RU2277137C1 - Focused vapor deposition - Google Patents

Abstract

FIELD: metallurgy; method and the device of the electron-beam evaporation and deposition of materials.

SUBSTANCE: the invention is pertaining to the field of metallurgy, in particular, to an method and the device of the electron-beam evaporation and deposition of materials. The process of evaporation and the process of deposition are conducted in the two separate chambers linked to each other through a hole. The various pressure is maintained in the chambers. The annular supersonic stream of the gas is formed around of the hole maintaining the pressure difference between the chambers and allowing the vapor flow to pass through the hole from one chamber into another. The process of evaporation is conducted at the pressure from 10^-4 up to 10^-1 Pa. The deposition is conducted in the range of the pressure from 10^-1 Pa up to the atmospheric pressure. The deposition is realized from the gas stream, which has caught the vapor passed through the hole, intermixed its components and focalized them. The invention also offers the device for realization of the method. The technical result of the invention consists: in the raised factor of the material usage and production of the chemically homogeneous composition of the condensates at evaporation from the several sources containing the various materials and without reduction of the power efficiency output of the process and without complication of the equipment; in the possibility to apply the electron-beam coatings on the inner surfaces of the articles, and also to conduct the coatings deposition at the low vacuum conditions on the Ni-, Co-, Ti-bases containing up to 20 % of W, Mo, Re and other refractory metal.

EFFECT: the invention ensures the raised factor of the material usage, production of the chemically homogeneous composition of the condensates at evaporation from the several sources of various materials without reduction of the power efficiency of the process and complication of the equipment; application of the electron-beam coatings on the inner surfaces of the articles; coatings deposition at the low vacuum conditions on the Ni-, Co-, Ti-bases containing up to 20 % of W, Mo, Re and other refractory metal.

25 cl, 8 dwg, 2 ex

Description

The invention relates to electron beam evaporation and deposition (condensation) of materials, in particular to deposition under low vacuum.

Electron beam evaporation and deposition of materials in a vacuum - EB-PVD technology (Electron Beam Physical Vapor Deposition) is by far the most widely used method for applying thin films and coatings. This method is used for applying heat-resistant and heat-protective coatings to parts of gas turbine engines and plants, for applying wear-resistant coatings, optical films, and also for creating semiconductor devices. Advantages of the method are the high deposition rate provided by powerful concentrated energy sources, the high purity of the deposited materials, achieved through the use of water-cooled crucibles, and a number of unique properties inherent in electron-beam (condensation) coatings. For example, heat-protective coatings made of zirconia ZrO ₂ stabilized with 7-8 wt.% Yttrium oxide Y ₂ O ₃ deposited by electron-beam method have a characteristic columnar structure that provides them with greater durability compared to heat-resistant coatings of the same chemical composition applied in other ways. However, the method of electron beam evaporation and deposition of materials in vacuum has its drawbacks. Among them - a low utilization rate of the material, i.e. the fraction of vaporized material that settles on the product, the need to maintain a high vacuum in the chamber (usually 10 ^-2 -10 ^-4 Pa). The disadvantages of the method include the impossibility of deposition of coatings on products of complex shape having "shaded" sections, which is a consequence of the fact that when coating in high vacuum, the vapor propagates from the source of evaporation in straight lines.

An attempt to eliminate some of the disadvantages of the known methods of evaporation and deposition in vacuum is the method described in US patent No. 4,788,082 (Schmitt, C 23 C 16/00, 1988) - "Jet Vapor Deposition" (JVD). In this method, resistive heating and evaporation of material inside the gas stream occurs. Then the material vapor is transported by a gas jet and is deposited from the gas onto the substrate. Precipitation occurs in low vacuum. The use of a carrier gas stream and low vacuum makes it possible to deposit coatings on products of complex shape, because the vapor molecules do not propagate in a straight line, but together with a gas stream, enveloping the relief of the surface on which the deposition occurs.

However, in its capabilities, this method cannot be compared with electron beam evaporation, because uses resistive heating, which leads to low evaporation and deposition rates and limits the range of evaporated materials.

A step forward in the development of electron beam evaporation and deposition technology was made with the proposal of a method called "Directed Vapor Deposition" (DVD) - US patent No. 5,534,314 (Wadley et al., C 23 C 8/00, 1996). According to this method, a gas stream flows from a nozzle into a vacuum chamber and moves above the surface of a material vaporized by an electron beam. The vapor of the material is captured by a gas stream, transported to the product and deposited from the gas onto the product:

The process of evaporation and deposition is carried out in low vacuum - from 1.3 × 10 ^-1 Pa to atmospheric pressure. Under conditions of such a low vacuum, the commonly used electron guns become inoperative due to the strong attenuation of the electron beam in the atmosphere of residual gases in the chamber, and also because for the guns to work in the chamber of the electron beam generator, it is necessary to maintain a vacuum of at least 10 ^-2 Pa . Therefore, to implement the method, an electron gun with differential pumping and an accelerating voltage of 60 kV was designed and manufactured. The differential pumping gun includes a chain of chambers located on the path of the electron beam, the last of which has a small hole leading the beam into the chamber with high pressure. Additional intermediate pumps are pumped out of the intermediate chambers, therefore, despite the fact that gas from the working chamber penetrates the gun through the outlet, such a system allows maintaining a high vacuum in the chamber of the electron beam generator. The electron guns commonly used for evaporation have an accelerating voltage of 10-20 kV. The higher accelerating voltage of the gun, developed for the DVD method, allowed to increase the mean free path of the electron beam in the atmosphere of residual gases in the chamber and, despite the loss of the beam energy, bring sufficient power to the material being evaporated.

Through the use of a carrier gas stream flowing around the deposition product, the DVD method expands the possibilities of deposition on products of complex shape. The possibility of simultaneous coating of the front and back, “shadow” side of fibers having a cylindrical shape was demonstrated (see http://www.ipm.virginia.edu/process/PVD/Pubs/thesis5.htm). In addition, the lack of high vacuum in the chamber allows for quick reloading of products without unproductive time spent pumping the chamber to operating pressure.

However, the DVD method did not produce a noticeable increase in material utilization.

