RU2167739C1 - Method of manufacturing part with single-crystal structure by oriented crystallization and device for method embodiment - Google Patents

Abstract

FIELD: foundry, particularly, methods for manufacture of machine parts with single-crystal structure, for instance, blades by oriented crystallization. SUBSTANCE: mold is installed into preheating chamber, heated and moved to metallization chamber. Then mold with metallized surfaces is moved to heating chamber in which it is located horizontally with its longitudinal axis. Melt is poured into mold. Mold with melt is placed into cooling chamber for formation of oriented or single-crystal structure in casting. Metallization of mold and cooling are performed under effect of two flows of mixtures of inert gas and powdery cooling agents from materials undergoing phase conversions with heat abstraction. Each chamber has appliance for transportation of molds in horizontal plane. Located beyond chambers are vacuum and gas system and systems of formation of cooling flows. Located in chambers are system of direction of cooling flows, systems of mold heating and melting. EFFECT: reduced material consumption and time for heating and cooling of molds, higher economical and production efficiency of process. 9 cl, 1 dwg, 4 tbl

Description

 The present invention relates to foundry, and more specifically relates to a method for manufacturing directed by crystallization parts with a single crystal structure and device for its implementation.

 This invention can be used, in particular, in the production of cast parts for gas turbine engines and gas turbine units, such as rotor blades.

 Directional crystallization is being manufactured now and in the future can be manufactured cast parts of critical purpose, operated at high temperatures, static and variable mechanical and thermal stresses. Examples of such parts are working and guide vanes. Depending on the conditions for the implementation of the method, cast parts can be formed as a single crystal or can be formed from columnar crystals oriented in the same direction. Directed crystallization can be obtained under various conditions of the method, cast parts with a columnar structure, a single-crystal structure, a combination of these structures. Differences in implementation conditions result in a different level of imperfection in the material of parts: volume microporosity ranging from ~ 1.0 to ~ 0.01% and the presence or absence of zones with defects in the crystal lattice in the form of chains and coaxially oriented zones ("freckles").

 The quality of the structure and the level of defectiveness of the part obtained by directional crystallization depends on the temperature gradient at the crystallization front and the crystallization rate. The high values of these thermophysical parameters provide high quality parts, that is, the stability of the single crystal structure in the entire part and the minimum level of defectiveness. At low temperature gradients and even at high solidification rates, it is impossible to obtain single-crystal and oriented columnar structures in detail. At high temperature gradients at the crystallization front and low solidification rates, parts with single-crystal and columnar structures have one degree or another of defectiveness, that is, parts have reduced operational reliability and durability.

 The values of the thermophysical crystallization parameters are determined, ceteris paribus, by the intensities of the two stages of the heat transfer process from the crystallizing alloy. Firstly, the intensity of heat transfer of crystallization of the alloy directly from the inner surface of the mold through the wall of the mold to its outer surface and, secondly, the intensity of heat removal from the outer surface of the mold. The limiting is, of course, the transfer of heat of crystallization through the wall from the inner to the outer surface of the mold.

 It is known that the rate of heat transfer through the wall of the mold is determined and controlled by the thermal conductivity of the material and the wall thickness of the mold. The higher the thermal conductivity of the mold material and the smaller the thickness of the mold wall, the higher the intensity of heat transfer through the mold wall to its surface.

 It is also known that the intensity of heat removal from the outer surface of the mold is controlled in a wide range and the higher this intensity, the higher the values of the thermophysical parameters of the formation of single-crystal structures in parts and the higher their quality.

