RU2605018C1 - Method of high-temperature multilayer composite on metal surface producing - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metal science, chemical-thermal treatment of metal articles, to production of structural purpose nano-structured materials, to friction and wear problem, and can be used for machines parts durability increasing in any industry. Method of producing high-temperature multilayer composite on metal part surface using HVOF involves surface treatment with HVOF in shielding atmosphere of preliminarily mechanically activated NiAl powder with shape memory effect to produce layer with thickness of 120-500 mqm with further plastic deformation at heating below temperature of martensitic transformation beginning, production of high-temperature layer by HVOF in shielding atmosphere of preliminarily mechanically activated mixture of Si, Y, BN, C, Co, Ni₃Al powders, with their ratio wt%: Si 4-13, Y 2-3, BN 12-20, C 2-8, Co 3-10, Ni₃Al is rest, with thickness of 150-500 mqm. It is followed by heating at temperature of 30-35 °C above solidus followed by ageing in two stages. At first stage performing heating to temperature of 1,000-1,100 °C with holding for 1-1.5 hours, at second stage is heating to temperature of 900-950 °C with holding for 2.5-3 hours. As shielding atmosphere in HVOF argon is used.

EFFECT: enabling higher heat-resistant characteristics, process time and costs reducing.

1 cl, 1 tbl, 1 ex

Description

The invention relates to the field of metal science, chemical-thermal treatment of metal products to the creation of nanostructured materials for structural purposes, to the problem of friction and wear and can be used to increase the durability of machine parts in any industry.

So, for example, it is known:

- a method of forming heat-resistant coatings based on nickel aluminide NiAl on steel parts, including nickel plating, applying the aluminum layer by a liquid-phase method and conducting diffusion annealing, the aluminum layer is applied from a melt of technically pure aluminum at a temperature of 800-850 ° C for 3-4 s and is carried out diffusion annealing at a temperature of 950-1100 ° C for 6-10 hours (RF patent No. 2507310); the disadvantage of this method is the duration of the process, low wear-resistant and heat-resistant characteristics;

- a method of obtaining a heat-resistant coating on the working blades of turbines of gas turbine engines or power plants, including ion implantation treatment of the surface of the blade, the formation of an internal heat-resistant layer and the application of an external heat-resistant layer of Al-Si-Y alloy with its ion implantation, ion-implantation treatment of the surface of the blade produced by ions of one or more elements Nb, Pt, Yb, Y, La, Hf, Cr, Si, an alloy composition is used as a material for forming the internal heat-resistant layer: Cr - from 18% to 30%, Al - from 5% to 13%, Y - from 0.2% to 0.65%, Ni - the rest, and an alloy with the composition: Si - from 4.0% to 12.0%; Y - from 1.0% to 2.0%; Al - the rest, and the application of an external heat-resistant layer is alternated with periodic implantation by ions of one or more elements of Nb, Pt, Yb, Y, La, Hf, Cr, Si with the formation of an external heat-resistant layer in the form of microlayers separated by implanted micro- or nanolayers (patent RF №2441104).

The disadvantage of this coating method is the duration of the process, the high cost, the small thickness of the heat-resistant layer and, as a consequence, low heat resistance.

As the closest analogue of the claimed invention, the selected method of obtaining a high-temperature multilayer composite on the surface of a metal part using high-speed flame spraying (RF patent No. 2513533).

The objective of the invention is to obtain a multilayer nanostructured heat-resistant composite containing a layer of material with a shape memory effect - heat-resistant layer.

The technical result of the proposed method is to increase the heat-resistant characteristics, reducing the time and cost of the process.

