Oxidation Behavior of T91 Steel in Water Vapor Atmosphere at 750°C

2014 ◽  
Vol 941-944 ◽  
pp. 193-197
Author(s):  
Guang Ming Liu ◽  
Cai Fu Wang ◽  
Gang Liu ◽  
Zhi Lei Liu ◽  
Ji Hong Tian
Keyword(s):  
Water Vapor ◽  
Oxidation Behavior ◽  
Early Stage ◽  
Oxidation Mechanism ◽  
Sample Surface ◽  
Mass Gain ◽  
Initial Stage ◽  
Oxidation Stage ◽  
Water Vapor Atmosphere ◽  
Gain Stage

The oxidation behavior of T91 steel in Ar-10%H2O atmosphere at 750°C was investigated. The morphology, microstructures and composition of oxide scales were examined by SEM/EDS and XRD. The results showed that the oxidation kinetics followed logarithmic law in the initial stage and parabolic law in the latter stage. At the early stage Cr-rich oxide film formed on the sample surface, which led to slow mass gain stage. In the latter oxidation stage, Fe ions diffused outward, resulting in fast oxidation stage. The oxidation scales consisted of two layers, an porous Fe2O3outer layer and an denser Cr-rich inner layer. Some cracks were formed between the inner and outer layers. The oxidation mechanism of T91 in water-vapor atmosphere at high temperature was discussed in brief.

Evolution of Al2O3 Scale Formed on Ni-Al-Pt Alloy in Atmospheres Containing Water Vapor

2011 ◽  
Vol 696 ◽  
pp. 132-137 ◽  
Author(s):  
Mitsunari Auchi ◽  
Shigenari Hayashi ◽  
Toshio Narita ◽  
Shigeharu Ukai
Keyword(s):  
Water Vapor ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Mass Gain ◽  
Oxidation Time ◽  
Dry Air ◽  
Initial Stage ◽  
Oxidation Stage ◽  
Pt Alloy ◽  
Complete Transformation

High temperature cyclic oxidation behavior of γ'-base Ni-25Al-10Pt (in at.%) alloy was investigated at 1000°C in air with and without 30vol.%H2O. The oxidation mass gain during the initial stage of oxidation was similar in both atmospheres, but the oxidation rate in air+H2O was lower in the longer steady-state oxidation stage. Metastable Al2O3, which formed during the initial stage of oxidation, transformed completely after about 100hr of oxidation in dry air. The transformation to α-Al2O3also occurred in air+H2O, but complete transformation to α-Al2O3was not observed during the oxidation time in the present study. θ-Al2O3grains remained for longer on the α-Al2O3layer in air+H2O and became significantly coarser with oxidation time. The present results indicate that water vapor delays the metastable to α-Al2O3phase transformation, and decreases the growth rate of α-Al2O3.

Oxidation Behavior of SiC/TiAl Composite Material

2007 ◽  
Vol 127 ◽  
pp. 109-114 ◽  
Author(s):  
Keizo Hashimoto ◽  
Yoko Fujino ◽  
Tomoyuki Kuramata
Keyword(s):  
Composite Material ◽  
Cross Sections ◽  
Oxidation Behavior ◽  
Oxidation Mechanism ◽  
Mass Gain ◽  
Optical Microscope ◽  
Fiber Reinforced ◽  
Promising Candidate ◽  
Specific Strength ◽  
Sic Fiber

SiC fiber reinforced intermetallic is one of the promising candidate material for the next generation space plane, because of its excellent high temperature specific strength and elastic modulus. Oxidation behavior of the fiber-reinforced intermetallic (FRIM) is one of the most important properties for the practical use in the severe environment. Recently fabrication process of CVD-SiC fiber reinforced γ-TiAl matrix composite has been developed. Oxidation behavior of SiC/γ-TiAl and γ-TiAl was studied. Cyclic oxidation experiments were executed at 900°C under the dry airflow for 200 hours. Mass gains of the specimens were measured. The cross sections of specimen were observed by optical microscope. Mass gain of the SiC/γ-TiAl composite material was two times larger than that of γ-TiAl. Surface of the SiC/γ-TiAl composite was covered with a comparatively thick oxide scale. Furthermore, formation of the oxide at the vicinity of interface between SiC fiber and γ-TiAl matrix was observed. Oxidation mechanism of SiC/γ-TiAl composite was discussed.

