Abradable dry film lubricant and the method for applying same and article made therefrom
View Patent ↗An article with an abradable dry powder coating thereon comprises an abradably coated article with a substrate surface and having at least one coating of a liquid primer on the substrate surface and then coating with at least one abradable dry powder coating on the surface of the liquid primer. The sequence of layers may also be reversed, or additional layers may be useful. The abradable dry powder coating is formed of a dry powder coating composition including a thermoset resin having a cure temperature combined with at least one filler material, wherein the filler is formed of a material which does not melt substantially at or below the cure temperature of the resin, whereby an abradable coating results employing a filler to make the coating. A method of making a composition for coating an article with a coating curable into an abradable coating is also disclosed, comprising melt-mixing an evaporative carrier-free mixture of a dry powder thermoset resin having a cure temperature, to form a mass composite, wherein the filler is formed of a material which does not substantially melt at or below the cure temperature of the resin, cooling the mass composite, and breaking the cooled mass composite into powder particles, thereby forming the composite powder composition.
1. An article with an abradable dry powder coating disposed thereon that is the product of a process, comprising:
applying a liquid primer to a surface of the article, wherein the liquid primer comprises a first thermosetting resin and a solvent; and
applying a dry powder coating over the liquid primer, wherein the dry powder coating comprises particles comprising a second thermosetting resin and a filler material, where the filler material does not melt at or below a cure temperature of the second thermosetting resin; and
curing the liquid primer and the dry powder coating to form a dry powder film lubricant wherein the dry powder film lubricant comprises a polymer matrix formed from the first thermosetting resin in a layer proximate the surface of the article and a porous layer formed from the particles of the dry powder coating adhered to one-another in a layer distal to the surface of the article;
wherein curing causes the dry powder particles to sinter, but curing completes without the particles of the dry powder coating flowing sufficiently to lose their discrete identities; and
wherein the porous layer formed from the particles of the dry powder coating adhere to one another in a layer distal from the surface of the article is thicker than the polymer matrix formed from the first thermosetting resin in a layer proximate to the surface of the article.
2. The coated article according to claim 1 , wherein the filler is of a type and is employed in an amount that make it effective to provide abrasion qualities.
3. The coated article according to claim 1 , wherein the filler is employed in an amount from about 15 to about 30 volume percent based on the volume of the dry powder coating.
4. The coated article according to claim 1 , wherein the dry powder coating further comprises a polymer wax selected from the group consisting of fluoropolymer wax, polyethylene wax and polypropylene wax.
5. The article of claim 1 , wherein the porous layer has 10%-80% porosity.
6. The article of claim 1 , wherein the liquid primer is a slurry.
7. The article of claim 1 , wherein the article is a piston.
8. The article of claim 1 , wherein the dry powder coating is the product of a process that comprises:
melt-mixing the second thermosetting resin and the filler material to form a composite;
cooling the composite; and
breaking up the cooled composite to form the dry powder.
9. The article of claim 1 , wherein:
applying a dry powder coating comprises applying a first dry powder coating over the liquid primer and applying a second dry powder coating over the first dry powder coating; and
the second dry powder coating forms a layer having a lower abrasion resistance than a layer formed by the first dry powder coating.
10. The article of claim 1 , wherein the article comprises a metal substrate.
11. The article of claim 1 , wherein:
the article is a component of a device;
the surface of the article with the abradable dry powder coating thereon is one of two mating surfaces of the device.
12. The article of claim 1 , wherein the porous layer formed from particles of the dry powder coating adhered to one-another in a layer distal from the surface is at least 0.0003″ thick.
13. A method of forming an abradable dry powder coating on an article, comprising;
applying a liquid primer comprising a first thermosetting resin and a solvent to a surface of the article;
applying the dry powder coating over the liquid primer, wherein the dry powder coating comprises particles comprising a second thermosetting resin and filler material;
wherein the filler material does not melt at or below a cure temperature of the second thermosetting resin; and
curing the liquid primer and the dry powder coating to form a dry powder film lubricant, wherein the dry powder film lubricant comprises a polymer matrix formed from the first thermosetting resin in a layer proximate the surface of the article and a porous layer formed from particles of the dry powder coating adhered to one another in a layer distal from the surface;
wherein curing causes the dry powder particles to sinter, but curing completes without the particles of the dry powder coating flow sufficiently to lose their discrete identities; and
wherein the porous layer formed from the particles of the dry powder coating adhere to one another in a layer distal from the surface of the article is thicker than the polymer matrix formed from the first thermosetting resin in a layer proximate to the surface of the article.
14. The method of claim 13 , further comprising forming the dry powder of the dry powder coating by a method comprising:
melt-mixing the second thermosetting resin and the filler material to form a composite;
cooling the composite; and
breaking up the cooled composite to form the dry powder.
15. The method of claim 13 , wherein applying the dry powder coating comprises applying the dry powder coating electrostatically.