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 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.

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

A Study on the Removal of Solder-Coated Layer of Photovoltaic Ribbon

2015 ◽  
Vol 778 ◽  
pp. 71-74
Author(s):  
Jin Seok Lee ◽  
Bo Yun Jang ◽  
Joon Su Kim ◽  
Young Soo Ahn ◽  
Gi Hwan Kang ◽  
...  
Keyword(s):  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Pure Copper ◽  
Oxidation Time ◽  
Initial Oxidation ◽  
Solar Module ◽  
Oxidation Method ◽  
Temperature Range ◽  
Coated Layer ◽  
Increasing Temperature

The oxidation behavior of photovoltaic ribbon was measured for 48 hours over the temperature range of 300°C to 800°C using thermogravimetric apparatus (TGA). It was found that weigh-gained of both samples was found to be increased with increasing temperature and it was dramatically increased at 800°C for 30 minutes of initial oxidation time. Pure copper with 99.55% purity was successfully recovered from the photovoltaic ribbon of spent solar module using cyclic oxidation method.

Oxidation Behavior of Stainless Steel with Electroless Ni-Fe-P Coatings

2010 ◽  
Vol 160-162 ◽  
pp. 1276-1279
Author(s):  
Shu Jiang Geng ◽  
Qian Wang
Keyword(s):  
Stainless Steel ◽  
Oxide Scale ◽  
Ferritic Stainless Steel ◽  
Oxidation Behavior ◽  
Mass Gain ◽  
Surface Oxide ◽  
Oxidation Time ◽  
Mass Ratio ◽  
Bare Steel ◽  
Electroless Ni

Ni-Fe-P coatings were deposited on ferritic stainless steel by means of electroless method. The oxidation behavior of the steel with these coatings were investigated at 800°C in air. The mass gain of the steel with Ni-Fe-P coatings deposited from solutions with different mass ratios of FeSO4 to NiSO4 decreased with increasing mass ratio. For the steel with Ni-Fe-P coating deposited in the solution with 0.25 of the mass ratio, the mass gain increased with the increase in oxidation time. While the mass gain of the steel with coatings deposited in solution with 0.5 and 0.75 of the mass ratio, respectively, became stable after 10-h oxidation. Compared with Ni-P, The Ni-Fe-P coatings improved the spallation resistance of the surface oxide scale. The oxide scale formed the bare steel consisted of Cr2O3 with TiO2 and (Mn,Cr)3O4 spinel. However, the oxide scale thermally grown on the steel with Ni-Fe-P coatings was composed of NiO, (Ni,Fe)3O4 spinel and Cr2O3.

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.

Cyclic Oxidation Behaviour of a Ni-Based Alloy at 900°C

2011 ◽  
Vol 80-81 ◽  
pp. 51-54 ◽  
Author(s):  
Xu Dong Lu ◽  
Ce An Guo ◽  
Jie Wang ◽  
Shu Wu Ma
Keyword(s):  
Weight Loss ◽  
Internal Oxidation ◽  
Cyclic Oxidation ◽  
Mass Gain ◽  
Tio2 Particle ◽  
Oxidation Behaviour ◽  
Analysis Method ◽  
Initial Stage ◽  
Cr2o3 Scales

The cyclic oxidation behaviour of Ni 5.5Al 2.6Ti 4.8Co 3.9Mo 5.0W 11.0Cr superalloy at 900 °C in air has been investigated by means of measuring the kinetics curves of the oxidation and analysis method of XRD and SEM/EDAX. The results show that the mass gain rapidly increases in the initial stage, and the weight loss and mass gain occurs alternately during the cyclic oxidation. An obvious oxidation and internal oxidation occurs during cyclic oxidation. Ti in the alloy oxidized, diffusing through the Al2O3 and Cr2O3 scales to form faceted TiO2 particle on the surface of the alloy. Al2O3 formed discontinuousness inner oxides in the alloy.

Oxidation Behavior of Cu Nanoparticles and Formation of Hollow Cu2O Spheres

2007 ◽  
Vol 561-565 ◽  
pp. 1703-1706 ◽  
Author(s):  
Ryusuke Nakamura ◽  
Daisuke Tokozakura ◽  
Jung Goo Lee ◽  
Hirotaro Mori ◽  
Hideo Nakajima
Keyword(s):  
Growth Rate ◽  
Oxide Film ◽  
Formation Process ◽  
Oxidation Behavior ◽  
Oxide Films ◽  
Volume Ratio ◽  
Oxidation Time ◽  
Cu Nanoparticles ◽  
Initial Stage

Oxidation behavior of Cu nanoparticles in the formation process of hollow Cu2O spheres was investigated by TEM. The thickness of Cu2O layers on Cu nanoparticles oxidized at 323 K in air was measured as a function of oxidation time. At the initial stage of oxidation until the oxide film with 2.5 nm in thickness is formed, the thickness of oxide films on Cu nanoparticles with the diameter of 10, 20 and 35 nm shows a nearly equal value regardless of diameter of Cu. After the formation of 2.5 nm layer, however, the growth rate of the oxide films on smaller nanoparticles becomes slower than that on larger nanoparticles. This result suggests that the voids formed at the Cu/Cu2O interface prevent Cu atoms from diffusing outward across the interface because the volume ratio of voids to inner Cu in smaller nanoparticles is much larger than that in larger nanoparticles.

scholarly journals Tailored Oxidation Barrier Coatings for Mo-Hf-B and Mo-Zr-B Alloys

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2215 ◽  
Author(s):  
Iryna Smokovych ◽  
Volodymyr Bolbut ◽  
Manja Krüger ◽  
Michael Scheffler
Keyword(s):  
Critical Temperature ◽  
Cyclic Oxidation ◽  
Mass Gain ◽  
Small Mass ◽  
Preceramic Polymer ◽  
Barrier Coatings ◽  
Oxidation Protection ◽  
Initial Stage ◽  
Protection Layer ◽  
Protection Coating

The cyclic oxidation response of Mo-14Hf-23B and Mo-14.8Zr-26B (compositions in at. %) was investigated in air at 800 °C, which is a critical temperature for Mo-based alloys because of the pesting phenomenon. Rapid oxidation was observed for the unprotected samples, and an oxidation protection coating was developed based on a preceramic polymer with silicon and boron as particulate fillers. Cyclic oxidation tests of the coated samples showed excellent oxidation protection: no Mo, Hf or Zr oxides were found after testing and a small mass gain in the initial stage of oxidation indicated the formation of a glassy protection layer on the alloys surfaces after exposure to air at 800 °C.

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