Physical Properties of Iron-Oxide Scales on Si-Containing Steels at High Temperature

Takeda, Mayu; Onishi, Takashi; Nakakubo, Shouhei; Fujimoto, Shinji

doi:10.2320/matertrans.m2009097

Cited by 228 publications

(94 citation statements)

References 9 publications

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“…Fe 2 O 3 →Fe 3 O 4 →FeO→Fe Effects of varying temperature on thermal conductivity of metallic iron and iron-oxides can be seen from the Figure 5 [17,18] , and it may be deduced as follows: ① Different iron-oxides have different thermal conductivity. ②The thermal conductivity of iron-oxides decline over time with increasing temperature.…”

Section: Fig 4 Phase Equilibrium Diagram Of Iron Oxides Reduced By Coalmentioning

confidence: 99%

“…Figure 6 shows the △G θ of the iron oxides and ilmenite reduced by C with increasing temperature. Figure 7 shows the Phase equilibrium diagram of iron oxides and ilmenite reduced by CO. 190900-161T 209000-168T 213000-171T 252600-177T 185000-155T 182500-127T 304600-173T Table 9 Thermodynamics on reduction of ilmenite by CO [18] Numbers Reaction Fig.6 Gθ of the iron oxides and ilmenite reduced by C with increase of temperature Fig.7 Phase equilibrium diagram of iron oxides and ilmenite reduced by CO In the temperature range of 1000˚C-1150˚C，△G θ of reaction equation (6) to (12) are greater than △ zero, thus, theoretically, these reactions were not be happened. At the same temperature range, G θ of reaction equation (2), (3), (4), (13) and (14) are less than zero, so, theoretically, these reactions should happened.…”

Section: Fig5 Effects Of Varying Temperature On Thermal Conductivitymentioning

confidence: 99%

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Investigation on Thermal Conductivity of Vanadium Titano-magnetite Concentrate Carbon-containing Pellets in Direct Reduction

Yang¹,

Pan²,

Ma³

et al. 2016

Proceedings of the 2016 International Forum on Energy, Environment and Sustainable Development

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Abstract. In this paper, internal heat transfer process of vanadium titano-magnetite concentrate carbon-containing pellets was analyzed in direct reduction at different temperatures. The thermal conductivity of vanadium-titanium magnetite carbon-containing pellets at different temperatures were determined under the condition of optimal process parameters taken from previous works. XRD was used to examine the phases of various products at different temperatures in direct reduction. Experimental results revealed that change in thermal conductivity of vanadium titano-magnetite concentrate was roughly the same as the common iron ore concentrate. The measured values of the thermal conductivity were consistent with the changing trend of the theoretical thermal conductivity. The thermal conductivity change within 0.06~0.12 W/m˚C in the temperature range of 300˚C-1150˚C. The thermal conductivity increase very rapidly when temperature exceeds 1000˚C． Vanadium titano-magnetite is an important ore, which contains diverse rare metals, such as vanadium, titanium, and iron and so on. Therefore, it is essential to know, how to make use of these ore. Traditionally, blast furnace was used to smelt vanadium titano-magnetite. Recently, the rapid development of direct reduction process formed enormous new direct reduction process, such as Fastmet, Krupp-Codir, and Comet and so on, because the flaw of blast furnace affects both economical and environment aspects [1][2][3][4][5] . Vanadium titano-magnetite concentrate is used to smelt hot metal and titanium slag. Vanadium titano-magnetite concentrate carbon-containing pellet for iron making is one of the new processes for smelting vanadium titano-magnetite concentrate. So far, a number of works for the study of vanadium titano-magnetite concentrate carbon-containing pellets for iron making were conducted by researchers all over the world [6][7][8] . It is said that vanadium titano-magnetite in China is different from other countries, and it is extremely hard to deal with this kind ore [9,10] . According to enormous investigation on vanadium titano-magnetite concentrate, carbon-containing pellets were studied by numerous researchers in china, and it was found that almost all of them focused on investigation of direct reduction of the vanadium tiano-magnetite concentrate [11][12][13] . However, the investigation on thermal conductivity of vanadium titano-magnetite concentrate carbon-containing was not conducted by them. And it is extremely important to understand the internal heat transfer of pellets with the variation of external circumstances. Therefore, it is very important to improve parameters of process in valid time.The heat transfer performance of vanadium titano-magnetite carbon-containing pellets in direct reduction is represented by its thermal conductivity. So, in this paper, internal heat transfer process of vanadium titano-magnetite carbon-containing pellets was analyzed, and experiments for determining thermal conductivity of vanadium-titanium magnetite carbon-containing...

