Electrically conductive fibers of Ti4O7 and Ti5O9

• US 20050029715A1
• Filed: 01/09/2004
• Published: 02/10/2005
• Est. Priority Date: 01/10/2003
• Status: Active Grant

• Current Assignee: Advanced Power Devices Incorporated
• Original Assignee: Advanced Power Devices Incorporated
• Inventors: Shelleman, David L., Tressler, Richard E., Adair, James H., Anderson, Julie M.
• Granted Patent: US 7,232,558 B2
• Time in Patent Office: Days
• US Class Current: 264/623
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3227 Lanthanum oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3244 Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3251 Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3256 Molybdenum oxides, molybdates or oxide forming salts thereof, e.g. cadmium molybdate
• CPC Class Codes: C04B 2235/3258 Tungsten oxides, tungstates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3262 Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
• CPC Class Codes: C04B 2235/3272 Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
• CPC Class Codes: C04B 2235/3275 Cobalt oxides, cobaltates or cobaltites or oxide forming salts thereof, e.g. bismuth cobaltate, zinc cobaltite
• CPC Class Codes: C04B 2235/3279 Nickel oxides, nickalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3281 Copper oxides, cuprates or oxide-forming salts thereof, e.g. CuO or Cu2O
• CPC Class Codes: C04B 2235/3286 Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
• CPC Class Codes: C04B 2235/3287 Germanium oxides, germanates or oxide forming salts thereof, e.g. copper germanate
• CPC Class Codes: C04B 2235/3293 Tin oxides, stannates or oxide forming salts thereof, e.g. indium tin oxide [ITO]
• CPC Class Codes: C04B 2235/3418 Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
• CPC Class Codes: C04B 2235/449 Organic acids, e.g. EDTA, citrate, acetate, oxalate
• CPC Class Codes: C04B 2235/5409 : expressed by specific surface values
• CPC Class Codes: C04B 2235/5454 : nanometer sized, i.e. below 100 nm
• CPC Class Codes: C04B 2235/6021 : Extrusion moulding
• CPC Class Codes: C04B 2235/652 : Reduction treatment C04B2235/664 takes precedence
• CPC Class Codes: C04B 2235/6582 : Hydrogen containing atmosphere
• CPC Class Codes: C04B 2235/664 : Reductive annealing
• CPC Class Codes: C04B 2235/79 : Non-stoichiometric products, e.g. perovskites (ABO3) with an A/B-ratio other than 1
• CPC Class Codes: C04B 2235/96 : Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 35/62259 : Fibres based on titanium oxide
• CPC Class Codes: C04B 35/6263 : characterised by their solids loadings, i.e. the percentage of solids
• CPC Class Codes: C04B 35/63 : using additives specially adapted for forming the products , e.g.. binder binders
• CPC Class Codes: C04B 35/632 : Organic additives
• CPC Class Codes: C04B 35/64 : Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: D01F 9/08 : of inorganic material working or processing of metal wire B21F; from softened glass, minerals or slags C03B37/00

Abstract

Solid, shaped and fired fibers of Ti₄O₇ and Ti₅O₉ are made by firing TiO₂ fibers in a reducing atmosphere. In a first aspect, the TiO₂ fibers are made by extruding into air a viscous TiO₂ gel and heat treating the resulting green fibers to remove solvent, decompose and to volatilize undesired constituents to form electrically conductive, refractory fibers of Ti₄O₇ and Ti₅O₉. In a second aspect, solid, shaped and fired fibers of Ti₄O₇ and Ti₅O₉ are made by firing extruded fibers from mixtures of TiO₂.

Claims

1. A method of manufacture of conductive refractory fibers comprising,

reacting an amount of a source of titanium with an amount of an acid to produce a sol comprising Titania and a liquid component,

evaporating the liquid component of the sol to produce a Titania gel

extruding the gel to produce a green fiber comprising titania,

drying the green fiber to produce a dried fiber comprising titania, and

firing the dried fiber in a mixture of flowing reducing gases to produce a conductive, refractory fiber that comprises a titanium oxide compound selected from the group consisting of Ti₄O₇ and Ti₅O₉.

2. The method of claim 1 wherein the source of titanium is a titanium alkoxide.

3. The method of claim 2 wherein the titanium alkoxide is titanium (IV) isopropoxide.

4. The method of claim 1 wherein the source of titanium is a titanium salt selected from the group consisting of titanium acetylacetonates, titanium naphthalates, and titanium octylates.

5. The method of claim 3 wherein the titanium (IV) isopropoxide has a purity of about 97% or greater.

6. The method of claim 5 wherein the acid is selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, lactic acid and acetic acid.

