RU2655563C1 - Method of the gas turbine engine blisk from titanium alloys protecting against dust abrasion erosion - Google Patents

Abstract

FIELD: motors and pumps.

SUBSTANCE: performing the hardening treatment with microspheres, polishing of the blisk blades edges, blisk blades surface layer material ion-plasma modification with the ion-plasma multilayer coating subsequent application with a specified number of the layers pairs in the form of titanium with metal layer and a layer of titanium with a metal and nitrogen compounds. Before the surface layer ion-plasma modification, performing the blisk surface electrolyte-plasma polishing. Surface layer Ion-plasma modification is carried out with nitrogen ions at an energy from 0.2 keV to 2.5 keV, dose of 1.5⋅10¹⁹ cm^-2 up to 2.5⋅10¹⁹ cm^-2, current strength from 0.1 mA/cm² up to 3 mA/cm², at a current frequency of 70 to 100 kHz. When coating application, as a metal in the titanium with a metal layers and in the titanium with a metal and nitrogen compounds layers vanadium is used. In the process of ion-plasma treatment, the blisk is rotated relative to its longitudinal axis, giving it oscillatory movements ensuring its entire working surface processing.

EFFECT: proposed is a method of the gas turbine engine blisk from titanium alloys protecting against dust abrasion erosion.

11 cl, 1 ex

Description

The invention relates to mechanical engineering and can be used in aircraft engine building and power turbine building to protect the pen of the working blades of a monowheel of a gas turbine engine made of titanium alloys from erosion damage while increasing endurance and cyclic durability.

A known method of vacuum ion-plasma coating on a substrate in an inert gas medium, including creating a difference in electric potentials between the substrate and the cathode and cleaning the surface of the substrate with an ion stream, reducing the potential difference and coating, annealing the coating by increasing the potential difference, the ion flux and the flow of evaporated material going from the cathode to the substrate is shielded, cleaning is carried out with inert gas ions, after cleaning, the screens are removed and the coating is applied in several stages ups to obtain the required thickness (RF patent 2192501, С23С 14/34, publ. 10.11.2002).

A known method of applying ion-plasma coatings to turbine blades, including sequential vacuum deposition of the first layer of titanium with a thickness of 0.5 to 5.0 μm, then applying a second layer of titanium nitride with a thickness of 6 μm (RF patent 2165475, IPC C23C 14/16 30/00, C22C 19/05, 21/04, publ. 04/20/2001).

The main disadvantage of this method is the provision of insufficiently high erosion resistance of the surface of the scapula. In addition, with an increase in the thickness of the coating (or of each of the coating layers), the adhesion and fatigue strength of parts with coatings decreases, which impairs their service life and reliability.

The rotor blades of the compressor GTE and GTU during operation are exposed to significant dynamic and static loads, as well as corrosion and erosion destruction. Based on the requirements for operational properties, titanium alloys are used for the manufacture of gas turbine compressor blades, which, compared to technical titanium, have higher strength, including at high temperatures, while maintaining a sufficiently high ductility and corrosion resistance (for example, titanium alloys of grades VT6, VT8, VT18U, VT3-1, VT22, etc.)

However, the turbine blades of these alloys are highly sensitive to voltage concentrators. Therefore, the defects formed in the manufacturing process of these parts are unacceptable, since they cause the occurrence of intense destruction processes. This causes problems when machining surfaces of turbomachine parts. In this regard, the development of methods for producing high-quality surfaces of turbomachine parts is a very urgent task.

The closest in technical essence and the achieved result to the claimed one is a method of protecting the compressor blades of a gas turbine engine from titanium alloys from dust-abrasive erosion, including hardening treatment with microspheres, polishing the edges of the blades of blisk, ion cleaning and ion implantation of a feather blade with subsequent application of an ion-plasma multilayer plasma coating as a given number of pairs of layers in the form of a layer of titanium with metal and a layer of compounds of titanium with metal and nitrogen (RF patent 2226227, IPC С23С 14/48, op bl. 27.03.2004).

