Sol-Gel Process for Anti-Corrosion Coatings
Pages 209-231
Saheli Bera, G. Udayabhanu, Ramanuj Narayan and T.K. Rout

DOI: http://dx.doi.org/10.6000/1929-5995.2013.02.04.4

Published: 31 December 2013

Abstract: This review paper summarizes the current state of the art of sol-gel technology for formulating anti corrosive protective coating. A brief description of the mechanism of sol-gel reactions, various parameters that influence the property of the final product and the course of the sol-gel reaction has been given. Different types of metal precursors that are extensively used in sol preparation and the advantages and disadvantages have also been mentioned in brief. Surface chemistry of sol-gel matrix and various stabilizing and destabilizing forces that are active on the surface of colloidal particles have also been discussed. Problems related to obtaining good quality product with uniformly distributed concentrations have been outlined. Possible pathways for further improvement of anti-corrosive properties of the coating have been described, such as incorporation of various types of additives into the sol matrix prior to coating. As a whole the present study summarizes the superiority and benefits of organic-inorganic hybrid coatings using sol-gel technique and having good protective and anti-corrosive properties.

Giesekus Constitutive Model for Thermoviscoelastic Fluids based on Ordered Rate Constitutive Theories
Pages 232-250
K.S. Surana, D. Nunezand J.N. Reddy

DOI: http://dx.doi.org/10.6000/1929-5995.2013.02.04.5

Published: 31 December 2013

Abstract: This paper presents derivation of Giesekus constitutive model in Eulerian description based on ordered rate constitutive theories for thermoviscoelastic fluids for compressible and incompressible cases in contra-, co-variant and Jaumann bases. The ordered rate constitutive theories for thermoviscoelastic fluids of orders (m, n) consider convected time derivative of order m of the deviatoric Cauchy stress tensor in a chosen basis (i.e. co-, contra-variant or Jaumann) as dependent variable in the development of constitutive theories for the stress tensor. Its argument tensors consist of density, temperature, convected time derivatives of the deviatoric Cauchy stress tensor of up to order m-1 and convected time derivative of up to order n of the conjugate strain tensor. In addition, constitutive theory for the heat vector compatible with the constitutive theory for the deviatoric stress tensor is also presented in co-, contra-variant and Jaumann bases. It is shown that the Giesekus constitutive model is a subset of the rate constitutive theory of orders m = n = 1. It is also shown that the deviatoric Cauchy stress tensor (contra-, co-variant or Jaumann basis) naturally results as dependent variable in the constitutive theory, and that currently used Giesekus constitutive model in deviatoric polymer Cauchy stress tensor is not derivable based on axioms and principles of the constitutive theory in continuum mechanics. Numerical studies are presented for fully developed flow between parallel plates for a dense polymeric liquid using the Giesekus constitutive model derived in this paper as well as currently used model.