The technical result is achieved by the proposed method for producing a high-temperature multilayer composite on the surface of a metal part using high-speed flame spraying, in which the surface treatment is carried out by high-speed flame spraying in a protective atmosphere of pre-mechanically activated NiAl powder with a shape memory effect to obtain a layer with a thickness of 120-500 μm followed by a plastic deformation upon heating below the temperature of the onset of martensitic transformation, high-temperature layer is obtained by high-speed flame spraying in a protective atmosphere of a pre-mechanically activated mixture of powders of Si, Y, BN, C, Co, Ni ₃ Al at their ratio, weight. %: Si 4-13, Y 2-3, BN 12-20, C 2-8, Co 3-10, Ni ₃ Al - the rest, with a thickness of 150-500 microns, to obtain a multilayer composite, then carry out heating at a temperature of 30-35 ° C above the solidus with its subsequent aging in two stages, in the first stage they are heated to a temperature of 1000-1100 ° C with a holding time of 1-1.5 hours, in the second stage they are heated to a temperature of 900-950 ° C with a holding of 2 5-3 hours. Moreover, argon is used as a protective atmosphere for high-speed flame spraying.

During high-speed gas-flame spraying of mechanically activated powders, the energy accumulated during mechanical activation is released, which provides more reliable adhesion and increase the strength properties of the multilayer composite, and a high deposition rate ensures the formation of a nanoscale structure. The indicated sequence of powder spraying during the formation of the composite “layer of a material with a shape memory effect - a reinforcing layer” provides an increase in its heat resistance, and a layer of a material with a shape memory effect blocks or slows the spread of defects during operation, which contributes to an increase in durability and strength properties.

The second layer of the following chemical composition Si-Y-BN-C-Co-Ni ₃ Al has increased heat resistance. Aging is carried out to increase the heat-resistant characteristics of a multilayer composite.

At the first stage, mechanical activation of NiAl powder, a mixture of powders is carried out with the following content of components, weight. %: Si 4-13, Y 2-3, BN 12-20, C 2-8, Co 3-10, Ni ₃ Al - the rest is subjected to mixing and grinding in a ball mill using grinding media (in the form of balls), containing WC-CrC-Ni. The mechanical activation of the powders is carried out in an AGO-2U ball mill. The powders are loaded and processed in an inert atmosphere (argon medium) with the following parameters: drum rotation frequency 1200-1500 min ^-1 , carrier speed 900-1000 min ^-1 , ball diameter 6 mm, operating time 15 min.

At the second stage, high-speed flame spraying is carried out in a protective atmosphere (argon medium) of mechanically activated powders. A vacuum is created in the chamber using a vacuum pump, then this vacuum is filled with argon from a metal cylinder. Next, mechanically activated powders NiAl, Si-Y-BN-C-Co-Ni- ₃ Al are filled into powder dispensers connected by powder supply hoses to the nozzle of a gas-flame burner. The nozzle of the gas-flame burner has two channels for introducing powders: the first channel of the nozzle connected to the powder dispenser, for feeding mechanically activated NiAl powder into the spraying zone, the second channel of the nozzle connected to the powder dispenser, for supplying a mechanically activated mixture of Si- powders to the spraying zone Y-BN-C-Co-Ni ₃ Al. Separate supply of mechanically activated powders to the spraying zone is possible due to the design of the nozzle of a gas-flame burner.

A high-temperature multilayer composite on the surface of a metal part is obtained as follows: first, a first layer is deposited on the basis of a mechanically activated powder with a memory effect of NiAl form with a thickness of 120-500 microns on a metal part; Next, on the first layer with a shape memory effect based on NiAl, we apply a second layer of a mechanically activated powder mixture of Si-YrBN-C-Co-Ni ₃ Al with a thickness of 150-500 μm, after applying the first layer with a shape memory effect, it is plastic deformed by up to 6% of the thickness of the first layer using a press consisting of upper and lower traverse. The process temperature is controlled by a pyrometer. A vacuum chamber with a viewing window is located on the frame. In the process of surface plastic deformation, the part is heated with the first layer using a transformer connected to the lower press beam. The whole process of obtaining a high-temperature multilayer composite is carried out automatically using the control unit, to which gas cylinders are connected using hoses. The sample with the composite for annealing is heated using a transformer. The vacuum chamber is mounted on the frame.

After receiving the composite, heating is carried out at a temperature of 30-35 ° C above the solidus temperature with aging for 0.5-1 hours, followed by aging in two steps: 1 step - 1000-1100 ° C, holding 1-1.5 hours; 2 stage - 900-950 ° C, exposure 2.5-3 hours. Heating is carried out using a transformer.

