Coating processes – Solid particles or fibers applied – Uniting particles to form continuous coating with...
Patent
1992-02-02
1994-04-12
Owens, Terry J.
Coating processes
Solid particles or fibers applied
Uniting particles to form continuous coating with...
427191, 427195, B05D 112
Patent
active
053024141
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to metallurgy, more specifically, a method of and an apparatus for applying a coating.
BACKGROUND ART
Protection of structures, equipment, machines, and mechanisms made of ferrous metals from corrosion and effect exerted by aggressive media, an improvement of specifications of materials, including obtaining materials with prescribed properties, and development of resource-saving processing technologies are important scientific, technical and practical problems.
These problems can be solved by various methods, including applying powder coatings with widely usable gas flame-spray, electric arc, detonation and plasma methods.
The gas flame-spray method is based on gas combustion products used at 1000.degree. to 3000.degree. C., creation of a flow of these gases in which powder particles being applied are fused. A velocity of 50 to 100 m/s is imparted to said particles, and the surface is treated with the gas and powder flow containing the fused particles. This treatment results in a coating. The low values of velocity and temperature of the applied particles substantially limit application of this method.
The explosive method eliminates these disadvantages in part, according to which the energy of detonating gases at 2000.degree. to 3500.degree. C. is used owing to which fact the velocity of the particles is substantially increased up to 400 to 700 m/s and their temperature is increased up to 2000.degree. to 3500.degree. C. to ensure application of coatings of powders of metals, alloys, and dielectrics. This method is highly disadvantageous in low productivity explained by the impact acceleration process of deposition: a resulting shock wave and a gas flow following it cause a high level of a thermal and dynamic pulse effect produced upon the product and also of acousting noise which restricts the possibilities of application of this method.
The most promising is a method of plasma deposition consisting in application of a powder coating to the surface of a product with a high-temperature gas jet (5000.degree. to 3000.degree. C.).
Known in the art is a method for applying coatings to the surface of a product whose material is selected from the group consisting of metals, alloys, and dielectrics, said method comprising introducing into a gas flow a powder of the material selected from the group consisting of metals, alloys, their mechanical mixtures or dielectrics to form a gas and powder mixture to be directed onto the surface of the product (the book V. V. Kudinov, V. M. Ivanov. Nanesenie Plazmoi Tugoplavkikh Pokryty /Application of Refractory Coatings with Plasma/. Mashinostroenie Publishing House, Moscow. 1981, pp.9 to 14).
The prior art method is characterized in that powder particles of a size of from 40 to 100 .mu.m are introduced into a high-temperature gas flow (5000.degree. to 3000.degree. C.) in the form of a plasma jet. Said powder particles are heated to the melting point or higher, the powder particles are accelerated by the plasma jet gas flow and directed to the surface being coated. Upon impingement, the powder particles interact with the surface of a product thus forming the coating. In the prior art method, the powder particles are accelerated by a high-temperature plasma jet and transferred, in molten state, to the product being coated; as a result, the high-temperature jet runs in the product to exert a thermal and dynamic effect upon its surface, i.e., causes local heating, oxidation and thermal deformations. For instance thin-walled products are heated up to 550.degree. C., oxidized and twisted while the coating peels off.
The high-temperature jet flowing into the surface of a product intensifies chemical and thermal processes, causes phase transformations and appearance of oversaturated and non-stoichiometric structures, and hence, the structural changes in the material. Also the high level of a thermal effect on the coating results in hardening heated melts and gas liberation during crystallization which bring about the formation of evolved porosity and
REFERENCES:
patent: 2861900 (1958-11-01), Smith et al.
patent: 4235943 (1980-11-01), McComas et al.
patent: 4256779 (1981-03-01), Sokol et al.
patent: 4289807 (1981-09-01), Christensen et al.
patent: 4416421 (1983-11-01), Browning
patent: 4627990 (1986-12-01), Saga et al.
patent: 4815414 (1989-03-01), Duffy et al.
patent: 4928879 (1990-05-01), Rotolico
patent: 5019429 (1991-05-01), Moskowitz et al.
"30,000 Degrees With The Plasma Jet", Journal of Metals (Jan. 1959) pp. 40-42.
Alkhimov Anatoly P.
Kosarev Vladimir F.
Nesterovich Nikolai I.
Papyrin Anatoly N.
Shushpanov Mikhail M.
Owens Terry J.
Papyrin Anatoly Nikiforovich
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