The closest in technical essence to the claimed method and equipment are the method and equipment described in US application No. 476,309 (Hass et al., C 23 C 14/30), which are a modification of the DVD method. In accordance with this method, a vapor stream of material vaporized by an electron beam is surrounded on all sides by a parallel stream of gas flowing out of an annular nozzle that is placed around the crucible. With this shape and location of the nozzle, the gas stream directs and focuses the vapor stream. The process of evaporation and deposition is carried out in low vacuum - from 0.1 Pa to 32 Pa, therefore, a gun developed in the previous modification of the method is used for evaporation.

Modification of the DVD-method can significantly increase the utilization of the material - from 5-10%, usual for the EB-PVD process, up to 25-35%. The increase in the utilization of the material occurs due to the fact that the gas stream compresses the steam stream located in its axial part and prevents the expansion of the steam to the sides. Another advantage of this method is the ability to obtain condensates that are uniform in chemical composition during evaporation from several adjacent sources containing different materials and surrounded by an annular nozzle. This is achieved due to turbulent and diffusion mixing of the components of the vapor in the gas stream. Studies of the structure and properties of ZrO ₂ - 7% Y ₂ O ₃ condensates obtained by the DVD method showed that the condensates have a columnar structure characteristic of electron beam ceramic coatings and a low coefficient of thermal conductivity (see http: //www.ipm .virginia.edu / research / PVD / Pubs / thesis6 / home.html). This confirmed the possibility of deposition of ceramic thermal protective coatings ZrO ₂ - 7% Y ₂ O ₃ with the required properties in low vacuum.

However, the modification of the DVD method also has several disadvantages. During the process of evaporation in low vacuum, the beam electrons experience many collisions with the molecules of residual gases in the chamber and with the molecules in the carrier gas stream. This leads to strong scattering and attenuation of the electron beam. The use of a high accelerating voltage of the gun increases the mean free path of the electron beam and allows the evaporation process to be carried out, however, this occurs due to large losses of the beam power on the way of its propagation in the chamber. As a result, the energy efficiency of the evaporation process (the fraction of the power of the heating source that is used to evaporate the material) decreases from 5-10%, typical of the EB-PVD process, to 2-3%, i.e. energy intensity of the process increases by 2-3 times. Another disadvantage is that evaporation under low vacuum requires a more complex and therefore more expensive electron gun. The problem of the complexity and cost of equipment, in particular, an electron gun, will increase many times when moving from today's, rather laboratory equipment, using ingots of evaporated material of small diameter, to equipment for industrial production. Finally, the problem of coating products with complex shapes is only partially solved in the DVD method - it is still impossible to apply coatings on the inner surface of products.

The claimed invention is aimed at solving the following problems:

- increase the utilization of the material;

- obtaining condensates uniform in chemical composition during evaporation from several sources containing different materials;

- deposition of coatings on products of complex shape having "shaded" areas;

- improving the quality of the applied coatings by ionization of the evaporated substance;

- application of electron beam coatings on the inner surface of products;

- applying electron beam coatings under high pressure in the deposition chamber, including at atmospheric pressure;

- deposition of coatings on a Ni-, Co-, Ti-base containing W, Mo, Re and other refractory metals, carried out in low vacuum.

- Prevention of reducing the energy efficiency of the process and the complexity and cost of the equipment used.

The last of these tasks is a requirement that must be satisfied by the solution of all other tasks. Some of these problems can be solved in a known manner (DVD-method), however, this solution contradicts the stated requirement to prevent a decrease in efficiency and complicate the equipment.

To solve these, as well as other problems, the claimed invention proposes a method of electron beam evaporation and deposition, characterized in that:

the evaporation process and the deposition process are carried out in two different chambers, an evaporation source located in a water-cooled crucible, which allows continuous feeding of the vaporized material, and means for creating an electron beam in the evaporation chamber are placed in the evaporation chamber, and the pressure in the chamber is maintained in the range from 10 ^{- 4} to 10 ^-1 Pa;

the product is placed in the deposition chamber, the pressure in the chamber is maintained in the range from 10 ^-1 Pa to atmospheric pressure, while the evaporation chamber and the deposition chamber are connected by an opening and the opening is arranged so that a vapor stream of material passes through the opening from the evaporation chamber into the deposition chamber;

in the deposition chamber, an annular supersonic gas jet is created around said hole, and the jet parameters are chosen such that there is no gas flow from the deposition chamber to the evaporation chamber;

vaporize the material using an electron beam;

deposit material on the surface of one or more products.

When implementing the proposed method, the following technical result is achieved.

The utilization of the material is increased due to the fact that the gas flow surrounding on all sides of the material vapor in the deposition chamber prevents the lateral expansion of the vapor and focuses it.

Coatings obtained by evaporation from several sources containing different materials have a uniform chemical composition along the deposition surface due to turbulent and diffusive mixing of the vapor components in the gas stream.

Due to the fact that the vapor is transported by gas, enveloping the relief of the deposition surface, deposition on products of complex shape is possible.

A significant advantage of the proposed method is that when it is implemented, there is no reduction in the energy efficiency of the process and the complexity and cost of the equipment used. The achievement of this result is made possible due to the fact that the evaporation process and the deposition process are carried out in two different chambers, interconnected by a hole, and different pressure is maintained in the chambers. The evaporation process is carried out at a pressure of from 10 ^-4 to 10 ^-1 Pa, which allows you to get rid of the attenuation of the electron beam in the chamber and the associated energy loss. It also makes it possible to use conventional, relatively inexpensive electronic guns. The deposition process is carried out at a higher pressure - from 10 ^-1 Pa to atmospheric, which allows us to solve the problem of increasing the utilization of the material and obtaining coatings uniform in chemical composition during evaporation from several sources containing different materials.