Example

At the first stage, mechanical activation of NiAl powder, a mixture of powders is carried out with the following components, weight. % silicon Si - 12; yttrium Y - 3; boron nitride BN - 20; graphite C - 5; cobalt Co - 5; Ni ₃ Al - the rest is subjected to mixing and grinding in a ball mill using grinding media (in the form of balls) containing WC-CrC-Ni. The mechanical activation of the powders is carried out in an AGO-2U ball mill. The powders are loaded and processed in an inert atmosphere (argon medium) with the following parameters: drum rotation speed 1300 min ^-1 , carrier rotation speed 950 min ^-1 , ball diameter 6 mm, operating time 15 min. At the second stage, high-speed flame spraying is carried out in a protective atmosphere (argon medium) of mechanically activated powders. A vacuum is created in the chamber using a vacuum pump, then this vacuum is filled with argon from a metal cylinder. Next, a mechanically activated powder from NiAl and a mechanically activated mixture of powders from Si-Y-BN-C-Co-Ni ₃ Al are filled into powder dispensers connected by powder supply hoses to the nozzle of a gas-flame burner. The nozzle of the gas-flame burner has two channels for introducing powders: the first channel of the nozzle connected to the powder dispenser, for feeding mechanically activated NiAl powder into the spraying zone, the second channel of the nozzle connected to the powder dispenser, for supplying a mechanically activated mixture of powders based on Si to the spraying zone -Y-BN-C-Co-Ni ₃ Al. Separate supply of mechanically activated powders to the spraying zone is possible due to the design of the nozzle of a gas-flame burner. We obtain a high-temperature multilayer composite on a metal surface as follows: first, a first layer of mechanically activated powder is deposited with a memory effect of NiAl form with a thickness of 500 μm on the surface of a metal part; Next, on the first layer with a shape memory effect based on NiAl, we apply a second layer - a mechanically activated mixture of powders of Si-Y-BN-C-Co-Ni ₃ Al with a thickness of 300 μm, after applying the first layer with a shape memory effect, it is plastic deformed 5% of the thickness of the first layer using a press consisting of upper and lower traverse. The process temperature is controlled by a pyrometer. A vacuum chamber with a viewing window is located on the frame. In the process of plastic deformation, the part is heated with the first layer by means of a transformer connected to the lower beam of the press. The whole process of obtaining a high-temperature multilayer composite on the surface of a metal part is carried out automatically using the control unit, to which gas cylinders are connected using hoses. The sample with the composite for annealing is heated using a transformer. The vacuum chamber is mounted on the frame. Then heating is carried out at a temperature 35 ° C higher than the solidus temperature with aging for 0.5 hour, followed by aging in two stages: 1 stage - 1100 ° C, aging 1 hour; 2 stage - 900 ° C, exposure 3 hours. Heating is carried out using a transformer. The test results are summarized in table 1.

As can be seen from table 1, the obtained high-temperature multilayer composite on the surface of a metal part with a shape memory effect has improved mechanical properties, static and cyclic heat resistance.

Claims (2)

1. A method of obtaining a high-temperature multilayer composite on the surface of a metal part using high-speed flame spraying, characterized in that the surface treatment is carried out by high-speed flame spraying in a protective atmosphere of a pre-mechanically activated NiAl powder with a shape memory effect to obtain a layer with a thickness of 120-500 μm followed by a plastic deformation upon heating below the temperature of the onset of martensitic transformation, a high-temperature layer is obtained moreover, high-speed flame spraying in a protective atmosphere of a pre-mechanically activated mixture of powders of Si, Y, BN, C, Co, Ni ₃ Al with their ratio, weight. %: Si 4-13, Y 2-3, BN 12-20, C 2-8, Co 3-10, Ni ₃ Al - the rest, with a thickness of 150-500 microns, then they are heated at a temperature of 30-35 ° C above the solidus, followed by aging in two stages, the first stage is heated to a temperature of 1000-1100 ° C with an exposure of 1-1.5 hours, the second stage is heated to a temperature of 900-950 ° C with an exposure of 2.5-3 hours . 2. The method according to p. 1, characterized in that argon is used as a protective atmosphere for high-speed flame spraying.