RU2588973C2 - Method for treatment of working surfaces of parts of bladed machines - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to material science, particularly to methods of sputtering of heat shielding coating, and can be used in aircraft building and other fields of industry in production of parts of turbine engines and plants. Procedure for application of heat shielding coating on working surfaces of parts of blade machine includes application of plasma sputtering onto a prepared surface of parts from nickel-based alloy coating out of zirconium oxide stabilised by yttrium, wherein coating is created in it gradient transition layer by means of two magnetrons, wherein by means of first magnetron is sputtered a first target from nickel-based alloy, which corresponds to composition of alloy parts, and by second magnetron is sputtered a second target made of zirconium with additives of stabilising element yttrium, wherein sputtering of first target is carried out in an argon atmosphere so that intensity of atomic stream formed from first target exceeds intensity of atomic stream formed from second target, after formation of solid metal layer oxygen is fed into working chamber of sputtered coating zirconium oxide, during deposition of partial oxygen pressure is smoothly increased to 1.5*10^-3 Pa and first power of magnetron is decreased until its complete disconnection, sputtering is continued until formation of zirconium oxide stabilised by yttrium, required thickness to produce nanostructured coating containing metal phase with composition corresponding to composition of alloy protected surface part, and phase of zirconium oxide stabilised by yttrium, with increasing of part surface fraction phase of zirconium oxide.

EFFECT: use of disclosed method is aimed at formation of smooth transition from metallic material to oxide without interphase boundaries of macroscopic size, which enables to form on working surfaces of parts coating, having sufficiently high value of adhesion and cohesion.

1 cl

Description

The invention relates to the field of materials science, in particular to methods of spraying heat-protective coatings, and can find application in aircraft and other areas of mechanical engineering in the production of parts for turbine engines and installations that require the formation on the working surfaces of coatings having a sufficiently high value of adhesion and cohesion.

Currently, when creating a coating with specified properties by the method of layer-by-layer spraying, macrophase interfaces are formed in planes parallel to the surface being treated, and under cyclic thermal loads, the difference in the thermal expansion coefficients can lead to delamination of the coating and its destruction.

A known method of spraying a thermal barrier coating using zirconia stabilized with Y ₂ O ₃ , including layer-by-layer coating of the product (Patent US 6180184, C23C 4/10, 01/30/2001 - prototype).

According to this method, a thermal barrier coating is obtained from heat-resistant alloys stabilized with yttrium zirconium oxide, which is layer-by-layer applied using vacuum electron beam spraying. This gives a coating having a columnar structure, manifested in one or more layers.

The disadvantage of this method is the ability to obtain through porosity, leading to corrosion of the substrate and to the destruction of the coating. In addition, in the process of layer-by-layer deposition, interfacial boundaries are formed in planes parallel to the surface, and with cyclic thermal loads, the difference in the values of thermal expansion coefficients can lead to delamination of the coating and its destruction.

The objective of the proposed technical solution is to eliminate these drawbacks and create a method of applying an oxide coating on a metal surface, the use of which will form a smooth transition from a metal material to an oxide coating without a macroscopic interface.

The solution to this problem is achieved by the fact that in the proposed method for processing the working surfaces of parts of blade machines, including applying a protective oxide coating on pre-machined and prepared surfaces of the parts, the subsequent formation on the metal surface of a composite metal-oxide structure with joint reactive spraying of metals, according to the invention in the applied coating create a gradient transition layer of a gradient nanocomposite material containing two The basics: a metal phase with a composition corresponding to the composition of the surface to be protected, which is located in the immediate vicinity of the surface to be protected, and a dielectric phase, mainly zirconium oxide of various stoichiometry, which is applied to the said metal phase, while the phase ratio in the transition layer changes with increasing oxide fraction phase as the film thickness increases, while ensuring a smooth transition from a metal material to an oxide without a macroscopic interface.

