Method for applying a polymer coating to a substrate

Abstract

Corrosion resistant non-polar polymer coatings and method for applying the coatings to substrates is described, wherein a source of non-polar polymer powder is deposited as a coating onto the surface of a substrate by high temperature thermal spray, wherein the non-polar character of the powder and any additives thereto is substantially preserved during the high temperature thermal spray by using a mixture of a non-oxidizing shielding gas or reducing gas, or combination of the two, at one or more locations along the thermal spray to displace or react with ambient oxygen.

Description

BACKGROUND OF THE INVENTIONThe present invention relates generally to corrosion resistant coatings for metallic or nonmetallic substrates, and more particularly to novel non-polar or non-polarizable polymer corrosion resistant coatings and system and method for applying the coatings.Conventional corrosion control or prevention coatings for metallic substrates typically use polar polymers in order to enhance adhesion to the substrate. However, the polar bonds represent a weakness in the coating of potentially allowing adsorption and transport of water and dissolved ions to the substrate and consequent corrosion of the substrate.The invention solves or substantially reduces in critical importance the problems with corrosion resistant polymer coatings in the prior art wherein non-polar and preferably also non-polarizable polymer powders are deposited by high temperature thermal and impact energy spray or plasma spray process as coatings for corrosion protection for metallic substrates....

AI Technical Summary

Benefits of technology

An additional advantage of the invention is substantial elimination of voids in the sprayed coating resulting from the momentum of impact from the velocity sprayed powder particles. Adsorption of water within thermal sprayed powder coatings is avoided by the elimination of free volume voids. The free volume in conventional coatings results from evaporation of solvents, condensing coatings with random voids, condensation chain extensions of oligomers with random voids, or cross-linking with random residual voids.

is substantial elimination of voids in the sprayed coating resulting from the momentum of impact from the velocity sprayed powder particles. Adsorption of water within thermal sprayed powder coatings is avoided by the elimination of free volume voids. The free volume in conventional coatings results from evaporation of solvents, condensing coatings with random voids, condensation chain extensions of oligomers with random voids, or cross-linking with random residual voids.

It is therefore a principal object of the invention to provide an improved corrosion resistant coating for metallic or non-metallic substrates.

It is a further object of the invention to provide a corrosion resistant coating using non-polar and non-polarizable polymers.

It is another object of the invention to provide low-cost corrosion resistant polymer coatings.

It is another object of the invention to provide void-free corrosion resistant polymer coatings for metallic substrates and method for applying the void-free coatings.

Problems solved by technology

However, the polar bonds represent a weakness in the coating of potentially allowing adsorption and transport of water and dissolved ions to the substrate and consequent corrosion of the substrate.

Because non-polar polymers do not usually adhere well to most substrates, the surface of the substrate may need to be roughened, such as by mechanical roughening (abrasion, sanding or the like) or by applying a semi-molten metal fiber or particle layer to the substrate prior to coating.

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