Method of applying coatings on alloys

 

(57) Abstract:

The invention relates to mechanical engineering and can be used, for example, to increase the durability of turbine blades of gas turbine engines or stationary gas turbines. The technical result of the invention is to improve the durability of the coatings and their stability. The method comprises the sequential application of the coating layer based on aluminum and the coating layer using an alloy based on Nickel, and during application of the coating layer based on Nickel use alloy of the following composition, wt.%: chrome 2-30, aluminum 2-15, tantalum 0.2 to 20, tungsten, 0.5 to 10, hafnium 0,2-6, yttrium 0.001 to 5, the silicon of 0.1-5, Nickel rest to 100 after application which conduct heat treatment at a temperature T1,05 TZackwhere TZack- temperature hardening alloys, which is applied coating.

The invention relates to the field of engineering, in particular to the section of chemical-heat treatment of alloys and can be used, for example, to increase the durability of turbine blades of gas turbine engines or stationary gas turbines.

A method of obtaining coatings on superalloys, which in fact is. 392169, MKI 4: 23 WITH 10/56, BI 32 for 1973) - similar.

Diffusion aluminide coatings have objective limits on health-related resorption of the coating layer at high temperature, and also because of their lack of ductility.

The known method of coating alloys, namely, that put the first layer of the coating based on aluminum, the second coating layer is Nickel-based, after which heat is applied ceramic layer on the basis of Zr2(RF patent 2053310, IPC 6: 23 4/12, B 3, 1996) prototype.

In the known solution the application layer based on aluminum carry chromolithograph, applying a layer of a Nickel-based produce plasma method, in the following composition, wt.%: chrome 2,5-3,5, cobalt, 0.5 to 1.5, aluminum 20-25, yttrium 0,25-0,5, silicon 0.5 to 1, the Nickel and the rest to 100.

The disadvantages of this method of coating alloys include the following: the method involves applying a layer of coating based on Nickel and the ceramic coating layer by powder plasma spraying, and the grain size of the powder is comparable with the thickness of the resulting layer (50 μm - pellet, 50 μm - thick coating layer). The quality of the layers on Onoda gas environment, oxidizing the metal surface, as coatings, and metal bases. Because of the high penetrating power of oxygen in the layer-based and Nickel-based ceramics is accelerated oxidation of the coating layers on the basis of aluminum and Nickel-based, which increases the internal stress generated due to the increase in specific volume of the oxide in the pores. This, in turn, leads to a sharp decrease in the values of ultimate stress of the separation layer based on Nickel and ceramic based primarily ceramics layer, and the shearing of the layers. The result is a sharp decline in the strength and durability of the coating.

The objective of this invention is to improve the durability of the coatings and their stability.

The stability of the coating preserves for a long service life of the chemical and phase composition of the coating, the preservation of its structure, the thickness of the coating and its constituent areas.

The problem is solved in the method of applying coatings on alloys, which provides for consistent application of the coating layer based on aluminum and the coating layer using an alloy based on Nickel, and when applying a layer of coating is FNI 0,2-6, yttrium 0.001 to 5, the silicon of 0.1 -5, Nickel rest to 100 after application which conduct heat treatment at a temperature T1,05 T Zack., where T Zack. - temperature hardening alloys, which is applied coating.

To solve the task alloy for the application of the coating layer based on Nickel alloyed with chromium, aluminum, tantalum, tungsten, hafnium, yttrium and silicon.

The main purpose of the chromium in the alloy is to provide high heat resistance at a relatively low aluminum content. To this end, the chromium content in the alloy should be at least 2%. At the same time, the chromium content in the alloy should not be higher than 30%, because at very high chromium content is markedly reduced strength characteristics of the coating. In addition, the high chromium content in the layer stabilizes the fragile education phase.

Tantalum provides improved strength characteristics of the coating layer deposited using an alloy based on Nickel by increasing the strength of the atomic bonds in the structure of the coating and is an effective element inhibition of diffusion of the atoms of the alloy in the coating. The content of tantalum in the alloy for the application of the coating layer is less than 0.2% is not enough for commentof, the concentration of tantalum over 20% in damage to the coating formed from a large number of brittle phases, which affects the strength characteristics of the coating. Tantalum also contributes to the strength and stability of the coating as by binding sodium oxide and thereby prevent the formation of sodium molybdate, and due to the suppression of the martensitic transformation in-phase coating, which enhances the cracking of the layer.