A known method of manufacturing a directed crystallization of a part with a single crystal structure (RU, 2157296), which consists in installing a heated casting ceramic mold with through porosity in the outer layers in a heating chamber on a lifting water-cooled table. Then pour the casting ceramic mold with a melt, the crystallization of which is carried out from the bottom up. The molded ceramic mold with crystallizing melt is moved from the vacuum heating chamber down to the cooling chamber. In the process of moving the mold, it is cooled by a crystallizer on the table, and, while moving in the cooling chamber, the casting ceramic mold is additionally cooled by two independent cooling streams of mixtures of inert gas and powder coolers. The essence of the technical solution consists in converting a low-conductivity (see table 1) ceramic mold into a relatively high-conductivity cermet. This transformation is achieved by manufacturing ceramic shell molds with known porosity of up to 15% in the surface outer layers and by subsequent impregnation of these mold layers in vacuum at temperatures close to 1500 ^° C with heat-conducting liquid metals, such as copper and aluminum. The proposed technical solution allows to increase the thermal conductivity of the mold wall up to ~ 15 times.

In this method, natural and artificial methods were used to remove heat from the outer surface of the molds during crystallization of the alloy and cooling the casting. The natural heat transfer by radiation in vacuum from a ceramic mold heated to ~ 1500 ^o C to the environment — water-cooled walls of the cooling chamber — is used.

The energy of phase transformations (melting, evaporation, and sublimation) in coolers was used for artificial heat selection. The efficiency of using the energy of phase transformations of solid powder coolers on the surface of the mold is as follows:
- all restrictions on the dimensions and weight of single-crystal cast parts are removed;
- the rates of formation of single-crystal structures can reach from 40-70 mm / min (N 2146185) to 100 or more mm / min (I.E. Tsatsulina "Super- and hyper-speed directed crystallization of heat-resistant alloys", M., "MISIS", 2000 g., p. 19).

 Each of the independent streams consists of a mixture of inert gas with powder coolers of various chemical composition and significantly different thermophysical characteristics. The upper stream contains a powdery cooler that undergoes only one phase transformation - melting. The highly heat-conducting cooler melted by the mold heat (see table 2) impregnates the porous layers of the ceramic mold, transforming it into a cermet. The lower stream contains a powdery cooler, which undergoes two phase transformations during melting and melting and evaporation, or one sublimation. Each of the independent flows is different in their physical mechanism of action. The upper stream is intended mainly for the selection of heat from the depth of the mold and its transfer due to the relatively high thermal conductivity of the cermet of the mold to the mold surface. The bottom stream is intended for heat removal from the mold surface due to melting and evaporation or sublimation of the cooler and heat transfer together with inert gas to the cooled inner surfaces of the cooling chamber for subsequent condensation, crystallization and cooling of the cooler and cooling in a gas inert gas system.

 Each of the independent streams is also different at the moment of the onset of action: always and always first turn on the stream, the powder cooler in which undergoes only one phase transformation - melting, and with the time delay necessary for impregnating the porous layers of ceramics with a highly heat-conducting metal, include the second stream, powder a cooler in which it undergoes one or two phase transformations to a vapor state.

 A device is known for manufacturing a crystallized directed part with a single-crystal structure (RU, 2157296), it contains a vacuum furnace, which consists of two water-cooled chambers located one above the other coaxially. The upper chamber is the heating chamber, and the lower chamber is the cooling chamber. The chambers are separated by a water-cooled partition with a hole. The device has a device located in the heating chamber for heating the mold until it is filled with the melt from the rotary melting crucible. The device has a table with a crystallizer. The form is mounted on the table with the possibility of its movement from the heating chamber to the cooling chamber through an opening in the partition.

 The device is also equipped with two types of independent and well-known devices located outside the furnace, for forming and two types of independent devices placed in the cooling chamber, for directing two cooling flows to the form. Devices for forming a cooling flow consist of two independent systems located outside the cooling chamber of the gas system, for forming a mixture of gas with powder coolers, for example, a well-known hopper, dispenser, etc. Devices for directing flows consist of spray systems located inside the cooling chamber. Spray systems have sprinklers located on the ring, the openings of the spray systems are directed to the mold.

 However, in this method and device, despite the possibility of achieving very high rates of formation of single-crystal structures in parts of any length and mass, it is impossible to create highly economical and high-performance technologies and equipment for casting single-crystal parts.

