Method for manufacturing high temperature seal

Abstract

FIELD: mechanical engineering.SUBSTANCE: invention can be used for the manufacture of seals between various stationary parts of gas turbine engines (GTE) operating under high temperature conditions, for example between the combustion chamber and the high-pressure turbine, as well as the joints of nozzle blocks and turbine housings. Overall, all this ensures efficient sealing of turbine components and, as a result, increases the efficiency of the gas turbine engine as a whole. The sealing package (seal) is a galvanically nickel-plated metal frame that has undergone heat treatment and has an applied organosilicate composition. In the method for manufacturing a high-temperature seal, which includes the manufacture of a frame from metal threads, a layer of galvanic nickel with a thickness of 9–15 μm is applied to the threads of the metal frame, then vacuum heat treatment is carried out at a temperature of 1130–1150 °C and pressure of 0.13–0.2 Pa ((1.0–1.5)×10–3 mm Hg) for 2.0–2.5 hours (Fig. 1), then a layer of organosilicate composition with a conditional viscosity of 11–13 s is applied, and curing at a temperature of 50–260 °C is carried out.EFFECT: increase in the density of the thread packing (increased tightness) due to the replacement of manual weaving with automated weaving, damping properties with the provision of high flexibility of its design for the possibility of its laying in the profile of the groove of the joint being sealed and, as a result, an increase in durability.1 cl., 5 dwg

Description

[0001] The invention relates to the field of mechanical engineering and can be used to manufacture seals between various stationary parts of gas turbine engines (GTE) operating under high temperature conditions, for example, between a combustion chamber and a high-pressure turbine, as well as between nozzle blocks and turbine housings.

[0002] A sealing element used in high-temperature gas turbine engine designs is known. It consists of a central bundle of ceramic fibers with a braided metal sheath consisting of wires placed on it (US 5358262 A, F16J 15 / 08, 15 / 22, 25.10.1994). A disadvantage of this known sealing element is its limited service life and difficulty in use when it is necessary to install it in a complex groove profile of the joint being sealed.

[0003] Also known is a sealing element used in high-temperature environments, for example, in gas turbine engine elements and made in the form of a rope twisted from strands of ceramic fibers, with a metal wire braid placed on it (prototype - US 5301595 A, F16J 15 / 22, 12.04.1994) This element is partially free from the disadvantages indicated in the previous analogue, but also does not provide high reliability of the seal when placed in a complex groove profile of the sealed joint with a long service life.

[0004] A sealing element used in gas turbine engine designs at high temperatures is known. It is made in the form of a rope with a metal wire braid placed on it (utility model - RU 154778 U1 F16J 15 / 02, 01 2006). This seal was selected as a prototype. This model partially eliminates the shortcomings noted in previous analogues, but does not fully possess the necessary damping properties, resulting in a long service life, insufficient sealing, and, as a result, reduced gas turbine efficiency.

[0005] The technical result achieved by using a seal manufactured using the claimed method is an increase in thread packing density (improved sealing) due to the replacement of manual weaving with automated braiding. This improves damping properties while ensuring high design flexibility for its placement within the groove profile of the joint being sealed, thereby increasing durability. Overall, this ensures effective sealing of turbine components and, consequently, increases the efficiency of the gas turbine engine as a whole. The seal package (seal) is a galvanically nickel-plated, heat-treated metal frame with an applied organosilicate composition.

[0006] The said technical effects are achieved by the fact that in the method for manufacturing a high-temperature seal, including the manufacture of a frame from metal threads, according to the present invention, a layer of galvanic nickel with a thickness of 9-15 μm is applied to the threads of the metal frame, then vacuum heat treatment is carried out at a temperature of 1130-1150 ° C and a pressure of 0.13-0.2 Pa ((1.0-1.5) x10 -3 mmHg) for 2.0-2.5 hours (Fig. 1), then a layer of organosilicate composition with a conditional viscosity of 11-13 sec is applied and curing is carried out at a temperature of 50-260°C.

[0007] The metal frame production is automated and carried out on machine tools. Wire diameters of 0.1-0.12 mm are used for the core and 0.14 mm for the first, second, and third braid layers. Three wires are connected in each strand. Using wire diameters less than 0.1 mm causes tangling, while diameters greater than 0.15 mm hinder the automatic formation of metal frames.

[0008] To increase the tightness, strength and elasticity of the seals, a layer of galvanic nickel with a thickness of 9-15 microns is applied to the surface of the metal frame wires.

[0009] A nickel layer thickness of less than 8 μm does not have a significant effect on the tightness and service life of the sealing element, while more than 15 μm reduces the flexibility and damping properties of the seal.

[0010] The composite metal frame design increases the volume of the metal component by 36-40%, resulting in a reduction in the proportion of cavities and a reduction in cooling air flow through the seal package. This improves sealing efficiency.

[0011] To ensure diffusion bonding of the nickel layer with the threads of the metal frame and strength characteristics after galvanic nickel plating, vacuum heat treatment of the seal is carried out at a temperature of 1130-1150 ° and a pressure of 0.13-0.2 Pa ((1.0-1.5)x10 -3 mmHg), within 2.0-2.5 hours.