The main disadvantage of the analogue is the lack of reliability of protection against erosion damage while reducing the endurance limit and cyclic durability. Moreover, the increase of these properties is especially important for such parts made of titanium alloys as compressor blades of gas turbine engines (GTE). In addition, all of the above methods can not be used to harden the surface of the blades and coating on the glare, because they cannot provide uniform processing of the entire working surface of the blisk.

The present invention is the creation of such a multilayer coating, which would be able to effectively protect the glare of gas turbine engines from titanium alloys from erosion wear under the influence of gas flows containing abrasive particles, while increasing the endurance limit and cyclic durability of the protected parts.

The technical result of the proposed method is to increase the resistance of the blade of the GTE compressor to erosion destruction while ensuring the specified endurance and cyclic durability of the protected elements of the blisk by ensuring uniform coating and uniform processing of the surface layer of the working surface of the blisk.

The technical result is achieved in that in a method for protecting a blisk of a gas turbine engine from titanium alloys from dust-abrasive erosion, including hardening by microspheres, polishing the edges of blades of blisk, ion-plasma modification of the material of the surface layer of blades of blisk with subsequent application of an ion-plasma multilayer coating with a given amount layers in the form of a layer of titanium with metal and a layer of compounds of titanium with metal and nitrogen, in contrast to the prototype before ion-plasma modification over The electrolyte-plasma polishing of the blisk surface is carried out by applying an electric potential from 320 V to 360 V using a 2-7% aqueous solution of a mixture of NH ₄ F and KF as an electrolyte with an NH ₄ F content of 16 to 26 weight. %, KF - the rest, while the ion-plasma modification of the surface layer is carried out by nitrogen ions at energies from 0.2 keV to 2.5 keV, with a dose of 1.5⋅10 ¹⁹ cm ^-2 to 2.5⋅10 ¹⁹ cm ^{- 2} , with a current strength of 0.1 mA / cm ² to 3 mA / cm ² , with a current frequency of 70 to 100 kHz, and when coating is used as a metal in layers of titanium with metal and in layers of compounds of titanium with metal and nitrogen, vanadium, moreover, during ion-plasma treatment of the blisk, it is rotated relative to its longitudinal axis with giving it oscillatory movements, providing processing of the entire working surface blisk, and ion-plasma treatment and coating are carried out simultaneously on both sides of the blisk, and titanium is applied simultaneously from two electric arc evaporators located on opposite sides of the blisk, and vanadium is applied from two electric arc evaporators, also located on both sides of the blisk, the coating is carried out simultaneously with all four of the mentioned evaporators.

The technical result is also achieved by the fact that in the method of protecting the compressor blades of a gas turbine engine made of titanium alloys from dust-abrasive erosion, the following options are possible: when applying the coating, the ratio of titanium to vanadium is used, weight. %: V from 4 to 12, the rest is Ti, and a layer of titanium with vanadium is applied with a thickness of 0.2 μm to 0.3 μm, and a layer of compounds of titanium with vanadium and nitrogen is applied with a thickness of 1.1 μm to 2.2 μm with a total thickness of the multilayer coating from 5.0 microns to 7.0 microns; applying layers of titanium compounds with vanadium is carried out in the mode of assisting with argon ions, and layers of titanium compounds with vanadium and nitrogen is carried out in the mode of assisting with nitrogen ions; electrolyte-plasma polishing is carried out at a current value from 0.2 A / dm ² to 0.5 A / dm ² and a temperature from 70 ° C to 90 ° C, for a period of 0.8 to 7 minutes; 0.3-0.8 weight is additionally introduced into the electrolyte composition. % TiF ₄ ; after applying the required number of coating layers, annealing is carried out, and annealing and coating are carried out in one vacuum volume in one technological cycle.

