scholarly journals Influence of Water Vapor and Temperature on the Oxide Scale Growth and Alpha-Case Formation in Ti-6Al-4V Alloy

2021 ◽  
Author(s):  
B. Öztürk ◽  
L. Mengis ◽  
D. Dickes ◽  
U. Glatzel ◽  
M. C. Galetz
Keyword(s):  
Water Vapor ◽  
Oxide Scale ◽  
Oxidation Behavior ◽  
Subsurface Layer ◽  
Oxygen Enrichment ◽  
Oxide Morphology ◽  
Dry Air ◽  
Subsurface Zone ◽  
Alpha Case ◽  
Influence Of Water

AbstractThe Ti-6Al-4V alloy is extensively used in aerospace, automotive and biomaterial applications. In the aerospace industry, the service temperature of Ti-6Al-4V is currently limited to 350 °C due to its insufficient oxidation resistance. Oxidation at higher temperatures causes the formation of a fast-growing oxide scale and an oxygen-enriched subsurface layer, which is known as the “alpha-case.” Additionally, the effect of water vapor on the oxidation behavior is critical. In the present study, the oxidation behavior of Ti-6Al-4V in dry air and air containing 10 vol.% H2O at 500, 600 and 700 °C for up to 500 h has been investigated. The main focus of this study is the examination of the different oxide scale morphologies along with the oxygen enrichment in the subsurface zone. It has been observed that spallation of the oxide scale is more severe in a water vapor-containing environment. In dry air, the oxide morphology shows the typical layered TiO2/Al2O3 structure after exposure at 700 °C for 300 h, while Al2O3 precipitates are present in the outermost part of the TiO2 scale when oxidized in wet air. This indicates that the solubility and diffusivity of Al3+ ions in TiO2 are influenced by water vapor. In addition, the extent of oxygen enrichment in the subsurface zone (alpha-case) as a function of temperature and time is determined by nanoindentation profiles. It was shown that in contrast to the scale formation, the alpha-case thickness is not affected by the presence of water vapor in the atmosphere.

Influence of water vapor on the oxidation behavior of aluminized coatings under low oxygen partial pressure

2011 ◽  
Vol 53 (12) ◽  
pp. 3978-3982 ◽  
Author(s):  
Linlin Xing ◽  
Yanjun Zheng ◽  
Lishan Cui ◽  
Maohu Sun ◽  
Mingzeng Shao ◽  
...  
Keyword(s):  
Water Vapor ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxidation Behavior ◽  
Low Oxygen ◽  
Influence Of Water

scholarly journals Scale Formation on HSLA Steel during Continuous Casting Part I: The Effect of Temperature–Time on Oxidation Kinetics

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1243 ◽  
Author(s):  
Rosa Maria Pineda Huitron ◽  
Pavel Ernesto Ramírez López ◽  
Esa Vuorinen ◽  
Pooria Nazen Jalali ◽  
Leonardo Pelcastre ◽  
...  
Keyword(s):  
Water Vapor ◽  
Continuous Casting ◽  
Oxide Scale ◽  
Surface Quality ◽  
Hsla Steel ◽  
Effect Of Temperature ◽  
Dry Air ◽  
Oxidation Rates ◽  
Steel Slabs

The findings in this work enhance the understanding of oxidation mechanisms and scale growth at high temperatures of a high strength low alloy (HSLA) steel for improving surface quality during continuous casting. The oxidation phenomenon was investigated under dry air and water vapor atmospheres by heating specimens at 1000, 1100, and 1200 °C at different holding times. Temperature and time had great effects on the kinetics, where faster (i.e., parabolic) oxidation rates were present under water vapor when compared with the dry air condition. Temperature strongly influenced the number of defects, such as pores, voids, gaps and micro-cracks, formed in the oxide scale. A phase analysis confirmed the presence of FeO as the first phase formed at the steel surface, Fe3O4 as the middle and thicker phase, and Fe2O3 as the last phase formed in the oxide/air interface. The micromechanics of the oxides demonstrated that a combination of phases with high (wüstite) and low plasticity (magnetite and hematite) could also have been the reason for the uneven cooling during Continuous Casting (CC) that resulted in the undesired surface quality of the steel slabs. This work gives a good look at the oxide scale effect on the surface quality of steel slabs through an understanding the kinetics during oxidation.

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.

scholarly journals Wet Oxidation Behavior of Near-Stoichiometric SiC Fibres in the Simulated Aeroengine Circumstance

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Liang Li ◽  
Ke Jian ◽  
Xianhe Mao ◽  
Yifei Wang
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Residual Strength ◽  
Oxidation Behavior ◽  
Annealing Temperature ◽  
Wet Oxidation ◽  
Silica Layer ◽  
Oxide Layer Thickness ◽  
Dry Air ◽  
Influence Of Water

The precursor-derived and near-stoichiometric SiC fibres (KD-S) were exposed at 1000–1500°C for 1 h in the simulated aeroengine circumstance of PH2O:O2:Ar = 14:8:78 KPa with the gas rate of 200 ml/min. The results indicated that the oxidized KD-S fibres were covered by silica layer. The oxygen content, grain size of silica, and oxide layer thickness increased, whereas the tensile strength decreased with rising annealing temperature. KD-S fibres treated under simulated aeroengine circumstances showed larger SiO2 grain size, thicker silica layer, and better residual strength than those annealed in dry air. The steam could accelerate the oxidation on KD-S fibres by reducing the active energy. The influence of water vapour on the oxidation behavior of KD-S SiC fibres was investigated and discussed as well.

Influence of water vapor on the oxidation behavior of Ti3AlC2 and Ti2AlC

2008 ◽  
Vol 58 (1) ◽  
pp. 29-32 ◽  
Author(s):  
Z.J. Lin ◽  
M.S. Li ◽  
J.Y. Wang ◽  
Y.C. Zhou
Keyword(s):  
Water Vapor ◽  
Oxidation Behavior ◽  
Influence Of Water

The growth mechanism of oxide scale with Pt on NiCoCrAlY coating in water vapor at 1050∘C

2020 ◽  
pp. 2150111
Author(s):  
Chen Hua ◽  
Peng Song ◽  
Taihong Huang ◽  
Xuan He ◽  
Chao Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Water Vapor ◽  
Oxide Scale ◽  
Oxidation Behavior ◽  
Oxidation Process ◽  
Alumina Scale ◽  
Crack Initiation And Propagation ◽  
Free Standing ◽  
Good Adherence ◽  
Initiation And Propagation

In this study, we focus on the oxidation behavior of the oxide scale with Platinum (Pt) on free standing NiCoCrAlY coating in air with water vapor at high temperature. The Pt layer is deposited on the NiCoCrAlY coating surface by electroplating, and then heat treatment at 1000[Formula: see text]C with Argon (Ar) protection. Cycle oxidation of the oxide scale with Pt is conducted in air and air with water vapor at 1050[Formula: see text]C. The results indicated that the spinels (NiCr2O[Formula: see text] are formed on the surface of the alumina scale in air and air with water vapor. However, this kind of spinel is inhibited in the air with water vapor and the scale on the coatings with Pt presents a good adherence during oxidation process. The thermal stress and crack initiation and propagation will be discussed.

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.

Sign in / Sign up

Export Citation Format

Share Document