7. The method of claim 5 wherein the acid is hydrochloric acid.

8. The method of claim 7 wherein the hydrochloric acid has a temperature of about 0°

C. to about 10°

C.

9. The method of claim 7 wherein the hydrochloric acid has a temperature of about 0°

C. to about 5°

C.

10. The method of claim 7 wherein the hydrochloric acid has a temperature of about 0°

C.

11. The method of claim 7 wherein the hydrochloric acid has a temperature of about has a molarity of about 11.97 M to about 12.4 M.

12. The method of claim 3 wherein the acid is hydrochloric acid and wherein the amount of hydrochloric acid and the amount of Ti (IV) isopropoxide are present in a ratio of hydrochloric acid to Ti (IV) isopropoxide of about 1:

4.5 to about 1;

5.5.

13. The method of claim 3 wherein the acid is hydrochloric acid and

wherein the amount of hydrochloric acid and the amount of Ti(IV)isopropoxide are present in a ratio of hydrochloric acid to Ti(IV)isopropoxide of about, preferably from about 1:

1 to about 4;

1.

14. The method of claim 3 wherein the acid is hydrochloric acid and

wherein the amount of hydrochloric acid and the amount of Ti (IV) isopropoxide are present in a ratio of hydrochloric acid to Ti (IV) isopropoxide of about 1:

1 to about 5;

1.

15. The method of claim 1 wherein the titanium source includes a metal dopant.

16. The method of claim 15 wherein the metal dopant includes a metal selected from the group consisting of Yttrium, Niobium and Tantalum.

17. The method of claim 16 wherein the metal dopant is an inorganic metal compound selected from the group consisting of Yttrium nitrate, Niobium nitrate and Tantalum nitrate.

18. The method of claim 15 wherein the metal dopant is an organic metal compound selected from the group consisting of metal alkoxides, alkaline metal compounds, metal acetyl acetonates, naphthene acid metal salts, transition metal octylates and oxtyl acid metal salts.

19. The method of claim 15 wherein the metal dopant is a transition metal alkoxide.

20. The method of claim 15 wherein the metal dopant is an alkaline metal compound is aluminum hydroxide.

21. The method of claim 15 wherein the metal dopant is a transition metal acetylacetonates.

22. The method of claim 15 wherein the metal dopant is a transition metal napthalates.

23. The method of claim 15 wherein the metal dopant is a transition metal octylates.

24. The method of claim 15 wherein the metal dopant is a oxtyl acid metal salt of a metal selected from the group consisting of aluminum, silicon, zirconium, tantalum, magnesium, indium, tin, molybdenum, tungsten and germanium.

25. The method of claim 19 wherein the transition metal alkoxide is selected from the group consisting of Mn(OC₂H₅)₂, Mn(OC₃H₇)₂, Mn(OC₄H₉)₂, Ni(OC₂H₅), Ni(OC₃H₂, Ni(OC₄H₉)₂, Co(OC₂H₉)₂, CO(OC₃H₇)₂, Co(OC₄H₉)₂, Fe(OC₂H₅)₂, Fe(OC₃H₇)₂, Fe(OC₄H₉)₂, Cu(OC₂H₅)₂, Cu(OC₃H₇)₂, Cu(OC₄H₉)₂, VO(OCH₃)₃, VO(OC₂H₅)₃, VO(OC₃H₇)₃, VO(OC₄H₉)₃ and Y(OC₄H₉)₃.

26. The method of claim 21 wherein the transition metal acetylacetonates is selected from the group consisting of Cu(C₅H₇O₂)₂, Co(C₅H₇O₂)₂, (H₂O)₂, Co(C₅H₇O₂)₃, Ni(C₅H₇O₂)₂ (H₂O)₂, Mn(C₃H₇O₂)₂ (H₂O)₂, Cr(C₅H₇O₂)₃, VO(C₅H₇O₂)₂, Fe(C₅H₇O₂)₃, La(C₅H₇O₂)₃, Y(C₅H₇O₂)₃, and Zr(C₅H/O₂)₄.

27. The method of claim 23 wherein the transition metal octylates is selected from the group consisting of Cu(C₇H₁₅COO)₂, Ni(C₇H₁₅COO)₂, Fe(C₇H₁₅COO) Mn(C₇H₁₅COO)₂, Co(C₇H₅COO)₂, Zr(C₇H₅COO)₂, Y(C₇H₁₅COO) and La(C₇H₁₅COO)₂.