The invention is illustrated graphic materials. Figure 1 shows a schematic diagram of the implementation of the method. Figure 2 shows a variant of the method using the rotation of the electron beam from the original direction by an angle from 20 ° to 180 °. Figure 3 shows a variant of the method, including the ionization of gas and vapor in the deposition chamber. Figure 4 shows a variant of the method, including the ionization of steam in the evaporation chamber. Figure 5 shows a variant of the method using a gas pipeline, which allows you to increase the degree of focusing of the steam stream. Figure 6 shows a variant of the method for coating on the inner surface of the product. 7 depicts a variant of the method in which an annular supersonic gas stream is created from the products of the combustion reaction, designed to precipitate the material at high pressure, for example, atmospheric. Fig. 8 shows an embodiment of the invention using the introduction of a reactant gas into the central portion of the annular gas stream.

The method is as follows. The evaporation chamber 1 and the deposition chamber 2 are interconnected by an opening 3 in the common wall 4. In the evaporation chamber there is an electron gun 5 and a water-cooled crucible 6, in which an ingot of the vaporized material is placed 7. The crucible allows continuous feeding of the vaporized material. A product is located in the deposition chamber 8. Around the opening between the chambers, there are means for creating an annular supersonic gas jet, including an annular prechamber 9, where the necessary overpressure is created, and an annular nozzle 10. In the deposition chamber, the gas flowing from the annular nozzle forms an annular supersonic jet 11. The jet has a “barrel-shaped” shape, characteristic of an underexpanded supersonic gas stream flowing into the flooded space. Pos. 12, a hanging shock wave separates the supersonic flow zone from the residual gas medium in the chamber. During the evaporation and deposition process, the annular supersonic jet allows maintaining the pressure drop between the chambers. During the process, the pressure in the evaporation chamber is maintained in the range from 10 ^-4 to 10 ^-1 Pa, in the deposition chamber is in the range from 10 ^-1 Pa to atmospheric pressure. The system includes a vacuum shutter between the evaporation chamber and the deposition chamber (not shown in FIG. 1). The vacuum shutter is opened immediately before the start of the deposition process and is closed immediately after the end of the deposition process. T.O. the hole between the chambers is open only during the deposition process and is closed during the evacuation of chambers and during reloading of products. This allows the carrier gas to be consumed only during deposition, as well as to quickly reload products in the deposition chamber. Due to the low vacuum in the deposition chamber, the time required to evacuate the chamber to operating pressure after the product is reloaded can be reduced to several minutes. The electron beam 13 reaches the surface of the vaporized material without energy loss due to collisions with residual gas molecules. To control the distribution of heating power over the evaporation surface, an electron beam scan can be used. As a result of heating the surface of the ingot with an electron beam and evaporation of the material in the evaporation chamber, a vapor stream of material 14 is formed. Most of the vapor stream passes through the hole from the evaporation chamber into the deposition chamber and enters the inner part 15 of the annular supersonic gas stream. Steam capture occurs due to the viscosity and diffusion interaction of steam with a gas stream. The steam captured by the gas stream is transported in the axial part 16 of the jet. Arrows 17 show the direction of streamlines — the trajectories along which the microvolumes of steam move. During transportation to the product in the deposition chamber, the vapor of the material is surrounded on all sides by a gas stream. The gas flow prevents lateral expansion of the vapor and, thus, provides focusing of the vapor stream. With further movement, a supersonic jet of gas and steam flows onto an obstacle - the product. In this case, as is known, gas decelerates in a direct shock wave and near the surface of an obstacle - a wall jet is formed. When a product flows around a wall jet, steam is deposited from the jet on the surface of the product. The possibilities of a gas jet for focusing and transporting the vapor enclosed in it, as well as for vapor deposition from a gas jet on the surface of a product under low vacuum conditions, have been convincingly demonstrated by JVD and DVD methods.

The pressure differential between the chambers connected by the hole is maintained due to the fact that the hole is surrounded by an annular supersonic gas stream. The hole between the chambers, surrounded by an annular supersonic gas stream directed toward the chamber with a higher pressure, is a gas-dynamic window. Such a gas-dynamic window allows, in particular, the transport of steam from the low-pressure chamber to the higher-pressure chamber. The pressure difference between the chambers is maintained by the kinetic energy of the gas stream. The supersonic jet works as a high-vacuum steam jet pump, pumping out residual gas from the evaporation chamber to the deposition chamber. Therefore, when steam enters the hole between the chambers, it is captured by a gas stream. The ability to maintain a differential pressure and pumping using a ring supersonic gas jet is known and experimentally verified. For example, in the work "Ermolov VI The structure and pumping properties of the inner part of the annular supersonic jet / UVTF. 1985. - 55, issue 1 - S.186-195." The pumping properties of an annular supersonic gas jet are investigated. Based on the results obtained, the article concludes that it is possible to use the inner part of the ring jet to increase the productivity of vacuum steam jet pumps. According to US Pat. No. 4,931,700, an annular supersonic gas jet is used to discharge an electron beam into the atmosphere. The system described in this patent allows maintaining a residual pressure of about 10 Pa with an external pressure of 10 ⁵ Pa. The pressure of the gas forming the jet (braking pressure) in this system is approximately 8 × 10 ⁵ Pa. The use of a gasdynamic window to remove an electron beam from a vacuum chamber and welding in the atmosphere is described in UK patent No. 1049057 and US patent No. 4,358,249. The use of a gasdynamic window to introduce a laser beam into a high pressure chamber is proposed in US Pat. No. 4,036,012.

For the gasdynamic window to work successfully, it is necessary that the gas jet be supersonic, because only in this case there is no reverse flow of gas forming the jet into the hole. In addition, it is necessary that the inner part of the annular jet be isolated from the deposition chamber by the supersonic flow region. This is necessary so that there is no breakthrough of pressure from the deposition chamber to the evaporation chamber along the axis of the annular jet. The flow in a supersonic gas stream flowing into the medium with a certain pressure is determined by the geometric parameters of the nozzle, the initial gas parameters (braking parameters), and the pressure in the medium. Therefore, for the gasdynamic window to work successfully, it is necessary that the nozzle geometry, initial parameters of the gas forming the jet, and the pressure drop between the prechamber and the deposition chamber be selected so as to ensure that there is no residual gas flow from the deposition chamber to the evaporation chamber.

