Coating processes – Solid particles or fibers applied
Reexamination Certificate
1998-11-23
2002-11-19
Parker, Fred J. (Department: 1762)
Coating processes
Solid particles or fibers applied
C427S191000, C427S192000, C427S427000, C148S537000
Reexamination Certificate
active
06482467
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a ceramic coated product, including a product by what is called fine nitriding, i.e., formation of a fine nitrogen compound layer on a surface layer of a metal material for the purpose of surface hardening or the like. The present invention also relates to a ceramic coating method for forming a ceramic coating layer, which should be taken in the wide sense, in manufacture of a ceramic coated product obtained by using as a raw material a nitride, an oxide or a boride, for the purpose of protection, decoration, lubrication or the like of the surface of a material to be treated as a workpiece, such as wear resistance, corrosion resistance or heat resistance thereof, using excellent mechanical properties of the ceramic; in coating of the ceramic coating layer; or in production of the ceramic coat.
More specifically, nitriding is a manner of ejecting an ejection powder by a reactive ejecting gas, for example, compressed nitrogen gas, on the surface of a metal product, as a workpiece, comprising a ferrous metal such as steel or cast iron, a metal product comprising a non-ferrous metal such as aluminum or brass, or a metal product comprising a powdery alloy, such as a hard metal, a ceramic alloy, or a cermet, or on the surface of a material to be treated comprising a ceramic or a mixture of these, so as to produce on the surface of the material to be treated a nitride layer of a compound resulting from the reaction of the ejection powder and the reactive ejecting gas. In particular, the present invention relates to ceramic coating, comprising a nitriding treatment step wherein nitriding treatment which has not been conventionally made practicable for nitriding of aluminum and aluminum alloys is made practicable at ordinary temperature, and relates to ceramic coating, as a general term having broad senses, comprising the nitriding treatment step in the present invention for forming or applying an inorganic material and an intermetallic compound, including the aforementioned nitride layer, on the surface of the aforementioned material to be treated.
2. Description of Prior Art
As conventional nitriding treatments, the following have been carried out: gas nitriding and oxynitriding using ammonia gas at about 550° C. for 20-100 hours; salt-bath nitriding to be performed at about 580° C. in a bath of a mixture of a cyanide and a cyanate; and ion nitriding in which nitrogen ionized in glow discharge is caused to penetrate and diffuse into steel in a decompressed atmosphere into which N2 is introduced. Besides, gas soft-nitriding and nitrosulphurizing treatments have been carried out.
Incidentally, ceramic coating methods are plasma thermal spray, PVD (physical vapor deposition), CVD (chemical vapor deposition), and the like methods.
The plasma thermal spray is a manner of supplying a thermal spray powder into a super high temperature and high-speed flow jet produced by ejecting from a narrow nozzle an inactive gas, such as argon, made into plasma by arc; and melting and accelerating the thermal spray powder to form a coat on the surface of a substrate. This manner has been applied to formation of a high density and high strength coat made of metal materials such as molybdenum and nickel based alloys, and formation of a thin film made of high melting-point materials such as ceramics.
The PVD method is a manner of heating a solid to a high temperature or vaporizing and condensing a solid forcibly, with no chemical reaction, to form a thin film, and is grouped into vapor deposition, ion plating, sputtering and the like.
The vapor deposition is a manner of heating and vaporizing a substance in a vacuum, and depositing it in a layer-form on a surface of a material to be treated, thereby forming a thin layer, and has a characteristic making it possible to easily make various substance a thin layer and obtain a large and uniform thin film, and the like characteristics.
The ion plating is a manner of using plasma generated by applying an electric field to ionize or excite vaporized atoms, thereby forming a thin film.
The sputtering is a manner of generating ionized plasma in a relatively low degree of vacuum, accelerating ionized argon and causing collision of the argon with a target (a solid material which is a target of collision of the accelerated particles) to sputter target atoms, thereby coating the surface of a material to be treated.
The CVD is a manner of forming a thin film by chemical reaction of vapor of a metal or a volatile compound in a gas phase, and is grouped into electric furnace, chemical flame, electron beam, laser, plasma and the like methods, dependently on a heat source for the gas phase reaction.
Conventional nitriding treatments, including gas nitriding, have problems that treating temperature is generally very high, that treating time is also long, that the cost of equipment is necessarily high, and that pollution accompanies in cyanogen treatment or the like.
Concerning in particular nitriding of aluminum, aluminum alloys and the like, nitriding is not liable to penetrate into their surface since an oxide film is formed on the surface. Nitriding in a vacuum can be carried out, but is of no practical use from the viewpoint of productivity and cost. As for stainless steel, nitriding treatment thereof has problems of decrease in its strength by washing by an acid, and an outbreak of pollution, as well as the same problems as in case of aluminum and the like.
Besides, conventional ceramic coating methods have the following problems.
For example, the vacuum vapor method has a problem that the cost of equipment is high for a vacuum tank, a rotary pump or a oil diffusion pump for evacuating the vacuum tank, and the like.
Besides, in the other methods, i.e., the PVD and various types of CVD, expensive equipment is necessary, and the methods have a problem of high cost.
The sputtering has a problem that the rate of depositing a film is at most several hundreds Å/minute, and this method is not suitable for forming a thick film.
The present invention has been made to solve the aforementioned problems. An object and an effect of the present invention are to provide a ceramic coated product and a coating method for it, making it possible to improve protecting and lubricating effects of the surface of a material to be treated, such as wear resistance, corrosion resistance and heat resistance thereof, and to raise commercial value of its appearance based on decoration, by a method for manufacturing, forming or producing a thin film which comprises ejecting an ejection powder on the surface of the material to be treated by reactive ejecting gas to form on the surface of the material to be treated a compound layer produced by reaction of the ejection powder and the reactive ejecting gas, in low-priced equipment. Specifically, an object and an effect of the present invention are to provide ceramic coating making it possible to carry out the same treatment as by conventional coating methods by blasting, in low-priced mechanical equipment, for a short time, improve protecting and lubricating effects of the surface of a material to be treated, such as wear resistance, corrosion resistance, and heat resistance thereof, make its appearance beautiful, and raise commercial value at a lower cost than conventional ceramic coating methods; or a product related to a ceramic coat containing fine nitride by a quite new manner in simple equipment at ordinary temperature, the equipment not causing pollution; and a coating method for it.
SUMMARY OF THE INVENTION
The means for attaining the ceramic-coated products of the present invention include a material to be treated, as a metal product having a nitrogen reactive component, and an ejection powder; a material to be treated comprising a mixture of the metal product and a ceramic, and an ejection powder; or a material to be treated comprising a ceramic, and an ejection powder containing a nitrogen reactive component. The fine nitride comprises a nitrogen compou
Fuji Kihan Co., Ltd.
Knobbe Martens Olson & Bear LLP
Parker Fred J.
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