Tungsten is introduced into the composition of the alloy to improve the strength characteristics of the coating, the inhibition of diffusion of the elements, reducing the junction temperature of the coating from brittle to plastic state when heated, and to develop an additional mechanism of deformation (twinning), which helps to increase the durability of the parts with the claimed coverage under cyclic thermo-mechanical deformation. Tungsten is contained in the coverage in the secondary, solid solutions. The positive effect from the introduction of tungsten is achieved when the content of tungsten in the alloy is not less than 0.5%. When the content of tungsten more than 10% of the coating formed topologically densely Packed phase type , which is accompanied by a sharp decrease in ductility, and therefore, stabile isothermal and cyclic oxidation by improving the adhesion of the oxide film with a metallic coating as due to the famous "pin" mechanism and due to the binding of the sulfur impurities in the refractory sulfides, and thereby prevent the formation of cavities filled with gaseous sulfur oxides, which cause chipping of the oxide film in the oxidation process.

Strengthening the protective properties of the oxide film is achieved by the introduction of hafnium and silicon, respectively, not less than 0.2% hafnium and not less than 0.1% silicon. Excessive hafnium content of more than 6% of silicon, about 5% are undesirable because the solubility of the elements in the main phases of the coating is limited, and the formation of additional compounds worsen the performance of the coating.

The positive effect from the introduction of an alloy of yttrium occurs when the yttrium content in the layer is not less than 0.001%. Too high yttrium content of more than 5% is impractical due to the deterioration of the strength properties of the coating, which is associated with a marked increase in the number of yttrium oxide in the coating layer.

Coatings using alloy based on Nickel can be implemented fairly large number of methods, such as plasma spraying, electron beam deposition, cathodic arc deposition, magnetron sputtering, vacuum-plasma technologies for high energy and C, who migrated to the surface during the plasma spraying wire, rod or powder alloy to cover. In the plasma flow, the powder particles are heated up to about 1000 K, the molten particles falling on the surfaces, filling and crystallize. The coating is formed by sequentially stacking deformable particles. Plasma spraying can be carried out in vacuum or in air. As a plasma-forming gas can be used are argon, helium, hydrogen or nitrogen. Using this method, the workpiece is heated by the plasma gun to 550-1100oC. the flow Rate of plasma gas (80% argon + 20% hydrogen) reaches 2M. The density of the coating reaches 99%. The structure of the coating - submergibility.

Electron beam evaporation is carried out by evaporation of the alloy coating by bombing the flow of electrons. Evaporated alloy condenses on the surface of the part. The coating is formed from the steam flow, which consists of neutral atoms. The evaporation rate is approximately 710-3(g-1cm2). The rate of growth of the layer thickness reaches 250-300 (NMS-1). Crystals coatings are predominantly in the direction of perp the th processed glass balls and then recrystallization annealing at a temperature of 950-1000oC.

Laser deposition is performed with the use of laser energy. The rate of growth of the layer thickness is 5-10 (MMS-1). Protection from oxidation during the deposition is carried out by using a protective gas, for example argon. The flow rate of particles during sputtering using a gas laser reaches 8-10 (MMS-1).

The methods can facilitate the process of managing qualitative and quantitative composition of the coatings on alloys, by using a pre-melted ingots of alloys. However, the use of several methods, especially electron beam, plasma, cathodic arc deposition ingots of the alloys has a number of disadvantages, for example:

the high porosity of the obtained coatings;

- uneven coating thickness, especially when the coating on parts of complex shape;

These drawbacks methods of coating based on aluminum (natural gas or slip, or powder eletrownia, chromolithography, alumosilicates and so on).

A new trend is the creation and application of a multi-component high-temperature coatings based on sequential deposition of coatings on the basis of Alicia after applying a layer based on aluminum is 29-32%, while in the layer deposited from an alloy based on Nickel content of aluminum is typically 7-10%. The Nickel content in the alloy, which cause the coating can be different. For example, in heat-resistant alloys the Nickel content is typically only 3-6%. So, get coverage with gradients on the aluminium content on the border to protect the alloy and on the border with the coating layer, which is obtained from an alloy based on Nickel.

To align the composition of the coating layer on its thickness and the formation of mainly two-phase structure of the coating of the and phases conduct heat treatment of the coating at a temperature T1,05 T Zack., where T Zack. - temperature hardening alloys that are coated.