If the gasdynamic window is used to pass through it a vapor stream, as proposed in the claimed invention, the vapor stream of the material prevents the outflow of gas molecules from the hole towards the chamber with lower pressure and, thus, acts as an additional steam-jet vacuum pump. Due to this, the pumping properties of the annular supersonic jet are further enhanced.

The annular supersonic gas jet in the proposed method simultaneously performs several functions: maintaining the pressure differential between the chambers, minimizing the return flow of carrier gas into the evaporation chamber, trapping the vapor molecules entering the hole between the chambers, mixing the steam components, focusing the vapor and transporting it to the product. Therefore, taking into account the goals and the specific embodiment of the method, it is necessary to optimize the set of parameters that determine the flow in the jet and its structure — nozzle geometry, initial parameters of the gas forming the jet, pressure difference between the prechamber and the deposition chamber, as well as the pressure difference between the evaporation chamber and the camera deposition. The pressure in the deposition chamber can be controlled, for example, by changing the flow area of the vacuum pipe between the chamber and the vacuum pump. To implement the method, means are also necessary for supplying and regulating the flow of carrier gas in the prechamber, pressure sensors in the evaporation, deposition and prechamber chambers (not shown).

Thus, as follows from the description of the method, the claimed invention makes it possible to increase the coefficient of use of the material, allows to obtain condensates uniform in chemical composition during evaporation from several sources containing various materials, and also to deposit coatings on products of complex shape. The solution of the tasks during the implementation of the method is achieved by the fact that the deposition is carried out from a gas jet, which allows focusing the steam, mixing the steam components and depositing the coating on the shaded areas. The tasks were solved with the fulfillment of the requirement to prevent a decrease in the energy efficiency of the process and the complication of equipment. A feature of the proposed method, which allows to fulfill the specified requirement, is that the evaporation process and the deposition process are carried out in two different chambers with different pressures, and the chambers are interconnected by a gas-dynamic window, which maintains a pressure differential and through which steam is transported from the chamber with lower pressure pressure chamber.

A possible variant of the method, using several sources of evaporation, which are located in such a way that the steam stream from each source enters the gas-dynamic window. In traditional electron beam evaporation and deposition from several sources located nearby and containing various materials, there is a strong heterogeneity of the chemical composition of the condensate along the deposition surface. When implementing the proposed method variant, steam from different sources, passing through the hole between the chambers, is focused by a gas stream. When steam moves together with a supersonic gas jet, diffusion as well as turbulent mixing of the vapor components occurs in the axial part of the flow, which allows obtaining a coating without a chemical composition gradient along the deposition surface. In this embodiment, the heating of various sources of evaporation can be carried out by separate electron guns or a single gun using scanning electron beam.

Figure 2 shows a variant of the method using the rotation of the electron beam from the original direction by an angle from 20 ° to 180 °. The angle of incidence of the electron beam (the angle between the beam and the normal to the evaporation surface) is usually chosen no more than 40-50 °. At large angles, the fraction of electrons reflected from the surface increases and the resulting loss of power of the electron beam. However, the configuration of the main version of the system imposes restrictions on the angle of incidence, because above the evaporation surface there is an opening between the chambers and an annular nozzle. In the proposed variant of the method, the beam has a curved path, which allows to reduce the distance between the upper surface of the crucible 6 and the hole between the chambers 3. This makes it possible to reduce the diameter of the annular nozzle, the flow rate of the carrier gas, and, accordingly, increase the efficiency of the process.

The proposed method also provides for the possibility of ionization of the material vapor and the supply of electric potential to the product. For ionization of material vapor, the use of a gas discharge with a hollow cathode is proposed. According to its characteristics, this type of gas discharge is most preferable in the used range of pressures and densities of gas and steam. The configuration of the proposed system allows ionization in two substantially different ways - ionization of vapor in the evaporation chamber or ionization of gas and vapor in the deposition chamber. During ionization of gas and vapor in the deposition chamber (Fig. 3), the anode 18 and the cathode 19 can be located, for example, on opposite sides of the gas and vapor stream. An electric arc arises between the anode and cathode 20. An electric potential, typically negative, is applied to the product. The magnitude of the electric potential can be, for example, from 1 to 10 kV. Under the influence of the negative potential, the positive ions of the evaporated material 21 arising in the plasma of the electric arc are accelerated to the product, further increasing their energy. Deposition using ionization makes it possible to obtain more dense and defect-free coatings, increase the adhesion of the coating to the substrate, and also control the structure of the condensate.

A variant of the method with steam ionization in the evaporation chamber (Fig. 4) can be implemented, for example, by placing an annular anode 18 between the evaporation source and the annular nozzle 18. In this embodiment, an electric arc 20 arises between the annular anode and the surface of the evaporated material. An annular nozzle may also be used as an anode.

The potential on the product can be modulated. Pulsating modulation of the potential on the product prevents the occurrence of an undesirable electric arc between the anode and the product. In addition, pulsating modulation of potential on the product increases the deposition efficiency in the case of deposition of non-conductive material.

Variants of the method are possible, allowing to increase the degree of focusing of the steam flow, as well as making it possible to control its shape. In the simplest of these options, it is proposed to place guide surfaces around the supersonic gas and vapor jets in the deposition chamber that change the direction of the jet and its shape. For example, two planes restricting a stream of gas and steam from two opposite sides make it possible to form a stream having not a circular but elongated cross section corresponding to the shape of the product.

In another embodiment, shown in FIG. 5, a gas pipeline 22 is placed in a deposition chamber around a supersonic jet of gas and steam. The task to which this variant of the method is directed is to obtain a more focused vapor stream. A gas pipeline surrounding a stream of gas and steam on all sides may have a cross section that narrows in the direction of the product. The movement of a gas stream inside a tapering gas pipeline is significantly different from its movement when it flows from a nozzle in a deposition chamber. As you know, with a decrease in the cross-sectional area of a supersonic gas flow, the flow velocity decreases (G.N. Abramovich. Applied gas dynamics. - M: Nauka, 1991. - 597 p.). The gas pipeline in this case is a supersonic diffuser in which the supersonic flow slows down to subsonic speed, passing through a system of oblique shock waves. The nature of the gas flow in the gas pipeline is determined by its shape. If for a given gas flow we will reduce the output section of the gas pipeline, the system of shock waves will move inside the gas pipeline to its inlet until it reaches the inside of the annular supersonic jet. This will lead to the opening of the supersonic flow region in the inner part of the annular jet and, consequently, to the appearance of a gas flow inside the evaporation chamber and to the loss of operability of the gas-dynamic window. Thus, for the implementation of this variant of the method, it is necessary to choose a combination of geometric parameters of the gas pipeline and the parameters of the jet, which ensures the absence of gas flow from the gas pipeline to the evaporation chamber and the normal operation of the gas-dynamic window. The advantage of the option is to increase the utilization rate of the material, as well as reducing the consumption of carrier gas required for the process.

