INVESTIGADORES
MOLINA fernando Victor
artículos
Título:
The role of Coulombic Forces in Quasi-two dimensional Electrochemical Deposition
Autor/es:
G MARSHALL,; P MOCSKOS; F. V. MOLINA; S DENGRA,
Revista:
Materials Research Society Monographs
Editorial:
Materials Research Society
Referencias:
Lugar: Warrendale, PA, USA; Año: 1997 vol. 451 p. 147 - 156
Resumen:
Recent work demonstrates the
relevant influence of convection during growth pattern formation in
thin-layer electrochemical deposition. Convection is driven mainly by
coulombic forces due to local charges at the tip of the aggregation and
by buoyancy forces due to concentration gradients. Here we study through
physical experiments and numerical modeling the regime under which
coulombic forces are important. In the experimental measurements fluid
motion near the growing tips of the deposit is visualized with neutrally
buoyant latex spheres and its speed measured with videomicroscope
tracking techniques and image processing software. The numerical
modeling consists in the solution of the 2D dimensionless Nernst-Planck
equations for ion concentrations, the Poisson equation for the electric
field and the Navier-Stokes equations for the fluid flow, and a
stochastic growth rule for ion deposition. A new set of dimensionless
numbers governing electroconvection dominated flows is introduced.
Preliminary experimental measurements and numerical results indicate
that in the electroconvection dominated regime coulombic forces increase
with the applied voltage, and their influence over growth pattern
formation can be assessed with the magnitude of the dimensionless
electric Froude number. It is suggested that when this number decreases
the deposit morphology changes from fractal to dense branching.