28. The method of claim 18 wherein the naphthene acid metal salt is a transition metal napthalates selected from the group consisting of cobalt naphthenate, copper naphthenate, manganese naphthenate, iron naphthenate, nickel naphthenate, vanadium naphthenate, yttrium naphthenate and lanthanum naphthenate.

29. The method of claim 1 wherein the liquid component evaporated by using a rotary evaporator.

30. The method of claim 1 wherein the extruding comprises an initial extruding at a first rate and a continuous extrusion at a second rate, wherein the first rate is about 2 to about 10 times greater than the rate of continuous extrusion.

31. The method of claim 1 wherein the extruding comprises an initial extruding at a first rate and a continuous extrusion at a second rate, wherein the first rate is about 2 to about 10 times greater than the rate of continuous extrusion.

32. The method of claim 1 wherein the extruding comprises an initial extruding at a first rate and a continuous extrusion at a second rate, wherein the first rate is about 5 times greater than the rate of continuous extrusion.

52. The method of claim 1 wherein the mixture of reducing gases includes CO/N₂ and CO₂/N₂.

54. The method of claim 1 wherein the mixture of reducing gases includes a first composition of 50% CO/50% N₂ and a second composition of 1% CO/99% N₂.

56. The method of claim 52 wherein the mixture of reducing gases flows at a rate of about 100 SCCM to about 1000 SCCM.

58. The method of claim 1 wherein the fibers are heated at about 1°

C./min. to about 10°

C./min. to a firing temperature of about 1050°

C. to about 1300°

C., held at the firing temperature for about 8 hr. to about 16 hrs, cooled at a rate of about 20°

C./min. to about 50°

C./min. to an intermediate temperature of about 600°

C. to about 800°

C., and then cooled to room temperature.

33. A method of manufacture of conductive refractory fibers comprising,

extruding the gel to produce a green fiber comprising titania,

drying the green fiber to produce a dried fiber comprising titania, and

firing the dried fiber in a mixture of flowing reducing gases to produce a conductive, refractory fiber that comprises a titanium oxide compound selected from the group consisting of Ti₄O₇ and Ti₅O₉.

34. A method of manufacture of conductive refractory fibers comprising,

forming a mixture comprising titania particles, organic binder, dispersant, and a liquid,

extruding the mixture to produce a green fiber comprising titania,

drying the green fiber to produce a dried fiber comprising titania, and

firing the dried fiber in a reducing atmosphere to produce a conductive, refractory fiber,

wherein the conductive, refractory fiber comprises a titanium oxide compound selected from the group consisting of Ti₄O₇ and Ti₅O₉.

35. The method of claim 34 wherein the mixture, prior to extrusion into a green fiber, is treated with a base selected from the group consisting of tetraethylammonium hydroxide, ammonium hydroxide, sodium hydroxide and potassium hydroxide.

36. The method of claim 34 wherein the mixture, prior to extrusion into a green fiber, is treated with a base selected from the group consisting of tetraethylammonium hydroxide and ammonium hydroxide

37. The method of claim 34 wherein the mixture, prior to extrusion into a green fiber, is treated with tetraethylammonium hydroxide to raise the pH of the mixture to about pH 5.

38. The method of claim 34 wherein the titania particles have an average particle size of about 50 nm to about 320 nm.

39. The method of claim 34 wherein the liquid is selected from the group consisting of distilled water and alcohol.

40. The method of claim 34 wherein the liquid is alcohol is selected from the group consisting of isopropyl alcohol, ethanol and methanol.

41. The method of claim 34 wherein the dispersant is selected from the group consisting of polyethylene imine, polyvinylpyrrolidone, ammonium polymethacrylate and polyacrylic acid.

42. The method of claim 34 wherein the organic binder is selected from the group consisting of polyvinylalchol, polyvinylpyrrolidone, dibutyl phthalate and latex acryloids.

43. The method of claim 34 wherein the Titania particles are present in the mixture in an amount of about 35 to about 50 vol % based on total volume of the mixture.

44. The method of claim 34 wherein the Titania particles are present in the mixture in an amount of about 45 to about 50 vol % based on total volume of the mixture.

45. The method of claim 34 wherein the Titania particles are present in the mixture in an amount of about 45 vol % based on total volume of the mixture.

46. The method of claim 43 wherein the organic binder is present in the mixture in an amount of about 3 wt. % to about 12 wt % based on total weight of the mixture.

47. The method of claim 43 wherein the organic binder is present in the mixture in an amount of about 4 wt. % to about 7 wt % based on total weight of the mixture.