It is necessary to maximally equalize the time durations τ ₁ , τ ₂ and τ _{3 of the} three main stages of single-crystal casting: thermal preparation of the mold over time τ ₁ , melting of the superalloy and pouring over the mold over time τ ₂ , formation of the single-crystal structure during τ ₃ during mold cooling with a melt
The time τ _{1 of} heating the mold to a casting temperature of ~ 1500 ^° C is currently several (up to 4.0) hours and should be reduced many times.

The time τ ₂ of superalloy melting and mold casting is currently 30–40 min at a melting rate of ~ 1 kg / min, there are no technical problems in reducing the melting time by 1.5–2.0 times.

The time τ _{3 for the} formation of a single-crystal structure in a part for a blade with a length of 500 mm varies depending on the casting speed: according to patent N 2157296 from 12.10.99 ~ 25 min.

Thus, a maximum reduction in time τ _{1 of} thermal preparation of the mold to fill is necessary.

All other things being equal (types and arrangement of heaters, power, etc.), the reduction of time τ ₁ can be achieved in two ways: by reducing the wall thickness and, accordingly, the mass of the mold and increasing the thermal conductivity of the mold material.

In the above method and apparatus, it is possible to increase the thermal conductivity of the ceramic mold by converting the low-conductivity ceramic of the mold into a significantly more (up to ~ 15 times) thermal conductive cermet. This technical solution was used exclusively to increase the rate of formation of a single-crystal structure and, moreover, in terms of implementation time — after filling a ceramic mold heated to ~ 1500 ^° C with a melt — this solution does not affect the analyzed time τ ₁ .
Thus, the analyzed method and device do not allow to reduce the material consumption of the mold and energy consumption for heating the mold, to reduce the time for heating and cooling the mold and to reduce the time spent on the manufacture of the part as a whole.

 The basis of the invention is the creation of a method for manufacturing a directed crystallization of a part with a single crystal structure and a device for its implementation with such their implementation, which would reduce the material consumption of the mold and energy consumption for heating the mold, reduce the time of heating and cooling the mold and, therefore, reduce the time spent to manufacture the most economical and productive part in general.

 The problem is solved in that in a method for manufacturing a directed crystallization of a part with a single crystal structure, including the installation of a ceramic casting mold, made with through porosity in the outer layers, in a heating chamber of a vacuum furnace, heating the casting mold, pouring the melt, moving the mold from the heating chamber to cooling chamber, its cooling by a stream from a mixture of inert gas and a powder cooler from a material that undergoes two phases during heat removal from a crystallizing melt transformations — melting and evaporation, or only one phase transformation — sublimation, before installing the mold in the heating chamber of the vacuum furnace, the mold is placed in the preheating chamber, heated and transferred to the metallization chamber, the outer layers are metallized in it by a stream from a mixture of inert gas and powder a cooler from a material that undergoes one phase transformation during melting - melting, while preliminary heating is carried out at a temperature higher than the pore melting temperature chock-shaped cooler.

 Preliminary heating of the mold is carried out to a temperature exceeding up to 200 degrees the melting temperature of the powder cooler.

 When metallizing the outer layers of the mold, the minimum temperature of the powder cooler is maintained within 50 degrees below its melting temperature.

 Preferably, the mold is placed in the heating chamber of the vacuum furnace with the longitudinal axis horizontally when heated.

 The flow from a mixture of an inert gas and a powder cooler in the cooling chamber of a vacuum furnace is directed, mainly, in a vertical plane with an inclination in the direction of movement of the mold.

 During metallization and cooling of the mold, its inner cavity and the inner surface of the melting crucible in the heating chamber are isolated from exposure, respectively, of powder particles and cooler vapors.

