scholarly journals High-Temperature Oxidation Behavior of Fe–10Cr Steel under Different Atmospheres

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3453
Author(s):  
Lei Cheng ◽  
Bin Sun ◽  
Chongyang Du ◽  
Wei Gao ◽  
Guangming Cao
Keyword(s):  
Water Vapor ◽  
Iron Oxide ◽  
Oxide Layer ◽  
Internal Oxidation ◽  
Oxidation Kinetics ◽  
Oxidation Temperature ◽  
Oxide Scales ◽  
Cross Sectional ◽  
Temperature Oxidation ◽  
Air Atmosphere

Using a thermogravimetric analyzer (TGA), Fe–10Cr steel was oxidized in dry air and in a mixed atmosphere of air and water vapor at a relative humidity of 50% and a temperature of 800–1200 °C for 1 h. The oxidation weight gain curves under the two atmospheres were drawn, the oxidation activation energy was calculated, and the phase and cross-sectional morphology of the iron oxide scales were analyzed and observed by X-ray diffractometry (XRD) and optical microscopy (OM). The results showed that when the oxidation temperature was 800 °C, the spheroidization of Fe–10Cr steel occurred, and the oxidation kinetics conformed to the linear law. At 900–1200 °C, the oxidation kinetics followed a linear law in the preliminary stage and a parabolic law in the middle and late stages. In an air atmosphere, when the oxidation temperature reached 1200 °C, Cr2O3 in the inner oxide layer was partially ruptured. In an atmosphere with a water vapor content of 50%, Cr2O3 at the interface reacted with H2O to generate volatile CrO2(OH)2, resulting in a large consumption of Cr at the interface. At the same time, a large number of voids and microcracks appeared in the iron oxide layer, which accelerated the entry of water molecules into the substrate, as well as the oxidation of Fe–10Cr steel, and caused the iron oxide scales to fall off. Due to the volatilization of Cr2O3 and the conversion from internal oxidation to external oxidation, the internal oxidation zone (IOZ) of Fe–10Cr steel under water vapor atmosphere decreased or even disappeared.

Oxidation of Tantalum Nitride

2013 ◽  
Vol 761 ◽  
pp. 125-129 ◽  
Author(s):  
Kazuya Hamaguchi ◽  
Tomoyuki Tsuchiyama ◽  
Junichi Matsushita
Keyword(s):  
High Temperature ◽  
Oxide Layer ◽  
Human Body ◽  
Body Fluid ◽  
High Temperature Oxidation ◽  
Tantalum Oxide ◽  
Mass Gain ◽  
Tantalum Nitride ◽  
Oxidation Temperature ◽  
Temperature Oxidation

Tantalum (Ta) can be use a suture for operation and implant material in order not to react with body fluid and stimulate a human body. In this study, the stable oxide of a tantalum, tantalum oxide layer produced by oxidation of the tantalum nitride, TaN powders by high temperature oxidation were investigated in order to determine the possibility of its a distributed aid for biomaterial composite such as an artificial root etc. The sample, TaN powder oxidized at high temperature exhibited a steady mass gain with increasing oxidation temperature. Based on the results of the XRD, tantalum oxide, Ta2O5 was detected on the samples. It is considered, the TaN showed a good oxidation film produced by high temperature oxidation.

scholarly journals HIGH TEMPERATURE OXIDATION OF AISI 439 FERRITIC STAINLESS STEEL IN SYNTHETIC AIR ATMOSPHERE

2018 ◽  
Vol 80 (5) ◽  
Author(s):  
Maria de Fatima Salgado ◽  
Jackeline Macêdo de Sousa Santos ◽  
Giscard Eanes Dias Viana ◽  
João Alberto Santos Porto ◽  
Gabriel de Souza Veras Fontinele ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Oxidation Kinetics ◽  
Principal Element ◽  
Oxidation Treatment ◽  
Temperature Oxidation ◽  
X Ray ◽  
Air Atmosphere ◽  
Steel Oxidation ◽  
Kinetics Of

Stainless steels may be used and exposed to aggressive gases at high temperatures. The oxidation behavior of AISI 439 ferritic stainless steel, was investigated by oxidation treatment at 850 ºC and 950 ºC, for 50h in Synthetic Air with 20% O2 atmosphere in a tubular oven and in a thermobalance. The oxidation kinetics of films are determined by measuring the mass versus oxidation time. The microstructure and chemical composition of the oxides were determined by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS).  Chemical analysis by EDS showed that films formed on AISI 439 stainless steel exhibited Cr as the principal element in the oxide film, in proportions to form the chromium oxide (Cr2O3) and the following elements: Mn, Fe, Ti and Si. Based on the oxidation kinetics, it was observed that steel oxidation follows the parabolic behaviour with increase in temperature and it produced the highest oxidation rate at 950 ºC and the lowest rate at 850 ºC. 