The process of electrolyte-plasma polishing of parts made of titanium and titanium alloys is as follows. The processed blisk from titanium or a titanium alloy is immersed in a bath with an aqueous electrolyte solution, a positive electric potential is applied to it, and a negative potential is applied to the electrolyte, as a result of which a discharge arises between the processed product and the electrolyte. The process of electrolyte-plasma polishing is carried out at an electric potential from 320 V to 360 V, and a 2-7% aqueous solution of a mixture of KF and NH ₄ F is used as the electrolyte, with their content, weight. %: 80% KF and 20% NH ₄ F. Polishing, depending on the blisk parameters and the given surface microgeometry, is carried out at a current value from 0.2 A / dm ² to 0.5 A / dm ² , at a temperature of 70 ° C to 90 ° C, over a period of 0.8 to 7 minutes. To improve the quality of processing, surfactants in a concentration of 0.4-0.8% or 0.3-0.8% TiF ₄ can be added to the electrolyte composition. Before polishing the blisk in the electrolyte according to the processing conditions, auxiliary elements from titanium or a titanium alloy are treated with a washout of the precipitate formed into the electrolyte, and processing of auxiliary elements is carried out until the polishing process is stabilized.

The treatment is carried out in an electrolyte environment while maintaining around the working surface the brightness of the vapor-gas shell. As a bath, a container made of a material resistant to electrolyte is used. The pH value of the electrolyte is in the range of 4-9. The electrolyte temperature is in the range of 70-90 ° C.

When carrying out electrolyte-plasma polishing, the following processes occur. Under the influence of flowing currents, the surface of the part is heated and a vapor-gas shell forms around it. Excessive heat arising from the heating of the part and the electrolyte is removed through the cooling system. At the same time, the set process temperature is maintained. Under the action of electric voltage (electric potential between the part and the electrolyte), a discharge arises in the vapor-gas shell, which is an ionized electrolytic plasma, which ensures the flow of intensive chemical and electrochemical reactions between the treated part and the medium of the gas-vapor shell.

When a positive potential is applied to the part, during the course of these reactions, the surface of the part is anodized with chemical etching of the formed oxide. Moreover, with anodic polarization, the vapor-gas layer consists of electrolyte vapors, anions, and gaseous oxygen. Since etching occurs mainly on microroughnesses, where a thin oxide layer is formed, and the anodizing processes continue, as a result of the combined action of these factors, the roughness of the treated surface decreases and, as a result, polishing of the latter occurs.

When processing in an electrolyte 2-7% aqueous solution of a mixture of KF and NH ₄ F at their content, weight. %: NH ₄ F from 16% to 26%, KF - the rest, the surface of the part is covered with a layer of easily soluble plaque from fluoride compounds formed by the displacement of oxygen (TiO ₂ + F-TiF ₄ ). At voltages from 320 V to 340 V, the discharge temperature is high enough to conduct a stable polishing process. Since the component does not directly contact the electrolyte due to the vapor-gas shell, the TiF ₄ compound evaporates, i.e. polishing is carried out through the evaporation of the fluorinated layer (mp. TiF ₄ = 238 ° C).

When treating blisk, it is advisable to introduce surfactants into the electrolyte. The introduction of a surfactant reduces the surface tension coefficient of the solution, which improves the state of the gas-vapor layer at the gas-liquid interface. However, significant concentrations of surfactants should not be created, since this can lead to the formation of unwanted indelible films on the surface of the product. In addition, an increase in the concentration of surfactants can lead to the opposite effect, i.e. an increase in the surface tension coefficient of the solution. The concentration of the main components of the electrolyte is a fairly variable value. Moreover, the lower limit of their concentration is determined by the need to ensure the quantitative dominance of fluorine ions over oxygen ions both in the film formed on the surface of the product and in the vapor-gas shell. The upper limit of the concentration of the electrolyte solution is limited by an increase in the number of toxic gaseous products (F-, NH ₃ ) formed during processing. To minimize joule-loss, the electrolyte must have sufficient electrical conductivity. When selecting an electrolyte concentration from a range from 2 to 7% aqueous solution of a mixture of KF and NH ₄ F (with wt.%: NH ₄ F from 16% to 26%, KF - the rest), as well as additional additives (surfactants in concentration of 0.4-0.8% or 0.3-0.8%) TiF ₄ ) it is also necessary to take into account the possibility of its continued use without additional adjustment of the composition.

