Coating processes – Direct application of electrical – magnetic – wave – or... – Ion plating or implantation
Reexamination Certificate
2001-06-05
2004-09-28
Padgett, Marianne (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Ion plating or implantation
C427S528000, C427S577000, C204S192380, C428S689000, C428S697000, C428S698000, C428S704000, C428S539500, C428S336000
Reexamination Certificate
active
06797335
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to metallurgy and machine building fields and more specifically to development of methods that improve service life and durability of machine components; to repair of components and reconstitution of their properties; and particularly to gas turbine blades and vanes; and primarily to coatings applied to metal surfaces of aircraft engine compressor blades and vanes.
BACKGROUND OF THE INVENTION
Frequently, aircraft and helicopters equipped with gas-turbine engines have to operate under conditions of considerable dust content in the air flow and high humidity of sea environment with aggressive elements of corrosive effects. These operation conditions result in abrasion-caused erosion and corrosion of aircraft parts, particularly the compressor blades. Under these conditions, geometry of blades is distorted , operating performances are deteriorated, fuel consumption increases, and engine maintenance and repair expenses grow considerably. The said deteriorating processes can not be efficiently avoided by installation of dust protective devices.
Eroded blades and vanes are generally restored by edge profile polishing or are replaced with new blades and vanes. Such blades and vanes are made of titanium-based alloys or high-alloy steels, which are expensive and difficult to process, so engine repair entails great expense.
U.S. Pat. No. 4,904,542, issued Feb. 27, 1990, reissued under Re.34,173 on Feb. 2, 1993, to Midwest Research Technologies Inc. describes a coating formed of a plurality of alternating layers of metallic and ceramic materials. The two materials selected for the layers have complementary wear resistant characteristics such that one is relatively ductile and the other is relatively hard and brittle. Preferably radio-frequency sputtering is employed to deposit the coating, since it does not produce excessive heating which could negate any prior heat treatment of the substrate onto which the coating is deposited.
Also known are RU Patents No.2,061,090 BI No.15, 1996 and No.2,106,429 BI No. 7, 1998, that describe methods of multi-layer coating deposition on parts and tools, including transition metal coatings. Zirconium is offered as an adhesive bondcoat that is applied to the substrate before the coating; or there is an alternative method of applying metal oxides between the metal layers.
A deposition technique is also known to produce thin films of CNx with implantation of nitrogen ions from plasma. U.S. Pat. No. 5,580,429 issued Dec. 3, 1996, to Northeastern University describes cathodic/anodic vacuum arc sources with a plasma ion implantation deposition system for depositing high quality thin film coatings on substrates. Both cathodic and anodic vacuum arc deposition sources, CAVAD, are used to create a plasma vapor from solid materials composing the cathode and/or anode in the cathodic and/or anodic arc, respectively. Gases, e.g., hydrogen or nitrogen can be in the deposited films by creating a background plasma of the desired gas using either RF energy, thermionic emission, or consequential ionization of the gas passing through the arc or around the substrate. Highly negative pulses are applied to the substrate to extract the ions and provide them with the appropriate energy to interact with the other species in the thin film formation on the substrate to form the desired films. The substrate is bombarded with ionized particles to form carbon nitrides with variable [N]/[C] ratios.
RU Patent No.2,062,818 issued Jun. 27, 1996, describes deposition of metal-containing coatings on large substrates in vacuum. The method includes inert gas ion beam cleaning of the substrate and metal-coating deposition by cathodic sputtering in the inert gas discharge when the substrate is bombarded with the inert gas ion beam that is formed by an accelerator of closed-type drift of electrons at an inert gas ion energy of 50-150 eV. Technically, this method is the closest one to the present invention.
However, the aforesaid U.S. Pat. No. 4,904,542, U.S. Pat. No. 5,580,429 and R.U. 2,062,818, R.U. 2,061,090, and R.U. 2,106,429 do not fully cover the problems of durability and wear resistance, especially as far as aircraft engine blade airfoil surfaces are concerned, which must meet various specific requirements to their wear and corrosion resistance properties and at the same time retain a certain level of their mechanical and, particularly, fatigue characteristics.
Therefore, there is a need to provide improved erosion and corrosion resistance and, as a result, improved reliability and durability of components of various machines, tools and equipment, especially gas turbine engine compressor blades and vanes. That is proposed to be achieved by vacuum plasma technology involving ion implantation.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a technique of coating deposition on metal surfaces, particularly on components of machines, steam and gas turbines, and even more specifically on aircraft engine compressor blades and vanes, that will ensure improved erosion and corrosion resistance and retain the sufficient level of mechanical properties, primarily, fatigue characteristics.
It is a further object to restore the metallic surface of an eroded or corroded metal substrate, particularly the profile surface of a working blade of a gas turbine engine compressor to its original geometric shape and profile parameters.
To achieve the aforementioned objects, a coating is deposited that consists of at least three or four microlayers with certain thickness and compositions. By the term “microlayer”, in this specification and claims, is meant a layer of pure metal, multiple-component substitution or interstitial metal alloy with non-metal atoms, or interstitial phases based on the said metals, i.e. the metal carbides, nitrides, borides, or complex compounds of the said phases, e.g., carbonitrides, carboborides, etc.
The said coating is produced by means of ion plasma deposition; in the preferred embodiments, the said coating consists of a special microlayer (hereinafter referred to as “submicrolayer”); the said submicrolayer is a rare earth metal, particularly scandium, yttrium or lanthanum and lanthanoids; the said coating also comprises a plurality of microlayers wherein each of said microlayers comprises a material selected from the group consisting of the Group IVA-VIA (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) or alloys thereof, interstitial solid solutions of elements (carbon, nitrogen, boron), nitrides, carbides, or borides of metals, wherein one or more of said microlayers has been subjected to high energy non-metallic (argon, nitrogen, carbon, boron) ion deposition.
The said microlayers of metals or said alloys or metal
on-metal compounds deposited by means of deposition of ions or neutral particles under an appropriate inert gas or non-inert gas, such as nitrogen, methane, acetylene, diborane, should be deposited to a desired thickness, preferably 0.1-10 microns.
The microlayer may be an essentially discrete layer distinct from the adjacent substrate or microlayers; or it may be a mixture therewith. Each of the microlayers may comprise a pure metal or an alloy thereof as prepared, for example, if more than one metallic cathode are simultaneously activated within the chamber or the cathodes are made of alloys. The order of the plurality of microlayers can be selected by opting between corresponding gas atmospheres in the working chamber and by activating the appropriate cathode(s). The number and order of microlayers constituting the fill coating and the inert or non-inert gas ions deposition can be selected depending on the specific requirements determined by the desired performances of machine parts or the whole machine. For example, it is essential that guide blades of the aircraft engine compressor had very hard and wear resistant surfaces, and at the same time fatigue characteristics of the substrate alloy would not play a restrictive role, since such blades are not subjected to high fatigue. On
Paderov Anatol y Nikolaevich
Ve Xler Jouri Genrihovich
Collard & Roe P.C.
Padgett Marianne
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