XTEM Observation of 4H-SiC (0001) Surfaces Processed by Plasma Assisted Polishing

2012 ◽  
Vol 497 ◽  
pp. 156-159
Author(s):  
Hui Deng ◽  
Kazuya Yamamura
Keyword(s):  
Water Vapor ◽  
Oxide Layer ◽  
Atmospheric Pressure ◽  
Oxidation Potential ◽  
Cross Sectional ◽  
Plasma Irradiation ◽  
Transmission Electron ◽  
Surface Damages ◽  
Pressure Water ◽  
20 Nm

We proposed a novel polishing technique named plasma assisted polishing (PAP) which combined atmospheric pressure water vapor plasma irradiation and soft abrasive polishing. Plasma irradiation oxidized the surface of workpiece and made it easier to be polished. PAP was applied to 4H-SiC, and an automatic flat surface without any scratches was obtained. In this study, we observed the processed surfaces using cross-sectional transmission electron microscopy (XTEM). The XTEM images showed us that an oxide layer with a thickness of about 20 nm was generated after plasma irradiation for 1 h, which proved the strong oxidation potential of OH radical in water vapor plasma. The surfaces processed by PAP were next observed, oxide layer was completely removed and no surface damages were introduced as the crystal structure of 4H-SiC was clearly observed and well ordered.

Oxidation Behavior of Coating Alloy CoCrMoSi and CoCrMoNiSi in Superheated Steam at 800˚C

2021 ◽  
Author(s):  
Bingjie Xiao ◽  
Xiao Huang ◽  
Matthew Yao
Keyword(s):  
Oxide Layer ◽  
Internal Oxidation ◽  
Power Plants ◽  
Oxidation Behavior ◽  
Superheated Steam ◽  
Surface Oxide ◽  
Laves Phase ◽  
Working Fluid ◽  
Protective Oxide ◽  
Cross Sectional

Abstract As steam power plants continue to move towards higher operating temperatures in order to improve efficiency, materials exposed to the working fluid are subjected to accelerated degradations in the forms of surface oxidation and reduced mechanical properties. In this study, the oxidation behavior of two cobalt base alloys, CoCrMoSi (T14) and CoCrNiMoSi (T19), was evaluated in superheated steam (SHS, 0.1MPa) at 800 °C for up to 500 hours. After the exposure, both T14 and T19 alloys experienced weight gain caused by oxidation. Visual observation and SEM surface analysis revealed that T19 had greater extent of surface oxide spallation than that seen on T14. From the cross-sectional evaluation, however, a thin, adherent oxide layer was found to have formed on T19. T14 in fact had suffered from excessive internal oxidation and the surface oxide was uneven. Based on the results obtained so far, it is believed that the finer Laves phase combined with greater amount of Cr in alloy T19 have enabled the formation of a protective oxide layer and thus reduced the extent of internal oxidation. Due to the extensive oxidation ingress along the large Laves phase, it is concluded that T14 is not suitable for applications in SHS at 800 °C.

Kinetic and Thermodynamic Aspects of High-Temperature Oxidation of Selected Ti-Based Alloys

2007 ◽  
Vol 263 ◽  
pp. 123-128 ◽  
Author(s):  
Dalibor Vojtěch ◽  
M. Mort'aniková ◽  
Pavel Novák
Keyword(s):  
High Temperature ◽  
Oxidation Kinetics ◽  
High Temperature Oxidation ◽  
Cyclic Oxidation ◽  
Penetration Rate ◽  
Metallic Substrate ◽  
Synergic Effect ◽  
Oxide Scales ◽  
Temperature Oxidation ◽  
Barrier Effects

In the presented work, high-temperature cyclic oxidation of pure Ti, Ti-7.8wt.%Si, Ti- 45.6wt.%Al and Ti-11.7wt.%Al-7.2wt.%Si alloys at 750 – 1050 °C in air were studied. It was found that both Si and Al strongly reduce the oxidation rate of titanium, mainly up to 850 °C. They incorporate into the oxide scales and reduce penetration rate of oxygen towards the metallic substrate. Mechanism of the barrier effects of the elements is discussed with respect to their distribution in alloys. It was observed by comparison of Al-containing and Si-containing alloys, that the influence of Si on the oxidation kinetics is significantly stronger. It can be supposed that a synergic effect of silicon and nitrogen is a reason for this behavior.

scholarly journals Interfaces in Oxides Formed on NiAlCr Doped with Y, Hf, Ti, and B

2017 ◽  
Vol 23 (2) ◽  
pp. 396-403 ◽  
Author(s):  
Torben Boll ◽  
Kinga A. Unocic ◽  
Bruce A. Pint ◽  
Krystyna Stiller
Keyword(s):  
Oxide Layer ◽  
Atom Probe Tomography ◽  
Outer Region ◽  
Atom Probe ◽  
Alloying Elements ◽  
Oxide Scales ◽  
Protective Oxide ◽  
Temperature Oxidation ◽  
Small Grains ◽  
Oxide Matrix

AbstractThis study applies atom probe tomography (APT) to analyze the oxide scales formed on model NiAlCr alloys doped with Hf, Y, Ti, and B. Due to its ability to measure small amounts of alloying elements in the oxide matrix and its ability to quantify segregation, the technique offers a possibility for detailed studies of the dopant’s fate during high-temperature oxidation. Three model NiAlCr alloys with different additions of Hf, Y, Ti, and B were prepared and oxidized in O2 at 1,100°C for 100 h. All specimens showed an outer region consisting of different spinel oxides with relatively small grains and the protective Al2O3-oxide layer below. APT analyses focused mainly on this protective oxide layer. In all the investigated samples segregation of both Hf and Y to the oxide grain boundaries was observed and quantified. Neither B nor Ti were observed in the alumina grains or at the analyzed interfaces. The processes of formation of oxide scales and segregation of the alloying elements are discussed. The experimental challenges of the oxide analyses by APT are also addressed.