To assess the resistance of blades to their resistance to erosion wear, the following tests were carried out. Samples of titanium alloys of grades VT6, VT8, VT8 m, VT41, VT18u, VT31, VT9, VT22, VT25u were coated, as in the prototype method (RF patent 2226227, IPC С23С 14/48, publ. 03/27/2004) , according to the conditions and modes of application described in the prototype method, and the coating according to the proposed method.

Modes of sample processing and coating according to the proposed method

Electrolyte-plasma polishing: electric potential from 320 V to 360 V, 300 V - unsatisfactory result (N.R.); 320 V - satisfactory result (U.R.); 330 V - (U.R.); 360 V - (U.R.); 370 V (N.P.); electrolytes: from 2% to 7% (1% - unsatisfactory result (N.R.); 2%; 3%; 5%; 7%; 8% - (N.R.); an aqueous solution of a mixture of KF and NH ₄ F, at their content, wt.%: NH ₄ F from 16% to 26% (14% - (N.P.); 16%; 20%; 24%; 26%; 28% - (N.R. )), KF - the rest.

Ion-plasma treatment with nitrogen:

energy - 0.1 keV (N.R.); 0.2 keV (U.R.); 0.7 keV (U.R.); 1.4 keV (U.R.); 2.1 keV (U.R.); 2.5 keV (U.R.); 2.7 keV (N.R.);

dose - 1.3⋅10 ^{19 cm-2} (N.R.); 1.5⋅10 ¹⁹ cm ^-2 (U.R.); 2.5⋅10 ¹⁹ cm ^-2 (U.R.); 3⋅10 ¹⁹ cm ^-2 (N.R.);

current strength - 0.07 mA / cm ² (N.R.); 0.1 mA / cm ² (U.R.); 0.8 mA / cm ² (U.R.); 1.6 mA / cm ² (U.R.); 2.4 mA / cm ² (U.R.); 3.0 mA / cm ² (U.R.); 3.4 mA / cm ² (N.P.);

current frequency - (from 70 to 100 kHz), 60 kHz (N.R.); 70 kHz (U.R.); 80 kHz (U.R.); 100 kHz (U.R.); 110 kHz (N.R.).

The layers of titanium compounds with vanadium were applied: from four simultaneously operating separate electric arc evaporators. The location of the evaporators is peripheral, on both sides of the glare, with alternating electric arc vanadium vaporizer with a titanium vaporizer. Electric arc evaporators were located in the peripheral part of the cylindrical working chamber of the ion-plasma installation, and the blisk rotated around its own longitudinal axis with oscillatory movements. The longitudinal axis coincided in orientation with the axis of the cylindrical working chamber of the installation and the flow of the applied material. The blisk’s rotation speed relative to its own axis was from 8 to 10 rpm. Oscillatory movements were 30 ° on either side of the vertical. Layers of titanium compounds with vanadium were applied in the mode of assisting with argon ions, and layers of titanium compounds with vanadium and nitrogen were carried out in the mode of assisting with nitrogen ions.

The thickness of the titanium layer with vanadium (0.2 μm to 0.3 μm): 0.1 μm (N.R.); 0.2 μm (U.R.) 0.3 μm (U.R.); 0.5 μm (N.R.). The thickness of the layer of titanium compounds with vanadium and nitrogen (1.1 μm to 2.2 μm): 0.9 μm (N.R.); 1.1 μm (U.R.); 1.5 μm (U.R.); 2.2 μm (U.R.); 2.5 μm (N.R.). Total coating thickness (from 5 μm to 7 μm): 4.0 μm (N.R.); 5.0 μm (U.R.); 7.0 μm (U.R.); 8.0 μm (N.R.).

The total thickness of the coating of the prototype and the coating applied by the proposed method ranged from 5 μm to 7 μm.

After coating, annealing was carried out in one vacuum volume of the installation in one technological cycle.