One of the problems of electron beam evaporation and deposition, which have not yet found a solution, is the vapor deposition on the inner surface of the products. To solve this problem, a variant of the method is intended, characterized in that a gas pipe 22 is placed in the deposition chamber around a supersonic jet of gas and steam, the gas pipe enters the internal cavity of the product 23, and the material is deposited on the internal surface of the product (Fig. 6). In this embodiment, the vapor and gas flow enters from the gas pipeline into the internal cavity of the product, where the vapor is deposited from the gas onto the surface of the internal cavity. The steam depleted gas through the outlet 24 leaves the internal cavity of the product. Like all other modifications of the method, this option requires the absence of a gas stream from the deposition chamber to the evaporation chamber. The absence of gas flow from the deposition chamber to the evaporation chamber is ensured by the choice of jet parameters and geometric parameters of the gas pipeline and product. In this embodiment, the product is a continuation of the gas pipeline, therefore, the parameters that determine the operability of the gas-dynamic window and the entire system as a whole also include the geometric parameters of the product. The implementation of this modification of the invention can expand the scope of electron beam evaporation and deposition. For example, such a variant of the method can be used for applying heat-resistant coatings of the type Ni- (Co) -Cr-Al-Y on the inner surface of gas turbine blades.

A possible variant of the method, characterized in that they carry out a chemical reaction of combustion in the combustion chamber and an annular supersonic gas stream is created from the combustion products. In this embodiment, as shown in FIG. 7, an oxidizing agent and fuel are supplied to the annular combustion chamber 25. The combustion products resulting from the combustion reaction expire through the nozzle and form an annular supersonic jet of carrier gas. The fuel components may be, for example, oxygen and kerosene or oxygen and acetylene. In this way, large pressures and flow rates of the carrier gas can be easily obtained; therefore, this variant of the method can be used at high pressures in the deposition chamber, up to atmospheric pressure. Using this variant of the method, the problem of heating the product to the deposition temperature is easily solved. Heating can be fully or partially carried out due to the thermal energy of the combustion products. This option makes electron beam evaporation possible at a pressure in the evaporation chamber of 10 ^-4 -10 ^-1 Pa and precipitation at atmospheric pressure. Precipitation at atmospheric pressure may be applicable, for example, for applying ceramic heat-shielding coatings to gas turbine blades.

A possible variant of the method in which the supersonic gas jet has the shape of an oval or ellipse in cross section. The jet, having an elliptical cross section, allows to increase the utilization of the material during deposition on elongated products. In addition, this form of nozzle and jet can be used when two or more sources of steam are in line.

As indicated above, for the gasdynamic window to work successfully, it is necessary that the gas jet be supersonic. It is known that when a gas flows out of a vessel under the influence of a pressure drop, a supersonic speed can be achieved without a supersonic nozzle. At a certain pressure drop, the value of which is determined by the adiabatic index of the gas, a supersonic flow rate can be obtained when the gas flows through an opening in the vessel wall. Such a hole is called a sonic nozzle. However, the shape of the nozzle determines not only the flow rate, but also the distribution of gas velocities in space, which significantly affects the magnitude of the gas back flow and, therefore, the operability of the gas-dynamic window. Therefore, the shape of the nozzle can be an important tool for controlling the focusing of the vapor and the deposition process. A variant of the invention is possible in which the formation of an annular supersonic gas jet occurs with the help of a profiled annular nozzle having a first tapering, then expanding shape. Such an annular supersonic nozzle is a type of nozzle with a central body.

A variant of the method is possible in which an annular supersonic gas jet is formed from several supersonic gas jets arranged in a circle around a hole connecting the evaporation chamber and the deposition chamber. The advantage of this option is the ability to create a gas stream of different intensities from different sides of the hole, which allows you to control the direction of the steam stream. In particular, this allows the steam flow to be deflected during the process, changing the gas flow rate through the nozzles forming separate jets.

An annular, supersonic jet may consist of an inert gas, such as argon or helium. The use of inert gas allows to ensure high purity of the resulting condensates. The molecular mass of the gas that makes up the jet affects both the flow parameters in the jet, such as the flow velocity, Mach number M, and the process of mutual diffusion of vapor and gas molecules. Thus, the use of a carrier gas with different molecular weights allows one to influence the process of flow, focusing of the steam flow, as well as the process of vapor deposition on the product.

A variant of the method is possible, characterized in that a gas is introduced into the composition of the gas used to create the annular supersonic jet, which can enter into chemical interaction with the vaporized material, and the material obtained as a result of chemical interaction is deposited on the surface of the product. In this embodiment, reactionary evaporation and precipitation occurs. The molecules of the reactant gas and vapor enter into a chemical reaction between themselves on the deposition surface and during movement in the stream. As the reacting gas, oxygen, nitrogen, hydrocarbons and other gases can be used. In this way, for example, ceramic heat-shielding coatings can be deposited from zirconia ZrO ₂ stabilized with 7 wt.% Yttrium oxide Y ₂ O ₃ , evaporating from individual sources of zirconium and yttrium, and introducing oxygen into the carrier gas. In addition, reactive evaporation and precipitation compensate for the effect of partial dissociation of compounds upon evaporation. For example, it is known that during electron-beam evaporation of zirconium dioxide ZrO ₂ , its partial dissociation occurs (Technology of thin films: reference book / Edited by L. Meissell, R. Glanga in 2 volumes, - M: Sovetskoe Radio, 1977 - T.1. - 664 p.). The presence of oxygen in the carrier gas stream allows for the complete oxidation of zirconium and to avoid changes in the chemical composition of the condensate when applying heat-protective coatings ZrO ₂ - 7% Y ₂ O ₃ .