Effect of Mo on the Oxidation Behavior of NiTiAl Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 1481-1484
Author(s):  
Jian Xu ◽  
Xin Qing Zhao ◽  
Sheng Kai Gong
Keyword(s):  
High Temperature ◽  
Oxide Scale ◽  
Oxide Layer ◽  
Oxygen Diffusion ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Oxide Scales ◽  
Cross Sectional ◽  
Oxidation Layer ◽  
Poor Adhesion

The effect of Mo on the oxidation behavior of TiNiAl at 1073K has been investigated. It is found that 1at.% Mo addition can increase the diffusion of Al in the alloys and promote the formation of dense and continuous Al-rich oxide layer. Therefore the oxygen diffusion can be effectively impeded and the oxidation behavior of TiNiAl is improved. The observation of the cross-sectional oxidation layer showed that beneath the top oxide scale a Mo-rich oxide layer formed. Because the oxide of Mo is volatile at high temperature, voids formed in the oxide scales during the oxidation process. 3at.% Mo addition could cause cracks between the oxide scale and the substrate, resulting in poor adhesion of the oxide scale to the substrate.

scholarly journals High-Temperature Oxidation of a High Silicon SiMo Spheroidal Cast Iron in Air with In Situ Change in H2O Content

2018 ◽  
Vol 925 ◽  
pp. 353-360 ◽  
Author(s):  
André Ebel ◽  
Serge Yapi Brou ◽  
Benoît Malard ◽  
Jacques Lacaze ◽  
Daniel Monceau ◽  
...  
Keyword(s):  
Cast Iron ◽  
Water Vapor ◽  
Oxidation Kinetics ◽  
Nodular Cast Iron ◽  
Isothermal Oxidation ◽  
Effect Of Temperature ◽  
Oxide Interface ◽  
Humid Air ◽  
Temperature Oxidation

Exhaust manifolds for diesel engines are made of high-Si ferritic nodular cast irons. It is experimentally well established that their oxidation kinetics are highly sensitive to the presence of water vapor, though the mechanism for such an effect is still controversial. In the present work, isothermal oxidation tests were performed on a SiMo nodular cast iron at 700°C and 800°C in dry and humid air for 25 and 50 hours. Other samples were oxidized for 50 h with in-situ change in H2O content after 25 h, switching from dry air to humid air or the other way round. Samples were then analyzed using XRD, SEM-EDS and Raman spectroscopy. Thermogravimetric records clearly showed the effect of temperature and environment on oxidation and decarburization. The kinetics of these phenomena depends on silica formation at the metal-oxide interface. At both temperatures, water vapor was seen to promote internal oxidation of Si instead of its external oxidation. This leads to higher oxidation kinetics at 700°C and higher decarburization kinetics at 800°C.

scholarly journals Effects of Cr, W, and Mo on the High Temperature Oxidation of Ni-Based Superalloys

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2934 ◽  
Author(s):  
Si-Jun Park ◽  
Seong-Moon Seo ◽  
Young-Soo Yoo ◽  
Hi-Won Jeong ◽  
HeeJin Jang
Keyword(s):  
Oxide Layer ◽  
Oxidation Rate ◽  
Cyclic Oxidation ◽  
Mass Gain ◽  
Cross Sectional ◽  
Temperature Oxidation ◽  
Sectional Structure ◽  
And Diffusion ◽  
Valence Number ◽  
Al Oxide

The oxidation behavior of Ni–9.5Co–(8~12)Cr–(2.5~5.5)Mo–(4~8)W–3Al–5Ti–3Ta–0.1C–0.01B alloys was investigated at 850 °C and 1000 °C The mass change, the phase of oxides, and the cross-sectional structure of specimens were analyzed after cyclic oxidation tests. The oxide scale was composed mainly of Cr2O3 and NiCr2O4, but NiO, TiO2, and CrTaO4 were also found. Al2O3 was formed beneath the Cr oxide layer. The Cr oxide layer and internal Al oxide acted as barriers to oxidation at 850 °C, while Al oxide was predominantly protective at 1000 °C. Cr increased the mass gain after oxidation test at both temperatures. Mo increased the oxidation rate at 850 °C but decreased the oxidation rate at 1000 °C. W slightly increased the mass gain at 850 °C but did not produce a significant effect at 1000 °C. The effects of Cr, Mo, W, and the temperature were discussed as well as the volatilization of oxides, the valence number of elements, and diffusion retardation.

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