BORON NITRIDE COATINGS FOR METAL PROCESSING AND METHODS OF USING THE SAME

1 . A release agent for metal processing equipment, the release agent comprising:

(a) boron nitride; and

(b) a fumed metal oxide.

2 . The release agent of claim 1 , wherein the boron nitride is selected from hexagonal boron nitride, platelet boron nitride, an agglomerate of boron nitride, or a combination of two or more thereof.

3 . The release agent of claim 1 , wherein the release agent comprises about 0.1 to about 50 wt. % boron nitride.

4 . The release agent of claim 1 , wherein the boron nitride is chosen from a hexagonal boron nitride, a platelet boron nitride, a boron nitride agglomerate, or a combination of two or more thereof.

5 . The release agent of claim 1 , wherein the fumed metal oxide is selected from a fumed silica, a fumed alumina, a fumed titania, a fumed titania-silicon mixed oxide, or a combination of two or more thereof.

6 . The release agent of claim 1 , wherein the release agent comprises the fumed metal oxide in an amount of about 0.01 wt. % to about 20 wt. %.

7 . The release agent of claim 1 , wherein the release agent comprises about the fumed metal oxide in an amount of from about 0.1 wt. % to about 10 wt. %.

8 . The release agent of claim 1 , wherein the release agent further comprises a filler chosen from talc, graphite, alumina (Al 2 O 3 ), water-soluble phosphate, colloidal silica, colloidal alumina, water-soluble phosphate salt, a silicate and/or molybdenum disulfide, SiO 2 , ZnO, ZrO 2 , CeO, TiO 2 , mica, or a combination of two or more thereof.

9 . The release agent of claim 1 , wherein the release agent is dispersed in an aqueous carrier.

10 . The release agent of claim 1 , which further comprises a pigment to impart color.

11 . The release agent of claim 10 where the pigment is an inorganic pigment chosen from a rutile, spinel, hematite, or phosphate pigment.

12 . The release agent of claim 11 where the pigment is substantially free of chromium compounds.

13 . A substrate defining a surface, the substrate comprising a coating of the release agent of claim 1 disposed on at least a portion of the surface.

14 . The substrate of claim 13 , wherein the coating has a thickness of from about 50 microns to about 500 microns

15 . The substrate of claim 13 , wherein the coating of the release agent comprises a plurality of coating layers.

16 . The substrate of claim 13 , wherein a coating comprises a first coating layer of the release agent, and a second coating layer of the release agent.

17 . The substrate of claim 16 , wherein the first coating layer has a thickness of from about 0.25 to about 25 microns.

18 . A method of forming a shaped metal article comprising:

providing an apparatus defining a mold cavity to form a shaped article, wherein a surface of the mold cavity comprises a coating of the release agent of claim 1 ;

supplying a metal to the mold cavity;

forming a shaped article; and

removing the article from the cavity.

19 . The method of claim 18 , wherein the metal comprises aluminum, iron, an iron aluminum alloy, or a combination of two or more thereof.

20 . A method of processing a metal to produce a metal article via a mold, shot sleeve, transition plate, thimble, ladle, launder joint, side wall arm, dummy block, billet, die bearing, shear blade, piercing mandrel, die surface, work piece coating, nozzle, or degassing tube, wherein the release agent of claim 1 is applied as a coating on the mold, shot sleeve, transition plate, thimble, ladle, launder joint, side wall arm, dummy block, billet, die bearing, shear blade, piercing mandrel, die surface, work piece coating, nozzle, or degassing tube.

21 . (canceled)