Erosion resistance of the surface of the samples was studied according to the TsIAM method (TsIAM Technical Report No. 10790: Experimental Study of the Wear Resistance of Vacuum Ion-Plasma Coatings in a Dusty Airflow, 1987. - 37 pp.) On a 12G-53 sandblasting jet-ejector type. For blowing, ground quartz sand with a density of p = 2650 kg / m ³ and a hardness of HV = 12000 MPa were used. Blowing was carried out at an air-abrasive flow velocity of 195-210 m / s, a flow temperature of 265-311 K, a pressure in the receiving chamber of 0.115-0.122 MPa, an exposure time of 120 s, an abrasive concentration in the flow of up to 2-3 g / m ³ . The test results showed that the erosion resistance of the coatings obtained by the proposed method increased by approximately 8 ... 9 times compared with the prototype coating.

In addition, endurance and cyclic durability tests were carried out on samples - blades cut from blisk after its ion-plasma treatment and coating. Samples from the following grades of titanium alloys (VT6, VT8, VT8 m, VT41, VT18u, VT31, VT9, VT22, VT25u) were tested in air. As a result of the experiment, the following was established: the conditional endurance limit (-1) of samples in the initial state (without coating) is 465-480 MPa, for samples hardened by the prototype method - 455-470 MPa, and by the proposed method - 490-510 MPa .

Thus, the comparative tests showed that the following techniques are used in the method for protecting the blisk of a gas turbine engine made of titanium alloys from dust-abrasive erosion: ion-plasma modification of the material of the surface layer of blaze blades; subsequent deposition of an ion-plasma multilayer coating with a given number of pairs of layers in the form of a layer of titanium with metal and a layer of compounds of titanium with metal and nitrogen; conducting electrolyte-plasma polishing of the surface before ion-plasma modification of the surface layer by applying an electric potential from 320 V to 360 V to the workpiece, using a 2-7% aqueous solution of a mixture of NH ₄ F and KF as an electrolyte with an NH ₄ F content of 16 to 26 weight. %, KF - the rest; ion-plasma modification of the surface layer with nitrogen ions at energies of 0.2 keV to 2.5 keV, dose from 1.5⋅10 ¹⁹ cm ^-2 to 2.5⋅10 ¹⁹ cm ^-2 , current from 0.1 mA / cm ² to 3 mA / cm ² , at a frequency of current from 70 to 100 kHz; use as a metal in layers of titanium with metal and in layers of compounds of titanium with metal and nitrogen, vanadium, in particular, with a ratio of titanium to vanadium, weight. %: V from 4 to 12%, the rest is Ti; rotation during ion-plasma processing of the blisk relative to its longitudinal axis with giving it oscillatory movements, providing processing of the entire working surface of the blisk; conducting ion-plasma treatment and coating simultaneously on both sides of the blisk; applying titanium simultaneously from two electric arc evaporators located on opposite sides of the blisk and applying vanadium from two electric arc evaporators also located on both sides of the blisk, applying coating simultaneously from all four mentioned evaporators; when applying a layer of titanium with vanadium with a thickness of 0.2 μm to 0.3 μm; when applying a layer of titanium compounds with vanadium and nitrogen with a thickness of 1.1 microns to 2.2 microns with a total coating thickness of 5.0 microns to 7.0 microns; the application of layers of titanium compounds with vanadium in the mode of assisting with argon ions, and layers of titanium compounds with vanadium and nitrogen in the mode of assisting with nitrogen ions; conducting electrolyte-plasma polishing at a current of 0.2 A / dm ² to 0.5 A / dm ² and a temperature of 70 ° C to 90 ° C for 0.8 to 7 minutes; additional introduction to the composition of the electrolyte 0.3-0.8 weight. % TiF ₄ ; after applying the required number of coating layers, annealing; Carrying out annealing and coating in one vacuum volume in one technological cycle, allows to increase the resistance of blades of the blades of the GTE compressor to erosion destruction while ensuring the specified endurance and cyclic durability of the protected blisk elements by ensuring uniform coating and uniform processing of the surface layer of the blisk working surface.