 The problem is also solved by the fact that a device for manufacturing a directed crystallization of a part with a single-crystal structure, containing a vacuum furnace with a vacuum system, having a mold heating chamber and a mold cooling chamber, a mold made with through porosity in the outer layers, installed with the ability to move from the heating chamber to the cooling chamber, a gas system located outside the vacuum furnace, two devices for forming flows from the mixture and an inert gas and a powder cooler located outside the vacuum furnace, a device for directing a stream from a mixture of an inert gas and a powder cooler from a material that undergoes two phase transformations during melting of heat from a crystallizing melt — melting and evaporation or one phase transformation — sublimation located in the cooling chamber and a device for directing a stream from a mixture of an inert gas and a powder cooler from a material to a mold, has undergone one phase transformation during melting - melting, is equipped with at least one block of chambers with vacuum shutters, consisting of interconnected pre-heating chambers and a metallization chamber of the outer layers of the mold, a docking device for sealing the space between the vacuum furnace and the chamber block while the mold is installed with the possibility of moving from the pre-heating chamber to the metallization chamber and the heating chamber, and at least one is adapted e for casting flow direction to form a mixture of inert gas and the cooling of the particulate material undergoes the selection of one phase transformation heat - melting is disposed within the plating chamber.

 The mold is installed in the heating chamber with the location of its longitudinal axis in the horizontal plane.

 The melting crucible of the heating chamber has an insulating cover.

 This invention allows to increase the intensification of heat transfer through the wall of the mold when it is heated and cooled due to a significant reduction in the thickness of the mold wall and the mold mass. The invention also provides a reduction in material consumption of the form and energy intensity of most stages of the technology of casting parts with a single crystal structure.

 Thus, in this invention, firstly, the horizontal arrangement of the axis of the mold during pouring and cooling reduces the load in all its sections from the metallostatic pressure of the melt by two or more times, and also reduces the load from the metal mass and the mold mass. Secondly, the horizontal arrangement of the form is preferably convex surfaces - back down. Only such an arrangement ensures the lowest possible loading at the most stressed points of the concave surfaces of the mold — the trough, at the points of maximum curvature. Thirdly, reducing the wall thickness of the mold up to two times. In this case, with a horizontal arrangement of the form, the load of a single section of it will not increase compared to the variant of the vertical position of the axis of the form. Moreover, the material loading in any section of the form from thermal stresses - the most dangerous from the point of view of maintaining strength under all technological cooling conditions during the formation of a single-crystal structure decreases in proportion to the decrease in wall thickness.

This invention allows, due to the horizontal arrangement of the mold to reduce the thickness of its walls and metallization of its outer layers at a temperature of ~ 700 ^o C, in the case of aluminum, to reduce the material consumption of the mold, reduce the time of heat preparation of the mold and energy consumption at all stages of the manufacturing technology and heat treatment mold, as well as at the stage of formation of a single crystal structure.

 The invention is further illustrated by a specific exemplary embodiment and the accompanying drawing, which schematically shows a horizontal section along the axis of the mold of a general view of a device for manufacturing a crystallized directional part with a single crystal structure according to the invention.

 A method of manufacturing a monocrystalline structure-directed part with crystallization is that a mold with through porosity is installed in the outer layers in the preheating chamber, the mold is preheated in the preheating chamber, then the mold is moved from the preheating chamber to the metallization chamber, and metallization in it the outer layers of the mold are carried out at a temperature below the maximum temperature of the preheating of the mold an outflow from a mixture of an inert gas and a powder cooler undergoing one phase transformation - melting. In this case, it is desirable to maintain the maximum temperature of the preheating of the mold up to 200 degrees above the melting temperature of the powder cooler. When metallizing the outer layers of the mold, the minimum temperature of the powder cooler in the stream from its mixture with an inert gas is maintained up to 50 degrees below its melting temperature. The metallized mold is moved and installed in a vacuum heating chamber with the longitudinal axis horizontally and a convex profile surface down. The mold with the metallized surface layers is heated in the heating chamber to the pouring temperature of the mold. A mold is poured with a metallized surface layer with a melt. The mold is moved from the vacuum heating chamber to the cooling chamber, it is cooled by a stream from a mixture of inert gas and a powder cooler from a material that undergoes two phase transformations during melting of heat from a crystallizing melt - melting and evaporation, or only one phase transformation - sublimation.

 The flow from a mixture of an inert gas and a powder cooler from a material that undergoes two phase transformations — melting and evaporation or one phase transformation — sublimation during heat removal from a crystallizing melt — was directed mainly in a vertical plane with an inclination in the direction of movement of the mold in the cooling chamber.

