Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/002—Making metallic powder or suspensions thereof amorphous or microcrystalline
  • B22F9/008—Rapid solidification processing
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
  • C23C4/131—Wire arc spraying

Definitions

• This invention relates to a process for improving the properties of materials, and more particularly to a process for producing a metallic coating from a rapidly solidified metal.
• Spray metallizing consists of heating a metal to a molten or semi-molten condition by passing it through a high temperature heat source, and depositing it in a finely divided form on a substrate.
• the molten or semi-molten particles flatten out on impacting the substrate and adhere to its surface.
• Subsequently deposited particles also flatten out, and adhere to those previously deposited, thus the structure of sprayed deposits is lamellar.
• the sprayed metal deposits resemble the derivative wire or powder chemically, but their physical properties, especially their microstructure, are quite different from those of the original wrought metal. Cohesion is achieved through mechanical and metallurgical bonding.
• certain materials can be fused to form a dense and uniform coating that is metallurgically bonded to the substrate.
• Fused coatings usually are required for protecting the substrate material during service at high temperatures, in abrasive and corrosive environments, or for developing a surface of uniformly high hardness.
• sprayed aluminum coatings on steel require heating to above 482 ⁇ C to etallurgically bond the coating to the steel.
• the material may be subsequently heated at 732°C to 1093 ⁇ C to provide a dense, uniform coating metallurgically bonded to the base metal.
• the present invention provides an economical and efficient process for arc spraying aluminum base alloys in which no subsequent thermal treatment is required.
• properties as high temperature strength and stability, corrosion and oxidation resistance and compatibility with the substrate, of an aluminum spray metallized coating, are improved in accordance with the invention by arc spraying a rapidly solidified, high temperature aluminum alloy onto a designated substrate.
• This procedure referred to hereinafter as arc spraying, results in the formation of a high temperature spray metallized coating.
• Subsequent thermal treatments, such as heating the coating to above the solidus of the alloy, heretofore required to adhere the coating to the substrate are virtually eliminated.
• Deposition and retention of a rapidly solidified alloy onto a substrate are effected in a single process step.
• the coated substrate exhibits improved * 5 ambient and elevated temperature mechanical an physical properties due to the microstructure of the *- rapidly solidified coating.
• the invention provides a process for producing a rapidly solidified aluminum 10 base alloy coating, comprising the steps of:
• Wire having a diameter suitable for arc 15 spraying may be fabricated directly by a friction actuated process or by conventional wire drawing techniques, and sprayed onto a substrate using arc spraying techniques to form a nearly fully dense spray metallized coating. Moreover, the attractive 20 properties of the rapidly solidified wire are retained. This process may be repeated such that the subsequent spraying is done on top of the sprayed coating.
• the sprayed metal coatings may then be finished by typical metal finishing operations such 25 as machining, grinding, burnishing and polishing provided that the precautions usually followed for sprayed metallized coatings are followed. Also components having the spray metallized coatings can withstand moderate forming operations such as 30 drawing, spinning, brake and roll forming, and embossing.
• the arc sprayed coatings are suitable for use * in components requiring corrosion, oxidation and elevated temperature protection for use as aerospace 35 components such as turbine blades, turbine vanes and fasteners; automotive components such as exhaust pipes, intake valves and cylinder barrels; and industrial components such as heat exchangers, fasteners for chemical piping and boilers, reactor tubes, and heat treating equipment.
• aerospace 35 components such as turbine blades, turbine vanes and fasteners
• automotive components such as exhaust pipes, intake valves and cylinder barrels
• industrial components such as heat exchangers, fasteners for chemical piping and boilers, reactor tubes, and heat treating equipment.
• Applications such as molds appointed for subsequent casting may arise that specifically utilize the higher temperature capability, i.e. hardness, of the rapidly solidified coating.
• the arc sprayed layers can be used for repairing coatings as well as engineering shapes made directly from the rapidly solidified materials.
• the coating can be applied to a substrate to repair a surface defect thereof.
• the arc sprayed layers can also be used to make the preforms for various composite materials wherein the substrate consists of continuous or woven fibers, bundles, whiskers or particulate made from a hard or semi-hard material such as refractory carbides, oxides or nitrides.
