The Effect of Platinum on the Growth and Adhesion of α-Al2O3 Scales

2020 ◽  
pp. 115-128
Author(s):  
E. C. Dickey ◽  
B. A. Pint ◽  
K. B. Alexander ◽  
I. G. Wright
Keyword(s):  
Al2o3 Scales ◽  
Α Al2o3

The effect of reactive elements on the segregation behavior and microstructure of α-Al2O3 scales on β-NiAl

1994 ◽  
Vol 52 ◽  
pp. 670-671
Author(s):  
K. B. Alexander ◽  
B. A. Pint
Keyword(s):  
Grain Boundaries ◽  
Oxidation Behavior ◽  
Cation Transport ◽  
Reactive Elements ◽  
Short Term ◽  
Segregation Behavior ◽  
Al2o3 Scales ◽  
High Temperature Alloys ◽  
Oxide Particles ◽  
Α Al2o3

In order to improve oxidation resistance, small quantities of certain oxygen-active or “reactive” elements (RE) such as Y, Zr, Hf, or Ce are added to chromia- and alumina-forming high temperature alloys. Many theories have been proposed to explain the effects of RE additions, with a number of these theories including some aspect of the observed segregation of RE ions to oxide scale grain boundaries and the metalscale interface. The RE-ion segregation to the scale grain boundaries has been proposed to affect the oxidation behavior by suppressing cation transport along grain boundaries. It has been demonstrated that the quantity of RE segregation at α-Al2O3 scale grain boundaries varies with oxidation time and temperature and is greatly affected by the formation of RE-rich oxide particles in the scale (particularly at the gas interface). A previous study of scale formation on Y-implanted β-NiAl found that the Y implant had only a short-term (<1 h) effect at high temperatures.

Stability of External α-Al2O3 Scales on Alloy 602 CA at 1100–1200 °C

2017 ◽  
Vol 90 (1-2) ◽  
pp. 119-133
Author(s):  
A. Chyrkin ◽  
R. Swadźba ◽  
R. Pillai ◽  
T. Galiullin ◽  
E. Wessel ◽  
...  
Keyword(s):  
Al2o3 Scales ◽  
Α Al2o3 ◽  
Alloy 602 Ca

Size effects of Y-enriched intermetallic precipitates in Fe-20Cr-5Al-0.25Y alloy on the spallation resistance of thermally grown α-Al2O3 scales

2020 ◽  
Vol 174 ◽  
pp. 108796
Author(s):  
Jian Li ◽  
Guangming Cao ◽  
Hao Wang ◽  
Weina Zhang ◽  
Chenggang Li ◽  
...  
Keyword(s):  
Size Effects ◽  
Al2o3 Scales ◽  
Intermetallic Precipitates ◽  
Α Al2o3 ◽  
Thermally Grown

scholarly journals Oxidation of Ni-Cr-Co-Al-Mo-Ti-Re-Ta-W-Ru Single Crystals at 1000 oC in Air

2020 ◽  
Vol 58 (4) ◽  
pp. 234-246 ◽  
Author(s):  
Junhee Hahn ◽  
Xiao Xiao ◽  
Dong Bok Lee
Keyword(s):  
Single Crystals ◽  
Oxidation Resistance ◽  
Oxide Scales ◽  
Al2o3 Scale ◽  
Temperature Oxidation ◽  
Outward Diffusion ◽  
Active Elements ◽  
Al2o3 Scales ◽  
Cast Alloys ◽  
Α Al2o3

Three kinds of Ni-based single crystals with the compositions of 63.8Ni-7.5Cr-5.1Co-4.8Al-1.9Mo- 0.9Ti-3Re-11.8Ta-1.2W, 61.4Ni-7.4Cr-5Co-4.8Al-1.8Mo-0.9Ti-3.1Re-11.6Ta-4W, and 60.9Ni-7.5Cr-5Co-4.8Al- 2Mo-1Ti-2.9Re-10.9Ta-1.2W-3.8Ru, in wt%, were cast in a Bridgman furnace. In the cast alloys, Cr, Co, Re, Mo, W, and Ru became microsegregated in dendrites consisting of γ-Ni, while Ni, Ta, and Al microsegregated in interdendrites consisting of eutectic γ/γ . The cast alloys were oxidized at 1000 oC up to 275 h in air to study the effect of alloying elements on high-temperature oxidation. The oxide scales consisted primarily of CrTaO4, with some NiCr2O4, NiO, and α-Al2O3. The oxidation resistance was dependent on the formation and continuity of the α-Al2O3 scale. Ta and W were beneficial, while Ru was harmful in improving the oxidation resistance. The selective oxidation of Al in dendrites led to the formation of thin, uniform α-Al2O3 scales, i.e., uniform oxidation. The competitive oxidation of active elements such as Al, Ti, and Ta in interdendrites led to the formation of porous, crack-susceptible oxide nodules, i.e., nodular oxidation. Less active elements such as Ru, Re, Ni, Co, Mo, W, and Cr tended to enrich in the vicinity of the oxide nodules. The oxidation progressed through the outward diffusion of cations and the inward diffusion of oxygen. This inward diffusion formed internal alumina islands, beneath the oxide scale.

