83 research outputs found
Synthesis of TiO2 Thin Films: Relationship Between Preparation Conditions and Nanostructure
A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes
Aluminium anodising in ultra-dense sulfate baths: discovery by overall kinetic and potentiometric studies of the critical role of interface colloidal Al2(SO4)3 nanoparticles in the mechanism of growth and nanostructure of porous oxide coatings
The origin of nucleation and development of porous nanostructure of anodic alumina films
Transport phenomena inside the pores involved in the kinetics and mechanism of growth of porous anodic Al2O3 films on aluminium
Development of a theory for the determination of the composition of the anodizing solution inside the pores during the growth of porous anodic Al2O3 films on aluminium by a transport phenomenon analysis
Aluminium anodising in low acidity sulphate baths: Growth mechanism and nanostructure of porous anodic films
The parallel dehydrative and dehydrogenative catalytic action of γ-Al2O3 pure and doped by MgO: Kinetics, selectivity, time dependence of catalytic behaviour, mechanisms and interpretations
Transformation of the overall strict kinetic model governing the growth of porous anodic Al2O3 films on aluminium to a form applicable to the non-stirred bath film growth
The strict and complex, overall kinetic model, governing the growth of
porous anodic Al2O3 films, was transformed to a form easily and directly
applicable to the galvanostatic anodization in a non-stirred bath at
constant bath temperature. It was shown that the transformed model
always acquires a form different from that of a stirred bath
anodization. The transformed model was applied to the experimental
results of film growth obtained at 25 degrees C, 15 mA cm(-2) and in a
wide range of H2SO4 concentration, 5-85% w/v. The application of the
transformed model provided, consistently with other experimental
observations, the existence of a critical electrolyte concentration near
5% w/v above which the normal mechanism of oxide production and film
growth is valid and below which a deficient growth of oxide is observed.
The transformed model permitted some predictions for the real pore
shapes. The experimental results and their treatment showed that the
electrolyte concentration affects parameters such as the mass and
porosity of the film, the pore base hemispherical surface area, the time
at which the pore external diameter approaches cell width, the time
interval in which the model applies and the parameters involved in the
transformed kinetic model; the manner of the effect of electrolyte
concentration on these parameters is significantly different from that
in the stirred bath. Their dependence on the electrolyte concentration
was well explained by the existence of a maximum in the rate of oxide
dissolution in an open circuit at a specific concentration, of a maximum
in the electrical conductivity at another specific concentration, and of
some resulting slight changes of the temperature inside the pores and
oxide bulk during anodization. Copyright (C) 1996 Elsevier Science Ltd
The parallel dehydrative and dehydrogenative catalytic action of gamma-Al2O3 pure and doped by MgO kinetics, selectivity, time dependence of catalytic behaviour, mechanisms and interpretations
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