The double gradient in aluminum alloy structures / and deposited on the aluminum layer-NiAl with one hand, and the coating layer on the Nickel-base structure, and a layer deposited on the aluminum-NiAl on the other hand, when heat treatment ensures the supply of Ni atoms in the formed vapor diffusion from the alloy, and the coating layer based on Nickel layer monoaluminate Nickel-NiAl. As a result, those who in MS and M23WITH6in the inner zone of the coating layer deposited on the aluminum adjacent to the alloy, the reduction of porosity on the border with the alloy and increase the ductility of the coating. The outer zone of the coating layer retains a fine-grained structure, which increases the strength and stability of the coating.

This method of coating alloys decreases the resistance to high-temperature oxidation at the initial stage of the coating. However, if the controlling factor is the strength of the coating after prolonged use, including heat resistance, coating of the inventive method provides a significant increase in resource their work.

Because the term "alloy" is commonly interpreted as a body, formed as a result of solidification of melts, consisting of two or more components (chemical individual substances), the concept of the alloys can be enabled and steel. The alloys can consist either only of metals or of metals with a low content of non-metals (e.g. iron and steel - alloy of iron with carbon) are metal alloys (see collegiate Polytechnical dictionary" edited by A. tx2">

Cooled turbine blades, cast alloy GS6U, after executing the processing operations of the blade surface to the coating was placed in a muffle furnace for gas eletrownia in the environment of the chlorides of aluminum ll3, ll2, ll. To ensure delivery of molecules of gaseous chlorides on the external and internal surfaces of the cooled turbine blades were turbulization of the gas stream. The process temperature was stabilized within 990-1010oWith, and the processing time at the stable temperature was 4 hours. Shipping aluminum to the surface of the parts was carried out by chemical reactions disproportionation:

3ll2-->Al+2ll3,

3ll-->2l+ll3.

Precipitated aluminum atoms interact with the atoms of Nickel alloy GS6U on the mechanism of the reaction diffusion and formed a coating on the basis of monoaluminate Nickel

Al+Ni-->-NiAl.

The maximum aluminum content in the coating layer was 28-32%. The thickness of the coating layer was 0,03-0,04 mm

The second coating layer was applied by condensation of an alloy based on Nickel the following composition, wt.%: Nickel 8, aluminum, 15, chromium - 6, tantalum 3, tungsten 2, hafnium 1,5, KremnyoC for 2 hours. The thickness of the layer of condensate was a 0.035 to 0.04 mm Heat treatment of the coating, namely diffusion annealing was performed in vacuum at a temperature of 1000oC10oC for 16 hours. The result was a uniform coating, in which the maximum content of aluminum in the heat treatment process decreased to 18-19%. The structure of the combined coating consisted mainly of a mixture of phases-NiAl and Ni3Al, and in the surface layer of the external area of the covering structure consisted mostly of phase-Ni3Al, and the area of the layer immediately adjacent to the alloy, contained particles of carbides M23WITH6and MC. The thickness of the coating layer after the heat treatment was 0,05-0,06 mm of One of the main parameters characterizing the stability of the coating during high-temperature oxidation, is its resistance to heat. The resistance of the applied coating was evaluated at a temperature of 1050oC for 1000 hours. After testing, the coating showed good protective properties.

In the technical solution adopted for the prototype, the first coating layer was applied by means of diffusive chromolithography powders in vacuum of the famous litter 3,5, aluminum 25, yttrium 0,5, silicon 1, Nickel rest to 100, and then applying a third heat-shielding layer. The result has been coated with the resistance during high-temperature oxidation at a temperature of 1050oWith 650 hours.

A comparison of the proposed solution with the known leads to the conclusion about the increase in stability of the coatings when applied using the proposed method.

Method of applying coatings on alloys, including consistent application of the coating layer based on aluminum and the coating layer using an alloy based on Nickel, characterized in that during application of the coating layer based on Nickel use alloy of the following composition, wt.%: chrome 2-30, aluminum 2-15, tantalum 0.2 to 20, tungsten, 0.5 to 10, hafnium - 0,2-6, yttrium 0.001 to 5, the silicon of 0.1-5, Nickel rest to 100 after application which conduct heat treatment at a temperature T1,05 TZackwhere TZack- temperature hardening alloys, which is applied coating.

