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The application of multiscale quasi 4D CT to the study of SrCrO4 distributions and the development of porous networks in epoxy-based primer coatings
- Source :
- Progress in Organic Coatings. 77:1946-1956
- Publication Year :
- 2014
- Publisher :
- Elsevier BV, 2014.
-
Abstract
- Transport paths for inhibitor release within a model strontium chromate (SrCrO4) inhibited/epoxy primer have been studied using a combination of tomography techniques. It has been found that the SrCrO4 particles form independent clusters within the model primer. The clusters have a range of fractal dimensions with the largest clusters (a few hundred microns in size) having a fractal dimension of 2.36. Leaching of the SrCrO4 from the primer appears to be initially through direct dissolution of particles in contact with the electrolyte but changes to diffusion through void pathways created by dissolution of the SrCrO4 phase. No evidence was found for the diffusion of chromate ions through the epoxy. Transport through such clusters does not follow Fickian diffusion, which has traditionally been employed to describe inhibitor release dynamics. Release kinetics typically follow a tm behaviour where t is time and m is an index which would be 0.5 for Fickian diffusion. Thus the overall release with time will evolve, being initially the result of direct dissolution, then at intermediate times, be dominated by transport through the fractal network and at the final stage go to zero since all the strontium chromate will be dissolved from the cluster connected to the surface. Clusters not connected to the surface remain undissolved and form additional reservoirs for further release in when local damage occurs in their vicinity. This new model of inhibitor transport creates new strategies for the development of self-healing properties for coatings.
- Subjects :
- Materials science
General Chemical Engineering
Mineralogy
Electrolyte
Fractal dimension
Diffusion
Strontium chromate
chemistry.chemical_compound
Materials Chemistry
Cluster (physics)
Electron computed tomography
Dissolution
X-ray computed tomography
Fractal networks
Chromate conversion coating
Organic Chemistry
Epoxy
Fick's laws of diffusion
Chromate
Surfaces, Coatings and Films
Chemical engineering
chemistry
visual_art
Chemical Engineering(all)
visual_art.visual_art_medium
Inhibited primers
Subjects
Details
- ISSN :
- 03009440
- Volume :
- 77
- Database :
- OpenAIRE
- Journal :
- Progress in Organic Coatings
- Accession number :
- edsair.doi.dedup.....ee970ca1bb56689cbddd959d3b2c7955