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Section: Fig 4 Phase Equilibrium Diagram Of Iron Oxides Reduced By Coalmentioning

confidence: 99%

Section: Fig5 Effects Of Varying Temperature On Thermal Conductivitymentioning

confidence: 99%

Investigation on Thermal Conductivity of Vanadium Titano-magnetite Concentrate Carbon-containing Pellets in Direct Reduction

Yang¹,

Pan²,

Ma³

et al. 2016

Proceedings of the 2016 International Forum on Energy, Environment and Sustainable Development

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“…A) Plot of Gibbs free energy versus P/B ratio at room temperature for selected oxides formed on metals. B) A plot of Gibbs free energy versus P/B ratio at 1000°C [28][29][30][31][32]. Table 1 Comparing molybdenum isotopes [6].…”

Section: Case Study: Materials Selection Criteria For Accident-toleramentioning

confidence: 99%

Materials selection for nuclear applications: Challenges and opportunities

et al. 2018

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a b s t r a c t a r t i c l e i n f oWe discuss the challenge of selecting materials for nuclear applications and outline the need for comprehensive databases to assist scientists and engineers in choosing materials that meet interdependent physical, chemical, and nuclear criteria. In conventional engineering, chemical and physical properties and the electronic structure of materials are typically the primary considerations; nuclear applications must also consider the nuclear physics characteristics of a material. Development of databases that correlate physical, chemical, and nuclear properties would accelerate and facilitate innovations in nuclear design.

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“…The oxide scale composed of Fe 3 O 4 that was included in the FEA simulation has a thickness of 0.5 mm and its material properties were taken from 11,12 .…”

Section: Tube Temperature Distributionmentioning

confidence: 99%

Influence of steam-side oxide scales on the creep life of a boiler superheater tube

Naď¹,

Létal²,

Buzík³

et al. 2018

Mater. Tehnol.

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Creep life is a limiting factor in the case of boiler tubes operating above the creep temperature and, for a given material, it is generally determined by the actual operating temperature and stress. Standard approaches to the calculation of a tube creep life mainly take into account the stress caused by pressure loading and the mean temperature in the tube wall. However, the estimation of the temperature and stress may be difficult for water-tube boilers because oxide scales tend to form on the inner surfaces of the tubes, exposed to steam and indirectly affecting the resulting creep life. As the scales increase the thermal resistance of a tube wall and, consequently, the wall temperature, the creep life is reduced. Moreover, the presence of oxide scales leads to a higher hydraulic resistance of a tube, which can cause further increase in the temperature in some tubes of the bundle if the oxide-scale growth rate is not uniform. Additionally, the elements increasing the creep strength may leach out of the surface should the scales be porous, thus inducing an even more pronounced decrease in the creep life. This paper investigates the effects of oxide scales on the creep life of boiler tubes in a cross flow. Thermal and stress conditions in the tubes are thoroughly investigated, using analytical as well as numerical approaches. Keywords: oxide scale, creep, superheater, tube, CFD, FEA Doba trajanja cevi super izmenjevalnikov toplote je omejena zaradi lezenja materiala pri visokih temperaturah obratovanja. Kriti~na temperatura lezenja je odvisna od napetosti, ki nastopajo med obratovanjem izmenjevalnika toplote. Standardni pristop za izra~un dobe trajanja zaradi lezenja materiala temelji na upo{tevanju napetosti, ki jih povzro~a delovni tlak prenasi~ene pare in povpre~ne temperature na stenah cevi. Vendar je temperaturo in napetosti te`ko oceniti, ker se na notranjih stenah cevi, ki so izpostavljene pari, nalaga oksidna plast oz. {kaja, kar neposredno vpliva na njihovo dobo trajanja. [kaja na stenah cevi zmanj{a toplotno prevodnost in s tem poslab{a prenos toplote in posledi~no spremeni temperaturo sten cevi, kar zmanj{a njihovo dobo trajanja. Poleg tega {kaja pove~a hidravli~no upornost cevi, ki nadalje povi{a temperaturo v nekaterih snopih cevi,~e rast {kaje ni enkomerna. Dodatno se lahko iz sten cevi zaradi {kaje izlu`ijo legirni elementi, ki pove~ujejo odpornost materiala proti lezenju. To lahko povzro~i poroznost oksidne plasti na ceveh, kar {e dodatno zmanj{a njihovo dobo trajanja. V~lanku avtorji obravnavajo vpliv oksidne {kaje na`ivljensko dobo cevi izmenjevalnikov toplote v toku ogrevalnih plinov pre~no na pretok pare. Analizirali so termi~ne in napetostne razmere v ceveh izmenjevalnika toplote z analiti~nimi in numeri~nimi metodami. Klju~ne besede: {kaja (oksidna plast), lezenje, super izmenjevalnik toplote, cevi izmenjevalnika, ra~unalni{ka dinamika fluidov (CFD), analiza z metodo kon~nih elementov (FEA)

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Physical Properties of Iron-Oxide Scales on Si-Containing Steels at High Temperature

Cited by 228 publications

References 9 publications

Investigation on Thermal Conductivity of Vanadium Titano-magnetite Concentrate Carbon-containing Pellets in Direct Reduction

Investigation on Thermal Conductivity of Vanadium Titano-magnetite Concentrate Carbon-containing Pellets in Direct Reduction

Materials selection for nuclear applications: Challenges and opportunities

Influence of steam-side oxide scales on the creep life of a boiler superheater tube

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