APPARTUS AND METHOD FOR PRODUCING SPUTTER-DEPOSITED COATINGS ON FLUIDIZED PARTICLE BEDS

Abstract

A method and an apparatus for producing metal and ceramic coatings on a fluidized bed of particles or fibers are described. The method utilizes a unique apparatus to transfer vibratory motion through a wall of a deposition chamber in order to produce a fluidized bed of particle or fluidized bed of fibers inside the chamber. The method and apparatus are versatile, allowing particles of different shapes, sizes, materials and masses to be fluidized and coated. The fluidization process allows uniform and conformal coatings on particles and fibers. Coatings of pure metals, alloys, or ceramic materials can be produced.

Claims

1.-22. (canceled)

23. An apparatus for physical vapor deposition of a coating onto a plurality of particles or fibers, the apparatus comprising: a holder in a chamber, a vacuum for reducing the pressure inside the chamber, a means for generating vibration external to the chamber, a sealed, mechanical linkage that extends through a wall of the chamber that is connected to the holder through the wall of the chamber, and a means for depositing a metal coating or a ceramic coating onto a plurality of particles or fibers in the holder.

24. The apparatus of claim 22 wherein the means for generating vibration is selected from the group consisting of electromagnetic and piezoelectric shakers.

25. The apparatus of claim 22 wherein the sealed, mechanical linkage comprises a rotary feed-through that transmits the vibration that is generated external to the chamber by the means for generating vibration through a wall of the chamber to the holder inside of the chamber while maintaining reduced pressure inside of the chamber.

26. The apparatus of claim 22 wherein the mechanical linkage comprises an angled metal or an angled composite rod.

27. The apparatus of claim 22 wherein the mechanical linkage comprises a first rigid angled rod that is coupled to the means for generating vibrations, a first shaft coupler rigidly connecting first rigid angled rod to a vacuum-rated rotary motion feedthrough, a second shaft coupler rigidly coupling the feedthrough to a second rigid metal rod that is rigidly connected to the holder.

28. The apparatus of claim 22 wherein the chamber includes more than one deposition source.

29. The apparatus of claim 22 wherein the means for generating vibrations and the sealed, mechanical linkage that extends through a wall of the chamber generates a vibrofluidized bed of particles or fibers.

30. The apparatus of claim 22 wherein said vacuum for reducing the pressure inside the chamber reduces the pressure inside the chamber below 10.sup.3 Torr.

31. The apparatus of claim 22 wherein said vacuum for reducing the pressure inside the chamber reduces the pressure inside the chamber below 10.sup.9 Torr.

32. The apparatus of claim 22 wherein said vacuum for reducing the pressure inside the chamber reduces the pressure inside the chamber below 10.sup.9 Torr.

33. The apparatus of claim 22 wherein said means for depositing a metal coating or a ceramic coating onto a plurality of particles or fibers in the holder is selected from the group consisting of physical vapor deposition, DC magnetron sputtering, RF magnetron sputtering, ion-beam assisted sputtering, high-power impulse magnetron sputtering and evaporation deposition sources.

34. The apparatus of claim 22 wherein said means for depositing a metal coating or a ceramic coating onto a plurality of particles or fibers in the holder includes DC magnetron sputtering.

35. The apparatus of claim 22 wherein said means for generating vibration external to the chamber shakes said holder between 2 and 1000 Hz.

36. The apparatus of claim 22 wherein said means for generating vibration external to the chamber that vibrates said holder at greater than 1000 Hz, at least 5 lbf and at least 0.25-inch peak-to-peak displacement.

37. The apparatus of claim 22 wherein said sealed, mechanical linkage that extends through a wall of the chamber that is connected to the holder through the wall of the chamber transfers vibratory motion through a wall of said chamber to said holder.

38. The apparatus of claim 22 wherein said means for depositing a metal coating or a ceramic coating onto a plurality of particles or fibers in the holder includes physical vapor deposition.

39. The apparatus of claim 22 wherein said sealed, mechanical linkage that extends through a wall of the chamber that is connected to the holder through the wall of the chamber comprises a ferro-magnetic fluid rotary feedthrough.

40. A composite material comprising coated particles produced by the apparatus of claim 23.

41. An apparatus for physical vapor deposition of a coating onto a plurality of particles or fibers, the apparatus comprising: a holder for particles or fibers in a chamber, a vacuum for reducing the pressure inside the chamber below 10.sup.3 Torr, a means for generating vibration external to the chamber that vibrates said holder between 2 and 1000 Hz, at least 5 lbf and at least 0.25-inch peak-to-peak displacement and that generates a vibrofluidized bed of particles or fibers, a rotary feed-through that transmits the vibration that is generated external to the chamber by the means for generating vibration through a wall of the chamber to the holder inside of the chamber while maintaining reduced pressure inside of the chamber and is connected to the holder through the wall of the chamber with a ferro-magnectic fluid rotary feedthrough, and a means for depositing a metal coating or a ceramic coating onto a plurality of the particles or fibers in the holder.

