A process for increasing the rejection of foreign crystals by a top-up sheet to a single crystal blade shroud

Abstract

The application discloses a process for increasing the inhibition of a shrinkage pad on single crystal blade rim plate mixed crystals, two equilateral triangle shrinkage pads equal to the width of the rim plate are welded on both sides of the wax rim plate, and the included angle between the shrinkage pad and the lower surface of the rim plate is 135 degrees; a bottom pouring-spiral seed selection method is adopted to combine the wax parts, the wax parts are longitudinally and uniformly distributed on a water-cooled bottom plate in a single layer, and a gate cup and the like are connected to make the wax parts form a complete wax tree. A slurry is prepared by mixing 320# electrically fused mullite powder and silica sol, electrically fused mullite sand with different particle sizes is hung on the surface of the slurry, and after natural drying, dewaxing and baking, a precision casting single crystal blade mold is obtained. Compared with the prior art, the application has the advantages that by increasing the triangle shrinkage pad, the edge area of the rim plate is kept in the liquid phase region for a long time, nucleation and mixed crystals are avoided, and the production qualified rate of the blade and the working performance thereof are greatly improved. The problems such as crystal boundary interference caused by increasing the seed crystal strip can be avoided.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy blade casting, and particularly to a process for suppressing impurities in the edge plates of single-crystal blades by adding feeding plates. Background Technology

[0002] Monocrystalline blades can eliminate transverse grain boundaries during their grain growth process, giving them better resistance to high-temperature creep, thermal fatigue, oxidation, and hot corrosion. This makes monocrystalline blades suitable for harsher working environments compared to other blades, which is why they are widely used in national defense, civilian applications, and other fields.

[0003] Despite the numerous superior properties of single-crystal blades, as their size increases, their internal structure becomes more complex, and the amount of refractory elements increases. During the fabrication of single-crystal blades, especially during directional solidification, varying heat dissipation conditions in the blade rim region lead to uneven solidification of the alloy liquid. This causes dendrite changes in the blade rim, resulting in the formation of impurities, which reduces the yield rate of blade production and affects its safe service life. During the directional solidification process, the solid-liquid interface is often concave, further contributing to the nucleation and formation of impurities at the rim edge.

[0004] Therefore, there is an urgent need to invent a process to suppress the formation of impurities on the rim plate. Summary of the Invention

[0005] The purpose of this invention is to add upward and outward inclined shrinkage-compensating wax sheets to the edge of the blade, so that the edge of the blade edge plate is always in the liquid phase region, thereby avoiding the formation of impurity crystals.

[0006] This invention provides a process for increasing the suppression of impurities on the edge plate of single-crystal blades by adding a shrinkage liner, characterized in that: as shown in the following... Figure 1 As shown, two equilateral triangular shrinkage plates 2, with the same width as the edge plate 1, are welded to both sides of the wax part edge plate 1, with an angle of 135° between them and the lower surface of the edge plate. The wax part is assembled using a bottom-pouring-spiral crystal selection method, with the wax part evenly distributed in a single layer longitudinally on a water-cooled base, and connected to a pouring cup to form a complete wax tree. A slurry is prepared by mixing 320# fused mullite powder and silica sol, and then fused mullite sand of different particle sizes is coated on its surface. After natural drying, dewaxing and firing are performed to obtain a precision-cast single-crystal blade shell.

[0007] Single-crystal blades were prepared using a high-efficiency solidification furnace (HRS) with a pulling rate of 3 mm / min, a casting temperature of 1550-1600℃, a holding furnace temperature of 1500℃ in both the upper and lower zones, and a pulling height of 240 mm.

[0008] All wax trees are made of medium-temperature molding wax, and all wax parts are connected by welding.

[0009] In the shell-making process, the powder-to-liquid mass ratio is 3.8:1, the silica sol pH value is 10, the shell is dried naturally for 8 hours, and the shell weight is 2.7-3.0 kg.

[0010] The dewaxing process involves a dewaxing temperature of 165-175℃, a dewaxing pressure of 0.6-0.7MPa, and a dewaxing time of 13-16min.

[0011] The shell-firing process involves a shell-firing temperature of 900-1000℃ and a shell-firing duration of 2-3 hours.

[0012] The thickness of the triangular shrinkage piece is 10 mm.