To carry out a chemical reaction with the vaporized material, a significantly smaller amount of gas is needed than to maintain the gas-dynamic window. Therefore, it is possible to reduce the flow rate of the reacting gas by introducing it not into the composition of the source gas entering the prechamber, but directly into the gas stream, into the central part of the jet. This can be implemented, for example, as shown in FIG. The reagent gas is supplied to the hollow ring 26 located on the inside of the annular nozzle 10. Then, through the channels 27 connecting the hollow ring to the nozzle, the reagent gas is supplied to the nozzle. In the near-wall region of the nozzle and in the inner region of the annular supersonic jet, a layer 28 of a mixture of carrier gas with a reagent gas is formed.

One of the options of the proposed method is aimed at solving the problem of deposition of coatings on a Ni-, Co-, or Ti- base containing W, Mo, Re and other refractory metals, carried out in low vacuum. Another disadvantage of the method of electron beam evaporation and deposition (EB-PVD) is the inability to evaporate from one source alloys containing elements whose vapor pressure differs by more than three orders of magnitude. During electron beam evaporation and deposition from a single source, it is difficult or impossible to obtain refractory metals and elements with low vapor pressure — W, Mo, carbon, and others — in Ni, Co, or Ti-based condensates. The well-known way to solve this problem - the use of multi-crucible evaporation - complicates the system and leads to heterogeneity of the chemical composition of the coatings along the thickness and along the products. To solve the problem in this modification of the method, the organometallic compound (MOS) is introduced into the gas composition used to create the annular supersonic jet, the product temperature is chosen so as to ensure thermal decomposition of this MOS, and the metal included in the specified MOS is deposited on the surface products simultaneously with the evaporated material.

The deposition of metals from organometallic compounds is known as the CVD method (Chemical Vapor Deposition) and is a serious competitor to the EB-PVD method in modern industry. [Syrkin V.G. "CVD method. Chemical vapor deposition." - M .: Nauka, 2000. - 496 p.]. Using the CVD method, the organometallic compound is heated and evaporated in vacuum or in a carrier gas atmosphere. Next, the MOC vapor is transported to a substrate heated to the thermal dissociation temperature of this MOC. As a result of thermal dissociation, the MOC decomposes, its organic part is removed from the substrate in the form of gas, and the metal atoms contained in the MOC remain on the substrate and form a condensate. As MOS, metal carbonyls - compounds of the type M _x (CO) y can be used. The carbonyls W, Mo, Re, V, Co, Ni, Fe, Cr, Ru, Tc, Rh, Pt and other metals are known. The main reaction of the thermal decomposition of carbonyls is: M _x (CO) _y → xM + USO. According to this reaction, a metal remains on the substrate, and CO evaporates from the substrate and is removed into the vacuum system. In addition to this reaction, a number of others occur on the substrate, as a result of which, in addition to the metal, carbon C remains in the amount of the condensate, in an amount depending on the temperature of the substrate.

When using this variant of the method, we carry out joint CVD / PVD deposition. At the same time, the temperature of the product is maintained such as to ensure condensation of the vapor of the material vaporized by the electron beam and to ensure thermal decomposition of the MOS. As a result of the joint vapor deposition of the evaporated material and the MOC vapor, a homogeneous multicomponent condensed material is formed on the surface of the product, which includes the components contained in the evaporated material and the metal and carbon contained in the MOC. In this embodiment, carbonyls of refractory metals, for example, W (CO) ₆ , Mo (CO) ₆ , Re ₂ (CO) _10, can be used as MOS. The use of carbonyls is convenient, in particular, in that they have a relatively low sublimation temperature, and for evaporation of many of them, for example, carbonyls W and Mo, it is sufficient to heat to a temperature of 50-70 ° С. Another advantage that carbonyls have over other MOCs, such as halides, is the absence of toxic and aggressive decomposition products. In addition to carbonyls, other compounds, for example, platinum bisacetylacetonate Pt (C ₅ H ₇ O ₂ ) ₂ , for the evaporation of which a temperature of 150-200 ° C, can be used as MOS. If you use this variant of the method together with the ionization of gas and vapor in the deposition chamber, it is possible to produce non-thermal dissociation of the MOC under the action of ionization.

The proposed method can be used to obtain a heat-resistant condensed material, i.e., a material based on Ni- (Co) -Cr-Al-Ti with the addition of 3-16 wt.% Refractory metals - W, Mo, Re and others, as well as containing 0.05-0.25 wt.% carbon. The temperature of electron-beam deposition of coatings on a Ni- or Co-base is usually 750-900 ° C. This temperature range is also suitable for the thermal dissociation of carbonyls. So, for the deposition of Mo carbonyl, the temperature of the substrate should be at least 200 ° C, and for the deposition of carbonyls W and Re, at least 400 ° C. The carbon content in the coating composition can be controlled by changing the temperature of the product, while a higher deposition temperature will correspond to a lower carbon content in the condensate. The deposition of coatings from heat-resistant alloys (superalloys) can be applicable, for example, to obtain structural coatings such as shells on blades with high wall cooling efficiency. Such coatings are described, for example, in US Pat. No. 5,626,462. Another application for the deposition of heat-resistant material is the repair of products from superalloys, for example, gas turbine blades. With such repairs, damaged areas of the product are cleaned, a mask with windows over the damaged areas is applied to the product, and repair material vaporized with an electron beam is deposited on the cleaned surface (US Patent Application No. 741,133). Using the inventive method, it is possible to repair products from superalloys based on Ni or Co, evaporating the base alloy with an electron beam and introducing W, Mo, Re and C from the MOC. It is also possible to repair products from other alloys, for example, titanium alloys Ti - 8% Al - 1% V - 1% Mo or Ti - 6% Al - 2% Sn - 4% Zr - 2% Mo, evaporating the titanium base alloy with an electron beam and introducing Mo from the MOC into the material to be deposited.