42. The apparatus of claim 41 further comprising a sealed, mechanical linkage that extends through a wall of the chamber that is connected to the holder through the wall of the chamber comprises a ferro-magnectic fluid rotary feedthrough.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0013] FIG. 1 illustrates a cross-sectional front view of one exemplary embodiment of system of the present invention.

[0014] FIG. 2 illustrates a cross-sectional plan view of the exemplary embodiment illustrated in FIG. 1.

[0015] FIG. 3 illustrates a close-up side view of an exemplary sample holder assembly.

DETAILED DESCRIPTION OF THE INVENTION

[0016] Embodiments of the present invention include methods for physical vapor deposition of one or more coatings onto a plurality of particles or fibers, that include: placing a plurality of particles or fibers in a holder in a chamber, sealing the chamber, reducing the pressure inside the chamber to create a vacuum, vibrating the holder and the plurality of particles or fibers in the holder with a means for generating vibration wherein the means for generating vibration is external to the chamber and is connected to the holder through the wall of the chamber via a sealed, mechanical linkage that extends through a wall of the chamber, and then depositing a metal or a ceramic coating onto the plurality of particles or fibers. Desirably, the magnitude and frequency of the vibrations is such that the particles or fibers vibrate in a fluid-like, random motion that facilitates physical deposition.

[0017] FIG. 1 illustrates a cross-sectional, front view of one exemplary embodiment of system of the present invention. FIG. 2 illustrates a cross-sectional plan view of the exemplary embodiment illustrated in FIG. 1. The exemplary system consists of an assembly of devices that can be used together to deposit coatings onto a fluidized bed of particles. In FIGS. 1 and 2, vacuum chamber 8 is sectioned for clarity of illustration. The perspective of FIG. 2 is indicated on FIG. 1 by line A-A. The perspective of FIG. 1 is indicated on FIG. 2 by line B-B.

[0018] An exemplary apparatus of the present invention includes a shaker device 1 that produces controlled mechanical vibration. Suggested shaker devices 1 include, but are not limited to, an electromagnetic or piezoelectric shaker or any other known means of providing vibration. Generally, the shaker should be capable of providing shaking in the approximate range of 2-1000 Hz, at least 5 lbf, and at least 0.25-inch peak-to-peak displacement. A suggested commercially available shaker includes, but is not limited to, a PM25A shaker by MB Dynamics. The output head 1A of shaker device 1 is rigidly coupled to a first rigid angled rod 2. First rod 2 may be composed of metal or composite materials. A first shaft coupler 3A rigidly joins first rod 2 to a vacuum-rated rotary motion feedthrough 4. A second shaft coupler 3B rigidly couples feedthrough 4 to a second rigid metal rod 5. Second rod 5 is rigidly connected to the sample holder assembly 6. One or multiple deposition sources 7 are directed at sample holder 6. Exemplary deposition sources 7 include, but are not limited to, RF magnetron sputtering, DC magnetron sputtering, ion-beam assisted sputtering, HiPIM (high-power impulse magnetron) sputtering, and evaporation deposition sources. Desirably, coupler 3B, shaft 5 and sample holder assembly 6 are all completely contained within vacuum chamber 8. Desirably, the vacuum chamber can be operated at sub-atmospheric pressure, preferably below 10.sup.3 Torr and more preferably below 10.sup.6 Torr.

[0019] Shaker 1, shaft 2 and coupler 3A are all, desirably, completely outside of chamber 8. Rotary feedthrough 4 transfers motion through the chamber wall, and deposition source 7 may have power and water connections through the walls of chamber 8. Shaker 1 vibrates one end of rod 2, which becomes a rotational motion at the other end of rod 2. Coupler 3A transmits the rotational motion to feedthrough 4. Feedthrough 4 transmits the rotary motion through the wall of chamber 8, to coupler 3B. Preferably, the feedthrough is vacuum-rated to 10.sup.9 Torr or lower, and has a one-piece shaft, so that very small and very fast motion can be transmitted into the vacuum chamber. An exemplary feedthrough is a CF Flanged Solid ShaftKJLC Standard ferro-magnetic fluid rotary feedthrough purchased from Kurt J. Lesker Company of Jefferson Hills, Pa. that is designed to provide rotary motion under high vacuum. Coupler 3B transmits the rotary motion to one end of shaft 5. The other end of shaft 5 effectively vibrates in an up and down motion, thus vibrating the sample holder assembly 6, and ultimately creating a fluidized bed of particles 15. This arrangement simplifies shaker 1 selection, design and maintenance as the shaker does not require seals, oils, electronics, and other parts that can withstand high vacuum for extended periods of time.

[0020] FIG. 3 illustrates a close-up side view of an exemplary sample holder assembly 6, as indicated by the dashed line boxes in FIGS. 1 and 2. Rod 5 is rigidly attached to plate 10 by screw 9. Threaded posts 11 are rigidly attached to plate 10 by nuts 12. Sample container 14 sits inside posts 11, and is clamped to posts 11 by a hose clamp 13. Sample particles 15 or alternatively, fibers, are contained in container 14.

