Patent EA-003524-B1 (EA)
Title: Thin-walled monolithic metal oxide structures made from metals, and methods for manufacturing such structures
Inventor: SHUSTOROVICH EUGENE
IPC: C23C8/18
Filed: 1997-04-29
Abstract: 1. A method for making a monolithic metal oxide structure, said method comprising the steps of: -providing a structure containing a metal selected from the group consisting of iron, nickel, titanium, and copper, wherein the metal-containing structure contains a plurality of surfaces in close proximity to on another, and -heating the metal-containing structure in an oxidative atmosphere at a temperature below the melting point of the metal while maintaining the close proximity of the metal surfaces to uniformly oxidize the structure and directly transform the metal to metal oxide. 2. A method according to claim 1, wherein the oxidative atmosphere is air. 3. A method according to claim 1, wherein the metal is iron, and the metal-containing structure is heated below about 1500 degree C to oxidize the iron substantially to hematite. 4. A method according to claim 3, wherein the iron-containing structure is heated between about 750 degree C and about 1200 degree C. 5. A method according to claim 4, wherein the iron-containing structure is heated between about 800 degree C and about 950 degree C. 6. A method according to claim 1, wherein the metal is nickel, and the metal-containing structure is heated below about 1400 degree C to oxidize the nickel substantially to bunsenite. 7. A method according to claim 6, wherein the nickel-containing structure is heated between about 900 degree C and about 1200 degree C. 8. A method according to claim 7, wherein the structure is heated between about 950 degree C and about 1150 degree C. 9. A method according to claim 1, wherein the metal is copper, and the structure is heated below about 1000 degree C to oxidize the copper substantially to tenorite. 10. A method according to claim 9, wherein the structure is heated between about 800 degree C and about 1000 degree C. 11. A method according to claim 10, wherein the structure is heated between about 900 degree C and 950 degree C. 12. A method according to claim 1, wherein the metal is titanium, and the structure is heated below about 1600 degree C to oxidize the titanium substantially to rutile. 13. A method according to claim 12, wherein the titanium-containing structure is heated between about 900 degree C and about 1200 degree C. 14. A method according to claim 13, wherein the structure is heated between about 900 degree C and about 950 degree C. 15. A method for making a magnetite structure comprising providing a structure consisting essentially of plain steel having a plurality of surfaces in close proximity to one another, transforming the plain steel structure to a hematite structure by heating the plain steel structure in an oxidative atmosphere between about 750 degree C and about 1200 degree C while maintaining the close proximity of the steel surfaces to oxidize the plain steel structure such that the hematite structure retains substantially the same physical shape as the plain steel structure, and then de-oxidizing the hematite structure to a magnetite structure by heating the hematite structure in a vacuum between about 1000 degree C to about 1300 degree C such that the magnetite structure retains substantially the same shape, size and wall thickness as the hematite structure. 16. A method according to claim 15, wherein the vacuum pressure is about 0.001 atmospheres. 17. A method according to claim 16, wherein the iron is oxidized to hematite by heating the plain steel structure between about 800 degree C and about 950 degree C, and the hematite is deoxidized to magnetite by heating the hematite structure to between about 1200 degree C and about 1250 degree C. 18. A monolithic metal oxide structure comprising a plurality of adjacent bonded surfaces, obtained from oxidizing a metal-containing structure having a plurality of surfaces in close proximity to one another, containing a metal selected from the group consisting of iron, nickel, copper, and titanium, by heating the metal-containing structure below the melting point of the metal, the monolithic metal oxide structure having substantially the same physical shape as the metal-containing structure. 19. A thin-walled monolithic flow divider consisting essentially of a metal oxide selected from the group consisting of iron oxides, nickel oxides, titanium oxides, and copper oxides, the flow divider having a wall thickness less than about one millimeter. 20. A flow divider according to claim 19, wherein the metal oxide is an iron oxide selected from the group consisting of hematite, magnetite, and combinations thereof. 21. A flow divider according to claim 20, wherein the wall thickness is about 0.07 to about 0.3 mm. 22. An open-celled monolithic metal oxide structure comprising a plurality of adjacent bonded corrugated layers 86 made of a metal oxide selected from the group consisting of iron oxides, nickel oxides, copper oxides and titanium oxides, wherein the metal oxide structure is obtained by oxidizing adjacent corrugated metal layers containing a metal selected from the group consisting of iron, nickel, copper and titanium, by heating the metal-containing structure below the melting point of the metal. 