 

Same patents:

The invention relates to mechanical engineering and can be used, for example, to increase the durability of turbine blades of gas turbine engines or stationary gas turbines

The invention relates to mechanical engineering and can be used in the coating thermal spray methods

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

The invention relates to mechanical engineering and can be used in the aviation and energy gazoturbostroenie for protection of parts of the CCD and GTU (nozzles, heating pipes, etc.,) from high temperature oxidation and corrosion
The invention relates to mechanical engineering and can be used when restoring a worn cast iron cylinder liners

The invention relates to the field of corrosion protection and can be used to obtain a heat-resistant alloys based on aluminum for plasma coatings heat resistant alloys Nickel-based

The invention relates to the coating of metallic materials and can be used to protect the surface of slabs of titanium alloys from gas saturating when heated under hot deformation

The invention relates to the field of metallurgy and can be used to protect the surface of titanium alloy ingots from gas saturating before the operation process heating floor hot deformation

The invention relates to the field of powder metallurgy and coating

The invention relates to the field of creation of new technologies coating by vacuum evaporation of metals and can be used in the manufacture of targets containing one or more layers of metals, for the study of the physics of the interaction of powerful laser radiation with matter, nuclear fusion and physics of shock waves
The invention relates to the field of engineering, in particular to materials based on titanium nitride coatings on steel and carbide, cutting and metallogenesis tool
The invention relates to the field of engineering, in particular to the materials based on titanium nitride coatings on steel and carbide, cutting and metallogenesis tool

The invention relates to microelectronics, in particular to the technology of very large scale integrated circuits

FIELD: manufacture of porous gas-absorbing units at reduced loss of particles.

SUBSTANCE: proposed method includes forming of coat at thickness of at least 0.5 mcm on surface of porous gas-absorbing body. Coat is formed from material compatible with conditions of use of gas-absorbing unit and selected from transition metals, rare-earth elements and aluminum by evaporation, sedimentation of plasma generated by arc discharge , sedimentation from ion beam or cathode sedimentation; particles of gas-absorbing body are coated by applying partial coat on external surface of gas-absorbing body.

EFFECT: enhanced efficiency.

19 cl, 3 dwg

FIELD: coating materials.

SUBSTANCE: method comprises applying a noble metal layer on the plates made of monocrystalline silicon and separating the layer from the substrate. The monocrystalline silicon is oxidized before the applying of the film. The film is applied by physical or chemical settling. The film is separated from the substrate by complete or partial dissolving of the substrate in floating solution. On dissolving the substrate, the metallic film is set on the surface of the floating solution or set in the other liquid to provide complete elevation of the metallic film by the surface tension.

EFFECT: simplified method.

4 cl, 7 ex

FIELD: mechanical engineering; modification of machine parts.

SUBSTANCE: proposed method includes preparation of surface of part and placing part and current-conducting material in area of treatment. Then, vacuum is formed in zone of treatment of part and negative potential is delivered to part and to current-conducting material, after which surface of part is cleaned and heated by plasma ions of current-conducting material. Accumulation and diffusion of current-conducting material on surface of part are performed at negative potential first setting its magnitude within 250-500 V and then within 0-150 V at temperature of part surface below temperature of loss of strength of material of part. Ni-based alloy is used as current-conducting material at the following composition of components, mass-%: Al, 3-15; Cr, 1-20; Y, 0.05-0.6, the remainder being Ni. In particular cases, part may be made from titanium or titanium-based alloy.

EFFECT: enhanced heat resistance and resistance to salt corrosion.

2 cl, 1 tbl, 7 ex

FIELD: processes for applying coatings by magnetron spraying, possibly application of coatings onto different articles of steels, hard alloys and refractory materials.

SUBSTANCE: method comprises steps of placing article in vacuum chamber, heating vacuum chamber and supplying oxygen into it; before spraying process creating in vacuum chamber evacuation with degree no more than 10-3Pa. Heating is realized till temperature no less than 100°C. Articles placed in vacuum chamber are subjected to ion cleaning after heating vacuum chamber and before starting material spraying. Ion cleaning is realized successively separately by oxygen and by argon for 5 - 15 min. Time period for ion cleaning by means of oxygen is no less than 2 min. Magnetron spraying is realized at rate no less than 6 micrometer/h; silver is used as material for spraying.

EFFECT: improved strength and density of coatings, enhanced adhesion of coatings, increased useful life period of coatings in condition of high temperature, possibility for applying coatings of purified materials with low content of impurities.

9 cl, 1 dwg

Up!