[0021] Suggested uses for particles produced by the methods and/or apparatus described herein include, but are not limited to, paint additives/pigments, reflective paints/coatings, dyes, metal matrix composites, polymer matrix composites, specialty metal alloys, specialty ceramics, time-release drugs, and passivated catalytic particles.

[0022] In exemplary embodiments, thin aluminum and/or tin oxide coatings were sputtered onto glass microspheres from 1-350 micrometers in diameter using DC magnetron sputtering. More specifically, metal coatings were sputtered onto glass microspheres having a size distribution of 212-250 micrometers in diameter (average diameter of about 230 m) and 1-75 micrometers in diameter (average diameter of about 35 m). Thus, suggested particle sizes include, but are not limited to, particles having an average major dimension between about 0.001 and about 25 millimeters and preferably particles having an average major dimension between about 1 and about 2000 microns. In certain embodiments, the particles have an aspect ratio of between about 10 and about 10,000. In other exemplary embodiments, metal coatings were deposited onto salt (NaCl) particles that were generally cubic in shape. Thus, the particles may be spherical, cubic, cylindrical, or prismatic. In certain embodiments, the particles are composed of ceramics. In still other embodiments, the particles are composed of oxides, nitrides, borides, or carbides. In other embodiments, the particles are composed of polymers. Suggested polymer particles include, but are not limited to, particles composed of polystyrene, polymethyl-methacrylate, polycarbonate, and polyvinylidene difluoride. Suggested fibers include, but are not limited to, glass fibers, carbon fibers, ceramic whiskers and so forth. In certain embodiments, the particle is water soluble. In certain embodiments, the particle is water reactive. In certain embodiments, the particle is oxygen reactive. And, in certain embodiments, the particle is scavengable such that after coating, the coated particle is placed in a scavenging environment to remove the particle and leave intact the coating as a free-standing shell, for example a thin metal coating can be deposited on a NaCl crystal and then the interior NaCl crystal dissolved with water to produce a cubic metal shell. In certain embodiments, the particle is selected from the group comprising NaCl, WCl.sub.6, WOClRuCl.sub.3.3H.sub.2O, Grubbs catalysts, and Schrock catalysts.

[0023] In some embodiments, the deposited coating is or at least includes a metal or a metal alloy. Suggested metal coatings include, but are not limited to, coatings that include Cu, Ag, Au, Al, Ni, Cr, Ti, and alloys that include any of the previously listed metals. Suggested metal coatings that provide a barrier that inhibits physical degradation of the particle due to environmental factors include, but are not limited to, coatings that consist of or otherwise include Cu, Ag, Au, Al, Ni, Cr, Ti, and alloys of the same. In certain other embodiments, the present invention provides a coated particle where the particle comprises a metal coating that provides increased electrical conductivity. In still other embodiments, the present invention provides a coated particle where the particle comprises a metal coating that provides a barrier that inhibits physical degradation of the particle due to environmental factors, for example humidity, oxygen, and corrosive chemicals. In yet other embodiments, the deposited coating is or otherwise comprises a ceramic. Suggested ceramic coatings include, but are not limited to, SiO.sub.2, Al.sub.2O.sub.3, SnO.sub.2, MgF.sub.2, TiO.sub.2, ZrO.sub.2, ZnS, MgO, AlN, SiN, BaTiO.sub.3, HfO.sub.2, Ta.sub.2O.sub.5 and so forth. In yet other embodiments, the present invention provides a coated particle where the particle comprises a ceramic coating that provides special optical properties, for example a spectral reflectivity band, a spectral absorption band, or anti-reflective properties. These special optical properties could be engineered over any part of the electromagnetic spectrum, for example within visible frequencies or infrared frequencies.

[0024] The present invention also provides a composite material and a method of making composite materials that include particles produced via the methods described herein and dispersed in a polymer matrix. The present invention also provides a composite material comprising particles produced via the methods described herein and dispersed in a metal matrix. And in other embodiments, the present invention provides a composite material comprising particles produced via the methods described herein and dispersed in a ceramic matrix.

[0025] Additional details of the invention may be found in a paper titled A fluidized-bed sputter deposition system for coating microparticles by Daniel M. Baechle, J. Derek Demaree, James K. Hirvonen and Eric D. Wetzel; a poster titled A Fluidized Bed Sputter Deposition System for Coating Microparticles that was presented by Daniel M. Baechle, J. Derek Demaree, James K. Hirvonen and Eric D. Wetzel at the Proceedings of the 54.sup.th annual Society of Vacuum Coaters Technical Conference in Chicago 2011; and a journal article titled Magnetron sputter deposition onto fluidized particle beds by D. M. Baechle, J. D. Demaree, J. K. Hirvonen, and E. D. Wetzel, in Surface and Coatings Technology, V221, p94-103, 2013. The previously listed documents and are hereby incorporated by reference herein.

[0026] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.