The Influence Of The Chemical-bonded Interface Of Fillers/Matrix Resin On The Failure Behavior Of Organic Coatings

This research focuses on the influence of the interface bonding state of fillers/matrixresin on the failure behavior of organic coatings under simulated ocean environment.Alternating pressure and cyclic wet-dry conditions are selected as experimental environmentaccording to the characteristics of actual environment of marine-related facilities andequipment applications, the epoxy resin and mica filler are also selected to establish a modelsystem. The natural mica coating is in contrast to modified mica coating for the research ofvariation in the protective properties and the failure process of the coating under differentenvironmental conditions, based on this comprehensive and systematic analysis of the failuremechanisms of the coating under different environment are made, then the mechanism of thechemical-bonded interface of fillers/matrix resin on the coating failure behavior is discussed.According to the research of the coating performance and structure before service, itreveals that the chemical-bonded interface of filler/matrix resin could improve the poor fillerdispersion and bad compatibility between filler and resin effectively, reduce the number ofinterface defects, thus increase in the coating compactness and obdurability are found, theprotective properties of the coating is enhanced naturally.Under alternating pressure, coating failure in ahead occurs mainly in the following tworeasons: accelerated penetration failure and mechanical action failure. Alternating pressurewill lead increase in the rate of water diffusion and the amount of permeation in the coatingdirectly and the physical structure of the coating is damaged, once reaches a certain level, thecoating will come up mechanical aging and fatigue, the coating strength and toughnessdecline in performance. Chemical bonded interface coating failure process and failure modesin alternating pressure did not change but delayed by slowing the process of penetration of thecorrosive medium. A good filler/matrix resin interface on one hand is able to inhibit the rapidpenetration of the water brought by the alternating pressure and the mechanical effect of thecoating to reduce the stress of water accumulating at the interface effectively, on the otherhand can reduce the destruction by alternating pressure.In cyclic wet-dry environments, the coating structure is destroyed due to volumeincreasing and shrinking alternately, and a fast stripping with metal matrix is found. In thethree stages of coating degradation, cyclic wet-dry conditions did not accelerate the early corrosive medium penetration stage, but accelerate metal corrosion reaction occurred and thedevelopment stage significantly, resulting in premature failure of the coating. Chemicalbonded interface could reduce coating defects in the initial state, and the degree of swellingand shrinkage during cycling, thereby reducing the damage caused by the cyclic wet and dryenvironment, ultimately reduce the degree of delamination with metal matrix effectively,consequently slowing the coating failure.