equilibria are established at these temperatures. No ternary compounds and appreciable solid solution regions based on components or binary compounds are found in the ternary system. A partially pseudobinary section Yb₃A₅-F triangulating the Al₂O₃-ZrO₂-Yb₂O system is established.     

Phase Constitution in Mixed Gd_2O_3 and B_4C by Sintering at High Temperature

The phase constitution in mixed Gd2O3 and B4C by sintering in graphite tube furnace at the temperature of 100～1489 ℃ in argon atmosphere was studied by means of XRD and TG-DTA. The results show that the impurity C reacts with O in the B4C at the temperature of 367～458 ℃. When the temperature is 800 ℃, Gd2O3 reacts with B4C, and the reaction products include GdB6, GdB4, GdBO3, GdBC and B. GdBC changes into GdB4 at 1200 ℃. When the temperature is 1470 ℃, GdB6 is obtained by the reaction of GdB4 with elemental B. The content of GdB6 is increasing with the prolonging time.     

π-J/ψ correlation and elliptic flow parameter v2 of charmed mesons at RHIC energy

We study the correlation between the trigger π and the associated J/ψ on near and away sides in Au＋Au collisions at sNN~（1/2） = 200 GeV. In the region of trigger momentum pt 〉 4 GeV/c, the π spectrum is composed of thermal-shower and shower-shower recombi     

AES Analysis of Ce and P Cosegregation at Grain Boundaries

The chemical state of grain boundary cosegregation of Ce and P in Fe-P-Ce alloy system was studied bymeans of Auger Electron Spectroscopy(AES).The Auger peaks of Ce segregated at grain boundaries are foundwithin the range of 60～180 eV.By comparing with the Auger spectra of the Fe-Ce-P intermetallic compound,it is supposed that there is a two-dimensional interfacial phase at grain boundaries with Ce and P cosegregationwhich is similar to the structure of the Fe-Ce-P compound.     

Thermodynamics of Calcium Ferrite Slags at 1200 and 1300°

Abstract

Oxygen isobars and liquidus isotherms of the system CaO-FeO-Fe₂O₃ at 1200 and 1300°C were determined by quenching samples equilibrated with CO₂–CO mixtures, The iron liquidus and the melt coexisting with two solids were carefully examined in terms of their composition as well as the equilibrium oxygen partial pressures, p _o2 . At 1200°C, p _o2 was 10^?7.70 atm when the slag coexisted with magnetite and dicalcium ferrite, At 1300°C, the melt region extends to the CaO–Fe₂O₃ join, where p _o2 was 10^?0.68 atm (air) or higher. Within the range of p _o2 from one order above that at iron saturation to 10^?4 atm, the slag composition, p _o2 , and the temperature T are related by the equation:

log (Fe^{+ + +} /Fe^{+ +} ) ? 0.170logp _O2 + 0.018 (wt% CaO) + 5500/T ? 2.52.

Activities of CaO(s), FeO(l), and Fe₃O₄ (S) in the slag were calculated from the p _o2 data by combining the available thermal data and/or by Gibbs-Duhem equation.

Résumé

Les isobares d'oxygene et les isothermes du liquidus du systeme CaO–FeO–Fe₂O₃ à 1200 et 1300°C ont été déterminées en trempant des échantillons équilibrés avec des mélanges CO₂–CO. Le liquidus du fer et le mélange coexistant avec deux solides ont été soigneusement étudiés en terme de composition et de pression partielle d'oxygène à l'équilibre, p _o2 . A 1200°C, p _o2 était de 10^?7.7 atm quand la scorie était en équilibre avec la magnétite et la ferrite de dicalcium. A 1300°C, le domaine du liquide s'étend jusqu'au joint CaO–Fe₂O₃ où p _o2 valait 10^?0.68 atm (air) ou plus. A l'intérieur du domaine de p _o2 qui s'étend d'un ordre au dessus de celle à la saturation en fer jusqu'à 10^?4 atm, la composition de la scorie, p _o2 et la température T sont reliées par l'équation:

log(Fe³⁺/Fe²⁺) ? 0.170logp _o2 + 0.018(pd %CaO) + 5500/T ? 2.52.

Les activités de CaO(s), FeO(l) et Fe₃O₄(S) dans la scorie ont été calculées a partir des valeurs de p _o2 en combinant les données thermodynamiques disponibles et/ou l'équation de Gibbs-Duhem.     

Lead and Zinc Futures Trading Called for Resumption at SHME

China's lead and zinc industry has changed significantly since 1998 when the lead and zinc futures trading at the Shanghai Metal Exchange (SHME) was eliminated. Industry analysts believe that it's time for the futures trading of lead and zinc to resume at the exchange. The development over the past few years in China's lead and zinc production and consumption has made the country to become a major force in the international lead and zinc market.     

Effect of TSL and PSL in Al^3＋-Doped BaFBr：Eu^2＋ at Difference Synthesis Conditions

Thermal stimulated luminescence (TSL) and photostimulated luminescence (PSL) were used to investigate the luminescent performance of Al^3 -doped BaFBr:Eu^2 in different synthetic conditions. Theory analysis shows that the decay of TSL spectra is different from that of PSL spectra. Theoretical calculation was used to investigate the effects of energy state in Al^3 -doped BaFBr:Eu^2 by different synthetic conditions. The relationship of color center‘s energy and different synthetic conditions is discussed.     

Stability and Heat Resistance of Silicide Coatings on Refractory Metals. Part 2. Stability and Heat Resistance of Silicide Coatings on Tungsten and Molybdenum at 1500-2000°C

The kinetics of diffusion redistribution of phases within the system WSi₂ W on heating tungsten silicide in air in the temperature range 1500-2000°C is studied. The stability and heat resistance of silicide coatings on tungsten is mainly governed by the diffusion of silicon towards the interphase boundaries W W₅Si₃, W₅Si₃ WSi₂, and WSi₂ SiO₂, formation at them of diffusion barriers of lower silicide W₅Si₃, and also a protective SiO₂ film at the outer boundary of the silicide coating. It is established that the transition rate for the higher to the lower tungsten silicide WSi₂ W₅Si₃ is on average four times slower than the transition rate for MoSi₂ Mo₅Si₃. It is shown that an increase in silicon concentration in the WSi₂ surface layer stimulates formation of diffusion barrier compounds at interphase boundaries. This leads to an increase in the stability of the phase composition and heat resistance of a silicide coating on metals. In particular at 1700°C the transition rate for molybdenum silicide on tungsten MoSi₂ (Mo, W)₅Si₃ is about twenty times slower than the transition rate for MoSi₂ Mo₅Si₃, and less by a factor of about eleven than the transition rate for WSi₂ W₅Si₃. Here there is also an increase in the heat resistance of silicide coatings on tungsten and molybdenum. It is shown that the SiO₂ film on tungsten silicide does not lose its protective properties up to 2000°C.     

Effect of TSL and PSL in Al~(3+)-Doped BaFBr∶Eu~(2+) at Difference Synthesis Conditions

BaFBr∶Eu2 +,asphoto gatedholeburningmateri al[1] ,scintillatorcrystallinematerialandX rayimagestoragematerial ,iscalledphotostimulatedluminescence(PSL)material[2 ] .Theimagingplate (IP)madeofthesephosphorsisnowusedwidelyasdisplayoftwo dimen sionalimagescausedbyionizationradiation[3] .Thecommercialapplicationofthesematerialsbe ganin 1983.Becauseofapplicationofthesephospho rs ,theconventionalX rayfilmmaybereplacedbythescreenmadeofPSLphosphors (alsocalledimagingplate ,IP) [4 ] .IPhasnotab…