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.

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A model of Kirkendall hollowing of core–shell nanowires and nanoparticles controlled by short-circuit diffusion

Acta Materialia ◽

10.1016/j.actamat.2014.09.050 ◽

2015 ◽

Vol 83 ◽

pp. 180-186 ◽

Cited By ~ 11

Author(s):

Leonid Klinger ◽

Oliver Kraft ◽

Eugen Rabkin

Keyword(s):

Short Circuit ◽

Core Shell ◽

Short Circuit Diffusion ◽

Shell Nanowires

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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 ◽

Cited By ~ 5

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.

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Movement of Oxygen in Skeletal Muscle

Physiology ◽

10.1152/physiologyonline.1986.1.5.147 ◽

1986 ◽

Vol 1 (5) ◽

pp. 147-149

Author(s):

PD Harris

Keyword(s):

Skeletal Muscle ◽

Intermittent Claudication ◽

Short Circuit ◽

Venous Blood ◽

Short Circuit Diffusion

In skeletal muscle the level of oxygen in outflowing venous blood is much higher than the level of oxygen in tissue. This puzzling finding suggests that oxygen moves in some unexpected way. The author uses the concept of short-circuit diffusion of oxygen between adjacent arterioles and venules to unravel the mystery and to provide new interpretations of microvascular responses to hypoxia and intermittent claudication.

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