Claims (11)

1. A method of protecting the blisk of a gas turbine engine made of titanium alloys from dust-abrasive erosion, including hardening by microspheres, polishing the edges of blades of blades, ion-plasma modification of the material of the surface layer of blades of blisk with subsequent application of an ion-plasma multilayer coating with a given number of pairs of layers in the form of a titanium layer with metal and a layer of compounds of titanium with metal and nitrogen, characterized in that before the ion-plasma modification of the surface layer, electrolyte-plasma is carried out the second polishing of the surface of the blisk by applying an electric potential from 320 V to 360 V to it using 2-7% aqueous solution of a mixture of NH ₄ F and KF as an electrolyte with an NH ₄ F content of 16 to 26 weight. %, KF - the rest, while the ion-plasma modification of the surface layer is carried out by nitrogen ions at energies from 0.2 keV to 2.5 keV, dose from 1.5⋅10 ¹⁹ cm ^-2 to 2.5⋅10 ¹⁹ cm ^{- 2} , a current strength of 0.1 mA / cm ² to 3 mA / cm ² , with a current frequency of 70 to 100 kHz, and when coating is used as a metal in layers of titanium with metal and in layers of compounds of titanium with metal and nitrogen, vanadium, moreover, in the process of ion-plasma treatment, the blisk is rotated relative to its longitudinal axis to give it oscillatory movements, ensuring the processing of the entire working the surface of the blisk, while the ion-plasma treatment and coating are performed simultaneously on both sides of the blisk, and the coating is carried out simultaneously from four evaporators, while for applying titanium, two electric arc evaporators are used that are located on opposite sides of the blisk, and for applying vanadium use two electric arc evaporators located on both sides of the blisk. 2. The method according to p. 1, characterized in that when applying the coating provide a ratio of titanium to vanadium, weight. %: V from 4 to 12, the rest is Ti, and a layer of titanium with vanadium is applied with a thickness of 0.2 μm to 0.3 μm, and a layer of compounds of titanium with vanadium and nitrogen is applied with a thickness of 1.1 μm to 2.2 μm with a total thickness of the multilayer coating from 5.0 microns to 7.0 microns. 3. The method according to p. 1, characterized in that the deposition of layers of titanium compounds with vanadium is carried out in the mode of assisting with argon ions, and layers of titanium compounds with vanadium and nitrogen are carried out in the mode of assisting with nitrogen ions. 4. The method according to p. 2, characterized in that the deposition of layers of titanium compounds with vanadium is carried out in the mode of assisting with argon ions, and layers of titanium compounds with vanadium and nitrogen are carried out in the mode of assisting with nitrogen ions. 5. The method according to p. 1, characterized in that the electrolyte-plasma polishing is carried out at a current value from 0.2 A / dm ² to 0.5 A / dm ² and a temperature from 70 ° C to 90 ° C for from 0 , 8 to 7 minutes 6. The method according to p. 2, characterized in that the electrolyte-plasma polishing is carried out at a current value from 0.2 A / dm ² to 0.5 A / dm ² and a temperature from 70 ° C to 90 ° C for from 0 , 8 to 7 minutes 7. The method according to p. 3, characterized in that the electrolyte-plasma polishing is carried out at a current value from 0.2 A / dm ² to 0.5 A / dm ² and a temperature from 70 ° C to 90 ° C for from 0 , 8 to 7 minutes 8. The method according to p. 3, characterized in that the electrolyte-plasma polishing is carried out at a current value from 0.2 A / dm ² to 0.5 A / dm ² and a temperature from 70 ° C to 90 ° C for from 0 , 8 to 7 minutes 9. The method according to any one of paragraphs. 1-8, characterized in that the composition of the electrolyte is additionally introduced 0.3-0.8 weight. % TiF ₄ . 10. The method according to any one of paragraphs. 1-8, characterized in that after applying the required number of coating layers, annealing is carried out, and the annealing and coating are carried out in one vacuum volume for one technological cycle. 11. The method according to p. 10, characterized in that after applying a predetermined number of coating layers, annealing is carried out, and annealing and coating are carried out in one vacuum volume in one technological cycle.