When transferring the process of converting ceramics to cermets from the period τ _{3 of the} formation of a single crystal structure into the period τ ₁ and to impregnate the outer porous layers, use a highly heat-conducting material with a relatively low melting point t ₁ , for example, aluminum or its alloys with t ₁ ≅ 700 ^o C, then the longest heating period of the mold from 700 to 1500 ^o C can be significantly reduced and reduced, respectively, τ ₁ . According to our calculations, the introduction of a new operation in the ceramic heating cycle - metallization by impregnation with aluminum at a temperature of ~ 700 ^o C can reduce the time τ ₁ several times.

Table 3 shows the data on the saturated vapor pressure P ₁ aluminum at temperatures above the melting point.

10^-3 Па всегда противодействуют капиллярному давлению P₃ жидкого алюминия в сквозных тупиковых каналах пористой стенки в наружных слоях керамической формы.It is known that the pressure P ₁ together with the residual pressure P ₂

10 ^-3 Pa always counteract the capillary pressure P _{3 of} liquid aluminum in the through blind channels of the porous wall in the outer layers of the ceramic form.

Naturally, a decrease in the value of P ₁ at ~ 1500 ^o C to a value corresponding to a temperature of ~ 700 ^o C (see table 3) will speed up the impregnation process in time, and, at the same time, will also increase the depth of impregnation. Consequently, the intensity of heat transfer will increase not only during the period _of formation of a single crystal structure during heat transfer from the internal to the external surface of the mold, but also from the external surface of the mold to the internal during the preparation of the mold for heat during the period τ ₁ .

 It is known that regardless of the thermophysical properties of the material of the form (see table 1) and the physical structure of its material - porous (through or insulated porosity) ceramics or cermets, the intensity of heat transfer through the wall is inversely proportional to its thickness. Consequently, any, and even more significant, decrease in the thickness of the mold wall significantly increases the intensity of heat transfer.

 Foreign and domestic patents and special literature on directional crystallization of superalloys, incl. the most informative monograph, “Supersplavy II”, M., “Metallurgy”, 1995, does not contain a description of technical solutions for the intensification of heat transfer processes in ceramic casting molds by reducing the wall thickness and, consequently, the mass. Moreover, with regard to large-sized cast single-crystal parts from superalloys, even the very formulation of this question is unknown, although a decrease in the wall thickness and mass of the ceramic or cermet form not only provides an intensification of heat transfer processes, but also reduces the material and energy consumption of the technology as a whole.

 The main obstacle to a significant reduction in the wall thickness of shell ceramic molds is the danger of mold destruction during pouring and during the formation of a single-crystal structure, which can continue for hours on modern technologies. The destruction of the ceramic form inside the vacuum units can have disastrous consequences and therefore unacceptable. Thus, a decrease in the mold wall thickness should not result in softening or, which is unlikely, deformation of the mold.

From our analysis of the stress state of the material of a large-sized ceramic shell mold together with a profit of length L ≥ 700 mm with a wall thickness of δ _f ≥ 5 mm, taking into account:
- axial tensile stresses in the cross sections of the mold from the mass of the metal and the mass of the mold;
- meridional bending stresses in the cross sections of the form from the action of the internal hydrostatic pressure of the liquid metal;
- meridional bending stresses in the cross sections of the mold from the action on the mold in the zone of formation of the monocrystalline structure of the pressure of the cooling stream (a mixture of inert gas and powder cooler undergoing phase transformations on the mold surface before vaporization) and evenly distributed pressure of the cooler vapor;
- thermal stresses in the zone of influence on the form of the cooling flow due to temperature differences in the mold wall along the length (height) of the zone of intensive cooling of the mold and the thickness of the mold wall in this zone, the following conclusions are made.

 From the point of view of mechanical loads (mass of the metal, mass of the mold, metallostatic pressure of the melt, pressure of the cooling stream and vapor pressure of the cooler), a significant 1.5 - 2.0 times decrease in the thickness of the mold wall while maintaining its constant strength is possible with a proportional decrease in the metallostatic pressure of the melt on the form.

