Coating processes – Spray coating utilizing flame or plasma heat – Organic containing coating
Statutory Invention Registration
2000-04-21
2002-07-02
Pihulic, Daniel T. (Department: 3641)
Coating processes
Spray coating utilizing flame or plasma heat
Organic containing coating
Statutory Invention Registration
active
H0002035
ABSTRACT:
BACKGROUND OF THE INVENTION
The 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. High temperature is considered herein to mean a temperature at which oxidation of the polymer may occur. Water, being a polar molecule, has an affinity for other polar molecules, including polar polymers, additives and substrates, but has no affinity for non-polar polymers. Accordingly, the non-polar materials in the coatings of the invention act to prevent water and dissolved ions from absorbing in, percolating through, or deteriorating the coating, and coating/substrate interface which allows corroding 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. The invention is further enhanced if the metal is a less corrosion prone version of the substrate metal being protected.
Another aspect of the invention is the prevention of non-polar polymers, additives and fillers from being polarized by oxidation during the high temperature thermal spray, plasma spray, or subsequent cure of the coating. In accordance with the teachings of the invention, oxidation may be prevented first by using a mixture of a shielding gas or reducing gas, or combination of the two, at one or more locations along the thermal spray to capture or preferentially react with ambient oxygen or residual oxy/fuel thermal spray oxygen.
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.
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.
It is a further object of the invention to provide an improved method for applying corrosion resistant polymer coatings without oxidation of the polymer.
It is another object of the invention to provide an improved device to implement shielding with reducing gas for high velocity, high temperature thermal spray.
It is yet another object of the invention to provide a device, gas, or method for shielding the powder from oxidation during the spray process.
These and other objects of the invention will become apparent as the detailed description of representative embodiments proceeds.
SUMMARY OF THE INVENTION
In accordance with the foregoing principles and objects of the invention, 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.
REFERENCES:
patent: 3723165 (1973-03-01), Longo et al.
patent: 4206248 (1980-06-01), Schmidlin
patent: 4707379 (1987-11-01), Neufuss et al.
patent: 4812335 (1989-03-01), Kuwajima et al.
patent: 5041713 (1991-08-01), Weidman
patent: 5106910 (1992-04-01), Weidman et al.
patent: 5285967 (1994-02-01), Weidman
patent: 5322715 (1994-06-01), Jouck et al.
patent: 5439710 (1995-08-01), Vogt et al.
patent: 5585146 (1996-12-01), Uenaka et al.
Metals Handbook, Ninth Edition, vol. 5: Surface Cleaning, Finishing, and Coating, American Society for Metals, pp. 361 and 375, 1982.
Baker Aileen J.
Kundert Thomas L.
Pihulic Daniel T.
Scearce Bobby D.
The United States of America as represented by the Secretary of
LandOfFree
Method for applying a polymer coating to a substrate does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for applying a polymer coating to a substrate, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for applying a polymer coating to a substrate will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2853100