Cyclic oxidation behavior of Fe-9Cr-1Mo steel in water vapor atmosphere

2009 ◽  
Vol 16 (4) ◽  
pp. 535-540 ◽  
Author(s):  
Du-qing Zhang ◽  
Guang-ming Liu ◽  
Guo-qun Zhao ◽  
Yan-jin Guan
Keyword(s):  
Water Vapor ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Water Vapor Atmosphere

High-Temperature Oxidation Behavior of Fe-Si-Ce Alloys

2016 ◽  
Vol 35 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Yong Su ◽  
Shunke Zhang ◽  
Guangyan Fu ◽  
Qun Liu ◽  
Yuanze Tang
Keyword(s):  
Grain Size ◽  
Oxidation Behavior ◽  
Oxidation Mechanism ◽  
Mass Gain ◽  
Optical Microscope ◽  
Oxide Scales ◽  
Temperature Oxidation ◽  
Beneficial Effects ◽  
Negative Effect ◽  
High Temperature Oxidation Behavior

AbstractThe oxidation behavior of Fe-Si-Ce alloys with different Ce content at 1,173 and 1,273 K has been studied by means of optical microscope (OM), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscope (SEM). Results show that the Ce addition refines the grain size of Fe-Si alloys, and correspondingly the grain size of the oxides decreases, which increases the grain boundary concentration and promotes the short-path diffusion of the alloying elements and oxygen. During oxidation, the positive effect of the grain refinement on the oxidation behavior of the alloy is more obvious than negative effect, so the Ce addition improves the oxidation resistances of the Fe-3Si alloys. Compared to Fe-3Si-0.5Ce alloy, Fe-3Si-5.0Ce alloy has the larger mass gain for the preferential oxidation of the excessive content of Ce exceeding its beneficial effects. The rare earth Ce changes the oxidation mechanism of Fe-Si alloys. Oxygen penetrates the oxide scales and reacts preferentially with Ce-rich phases, which results in the pinning effect and improves the adhesion of the oxide scales.

Effect of Pack Cementation Temperature on Oxidation Behavior of NiCoCrAl Coated Layer

2015 ◽  
Vol 1112 ◽  
pp. 353-358 ◽  
Author(s):  
Eni Sugiarti ◽  
Kemas A. Zaini ◽  
Yong Ming Wang ◽  
Naoyuki Hashimoto ◽  
Somei Ohnuki ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Oxidation Mechanism ◽  
Intermediate Stage ◽  
Pack Cementation ◽  
Coated Sample ◽  
Initial Oxidation ◽  
Oxidation Stage ◽  
And Diffusion

The oxidation behavior of NiCoCrAl coatings deposited on carbon steel was evaluated at 800 °C for 100 h in atmospheric air. The effect of different coating process on the oxidation of carbon steel was studied. The oxidation mechanism was discussed based on oxidation rate, formation of oxide scale, and microstructure of the coated sample. The oxidation rate significantly increased owing to the formation of metastable Al2O3 during initial oxidation stage. The oxidation rate decreased due to the transformation from d, q to a-Al2O3 from the intermediate stage up to final stage of 100 h oxidation. The effect of pack cementation temperature contributed to the thickness and diffusion of coated elements. The experimental results showed that sample developed at 800 °C exhibited better oxidation resistance than sample developed at 900 and 1000 °C.

The Effect of Water Vapor on Thermal Oxide Grown on Inconel 690

2014 ◽  
Vol 670-671 ◽  
pp. 74-81 ◽  
Author(s):  
Anusara Srisrual ◽  
Jean Pierre Petit ◽  
Yves Wouters ◽  
Alain Galerie
Keyword(s):  
Water Vapor ◽  
Oxide Film ◽  
Oxidation Mechanism ◽  
Oxide Morphology ◽  
Thermal Oxide ◽  
Inconel 690 ◽  
Influence Of Water ◽  
Water Vapor Atmosphere ◽  
The One ◽  
Effect Of Surface

Nickel based alloys are well considered materials for uses in high temperature applications. Inconel 690 is the one of outstanding candidate with the superior properties. The aim of this report is to present the influence of water vapor on thermal oxide film. Inconel 690 was oxidized under dry and wet atmosphere at 900°C for 30 hours. The oxidized samples were characterized by SEM/EDS, Raman spectroscopy, and photoelectrochemical technique. The results illustrated that typical thermal oxides grown on alloy composed of Cr, Fe, Ni, in forms of Cr2O3, NiFe2O4, NiCr2O4, Fe2O3, Fe2–xCrxO3and/or solid solution of NiFe2O4−NiCr2O4. The presence of water vapor affected on oxide morphology, its stoichiometry, and also semiconducting behavior. Oxide film grown under water vapor atmosphere show the homogeneity. Water vapor promoted the predominated oxide of Cr2O3with n−type semiconducting. Moreover the characterization revealed the effect of surface orientation on oxidation mechanism in case of sample which oxidized in oxygen atmosphere.