 From the point of view of thermal stresses in the form from temperature extremes over the wall thickness, it was found that these stresses are directly proportional to the wall thickness and inversely proportional to the thermal conductivity of the mold material.

 From the point of view of the interaction of stresses from mechanical and thermal loads, the most dangerous are the points on the concave surfaces of the mold, where the stresses from the metallostatic pressure, the pressure of the cooling flow and the vapor pressure of the cooler are combined with the stresses from the temperature difference across the mold wall thickness.

 A device for manufacturing a directed crystallization part with a single crystal structure, a horizontal section of which is shown in the accompanying drawing, contains a vacuum oven 1 and at least one chamber unit 2 with a device for transporting the mold in a horizontal plane (not shown in the drawing). The horizontal section is formed by a plane passing through the axis of the ceramic mold 3 made with through porosity in the outer layers. The vacuum furnace 1 with a vacuum system includes a mold heating chamber 4 and a mold cooling chamber 5, a vacuum shutter 6 separating the heating chamber 4 and the cooling chamber 5. The block 2 of the chambers comprises a pre-heating chamber 8 and a metallization chamber 9 interconnected by a vacuum shutter 7. At least one device 10 is located inside the chamber 9 for directing flows to the mold 3 from a mixture of an inert gas and a powder cooler from a material undergoing one phase transformation — melting. The chamber 9 has, on the side of the heating chamber 4, a vacuum shutter 11. Between the vacuum furnace 1 and the chamber block 2 there is a docking device 12 for sealing the space between the vacuum furnace 1 and the chamber block 2. The mold 3 is mounted to move it from the preheating chamber 8 to the metallization chamber 9, the heating chamber 4, and the cooling chamber 5. The preheating chamber 8 has a vacuum shutter 13 for connection with the environment. The heating chamber 4 has, on the side of the metallization chamber 9, a vacuum shutter 14. The cooling chamber 5 also has a vacuum shutter 15 for connection with the environment. The vacuum furnace 1 and the chamber block 2 have an independent vacuum system (not shown in the drawing), a gas system (not shown in the drawing) located outside the vacuum furnace 1 and the chamber block 2 are two types of devices (not shown) for forming flows from mixtures of inert gas and powder coolers located outside the vacuum furnace 1 and the block 2 of the chambers.

 The device also has a device 16 for directing flows to the mold 3 from a mixture of inert gas and a powder cooler from a material that undergoes two heat transformations — melting and evaporation, or one phase transformation — sublimation located in the cooling chamber 5 during heat removal from crystallizing melt. .

 Condensers are located in chambers 5 and 9 for separating the carrier gas and vapor of the cooler and for condensation, crystallization and cooling of the cooler. In the vacuum furnace 1 and block 2 there is an independent mechanism for moving forms 3 inside the chambers 4, 5, 8, 9 and beyond. Capacitors and the mechanism for moving the form 2 are not shown in the drawing. A vacuum system, a gas system adapted to form flows from a mixture of an inert gas and a powder cooler and devices 10, 16 for directing flows to a mold 3, are well known (see RU 2146185; RU 2157296).

 In chambers 4, 8 and 9, heaters 17 are located for the thermal preparation of form 3 for pouring. In the chamber 4 there is at least one melting furnace 18 for melting and casting with an insulating cover (the cover is not shown in the drawing). Charging devices 19 for the charge are located outside the chamber 4. In the direction of arrow A, the figure shows the direction of movement of the mold 3. The insulating cover isolates the interior of the furnace 18 during the period of action on the mold 3 in the cooling flow cooling chamber 5. The direction of arrows B shows the direction of flow of the cooler.

 In this example, the mold 3 is made with a wall thickness of 1.5 - 2.0 times less than when placing it with the longitudinal axis vertically.