[0012] To further improve the tightness and density of the thread packing, the sealing package is impregnated with an organosilicate composition (OS-82-05).

[0013] To impregnate the nickel-plated metal frame after vacuum heat treatment, an optimal organosilicate composition with a nominal viscosity of 11-13 sec is used. This viscosity ensures maximum compaction of the metal frame. At viscosities of 8 and 10 sec, the organosilicate composition is not retained in the cavities between the metal frame threads, and at viscosities of 15 and 21 sec, a continuous thick coating layer is visible along the entire outer surface, obscuring the braided relief of the frame. In the cross-section, no organosilicate composition leakage into the frame is observed; the wires are virtually clean, with only minor traces of the composition.

[0014] At a viscosity of 8 sec, the organosilicate composition is virtually absent on the outer turns of the braided frame. The composition spreads along the lower rows of wires in the frame. At the ends of the frame, the organosilicate composition is present on the outer turns, but not on all turns or along the entire length. In cross-section, the gaps between the wires are not filled with the organosilicate composition; a thin layer of the composition is visible on the wire surface.

[0015] At a viscosity of 10 sec, a layer of organosilicate composite is present on the outer surface of the frame, along all wires in the middle and at the ends. In cross-section, the gaps between the wires are partially filled with the composite, and a layer of the composite is present on the wire surface.

[0016] At a viscosity of 12 sec, the entire outer surface of the frame is covered with a dense layer of organosilicate composite. The composite is observed flowing into the lower rows of wires in the frame. In the cross-section, the composite fills the gaps between the wires.

[0017] This method for obtaining a new design of flexible seals and an automated method for manufacturing metal frames can be used to improve the sealing of the gas-air duct of the stator of turbines of gas turbine engines.

[0018] Fig. 1 shows the microstructure of the metal frame threads made of EP648 alloy with a 13.8 μm thick galvanic nickel layer.

[0019] Fig. 2 shows the appearance of the seal after nickel plating and heat treatment.

[0020] Fig. 3 shows the external appearance of the seal after applying an organosilicate composition with a conditional viscosity of 11-13 sec.

[0021] Fig. 4 shows the structure of the seal after applying an organosilicate composition with a conditional viscosity of 11-13 sec. in cross section.

[0022] Fig. 5 shows samples of seals manufactured for practical use.

[0023] As an example of a specific application, the production of a high-temperature rope-type seal made of EP648 alloy with a layer of galvanic nickel and impregnated with an organosilicate composition can be considered.

[0024] Example.

[0025] For the production of the seal, a new metal frame was designed and manufactured, developed in accordance with the requirements of the gas turbine design documentation.

[0026] For the production of the metal frame, wire made of heat-resistant nickel alloy ХН50ВМТЮБ (ЭП648) with a diameter of 0.12 mm was used.

[0027] The metal frame is manufactured using automated machining equipment. The manufactured metal frame is degreased, rinsed in water, air-dried, and then electroplated with nickel.

[0028] Nickel plating bath composition:

[0029] 1) nickel sulfate;

[0030] 2) sodium sulfate;

[0031] 3) boric acid;

[0032] 4) sodium chloride:

[0033] 5) magnesium sulfate (7 aqueous);

[0034] pH = 5.2 - 5.8.

[0035] Nickel deposition rate 0.1-0.4 μm / min.

[0036] Current density 0.5-2.0 A / dm 2 .

[0037] Holding time 50-80 min.

[0038] Bath temperature 18-30°.

[0039] A nickel layer with a thickness of 13.8 μm was obtained. (Fig. 1).

[0040] After galvanic nickel plating, the metal frame (sealing package) goes through the following processing (manufacturing) stages:

[0041] - heat treatment in vacuum: 0.13-0.2 Pa ((1.0-1.5)x10 -3 mmHg), 2 hours, at a temperature of 1130-1150°C;

[0042] - impregnation with organosilicate composition OS-82-05 with a viscosity of 11-13 sec;

[0043] - curing of organosilicate composition with a stepwise change in temperature:

[0044] 50 + 10°C, 30-45 min; 100 + 10°C 30-45 min; 150 + 10°C, 30-45 min; 200 + 10°C, 60-75 min; 260 + 10°C, 180-200 min. for its uniform polymerization.

[0045] The cavities between the threads were filled with organosilicate composition OS 82-05, Fig. 4.

[0046] The appearance of the seals manufactured for installation on the engine is shown in Fig. 5.

Claims

1. A method for manufacturing a high-temperature seal, including the manufacture of a frame from metal threads, characterized in that a layer of galvanic nickel with a thickness of 9-15 μm is applied to the threads of the metal frame, then vacuum heat treatment is carried out at a temperature of 1130-1150 °C and a pressure of 0.13-0.2 Pa for 2-2.5 hours, then a layer of organosilicate composition with a conditional viscosity of 11-13 s is applied and curing is carried out at a temperature of 50 to 260 °C.

2. The method according to paragraph 1, characterized in that the curing of the composition is carried out stepwise at temperatures of 50 ± 10°C 30-45 min; 100 ± 10°C 30-45 min; 150 ± 10°C 30-45 min; 200 ± 10°C 60-75 min; 260 ± 10°C 180-200 min.

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