• the rapidly solidified alloys may be combined with a reinforcing phase to form a composite a described in U.S. Patent Application Serial No. 242,989, filed September 12, 1988, which application is incorporated herein by reference thereto, prior to being formed into a wire.
• Fig. 1 is a scanning electron photomicrograph of the surface of a wire arc sprayed coating composed of rapidly solidified aluminum based iron, vanadium and silicon containing alloy uniformly deposited on planar flow cast aluminum based iron, vanadium and silicon containing ribbon fabricated by the present invention
• Fig. * 2 is an optical light photomicrograph of a cross section of a wire arc sprayed coating composed of rapidly solidified aluminum based iron, vanadium and silicon containing alloy deposited onto planar flow cast aluminum based iron, vanadium and silicon containing ribbon fabricated by the present invention
• Fig. 3 is a transmission electron photomicrograph of a wire arc sprayed coating composed of rapidly solidified aluminum based iron, vanadium and silicon containing alloy fabricated by the present invention.
• the aluminum base, rapidly solidified alloy appointed for use in the process of the present invention has a composition consisting essentially of the formula Al bal Fe a Si b X c wherein X is at least one element selected from the group consisting of Mn, V, Cr, Mo, W, Nb, Ta, "a" ranges from 1.5-8.5 at %, "b” ranges from 0.25-5.5 at %, "c” ranges from 0.05-4.25 at % and the balance is aluminum plus incidental impurities, with the proviso that the ratio [Fe+X]:Si ranges from about 2.0:1 to 5.0:1.
• the alloy include aluminum-iron-vanadium-silicon compositions wherein the iron ranges from about
• vanadium ranges from about 0.25-4.25 at %
• silicon ranges from about 0.5-5.5 at %.
• Another aluminum base, rapidly solidified alloy suitable for use in the process of the invention has a composition consisting essentially of the formula Al bal Fe a Si b X c wherein X is at least one element selected from the group consisting of Mn, V, Cr, Mo, W, Nb, Ta, "a" ranges from 1.5-7.5 at %, “b” ranges from 0.75-9.5 at %, “c” ranges from 0.25-4.5 at % and the balance is aluminum plus incidental impurities, with the proviso that the ratio [Fe+X]:Si ranges from about 2.01:1 to 1.0:1.
• Still another aluminum base, rapidly solidified alloy suitable for use in the process of the invention has a composition consisting essentially of the formula Al bal Fe a Si b X c wherein X is at least one element selected from the group consisting of Mn, V, Cr, Mo, W, Nb, Ta, Ce, Ni, Zr, Hf, Ti, Sc, "a” ranges from 1.5-8.5 at %, H b H ranges from 0.25-7.0 at %, and "c” ranges from 0.05 to 4.25 at %, the balance being aluminum plus incidental impurities.
• Still another aluminum base, rapidly solidified alloy that is suitable for use in the process of the invention has a composition range consisting essentially of about 2-15 at % from the group consisting of zirconium, hafnium, titanium, vanadium, niobium, tantalum, erbium, about 0-5 at % calcium, about 0-5 at % germanium, about 0-2 at % boron, the balance being aluminum plus incidental impurities.
• a low density aluminum-lithium base, rapidly solidified alloy suitable for use in the present process has a composition consisting essentially of the formula Al bal Zr a Li b Mg c T d , wherein T is at least one element selected from the group consisting of Cu, Si, Sc, Ti, B, Hf, Cr, Mn, Fe, Co and Ni, "a” ranges from 0.05-0.75 at %, "b” ranges from 9.0-17.75 at %, “c” ranges from 0.45-8.5 at % and “d” ranges from about 0.05-13 at %, the balance being aluminum plus incidental impurities.
• the powder can be composed of rapidly solidified alloy combined with the particles of a re nforcing material present in an amount ranging from about 0.1 to 50 percent by volume, the powder having been ball milled to enfold metal matrix material around each of the particles.
• the metal alloy quenching techniques used to fabricate these alloys generally comprise the step of cooling a melt of the desired composition at a rate of at least about 10 5o C/sec.
• a particular composition is selected, powders or granules of the requisite elements in the desired portions are melted and homogenized, and the molten alloy is rapidly quenched on a chill surface, such as a rapidly moving metal surface, an impinging gas or liquid.
• the aluminum alloy When processed by these rapid solidification methods the aluminum alloy is manifest as a ribbon, powder or splat of substantially uniform microstructure and chemical composition.