 This device may have an insulating cover made of heat-resistant material (not shown in the drawing) installed on the profitable part 20 of the mold 3 and located in the metallization chamber 9 for removing the insulating cover from the mold 3 after the metallization of the insulating cover (not shown). A device 10 for directing flows to a mold together with a device for their formation, not shown in the drawing, ensures that the temperature of the powder cooler is kept to a minimum temperature of 50 degrees below the temperature of its phase transformation - melting.

 A device for manufacturing a directed crystallization of a part with a single crystal structure works, as an example of this cycle, as follows.

 On the profitable part 20 of mold 3 made with porous outer layers, a removable insulating cover made of heat-resistant material is installed before mold 3 is placed in chamber 8. Form 3 with an insulating cover through the vacuum shutter 13 is installed using the mechanism for moving the forms 3 of the block 2 into the action zone of the heaters 17 of the preheating chamber 8. When the temperature in the zones of action of the heaters 8 and 9 of block 2 is reached, exceeding up to 200 degrees, the melting temperature of the cooler in the device 10 form 3 through the vacuum shutter 7 between chambers 8 and 9 is moved from chamber 8 to chamber 9. During this movement, all parts of form 3 from the seed to the profitable part 20, a zone is sequentially passed in which a stream from device 10 from a mixture of an inert gas and a powder cooler undergoing one phase transformation — melting — is fed to the mold 3. In this case, the temperature of the flow of the mixture of inert gas and the cooler at the outlet of the device 10 is maintained up to 50 degrees below the melting temperature of the cooler. The molten cooler under the influence of capillary forces impregnates - metallizes the outer porous layers of form 3 to the entire depth of the through porosity at a temperature in the zone of action of the heaters 17 in the chamber 9 to 200 degrees above the melting temperature of the cooler in the stream of the device 10.

 Upon completion of metallization of the surface layers of the ceramic mold 3, which has become cermet, the mold 3 through adjacent vacuum gates 11, 14 in the chamber 9 and in the chamber 4 by the mechanism for moving the molds 3 of the furnace 1 is installed in the zone of action of the heaters 17 of the chamber 4. In the process of installing the mold 3 and up to its end, the insulating cover from the profitable part of form 3 is removed with a special device. When mold 3 reaches the technologically necessary temperature and its distribution along the length of mold 3, and when the superalloy melt is ready in the melting furnace 18, mold 3 is filled. After mold 3 is filled, the rotary kiln 18 returns to its original position and for the period of exposure of mold 3 to the cooling flow in to the cooling chamber 5, the furnace 18 is closed with a lid to isolate the inner surface of the furnace 18 and the metal in it from interaction with cooler fumes. Form 3 with the melt through the vacuum shutter 6, connecting the heating chamber 4 to the cooling chamber 5, is moved to the chamber 5. During this movement, all parts of form 3, from the seed to the profitable part 20, are sequentially delivered directly at the entrance to the chamber 5 , into the zone of action of the cooling stream from the device 16, directed mainly vertically with an inclination towards the movement of form 3, from a mixture of inert gas and a powder cooler undergoing on the surface of form 3 or two phase transformations - melting and evaporation of, or one - sublimation. Upon the exit of any section of form 3 from the flow zone from the device 16, a single-crystal structure is formed in the hardened part of the casting. Outside the flow zone 16, the mold and single-crystal casting are cooled by the water-cooled walls of the chamber 5. The vapor of the cooler is condensed, crystallized and cooled by special condensers on the walls of the chamber 5, the inert gas is removed through the condensers by a vacuum system for further use. A fully formed single-crystal casting is removed from the chamber 5 through a vacuum shutter 15 by the mechanism for moving the molds 3 of furnace 1. This completes the cycle of manufacturing a part with a single-crystal structure.

 Thus, the proposed method and device for its implementation allows: firstly, to increase the productivity of the process as a whole by reducing the time of thermal preparation of mold 3 and the time of formation of a single-crystal structure in the casting, and secondly, to reduce the material consumption of mold 3 by two times reducing labor costs and time for the manufacture of shell form 3, and thirdly, to reduce energy consumption for the heat treatment of shell form 3, for its cooling, as well as for disposal and regeneration of material forms 3.

