- Author
- Bentz, D. P. | Nguyen, T.
- Title
- Simulation of Diffusion in Pigmented Coatings on Metals Using Monte-Carlo Methods.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Journal
- Journal of Coatings Technology, Vol. 62, No. 783, 57-63, April 1990
- Keywords
- metals | coatings | simulation | algorithms | thickness | pigment volume concentration | pigment dispersion | pigment shape-orientation | surface defects (pinholes) | cycle exposures
- Abstract
- The degradation of many organic coating systems is controlled by processes occurring at the coating-substrate interface. These degradation processes require that species, such as H2O, O2, or ions, diffuse from the atmosphere, through the coating, to the interfacial region. This paper presents a two-dimensional model for the diffusion of these species through a pigmented coating. The model is implemented via digitized Monte Carlo simulations of the random walk behavior of individual species within the coating layer. The model has been developed to include a variety of parameters such as coating thickness, pigmentation (pigment volume concentration, pigment particle geometry, pigment absorption characteristics, etc.), and pinholes at the coating-atmosphere interface. Results are presented for a number of cases which explore the effects of pigment volume concentration, pigment dispersion, pigment shape and orientation, the presence of surface defects, and constant vs cyclic environments. Key features of the digitized simulation model are its flexibility, the visualization it provides the researcher, and the possibility of executing the algorithms on digitized images of cross sections of real coating systems.