• the substantially uniformly structured ribbon, powder or splat may then be pulverized to a particulate for further processing.
• the rapidly solidified aluminum alloy particulate has properties that make it amenable to direct friction actuated extrusion into wire, as well as numerous powder metallurgy techniques used to fabricate such powders, including vacuum hot degassing and compacting the rapidly solidified powder into near fully dense billets at temperatures where the majority of the adsorbed gases are driven from the powder surfaces and that decomposition of any dispersed phases does not occur.
• the billets may thereafter be compacted to full density in a blind died extrusion press, forged, or directly extruded into various shapes including profiled extrusions and wire.
• the substrate may be water or gas cooled, or may be heated directly or indirectly during the processing. The optimum substrate temperature is dependent on the rapidly solidified alloy and the dispersed phases which must be formed during solidification.
• the rapidly solidified alloy in the form of a wire is arc sprayed to form a coating.
• the arc spraying step comprises the steps of (i) striking an arc between two strands of said wire to melt the tips thereof; and (ii) atomizing said melt in said arc by impinging a high pressure inert gas thereagainst.
• Arc spraying involves initially striking an arc between two strands of a conductive metal wire and essentially atomizing any molten metal which forms in the arc by impinging a high pressure inert gas onto the molten wire tips. Since arc spraying is a consumable process, wire is continually fed and the arc and metal source are maintained.
• the rapidly solidified alloy must be provided as a wire that can range in size from 0.05 cm to 0.25 cm in diameter and more preferably from about 0.1 cm to 0.18 cm in diameter, the optimum wire diameter depending on the alloy composition, the voltage across the wires and the feed sizes physically allowed by the arc spraying apparatus.
• the wire suitable in diameter for arc spraying may be fabricated directly by a friction actuated process or by conventional wire drawing techniques.
• Arc spraying may be performed for varying lengths of time depending on the thickness of the sprayed preform required.
• the attractive microstructure and mechanical and physical properties of the rapidly solidified wire are retained. This process may be repeated such that subsequent spraying is done on top of the sprayed coating, and multi-layered coatings may be fabricated.
• the sprayed coatings require no diffusion treatment as the arc sprayed material retains the attractive microstructure and mechanical and physical properties of the rapidly solidified wire.
• alloy A a rapidly solidified alloy having a diameter of 0.16 cm and the composition aluminum balance, 4.06 at % iron, 0.70 at % vanadium, 1.51 at % silicon
• FIG. 1 is a scanning electron photomicrograph of the surface of wire arc sprayed coating composed of rapidly solidified aluminum based iron, vanadium and silicon containing alloy matrix deposited on planar flow cast aluminum based iron, vanadium and silicon containing ribbon. Individual areas or splats corresponding to solidified droplets of sprayed molten alloy were observed. The coating was uniform and contiguous.
• Fig. 2 is a light photomicrograph of a cross section of a wire arc sprayed preform composed of rapidly solidified aluminum based iron, vanadium and silicon containing alloy matrix deposited on planar flow cast aluminum based iron, vanadium and silicon containing ribbon.
• TEM Transmission electron microscopy
• Polished TEM foils were examined in a Philips EM 400T electron microscope.
• a transmission electron photomicrograph of a wire arc sprayed coating composed of rapidly solidified aluminum based iron, vanadium and silicon containing alloy fabricated by the present invention is shown in Fig. 3.
• the microstructure of the deposited layer was observed to be composed of fine 50-100 nm diameter Al 13 (Fe,V) 3 Si dispersoids uniformly distributed in an aluminum solid solution matrix. This microstructure is very similar to that typically observed in the planar flow cast, rapidly solidified alloy A ribbon as well as in components consolidated from rapidly solidified powder particles using powder metallurgical techniques.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Coating By Spraying Or Casting (AREA)
• Mobile Radio Communication Systems (AREA)

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• 1991
  • 1991-01-15 DE DE69102422T patent/DE69102422T2/de not_active Expired - Fee Related
  • 1991-01-15 WO PCT/US1991/000301 patent/WO1991010760A2/en active IP Right Grant
  • 1991-01-15 JP JP3505040A patent/JPH05502911A/ja active Pending
  • 1991-01-15 EP EP91905287A patent/EP0513238B1/de not_active Expired - Lifetime

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