Structural Imperfections in thin Oxide Films Formed on Some Fe- and Ni-Base Alloys

1970 ◽  
Vol 28 ◽  
pp. 510-511
Author(s):  
L. P. Lemaire ◽  
D. E. Fornwalt ◽  
F. S. Pettit ◽  
B. H. Kear
Keyword(s):  
Oxide Scale ◽  
Oxidation Process ◽  
Short Circuit ◽  
Protective Oxide ◽  
Protective Oxide Scale ◽  
Thin Oxide Films ◽  
Diffusion Paths ◽  
Oxidation Resistant ◽  
Structural Imperfections ◽  
Short Circuit Diffusion

Oxidation resistant alloys depend on the formation of a continuous layer of protective oxide scale during the oxidation process. The initial stages of oxidation of multi-component alloys can be quite complex, since numerous metal oxides can be formed. For oxidation resistance, the composition is adjusted so that selective oxidation occurs of that element whose oxide affords the most protection. Ideally, the protective oxide scale should be i) structurally perfect, so as to avoid short-circuit diffusion paths, and ii) strongly adherent to the alloy substrate, which minimizes spalling in response to thermal cycling. Small concentrations (∼ 0.1%) of certain reactive elements, such as yttrium, markedly improve the adherence of oxide scales in many alloy systems.

scholarly journals An Approach to Describing the Simultaneous Erosion and High Temperature Oxidation of Alloys

1990 ◽  
Author(s):  
I. G. Wright ◽  
V. K. Sethi ◽  
V. Nagarajan
Keyword(s):  
High Temperature ◽  
Oxide Scale ◽  
High Temperature Oxidation ◽  
Oxidation Process ◽  
Alloy Surface ◽  
Oxide Growth ◽  
Protective Oxide ◽  
Temperature Oxidation ◽  
Protective Oxide Scale ◽  
Alloy Oxidation

The rate of wastage of an alloy surface subjected to erosion under conditions where high-temperature oxidation can occur can be significantly greater than that arising from erosion alone. This is because the erosion conditions can act to accelerate the oxidation process by causing regular shedding of the otherwise protective oxide scale. It is suggested that an important parameter in determining the rate of erosion-oxidation is the erodent flux, since the time available for oxide growth (or regrowth) in a given area is determined by the interval between successive erodent impacts. Using this simple premise, an approach is suggested by which the rate of erosion-oxidation can be related to the factors that control the alloy oxidation process, and those that describe the erosive environment. The assumptions made are examined, and some of the implications of this approach are discussed.

An Approach to Describing the Simultaneous Erosion and High-Temperature Oxidation of Alloys

1991 ◽  
Vol 113 (4) ◽  
pp. 616-620 ◽  
Author(s):  
I. G. Wright ◽  
V. K. Sethi ◽  
V. Nagarajan
Keyword(s):  
High Temperature ◽  
Oxide Scale ◽  
High Temperature Oxidation ◽  
Oxidation Process ◽  
Alloy Surface ◽  
Oxide Growth ◽  
Protective Oxide ◽  
Temperature Oxidation ◽  
Protective Oxide Scale ◽  
Alloy Oxidation

The rate of wastage of an alloy surface subjected to erosion under conditions where high-temperature oxidation can occur can be significantly greater than that arising from erosion alone. This is because the erosion conditions can act to accelerate the oxidation process by causing regular shedding of the otherwise protective oxide scale. It is suggested that an important parameter in determining the rate of erosion-oxidation is the erodent flux, since the time available for oxide growth (or regrowth) in a given area is determined by the interval between successive erodent impacts. Using this simple premise, an approach is suggested by which the rate of erosion-oxidation can be related to the factors that control the alloy oxidation process, and those that describe the erosive environment. The assumptions made are examined, and some of the implications of this approach are discussed.

Engine Testing of an Advanced Alloy for Microturbine Primary Surface Recuperators

2005 ◽  
Author(s):  
Wendy J. Matthews ◽  
Terry Bartel ◽  
Dwaine L. Klarstrom ◽  
Larry R. Walker
Keyword(s):  
Steady State ◽  
Oxide Scale ◽  
Engine Test ◽  
Test Results ◽  
Protective Oxide ◽  
Protective Oxide Scale ◽  
Cyclic Operation ◽  
Engine Testing

HAYNES® alloy HR-120® has been identified as a potential alloy for the manufacture of primary surface recuperators. Primary surface recuperator components have been manufactured from HR-120, and actual microturbine testing is on going. Initial engine test results indicate the formation of a protective oxide scale that is resistant to both steady-state and cyclic operation with no evidence of accelerated attack, and which is likely to meet or exceed the desired 80,000 hour component life.

The importance of interfacial chemistry in protective oxide scale adherence

1988 ◽  
Vol 30 (3-4) ◽  
pp. 259-266 ◽  
Author(s):  
J. G. Smeggil ◽  
N. S. Bornstein ◽  
M. A. DeCrescente
Keyword(s):  
Oxide Scale ◽  
Interfacial Chemistry ◽  
Protective Oxide ◽  
Protective Oxide Scale ◽  
Scale Adherence ◽  
Oxide Scale Adherence

scholarly journals Effect of SiO2 Dispersion on Chlorine-Induced High-Temperature Corrosion of High-Velocity Air-Fuel Sprayed NiCrMo Coating

CORROSION ◽  
10.5006/2802 ◽  
2018 ◽  
Vol 74 (9) ◽  
pp. 984-1000 ◽  
Author(s):  
Esmaeil Sadeghi ◽  
Nicolaie Markocsan ◽  
Tanvir Hussain ◽  
Matti Huhtakangas ◽  
Shrikant Joshi
Keyword(s):  
High Temperature ◽  
Oxide Scale ◽  
Corrosion Product ◽  
Weight Change ◽  
High Velocity ◽  
Short Circuit ◽  
High Temperature Corrosion ◽  
Lower Weight ◽  
Short Circuit Diffusion ◽  
Highly Porous

NiCrMo coatings with and without dispersed SiO2 were deposited using high-velocity air-fuel technique. Thermogravimetric experiments were conducted in 5% O2 + 500 vppm HCl + N2 with and without a KCl deposit at 600°C for up to 168 h. The SiO2-containing coating showed lower weight change as a result of formation of a protective and adherent Cr-rich oxide scale. SiO2 decelerated short-circuit diffusion of Cr3+ through scale’s defects, e.g., vacancies, and promoted the selective oxidation of Cr to form the protective Cr-rich oxide scale. Furthermore, the presence of SiO2 led to less subsurface depletion of Cr in the coating, and accordingly less corrosion of the substrate. The formed corrosion product on the SiO2-free coating was highly porous, non-adherent, and thick.

The role of (FeCrSi)2(MoNb)-type Laves phase on the formation of Mn-rich protective oxide scale on ferritic stainless steel

2018 ◽  
Vol 132 ◽  
pp. 214-222 ◽  
Author(s):  
Harri Ali-Löytty ◽  
Markku Hannula ◽  
Timo Juuti ◽  
Yuran Niu ◽  
Alexei A. Zakharov ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Oxide Scale ◽  
Ferritic Stainless Steel ◽  
Laves Phase ◽  
Protective Oxide ◽  
Protective Oxide Scale
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