Leaching from coatings pigmented with strontium aluminium polyphosphate inhibitor pigment- evidence for a cluster-percolation model

Li leaching from Li carbonate-primer: Transport pathway development from the scribe edge of a primer/topcoat system

“…Closely related to the PVC and CPVC is the concept of the percolation threshold which has been discussed by the current authors as well as others [36,74]. These studies suggest that when any individual cluster of particles dissolves it then reaches the percolation threshold, i.e., a point where all voids in the cluster provide a continuous transport network for leaching.…”

“…This is because the binder adjacent to inorganic particles will be saturated with water but, like ions from the external electrolyte, ions from the internal electrolyte cannot diffuse into the binder at this early stage of immersion because the free volume of the PU is smaller than the ion sizes [30]. Similar conclusions have been reached for epoxy systems [36][37][38][39]. Two effects result from this water-uptake.…”

“…Thus, ions from the internal electrolyte, created from dissolution of particles further away from the leaching interface, could only enter the external electrolyte through a network of channels created by partial/complete dissolution of connected particles perhaps facilitated by mechanical rupture of the PU. This is the model based on leaching through particles clusters [30,36,37,40,41]. The authors earliest work studied an epoxy primer where SrCrO 4 was the only component, so only SrCrO 4 particle clusters were observed [40].…”

“…The authors earliest work studied an epoxy primer where SrCrO 4 was the only component, so only SrCrO 4 particle clusters were observed [40]. Latter studies showed that where there are more than one inorganic particle type then all the different types of particles can be involved in network formation [30,36,42].…”

Encapsulated Corrosion Inhibitive Pigment for Smart Epoxy Coating Development: An Investigation of Leaching Behavior of Inhibitive Ions

“…Organic coatings protect metal structures from corrosion by acting as a physical barrier between the substrate and the aggressive environment. The organic resin together with barrier pigments restricts the transportation of corrosive ions to the substrate and increases the ionic resistance between the local anodes and cathodes on the surface of the substrate. , However, coating films are rarely defect-free . In addition, exposure time and interactions with the environment can either exacerbate the initial defects or generate new ones, compromising the barrier properties of the coating …”