23. An open-celled structure according to claim 22, wherein the metal oxide is an iron oxide selected from the group consisting of hematite, magnetite, and combinations thereof. 24. An open-celled structure according to claim 23, wherein cells of the corrugated layers are triangular in shape, and adjacent corrugated layers are stacked while mirror reflected. 25. An open-celled structure according to claim 24, wherein at least some of the triangular corrugated layers comprise parallel channels positioned at an angle alpha to a flow axis which bisects the angle formed by the parallel channels of adjacent corrugated layers. 26. An open-celled structure according to claim 25, wherein the parallel channels of a first corrugated layer are positioned to intersect at an angle 2alpha to the parallel channels of a second corrugated layer. 27. An open-celled structure according to claim 26, wherein the angle alpha is from 10 degree to 45 degree . 28. An open-celled structure according to claim 24, wherein the triangular cells are formed with a triangle apex angle of about 60 degree to about 90 degree . 29. An open-celled structure according to claim 28, wherein the corrugated layers have a cell density of about 250 to about 1000 cells/in<2>. 30. An open-celled structure according to claim 22, wherein the thickness of each corrugated metal layer is about 0.025 to about 0.1 mm. 31. A method of making an open-celled monolithic metal oxide structure comprising providing a plurality of adjacent corrugated layers in close proximity to one another made of a metal selected from the group consisting of iron, nickel, copper, and titanium, and oxidizing the metal by heating the layers below the melting point of the metal while maintaining the close proximity of the layers to form bonded adjacent corrugated metal oxide layers selected from the group consisting of iron oxides, nickel oxides, copper oxides and titanium oxides. 32. A method according to claim 31, wherein the metal is iron, and the metal oxide formed is selected from the group consisting of hematite, magnetite, and combinations thereof. 33. A method according to claim 32, wherein the corrugated metals layers are triangular in shape, and adjacent layers are stacked while mirror reflected. 34. A method according to claim 33, wherein at least some of the triangular corrugated metal layers comprise parallel channels positioned at an angle alpha to a flow axis which bisects the angle formed by the parallel channels of adjacent corrugated layers. 35. A method according to claim 34, wherein the parallel channels of a first corrugated layer are positioned to intersect at an angle 2alpha to the parallel channels of a second corrugated layer. 36. A method according to claim 35, wherein the angle alpha is from 10 degree to 45 degree . 37. A method according to claim 33, wherein the triangular cells are formed with a triangle apex angle 6 of about 60 degree to about 90 degree . 38. A method according to claim 37, wherein the corrugated metal layers have a cell density of about 250 to about 1000 cells/in<2>. 39. A method according to claim 33, wherein a pressure of up to about 50 gm/cm<2> is applied to the corrugated metal layers during heating to maintain the close proximity of the layers. 40. A method according to claim 31, wherein the thickness of each corrugated metal layer is about 0.025 to about 0.1 mm. 41. A method of making a metal oxide filter comprising providing a metal source containing a plurality of metal filaments in close proximity to one another and selected from the group consisting of one or more of iron, nickel, copper, and titanium filaments, and heating the metal filaments in an oxidative atmosphere below the melting point of the metal while maintaining the close proximity of the filaments to oxidize the filaments and directly transform the metal to metal oxide, wherein the metal oxide structure retains substantially the same physical shape as the metal source. 42. A method according to claim 41, wherein the metal is iron. 43. A method according to claim 42, wherein the filaments have a diameter of about 10 to about 100 microns. 44. A method according to claim 43, wherein the metal source is selected from the group consisting of felts, textiles, wools, and shavings. 45. A method according to claim 44, wherein a pressure of up 91 to about 30 gm/cm<2> is applied to the metal source during heating to maintain the close proximity of the filaments. 46. A method according to claim 42 wherein the iron filaments are heated between about 750 degree C and about 1200 degree C to oxidize the iron to hematite. 47. A method according to claim 46, wherein the iron filaments are heated between about 800 degree C and about 950 degree C. 48. A method according to claim 42, wherein the iron source consists essentially of plain steel