Thus, an advantage of the described modification of the method is the ability to precipitate a multicomponent condensed material based on Ni, Co or Ti with the addition of W, Mo, Re and other refractory metals, as well as carbon. Another advantage of this option is the constancy of the chemical composition of the material obtained along the deposition surface. This technical result is achieved due to the simultaneous CVD / PVD deposition of carrier gas from the jet onto the surface of the product.

The claimed invention also provides equipment for implementing the method. Equipment is offered, including:

an evaporation chamber having an operating pressure of from 10 ⁻⁴ to 10 ⁻¹ Pa;

a deposition chamber having an operating pressure of 10 ^-1 Pa to atmospheric and connected to the evaporation chamber by an opening, the opening being arranged so that a vapor stream of material passes through the opening from the evaporation chamber to the deposition chamber;

means for creating an annular supersonic gas jet in the deposition chamber around said hole, the jet parameters ensuring that there is no gas flow from the deposition chamber to the evaporation chamber;

means for creating an electron beam in the evaporation chamber;

water-cooled crucible, allowing continuous supply of evaporated material, placed in the evaporation chamber.

The equipment includes two chambers interconnected by a hole. The connecting hole may be a hole in the common wall between the chambers. The hole should be positioned so that a stream of material vapor passes through it from the evaporation chamber to the deposition chamber, for example, coaxially with the crucible. To maintain the required pressure in the evaporation chamber, a vacuum diffusion pump can be used. A high vacuum is not required in the deposition chamber; therefore, to pump the chamber to the required pressure, a steam-jet booster or oil pump is sufficient. The equipment must ensure the functioning of the gas-dynamic window, i.e. maintaining the pressure differential between the chambers without leakage of gas into the evaporation chamber. Means for creating an annular supersonic gas jet can consist of an annular prechamber, where the necessary excess pressure is created, and an annular nozzle, which is designed to accelerate the gas flow to a supersonic speed. An annular prechamber and an annular nozzle surround the opening between the evaporation and deposition chambers. The annular nozzle may have a first tapering, then expanding shape. The overpressure in the prechamber in front of the nozzle should be sufficient so that, for the selected geometric parameters of the nozzle, there is no gas flow from the deposition chamber to the evaporation chamber.

The equipment includes a crucible, typically a water-cooled copper, in which the vaporized material is located, usually in the form of an ingot. Since a relatively high vacuum is maintained in the evaporation chamber, from 10 ^-4 to 10 ^-1 Pa, a conventional electron gun with a relatively low accelerating voltage of 10-20 kV can be used as a means to create an electron beam.

An equipment option is possible, including means for turning the electron beam from the original direction by an angle from 20 ° to 180 °. For rotation of the electron beam, for example, a transverse magnetic field can be used. When using such an electron gun, it is possible to reduce the distance between the evaporation surface and the hole between the chambers, which reduces the diameter of the annular nozzle and the flow rate of the carrier gas.

The technical result achieved by using the proposed equipment is the implementation of the proposed method of deposition.

The invention is illustrated by the following examples.

Example 1

Electron beam evaporation and deposition of a ceramic heat-protective coating ZrO ₂ - 7% Y ₂ About ₃ . The evaporated material in the form of an ⌀ 51 mm ingot is placed in a water-cooled copper crucible. The pressure in the evaporation chamber is maintained from 10 ⁻³ to 10 ⁻⁴ Pa. Using an electron gun with an accelerating voltage of 18 kV, the ingot is heated until it melts and the required evaporation temperature is reached. The current of the beam of the gun is 1.2-1.5 A. The feed speed of the ingot is 0.7-1.0 mm / min. Around the hole between the chambers create an annular supersonic jet of gas. For this, a pre-chamber is maintained at a pressure of 100-200 Pa. A pressure of 5-10 Pa is maintained in the deposition chamber. Immediately before the deposition process begins, a vacuum shutter is opened between the chambers. The material is deposited on the product. The temperature of the product during the deposition process is maintained equal to 1040 ° C.

Example 2

Carry out the deposition of the heat-resistant alloy Ni - 12% Co - 13% Cr - 7% Al - 2% Ti - 3% Mo - 10% W - 3% Re - 0.1% C. To do this, use a modification of the method that implements simultaneous CVD / PVD deposition.

Alloy Ni - 14% Co - 15% Cr - 8% Al - 2.5% Ti in the form of an ingot ⌀ 51 mm is placed in a copper water-cooled crucible. The pressure in the evaporation chamber is maintained from 10 ⁻³ to 10 ⁻⁴ Pa. Using an electron gun with an accelerating voltage of 18 kV, the ingot is heated until it melts and the required evaporation temperature is reached. The beam current of the electron gun is 1.4 A. The ingot feed rate is 1.1 mm / min. Organometallic compounds - Mo, W, Re carbonyls, which are in the form of a powder, are placed in separate vessels. Vessels with carbonyls are heated to the temperature necessary for their sublimation (evaporation from a solid state) - 65 ° C for Mo and W carbonyls, and 125 ° C for Re carbonyl. Carbonyl vapor is introduced into the carrier gas. In this case, the temperature of the channels connecting the vessels with the carbonyls and the prechamber is maintained equal to the temperature of the vessels with the carbonyls in order to prevent the carbonyls from precipitating on the walls of the channels. The consumption of carbonyls is controlled by changing the sublimation temperature and / or the bore of the connecting channels. Around the hole between the chambers create an annular supersonic gas stream, maintaining the pressure in the prechamber 100-200 Pa. A pressure of 8-10 Pa is maintained in the deposition chamber. After opening the vacuum shutter, CVD / PVD is co-deposited onto the surface of the product. The temperature of the product during the deposition process is maintained equal to 920 ° C.

Thus, as follows from the description, the proposed deposition method and equipment for its implementation have significant advantages over the known. The main ones are:

increasing the utilization of the material and obtaining condensates homogeneous in chemical composition during evaporation from several sources;

containing various materials without reducing the energy efficiency of the process and complicating the equipment;

deposition of electron beam coatings on the inner surface of products;

deposition of coatings on a Ni-, Co-, Ti-base containing up to 20% W, Mo, Re and other refractory metals, carried out under low vacuum.