 For a gas-turbine working blade with a length of 500 m with a profit (150 mm) of a heat-resistant nickel-based alloy when casting in a ceramic shell mold 3 with a wall thickness of 9 mm with a through porosity of 5% to a depth of ~ 7.5 mm from the outer surface of mold 3, obtained the following results.

 Table 4 shows comparative data on the duration of the stages of casting of single-crystal vanes according to RU 2157296 from 12.10.99 and the proposed method.

 Thus, with the help of the invention, the best results are achieved in the manufacture of single-crystal large-sized blades in terms of economy (material, energy and labor costs) and productivity. The parts manufactured by the proposed method and device in terms of quality indicators (in terms of fracture strength and defectiveness level) do not differ from those obtained by the method according to Russian patent N 2157296 from 12.10.99.

Claims (9)

 1. A method of manufacturing a directed crystallization of a part with a single-crystal structure, including the installation of a ceramic mold made with through porosity in the outer layers in a heating chamber of a vacuum furnace, heating the mold, pouring with melt, moving the mold from the heating chamber to the cooling chamber, cooling it a stream from a mixture of an inert gas and a powder cooler from a material that undergoes heat during melting from a crystallizing melt for phase transformations — melting and evaporation e or only one phase transformation - sublimation, characterized in that before installing the mold in the heating chamber of the vacuum furnace, the mold is placed in the preheating chamber, heated and moved to the metallization chamber, the outer layers are metallized in it by flow from an inert gas mixture and a powder cooler from a material that undergoes a single phase transformation during melting, which is melting, while preliminary heating is carried out to a temperature higher than the melting temperature of the pores bucket cooler.  2. The method according to claim 1, characterized in that the preliminary heating of the mold is carried out to a temperature exceeding up to 200 degrees. melting temperature of the powder cooler.  3. The method according to claim 1 or 2, characterized in that during metallization of the outer layers of the mold, the minimum temperature of the powder cooler is maintained within 50 degrees. below its melting point.  4. The method according to any one of claims 1 to 3, characterized in that when heated, the mold is placed horizontally in the heating chamber of the vacuum furnace with a longitudinal axis.  5. The method according to any one of claims 1 to 4, characterized in that the stream from a mixture of inert gas and powder cooler in the cooling chamber of the vacuum furnace is directed, mainly in a vertical plane with an inclination in the direction of movement of the mold.  6. The method according to any one of claims 1 to 5, characterized in that during metallization and cooling of the mold, its inner cavity and the inner surface of the melting crucible in the heating chamber are isolated from exposure, respectively, of powder particles and cooler vapor.  7. A device for manufacturing a directed crystallization of a part with a single crystal structure, containing a vacuum furnace with a vacuum system having a mold heating chamber and a mold cooling chamber, a mold made with through porosity in the outer layers, mounted to move from the heating chamber into the cooling chamber, a gas system located outside the vacuum furnace, two devices for forming flows from a mixture of inert gas and powder cooling a device located outside the vacuum furnace, a device for directing a stream from a mixture of an inert gas and a powder cooler from a material that undergoes two phase transformations during melting of heat from a crystallizing melt — melting and evaporation, or only one phase transformation — sublimation located in the chamber cooling device and a device for directing to a mold a flow from a mixture of inert gas and a powder cooler from a material that undergoes one phase during heat removal the first transformation is melting, characterized in that it is equipped with at least one block of chambers with vacuum gates, consisting of interconnected pre-heating chambers and a metallization chamber of the outer layers of the mold, a docking device for sealing the space between the vacuum furnace and block of chambers, while the mold is installed with the possibility of moving from the pre-heating chamber to the metallization chamber and the heating chamber, and at least one device for directions to the casting mold of a stream from a mixture of inert gas and a powder cooler from a material that undergoes one phase transformation during melting - melting, is located inside the metallization chamber.  8. The device according to claim 8, characterized in that the mold is installed in the heating chamber with the location of its longitudinal axis in the horizontal plane.  9. The device according to claim 7 or 8, characterized in that the melting crucible of the heating chamber has an insulating cover.

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