In an application of the method, a magnetron system with two magnetrons is used to create the aforementioned gradient transition layer, whereby a target with a metal alloy, the composition of which corresponds to the composition of the metal product, and mainly containing nickel, is sprayed using the first magnetron, and a target from zirconium with additives of stabilizing elements, mainly yttrium, and the initial sputtering of the targets is carried out in an argon atmosphere in such a way that the intensity of the atomic flux generated from the first nickel target exceeds the intensity of the atomic flux from the zirconium target, and after the formation of the primary continuous metal layer, oxygen is added to the working chamber and the deposition process is reactive with the formation of zirconium oxide in the sprayed film with unoxidized nickel, while during the deposition, the oxygen partial pressure is gradually increased to a pressure of about 1.5 x 10 ^-3 Pa, and the power of a first magnetron sputtering target with meta -crystal alloy is reduced until it is completely off, and then continue spraying pure zirconium oxide until it reaches the desired thickness.

The proposed method is implemented as follows.

To increase the adhesion strength of the yttrium stabilized zirconia coating sprayed onto the working surfaces of the blade machine parts, a transition layer is made of a gradient nanocomposite material containing two phases: a metal phase with a composition corresponding to the composition of the surface to be protected, and a dielectric phase, zirconium oxide itself of various stoichiometry. The phase ratio in the transition layer is not constant, but varies with increasing proportion of the oxide phase as the film thickness increases. As a result of creating such a gradient layer, a smooth transition is formed from a metal material to an oxide without a macroscopic interface.

To create the specified gradient transition layer, a magnetron system with two magnetrons is used. The first magnetron sprays a target whose composition corresponds to the composition of a metal product, for example, KhN71MTUB nickel alloy, and the second magnetron sprays a zirconium target with additives of stabilizing elements, for example yttrium. The initial sputtering of targets is carried out in an argon atmosphere, and the intensity of the atomic flux generated from the nickel target exceeds the intensity of the atomic flux from the zirconium target. After the formation of the primary continuous metal layer, oxygen is added to the working chamber, after which the deposition process becomes reactive - oxide begins to form in the sprayed film. Due to different binding energies in nickel oxide and zirconium oxide, zirconium oxide forms in the coating being formed, while nickel remains unoxidized.

Thus, as a result of the simultaneous sputtering of a nickel alloy and zirconium in a mixed oxygen-argon atmosphere, a metal-oxide composite material is deposited. In the sputtering process, the oxygen partial pressure increases gradually to a pressure of about 1.5 x 10 ^-3 Pa, a magnetron power spraying metal alloy decreases until its complete disconnection. After this, the deposition of pure zirconium oxide continues until it reaches the required thickness.

In this case, the formed gradient layer is not only composite, but also nanostructured, since the characteristic sizes of inclusions of each phase are from units to several tens of nanometers depending on the volume fraction of the phase.

The obtained nanostructured structure not only increases the mechanical strength of the coating, but also leads to an isotropic distribution of internal stresses under cyclic thermal loads, which increases the heat resistance and heat resistance of the coating.

Using the proposed technical solution will allow you to create a method of applying an oxide coating on a metal surface, the use of which will form a smooth transition from a metal material to an oxide without a macroscopic interface, which, ultimately, will increase the mechanical strength of the coating and will lead to an isotropic distribution of internal stresses cyclic thermal loads, which will increase the heat resistance and heat resistance of the coating.

Claims (1)

A method of applying a heat-protective coating to the working surfaces of a blade part of a machine, including applying plasma spraying to previously prepared surfaces of a nickel-based alloy of a yttrium stabilized zirconia oxide coating, characterized in that the coating is carried out by creating a gradient transition layer in it using two magnetrons wherein, by means of the first magnetron, the first target is made of a nickel-based alloy, the composition of which corresponds to the composition of the de tali, and by means of a second magnetron, a second target is made of zirconium with the addition of a stabilizing element of yttrium, and the targets are first sputtered in an argon atmosphere so that the intensity of the atomic flux generated from the first target exceeds the intensity of the atomic flux generated from the second target, after the formation of a continuous metal layer on the surface of the part, oxygen is supplied to the working chamber to form zirconium oxide in the sprayed coating, while in the process apyleniya oxygen partial pressure gradually increased to 1.5 x 10 ^-3 Pa, and the power of the first magnetron is reduced until it is completely off, and then continue spraying until the formation of zirconium oxide stabilized with yttrium, the desired thickness, the obtained nanostructured coating, comprising a metallic phase with the composition corresponding to the alloy composition of the protected surface of the part, and the phase of zirconium oxide stabilized with yttrium, with a fraction of the phase of zirconium oxide increasing from the surface of the part.