The specified technical result is achieved in that the deposition is carried out from a jet of gas, which allows you to mix the components of the vapor and focus the steam. In this case, the evaporation process and the deposition process are carried out in two different chambers with different pressures, and the chambers are interconnected by a gas-dynamic window, which maintains a pressure differential and through which steam is transported from one chamber to another.

Claims (25)

1. The method of electron beam evaporation and deposition, characterized in that the evaporation chamber is placed at least one source of evaporation located in a water-cooled crucible that allows for continuous feeding of the vaporized material, and means for creating an electron beam in the evaporation chamber, the pressure in the evaporation chamber is maintained in the range of 10 ^-4 to 10 ^-1 Pa, is placed in a deposition chamber, at least one item in a chamber maintained at a pressure in the range of 10 ^-1 Pa to atmospheric pressure, with ka The evaporation rate and the deposition chamber are connected by an opening and the opening is arranged so that a vapor stream of material passes through the opening from the evaporation chamber into the deposition chamber, an annular supersonic gas jet is created around the opening in the deposition chamber, and the jet parameters are selected such that the gas flow from the deposition chamber there is no evaporation chamber, the material is vaporized using an electron beam and the material is deposited on the surface of one or more products. 2. The method according to claim 1, characterized in that use several sources of evaporation. 3. The method according to claim 1, characterized in that the electron beam is rotated from the original direction by an angle from 20 to 180 °. 4. The method according to claim 1, characterized in that the gas and steam are ionized in the deposition chamber using a hollow cathode and an electric potential is supplied to the product. 5. The method according to claim 1, characterized in that the steam is ionized in the evaporation chamber using a hollow cathode and an electric potential is supplied to the product. 6. The method according to claim 4, characterized in that use pulsating modulation of potential on the product. 7. The method according to claim 5, characterized in that use pulsating modulation of potential on the product. 8. The method according to one of claims 1 to 7, characterized in that in the deposition chamber around the supersonic stream of gas and steam guide surfaces are placed. 9. The method according to one of claims 1 to 7, characterized in that a gas pipe is placed in the deposition chamber around a supersonic jet of gas and steam, the jet parameters and the geometric parameters of the gas pipe being selected such that there is no gas flow from the deposition chamber to the evaporation chamber. 10. The method according to one of claims 1 to 7, characterized in that a gas pipe is placed in the deposition chamber around a supersonic jet of gas and steam, the gas pipe enters the internal cavity of the product, the jet parameters, the geometric parameters of the gas pipeline and the product being chosen such that the gas stream from the deposition chamber to the evaporation chamber is absent and the material is deposited on the inner surface of the product. 11. The method according to one of claims 1 to 7, characterized in that the chemical reaction of combustion in the combustion chamber is carried out and an annular supersonic gas stream is created from the products of the combustion reaction. 12. The method according to one of claims 1 to 7, characterized in that the supersonic gas stream has the shape of an oval or ellipse in cross section. 13. The method according to one of claims 1 to 7, characterized in that the annular supersonic gas stream is formed using an annular nozzle, which first has a tapering, then expanding shape. 14. The method according to one of claims 1 to 7, characterized in that the annular supersonic gas stream is formed from several supersonic gas streams located around the circumference around the hole connecting the evaporation chamber and the deposition chamber. 15. The method according to one of claims 1 to 7, characterized in that the annular supersonic jet consists of an inert gas. 16. The method according to one of claims 1 to 7, characterized in that the gas used to create a chemical interaction with the vaporized material is introduced into the composition of the gas used to create the annular supersonic jet, and the material obtained as a result of chemical interaction is precipitated on the surface of the product. 17. The method according to one of claims 1 to 7, characterized in that gas is introduced into the central part of the annular supersonic jet, which can enter into chemical interaction with the vaporized material, and the material obtained as a result of chemical interaction is deposited on the surface of the product. 18. The method according to one of claims 1 to 7, characterized in that the organometallic compound is introduced into the composition of the gas used to create the annular supersonic jet, the product temperature is chosen so as to ensure thermal decomposition of the organometallic compound, and the metal included in the specified organometallic compounds are deposited on the surface of the product simultaneously with the evaporated material. 19. The method according to one of claims 1 to 7, characterized in that the organometallic compound is introduced into the central part of the annular supersonic jet, the temperature of the product is chosen so as to ensure thermal decomposition of the organometallic compound, and the metal included in the specified organometallic compound is deposited on the surface of the product simultaneously with the evaporated material. 20. Equipment for electron beam evaporation and deposition on the product, including an evaporation chamber having an operating pressure of 10 ^-4 to 10 ^-1 Pa, a deposition chamber having an operating pressure of 10 ^-1 Pa to atmospheric and connected to the evaporation chamber by a hole, arranged so that the vapor stream of the material passes through the hole from the evaporation chamber to the deposition chamber, means for creating an annular supersonic gas jet in the deposition chamber around the said hole with parameters ensuring the absence of gas flow from the wasp chamber Denia evaporation chamber, means for generating an electron beam to the evaporation chamber, a water-cooled crucible, allowing to carry out continuous feeding the evaporated material placed in the evaporation chamber. 21. The equipment according to claim 20, including means for ionizing gas and vapor in the deposition chamber, means for ionizing steam in the evaporation chamber, means for supplying potential to the product, and means for pulsating modulation of potential on the product. 22. The equipment according to claim 20, comprising a gas pipeline surrounding a supersonic jet of gas and steam and entering the internal cavity of the product, the jet parameters, the geometric parameters of the gas pipeline and the product being selected such that there is no gas flow from the deposition chamber to the evaporation chamber. 23. The equipment according to claim 20, characterized in that the means for creating an annular supersonic gas jet include a combustion chamber and means for carrying out a chemical combustion reaction in a combustion chamber. 24. The equipment according to claim 20, including means for rotating the electron beam from the original direction by an angle of 20 to 180 °. 25. Equipment according to one of claims 20-24, comprising an annular nozzle that first has a tapering, then expanding shape and is used to form an annular supersonic gas jet.

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