Method for plasma coating

 

(57) Abstract:

The invention can be used in mechanical engineering, nuclear energy, metallurgy during recovery of parts from various metals and alloys, or restoring large stamps in places of local wear. The method includes abrasive-jet machining of the surface, causing the surface layer of intermetallic Ni-Al of a thickness not exceeding 0.2 mm, touch plasma jets workpiece surface, the excitation of the electric arc and the flow of the coating material in a stream of plasma and electric arc excite an alternating or pulsating current, and the relative speed of advancement of the plasma torch must be no less than works in the frequency of the excitation spot on the workpiece surface and the conditional size of this spot. The invention is aimed at improving the quality of the coating. 2 Il.

The invention relates to the field of coating and can be used in mechanical engineering, nuclear energy, metallurgy during recovery of parts from various metals and alloys, or restoring large stamps in places of local wear.

A known method of applying plasma spraying, including Milyausha alloys and the subsequent melting of the coating [1].

The disadvantage of this method is that the manifestation of the effect of "fogging" of coverage necessary parts to a temperature of 950 1200...oWith depending on camofluage alloys. The low thermal conductivity of the materials stamps high-strength alloyed steels does not allow even heating of the coating over the entire area restored area when using concentrated heat fluxes. At a high level of thermal stresses due to temperature gradient in the system floor-detail on flat surfaces, the coating can flake at the edges and cracks.

Uniform heating of the coating bulky items-stamp to the above temperatures in some cases impossible due to warping of parts and lowering its mechanical properties.

The known method of thermal coating, in particular of powder coatings on conductive materials [2].

The disadvantage of this method is that the coating is applied to the conductive material and do not provide the required quality.

There is also known a method of plasma spraying of details, including what and cooling the deposited layer while rotating parts, when this is applied the coating layer thickness of 0.3-0.5 mm, which upravlyaut by reducing the distance of the spraying and the termination of the powder supply with simultaneous blowing of the opposite side parts argon with a flow rate of 1.5-2 m3/h for 5-10 seconds, and then include the powder supply, setup the initial spraying distance, stop the flow of argon to the opposite side of the part and sprayed coating to the desired thickness [3].

The disadvantage of this method is the impossibility of application of coatings on various items of complex shape, such as stamps, as well as a large flow of argon, which blows the opposite sprayed surface side.

This technical solution chosen by the authors as a prototype.

The aim of the present invention is to improve the quality of the coating and workability when it is applied to products of complex shape due to the simultaneous deposition and melting of the powder material.

This technical result is achieved by the fact that in the sputtering method, powder coatings, including abrazivostruynoy surface treatment, application layer, the approximation of the plasma torch to the surface, the powder supply and application of coating is creating a conductive channel between the nozzle of the plasmatron and the surface of the part touch to excite an electric arc variables or pulltrouser current with simultaneous supply of powder that allows you to transfer the heated and molten powder particles on the surface of the part, which in places of binding spots, rafting, welded to the material of the workpiece, and the relative speed of advancement of the plasmatron should be no less than works in the frequency of the excitation spot on the workpiece surface and the conditional size of this spot.

Drawing on processed using abrazivostruynoy processing the surface layer of intermetallic Ni-Al of a thickness not exceeding 0.2 mm is necessary to protect the parts from oxidation during subsequent coating.

The simultaneous excitation of the electric arc alternating or pulsating current with the approach of the plasmatron to contact jet plasma surface details and flow of the coating material into the plasma jet, as well as the condition that the relative speed of advancement of the plasmatron must be greater than or equal to the product of the frequency of the excitation spot on the workpiece surface and the conditional spot size, help to improve the coating quality even on large parts.

The proposed method for plasma deposition of p is ructure the deposited layer.

Example.

The detail of steel 40 X was applied the coating material composition of Fe-Ni-Cr-B-Si with a thickness of 1 mm

Conducted pre-conventional abrazivostruynaya processing.

On the prepared surface by plasma spraying a layer of the composition (Ni-Al) with a thickness of 0.01 mm, the Dispersion of the powder 20...60 μm. Distance when spraying from a nozzle of the plasmatron to the surface 150 mm

Further, by connecting, for example, the electrodes of the welding transformer to the workpiece and the anode plasmatron produced spray material (Fe-Ni-Cr-B-Si) dispersion of 60. .. 100 μm. Distance when spraying from a nozzle of the plasma torch to the workpiece 60 mm

Upon excitation of the arc from the welding transformer in the plasma jet on the surface staining of binding of the arc, in which the melt sprayed powder particles. The speed of the relative movement of the plasmatron and parts amounted to 50 mm/s, because conventionally, the spot diameter is 1 mm

In the deposition with simultaneous melting of the surface was obtained coating thickness of 1 mm.

The coating structure is a "classic" structure of the cast material, which is shown in Fig.1.

The connection of the mother is

Application materials on the proposed method allows to obtain the melted coating, United with the surface of the part on the "metal" level, and restore local worn surfaces on large parts.

Sources of information

1. Kudinov centuries, Ivanov Century. And. Application of plasma refractory coatings. - M.: Mashinostroenie, S. 148-168, 1981

2. Abstracts of all-Union conference on theory and practice of gas-thermal coating. h 1, Riga, 1980, S. 30, 149-150.

3. RF patent 2135630 "Method of plasma spraying", IPC C 23 C 4/12, author: Kalinichenko A. B., patentee: Military automobile Institute, SRO (prototype).

Method for plasma coating comprising abrasive-jet machining of the workpiece surface, applying a layer approximation of the plasma torch to the surface, the flow of powder coating and applying it to the workpiece, wherein the layer is applied from Ni-Al of a thickness not exceeding 0.2 mm, the plasma torch closer to the surface to touch her jet plasma, touch to excite an electric arc alternating or pulsating current with simultaneous supply of powder, the speed of the relative movement of the plasma torch and the workpiece Dol is on.

 

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FIELD: metal coats, in particular for gas turbine engines operating at high temperature.

SUBSTANCE: claimed metal coat contains (mass %) cobalt up to 18; chromium 3.0-18; aluminum 5.0-15; yttrium 0.1-1.0; hafnium up to 0.6; silicium up to 0.3; tantalum 3/0-10; tungsten up to 9.0; rhenium 1.0-6.0, molybdenum up to 10, and balance - nickel. Method of invention includes providing of support from at least one metal materials based on nickel, cobalt or iron followed by application of coating layer.

EFFECT: coats of high oxidation resistance and endurance strength.

33 cl, 1 tbl

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