RU2591098C2 - Method of applying composite oxide coating on metal surface - 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 part working surface of nickel-based alloy includes application of plasma sputtering onto a prepared part surface coating of zirconium oxide stabilized by yttrium, wherein coating is created in it gradient transition layer by means of two magnetrons, wherein by means of first of 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, exceed intensity of atomic stream formed from second target, wherein after formation of solid metal layer oxygen is fed into working chamber of sputtered coating zirconium oxide sputtering oxygen partial pressure is smoothly increased to 1.5·10^-3 Pa, and power of first magnetron is decreased to 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 a coating on working surfaces, having sufficiently high adhesion and cohesion.

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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.

At present, when creating a coating with the 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 values of thermal expansion coefficients can lead to delamination of the coating and its destruction.

A known method of spraying a heat-protective coating using zirconia stabilized with Y ₂ O ₃ , including layer-by-layer coating of the product (US Patent 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 spraying, interfacial boundaries are formed in planes parallel to the surface and during 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 a heat-protective coating to the working surface of a part made of nickel-based alloy, the use of which will allow a smooth transition from a metal material to an oxide coating without a macroscopic interface.

The solution of this problem is achieved by the fact that in the proposed method of applying a heat-protective coating to the working surface of a nickel-based alloy part, including applying plasma spraying to previously prepared surfaces of a yttrium stabilized zirconia oxide coating part, according to the invention, the coating is applied by creating a gradient transition layer using two magnetrons, with the first magnetron sputtering the first target from an alloy based on nickel, with which corresponds to the alloy composition of the part, and by means of the second magnetron a second zirconium target with the addition of a stabilizing element of yttrium is sprayed, the targets being 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, in this case, after the formation of a continuous metal layer on the surface of the part, oxygen is supplied to the working chamber for formation in the sprayed PTFE coating of zirconium oxide, wherein during deposition the oxygen partial pressure is gradually increased to 1.5 × 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, desired thickness, wherein get a nanostructured coating containing a metal phase with a composition corresponding to the composition of the alloy to protect the surface of the part and a phase of yttrium stabilized zirconium oxide, increasing from the surface of the part fraction of the zirconium oxide phase.

The proposed method is implemented as follows.

Create a transition layer 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, actually zirconium oxide 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 matches the composition of the metal product, and the second magnetron sprays a zirconium target with yttrium additives. 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. During the deposition process, the partial pressure of oxygen gradually increases to a pressure of the order of 1.5 · 10 ^-3 Pa, and the power of the magnetron sputtering the metal alloy decreases until it is completely turned off. 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 a heat-shielding coating to the working surface of a part made of nickel-based alloy, the use of which will allow you to form a smooth transition from a metal material to oxide without a macroscopic interface, which will ultimately increase the mechanical strength of the coating, and will lead to an isotropic distribution of internal stresses during cyclic thermal loads, which will increase the heat resistance and heat resistance of the coating tiya.

Claims (1)

A method of applying a heat-protective coating to the working surface of a nickel-based alloy part, including applying plasma spraying to previously prepared surfaces of a yttrium stabilized zirconia oxide coating part, characterized in that the coating is carried out by creating a gradient transition layer in it using two magnetrons, by means of the first magnetron, the first target is made of an alloy based on nickel, the composition of which corresponds to the composition of the alloy of the part, and m of the second magnetron sputter the second target from zirconium with the addition of a stabilizing element of yttrium, and first the sputtering of the targets is carried out 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, the surface of a part of a continuous metal layer, oxygen is supplied to the working chamber to form zirconium oxide in the sprayed coating, while in the process of spraying, the partial The oxygen pressure is gradually increased to 1.5 · 10 ^-3 Pa, and the power of the first magnetron is reduced until it is completely turned off, then spraying is continued until the formation of yttrium stabilized zirconium oxide of the required thickness, and a nanostructured coating containing a metal phase with the composition is obtained corresponding to the composition of the alloy of the surface of the part to be protected, and the phase of yttrium stabilized zirconia, with a fraction of the zirconia phase increasing from the surface of the part.