48. The method of claim 43 wherein the organic binder is present in the mixture in an amount of about 5 wt. % based on total weight of the mixture.

49. The method of claim 46 wherein the liquid is present in the mixture in an amount of about 50 vol % to about 65 vol % based on total volume of the mixture.

50. The method of claim 46 wherein the liquid is present in the mixture in an amount of about 50 vol % to about 60 vol % based on total volume of the mixture.

51. The method of claim 46 wherein the liquid is present in the mixture in an amount of about 55 vol % based on total volume of the mixture.

53. The method of claim 34 wherein the mixture of reducing gases includes CO/N₂ and CO₂/N₂.

55. The method of claim 34 wherein the mixture of reducing gases includes a first composition of 50% CO/50% N₂ and a second composition of 1% CO/99% N₂.

57. The method of claim 53 wherein the mixture of reducing gases flows at a rate of about 100 SCCM to about 1000 SCCM.

59. The method of claim 34 wherein the fibers are heated at about 1°

C./min. to about 10°

C./min. to a firing temperature of about 1050°

C. to about 1300°

C., held at the firing temperature for about 8 hr. to about 16 hrs, cooled at a rate of about 20°

C./min. to about 50°

C./min. to an intermediate temperature of about 600°

C. to about 800°

C., and then cooled to room temperature.

60. A method of manufacture of Ti₄O₇ conductive refractory fibers comprising,

reacting an amount of titanium (IV) isopropoxide with an amount of HCl to produce a sol comprising titania and a liquid component, wherein the titanium (IV) isopropoxide is present in an amount that is about five times the amount of HCl,

evaporating the liquid component of the sol to produce a Titania gel

extruding the gel to produce a green fiber comprising titania,

drying the green fiber to produce a dried fiber comprising titania, and

firing the dried fiber in a mixture of flowing reducing gases to produce a conductive, refractory fiber that comprises Ti₄O₇.

61. The method of claim 60 wherein the HCl has a temperature of about 0°

C.

62. polyethylene imine The method of claim 60 wherein the flowing reducing gases include a first composition of 50% CO/50% N₂ and a second composition of 1% CO/99% N₂

63. The method of claim 63 wherein the firing of the dried fibers comprises heating the dried fibers at 10°

C./min up to 1067°

C., holding the fibers at 1067°

C. for 12 hours and cooling to room temperature at 20°

C./minute.

64. A method of manufacture of conductive refractory fibers comprising,

forming a mixture comprising Titania particles which have an average particle size of 320 microns, polyethylene imine and distilled water,

extruding the mixture to produce a green fiber comprising titania,

drying the green fiber to produce a dried fiber comprising titania, and

firing the dried fiber in a reducing atmosphere to produce a conductive, refractory fiber comprising Ti₄O₇.

65. The method of claim 65 wherein the Titania particles, polyethylene imine and distilled water are present in a ratio of Titania:

polyethylene imine;

water is about 40;

1;

19.

66. The method of claim 65 wherein the mixture is extruded at an initial rate of about 50 cm/sec and then at a continuous rate of about 10 cm/sec.

67. The method of claim 67 wherein the flowing reducing gases include a first composition of 50% CO/50% N₂ and a second composition of 1% CO/99% N₂

68. The method of claim 68 wherein the firing of the dried fibers comprises heating the dried fibers at 10°

C./min up to 1067°

C., holding the fibers at 1067°

C. for 12 hours and cooling to room temperature at 20°

C./minute.

69. A method of manufacture of conductive refractory fibers comprising,

forming a mixture comprising Titania particles which have an average particle size of 50 nanometer, polyethylene imine, and distilled water,

extruding the mixture to produce a green fiber comprising titania,

drying the green fiber to produce a dried fiber comprising titania, and

firing the dried fiber in a reducing atmosphere to produce a conductive, refractory fiber comprising Ti₄O₇.

70. The method of claim 70 wherein the Titania particles, polyethylene imine and distilled water are present in a ratio of Titania:

polyethylene imine;

water of about 20;

1;

6.1.

71. The method of claim 71 wherein the mixture is extruded at an initial rate of about 50 cm/sec and then at a continuous rate of about 10 cm/sec.

72. The method of claim 71 wherein the flowing reducing gases include a first composition of 50% CO/50% N₂ and a second composition of 1% CO/99% N₂

73. The method of claim 71 wherein the firing of the dried fibers comprises heating the dried fibers at 10°

C./min up to 1067°

C., holding the fibers at 1067°

C. for 12 hours and cooling to room temperature at 20°

C./minute.