Anisotropy of interfacial defects in the initial stage of MOVPE GaAs growth On Si

1990 ◽  
Vol 48 (4) ◽  
pp. 592-593
Author(s):  
C. Vannuffel ◽  
C. Schiller ◽  
J. P. Chevalier
Keyword(s):  
Early Stage ◽  
Threading Dislocations ◽  
Mbe Growth ◽  
Detailed Mechanism ◽  
Si Substrates ◽  
Initial Stage ◽  
Interfacial Defects ◽  
Interfacial Dislocations ◽  
Step Growth ◽  
Essential Problem

Recently, interest has focused on the epitaxy of GaAs on Si as a promising material for electronic applications, potentially for integration of optoelectronic devices on silicon wafers. The essential problem concerns the 4% misfit between the two materials, and this must be accommodated by a network of interfacial dislocations with the lowest number of threading dislocations. It is thus important to understand the detailed mechanism of the formation of this network, in order to eventually reduce the dislocation density at the top of the layers.MOVPE growth is carried out on slightly misoriented, (3.5°) from (001) towards , Si substrates. Here we report on the effect of this misorientation on the interfacial defects, at a very early stage of growth. Only the first stage, of the well-known two step growth process, is thus considered. Previously, we showed that full substrate coverage occured for GaAs thicknesses of 5 nm in contrast to MBE growth, where substantially greater thicknesses are required.

scholarly journals In-situ NiO nanostructure growth during heating in water vapor atmosphere

2021 ◽  
Vol 27 (S1) ◽  
pp. 2102-2103
Author(s):  
Boyi Qu ◽  
Klaus van Benthem
Keyword(s):  
Water Vapor ◽  
Water Vapor Atmosphere

scholarly journals Oxidation Behavior of Maraging 300 Alloy Exposed to Nitrogen/Water Vapor Atmosphere at 500 °C

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1021
Author(s):  
Mauro Andres Cerra Florez ◽  
Gemma Fargas Ribas ◽  
Jorge Luiz Cardoso ◽  
Antonio Manuel Mateo García ◽  
Joan Josep Roa Rovira ◽  
...  
Keyword(s):  
Water Vapor ◽  
Oxide Layer ◽  
Magnetic Layer ◽  
Adhesive Force ◽  
Point Of View ◽  
Maraging Steels ◽  
Cobalt Spinel ◽  
Water Vapor Atmosphere ◽  
Iron Nickel ◽  
Ferrite Cobalt

Aging heat treatments in maraging steels are fundamental to achieve the excellent mechanical properties required in several industries, i.e., nuclear, automotive, etc. In this research, samples of maraging 300 alloy were aged using a novel procedure that combines different steps with two atmospheres (nitrogen and water vapor) for several hours. The oxidized surface layer was chemical, microstructural and micromechanically characterized. Due to the thermodynamic and kinetic conditions, these gases reacted and change the surface chemistry of this steel producing a thin iron-based oxide layer of a homogeneous thickness of around 500 nm. Within the aforementioned information, porosity and other microstructural defects showed a non-homogeneous oxide, mainly constituted by magnetite, nickel ferrite, cobalt ferrite, and a small amount of hematite in the more external parts of the oxide layer. In this sense, from a chemical point of view, the heat treatment under specific atmosphere allows to induce a thin magnetic layer in a mixture of iron, nickel, and cobalt spinel ferrites. On the other hand, the oxide layer presents an adhesive force 99 mN value that shows the capability for being used for tribological applications under sliding contact tests.

Evaluation of Li mass loss from Li2TiO3 with excess Li pebbles in water vapor atmosphere

2018 ◽  
Vol 136 ◽  
pp. 362-366 ◽  
Author(s):  
Kazunari Katayama ◽  
Haruaki Sakagawa ◽  
Tsuyoshi Hoshino ◽  
Satoshi Fukada
Keyword(s):  
Water Vapor ◽  
Mass Loss ◽  
Water Vapor Atmosphere
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