[0013] Compared with the prior art, the advantages of this invention are:

[0014] The process for suppressing impurities on the edge plate of single-crystal blades by adding a triangular shrinkage liner, as described in this invention, keeps the edge region of the edge plate in the liquid phase for a long time, avoiding nucleation and impurity crystal formation, and significantly improving the blade production yield and its working performance. It also avoids problems such as grain boundary interference caused by adding crystal guides. Attached Figure Description

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0016] Figure 1 This is a schematic diagram illustrating how to add triangular shrinkage plates to a single-crystal blade. Detailed Implementation

[0017] The present invention will be further explained below with reference to specific implementation schemes, but it is not limited to the present invention. The structures, proportions, sizes, etc. shown in the accompanying drawings are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0018] A process for increasing the suppression of impurities on the edge plate of single-crystal blades by adding a shrinkage liner, characterized in that: as follows Figure 1 As shown, two equilateral triangular shrinkage plates 2, with the same width as the edge plate 1, are welded to both sides of the wax part edge plate 1, with an angle of 135° between them and the lower surface of the edge plate. The wax part is assembled using a bottom-pouring-spiral crystal selection method, with the wax part evenly distributed in a single layer longitudinally on a water-cooled base, and connected to a pouring cup to form a complete wax tree. A slurry is prepared by mixing 320# fused mullite powder and silica sol, and then fused mullite sand of different particle sizes is coated on its surface. After natural drying, dewaxing and firing are performed to obtain a precision-cast single-crystal blade shell.

[0019] First, wax parts and triangular shrinkage plates are prepared. The wax parts and shrinkage plates are then welded together according to a specified method. Next, the gating system is prepared using a bottom-pouring crystal selection method for assembly. Medium-temperature wax is used, with a wax tree height of 240mm. Each group consists of 6 wax parts. The entire mold assembly undergoes a tight casting process involving coating and sandblasting to form the shell. The slurry is prepared by mixing 320-mesh fused mullite powder with S-830 specification silica sol at a powder-to-liquid mass ratio of 3.8:1. The silica sol has a pH of 10. Fused mullite sand of 80-80-60-46-24-24 grades is used, and each layer dries for 8 hours. After the mold shell is prepared, dewaxing is performed at 165 degrees Celsius and 0.65 MPa. The firing temperature is 900 degrees Celsius, and the firing time is 2 hours.

[0020] After firing, the shell was washed with tap water and allowed to air dry for 48 hours. Then, it was placed in a high-speed solidification furnace (HRS) and raised to the designated position at a uniform speed of 200 mm / min, followed by a further uniform speed of 30 mm / min to the target position. The alloy liquid refining temperature was 1600℃, the casting temperature was 1550-1560℃, and the temperature of both the upper and lower zones of the holding furnace was 1500℃. The vacuum degree before pouring the alloy liquid into the shell should be below 1 Pa. The shell was then pulled downwards at a uniform speed of 3 mm / min to a height of 240 mm. After the directional solidification process, the shell was cleaned, cut, cored, heat-treated, and macro-etched. The etching solution ratio was hydrochloric acid:hydrogen peroxide 8:1. Grain inspection after cleaning revealed that all blades prepared using this process had no impurities at the blade edge.

[0021] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for increasing the suppression of impurities on the edge plate of a single-crystal blade by adding a shrinkage liner, characterized in that: The process of adding shrinkage plates to suppress impurities on the edge plate of a single crystal blade involves welding two equilateral triangular shrinkage plates (2) with the same width as the edge plate on both sides of the edge plate (1), with the included angle between the shrinkage plates and the lower surface of the edge plate (1) being 135°. The wax parts are assembled using the bottom-injection-spiral crystal selection method. The wax parts are evenly distributed in a single layer on the water-cooled base and connected to the pouring cup to form a complete wax tree. A slurry is made by mixing 320# fused mullite powder and silica sol. Then, fused mullite sand of different particle sizes is coated on its surface. After natural drying, the wax is dewaxed and fired to obtain a precision-cast single-crystal blade shell. Single-crystal blades were prepared using a high-efficiency solidification furnace with a pulling rate of 3 mm / min, a casting temperature of 1550-1600℃, a holding furnace temperature of 1500℃ in both the upper and lower zones, and a pulling height of 240 mm.

2. The process for suppressing impurities on the edge plate of a single-crystal blade by adding a shrinkage liner according to claim 1, characterized in that: All the wax trees are made of medium-temperature molding wax, and all wax parts are connected by welding.

3. The process for suppressing impurities on the edge plate of a single-crystal blade by adding a shrinkage liner according to claim 1, characterized in that: In the process of obtaining the precision-cast single-crystal blade shell, the powder-to-liquid mass ratio is 3.8:1, the silica sol pH value is 10, the shell is dried naturally for 8 hours, and the shell weight is 2.7-3.0 kg.

4. The process for suppressing impurities on the edge plate of a single-crystal blade by adding a shrinkage liner according to claim 1, characterized in that: The dewaxing process after natural drying involves a dewaxing temperature of 165-175℃, a dewaxing pressure of 0.6-0.7MPa, and a dewaxing time of 13-16min.

5. The process for suppressing impurities on the edge plate of a single-crystal blade by adding a shrinkage liner according to claim 1, characterized in that: The shell-firing temperature for the dewaxing and firing process after natural drying is 900-1000℃, and the firing time is 2-3 hours.

6. The process for suppressing impurities on the edge plate of a single-crystal blade by adding a shrinkage liner according to claim 1, characterized in that: The thickness of the triangular shrinkage plate is 10mm.

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