FeCrAl Alloys Produced by Roll-Bonding and Annealing of Al(RE)-Clad Stainless Steel: How Addition of Hf and Zr Affects their Oxidation Behaviour

2008 ◽  
Vol 604-605 ◽  
pp. 133-137 ◽  
Author(s):  
D. Pilone ◽  
F. Felli ◽  
U. Bernabai
Keyword(s):  
Stainless Steel ◽  
Oxidation Behaviour ◽  
Reactive Elements ◽  
Thermal Expansion Mismatch ◽  
Roll Bonding ◽  
Scale Adhesion ◽  
Al2o3 Scales ◽  
Cold Rolling And Annealing ◽  
Steel Alloying ◽  
Α Al2o3

The process involving cold rolling and annealing of Al-steel-Al sandwiches allows to produce an alloy containing more than 7 wt.% of Al. Unfortunately many α-Al2O3 scales tend to spall during thermal cycling because of thermal expansion mismatch between the alloy and the scale. Small additions to the ferritic stainless steel of oxygen reactive elements are known to improve the adhesion of α-Al2O3 scales. In this work hafnium and zirconium were added to the aluminium foil before roll bonding and their behaviour during the diffusion bonding was evaluated. This novel doping method was proven to be effective in improving scale adhesion and alloy lifetime. Moreover it allows to overcome problems related to steel alloying with reactive elements and reduces the quantity of expensive reactive elements that needs to be added to the steel foil.

Preparation and Properties of Porous α-Al2O3 Based Ceramic Disk Substrates

2013 ◽  
Vol 28 (6) ◽  
pp. 599-604 ◽  
Author(s):  
Sheng-Bo CHEN ◽  
Xu-Guang LIU ◽  
Bao-Quan ZHANG
Keyword(s):  
Ceramic Disk ◽  
Α Al2o3

Epitaxial mist chemical vapor deposition growth and characterization of Cu3N films on (0001)α-Al2O3 substrates

2020 ◽  
Vol 13 (7) ◽  
pp. 075505
Author(s):  
Tomohiro Yamaguchi ◽  
Hiroki Nagai ◽  
Takanori Kiguchi ◽  
Nao Wakabayashi ◽  
Takuto Igawa ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Chemical Vapor Deposition Growth ◽  
Α Al2o3

scholarly journals The Influence of Aluminum Content on Oxidation Resistance of New-Generation ODS Alloy at 1200 °C

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1478 ◽  
Author(s):  
Luděk Stratil ◽  
Vít Horník ◽  
Petr Dymáček ◽  
Pavla Roupcová ◽  
Jiří Svoboda
Keyword(s):  
Oxidation Resistance ◽  
Cross Sections ◽  
Aluminum Content ◽  
Energy Dispersive Spectrometer ◽  
Oxide Dispersion Strengthened ◽  
Xrd Analysis ◽  
Al Content ◽  
Α Al2o3 ◽  
New Generation ◽  
Ods Alloy

The aim of the paper is to evaluate the effect of aluminum content on the oxidation resistance of new-generation of oxide dispersion strengthened (ODS) alloy at 1200 °C. Three grades of the alloy of chemical composition Fe-15Cr-xAl-4Y2O3 with different Al contents x = 0.3 wt.%, 2.0 wt.% and 5.5 wt.% are prepared by mechanical alloying. The alloys are consolidated by high temperature rolling followed by heat treatment. To study the oxidation resistance the samples are isothermally aged in the air for 1 h, 4 h, 16 h and 64 h at 1200 °C. The oxidation kinetics, composition and formation mechanism of the oxide layers are analyzed. The weight gain of prepared steels is estimated. The kinetics of oxidation is studied on metallographic cross-sections of the exposed samples by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) analysis. The oxides on the surfaces are identified by X‑ray diffraction (XRD) analysis. The Al content significantly enhances the oxidation resistance of the alloy. For a sufficiently high Al content in the alloy a compact oxide layer of α‑Al2O3 on the surface is formed, which significantly suppresses further oxidation process.

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