Impregnation of grinding wheels using supercritical fluids
View Patent ↗An additive impregnated abrasive article and method for fabricating the same is provided. The method includes providing an abrasive article having a pore structure, dissolving an additive in a supercritical fluid, and exposing the abrasive article to the additive-laden supercritical fluid, so that the fluid disperses through the pore structure. The supercritical fluid is then brought to below its critical point for a period of time sufficient to dissociate the additive from the fluid, so that the additive is deposited within the pore structure of the abrasive article.
1. A method for fabricating a heterogeneous additive impregnated abrasive article, said method comprising:
a) providing a heterogeneous abrasive article having a pore structure;
b) dissolving an additive in a supercritical fluid, wherein the additive is selected from the group consisting of: alkanes, C16-C40 alkanes and their non-polar derivatives, C10 or greater cycloalkanes and their non-polar derivatives, C10 or greater alkenes and their non-polar derivatives, C10 or greater arenes and their non-polar derivatives, alkanes with molecular structures greater than n-octadecane (C18H38), cycloalkanes, cyclic paraffins, non-polar derivatives of cycloalkanes that have melting points in excess of about 50 degrees Celsius, arenes, aromatic hydrocarbons, biphenyl (C12H10), non-polar derivatives of arenes, butyl carbamate, non-polar sulfur containing compounds, non-polar polyethylenes, fluoropolymers, polytetrafluoroethylene, tetracosane (C 24 H 50 ), lipids, hydrocarbons, waxes, fluoropolymer resins, dyes, paraffin wax, camauba wax, and mixtures thereof;
c) exposing the abrasive article to the additive-containing supercritical fluid in a reaction vessel at a pressure in excess of atmospheric pressure, whereby the additive is carried into the pore structure; and
d) depressurizing the reaction vessel to dispose the supercritical fluid below its critical point for a period of time sufficient to dissociate the additive from the fluid, whereby the additive is deposited within the pore structure.
2. The method of claim 1 , wherein the abrasive article is substantially insoluble in the supercritical fluid.
3. The method of claim 2 , wherein the abrasive article comprises abrasive grain and bond material.
4. The method of claim 3 , wherein the bond is selected from the group consisting of inorganic, organic, and metallic bonds.
5. The method of claim 4 , wherein the bond comprises vitrified bond material.
6. The method of claim 4 , wherein the abrasive article comprises resinous bond material.
7. The method of claim 6 wherein the resinous bond material comprises a resin selected from the group consisting of phenolic resins, epoxy resins, unsaturated polyester resins, bismaleimide resins, polyimide resins, cyanate resins, melamine polymers, and mixtures thereof.
8. The method of claim 3 wherein said abrasive grain comprises an abrasive grain selected from the group consisting of diamond, cubic boron nitride, fused alumina, sintered alumina, sintered sol gel alumina, alumina-zirconia, alumina-oxynitrides, silicon carbide, fused or sintered alloys of alumina with at least one ceramic oxide selected from the group consisting of M g O, C O O, TiO 2 , V 2 O 3 Cr 2 O 3 , tungsten carbide and combinations thereof.
9. The method of claim 3 wherein said abrasive grain comprises an average particle size ranging from:
greater than or equal to about 0.5 microns; and
less than or equal to about 5000 microns.
10. The method of claim 3 , wherein the abrasive article comprises superabrasive grain.
11. The method of claim 1 , wherein said dissolving b) and said exposing c) further comprise heating the vessel.
12. The method of claim 1 , wherein said abrasive article is cured prior to said exposing c) of said article to said additive-containing supercritical fluid.
13. The method of claim 12 , wherein said disposing d) further comprises lowering the temperature of the vessel.
14. The method of claim 1 wherein said additive comprises a non-polar organic material.
15. The method of claim 1 wherein said additive is selected from the group consisting of: alkanes; C16-C40 alkanes and their non-polar derivatives; C10 or greater cycloalkanes and their non-polar derivatives, C10 or greater alkenes and their non-polar derivatives, C10 or greater arenes and their non-polar derivatives, lipids, hydrocarbons, waxes, fluoropolymer resins, and mixtures thereof.
16. The method of claim 15 wherein said additive comprises tetracosane.
17. The method of claim 15 wherein said additive comprises wax.
18. The method of claim 1 wherein the supercritical fluid is selected from the group consisting of CO 2 , ethane, propane, butane, H 2 O, and combinations thereof.
19. The method of claim 1 wherein said supercritical fluid comprises carbon dioxide.