阅读说明：本技术 一种单晶高温合金涡轮叶片陶瓷模壳的制备方法 (Preparation method of ceramic mould shell of single crystal high-temperature alloy turbine blade ) 是由 朱鑫涛 王富 徐文梁 顾国楼 赵保解 朱玉棠 于 2019-11-01 设计创作，主要内容包括：本发明属于精密铸造应用技术领域,具体公开了一种单晶高温合金涡轮叶片陶瓷模壳的制备方法,包括以下步骤：步骤一、设计三维数字化模型。步骤二、设计铸件蜡模的底盘、叶片铸件、选晶器结构的接口。步骤三、将步骤一中的三维模型转换为STL格式,然后得到光固化3D打印机用数据,最后使用基于面曝光法的光固化3D打印机机。步骤四,将浇注系统蜡模、3D打印的选晶器原型、叶片蜡模组合。步骤五,将步骤四所述组合后的蜡模进行脱蜡,焙烧,清灰,裂纹检查,得到单晶高温合金涡轮叶片陶瓷模壳。本发明的有益效果在于：1、采用3D打印技术制造选晶器,缩短工艺开发周期,简化工艺流程；2、采用3D打印技术制造选晶器结构,可实现不同叶片选晶器的定制化。(The invention belongs to the technical field of precision casting application, and particularly discloses a preparation method of a ceramic mould shell of a monocrystalline high-temperature alloy turbine blade, which comprises the following steps: step one, designing a three-dimensional digital model. And step two, designing the chassis of the casting wax mold, the blade casting and the interface of the crystal selector structure. And step three, converting the three-dimensional model in the step one into an STL format, then obtaining data for the photocuring 3D printer, and finally using the photocuring 3D printer based on a surface exposure method. And step four, combining the wax mold of the pouring system, the crystal selector prototype printed by the 3D printing and the blade wax mold. And fifthly, dewaxing, roasting, deashing and checking cracks of the wax mold combined in the fourth step to obtain the ceramic mold shell of the single-crystal high-temperature alloy turbine blade. The invention has the beneficial effects that: 1. the 3D printing technology is adopted to manufacture the crystal selector, so that the process development period is shortened, and the process flow is simplified; 2. the 3D printing technology is adopted to manufacture the crystal selector structure, and customization of different blade crystal selectors can be realized.)

1. A preparation method of a ceramic mould shell of a monocrystalline high-temperature alloy turbine blade is characterized by comprising the following steps: the method comprises the following steps:

designing a three-dimensional digital model of a crystal selector structure according to casting process requirements;

secondly, designing the chassis of the casting wax mold, the blade casting and the interface of the crystal selector structure according to the crystal selector structure;

step three, firstly converting the three-dimensional model in the step one into an STL format, processing an STL format file, wherein the layering thickness is not more than 100-120 mu m, carrying out shell extraction processing on a crystal selector structure, wherein the shell extraction thickness is 2-4 mm, then adding a support structure and determining the placing position of a prototype in a forming machine to obtain data for a photocuring 3D printer, finally carrying out 3D printing and forming on the crystal selector structure by using a photocuring 3D printer based on a surface exposure method and adopting casting special photosensitive resin, and spraying 35 mass fractions of polyethylene wax emulsion on the surface of the prepared crystal selector structure by adopting an ultrasonic atomization film coating method;

combining a casting system wax mold, a 3D printed crystal selector prototype and a blade wax mold;

and fifthly, dewaxing, roasting, deashing and checking cracks of the wax mold combined in the fourth step to obtain the ceramic mold shell of the single-crystal high-temperature alloy turbine blade.

2. The method of claim 1, wherein the method comprises: firstly, selecting a C-type crystal selector with the overall length of a blade casting below 100mm, and selecting a spiral crystal selector with the overall length of more than 100mm, wherein the main structural parameter of the C-type crystal selector is a screw pitch, the main structural parameter of the spiral crystal selector is a helix angle, the screw pitch selection range of the C-type crystal selector is 15-40 degrees, and the helix angle selection range of the spiral crystal selector is 15-40 degrees; then determining basic parameters of a formwork overall structure, a pouring system, a crystal selection system and a casting mold wall thickness according to casting process requirements, modeling a casting by using three-dimensional CAD modeling software, and analyzing by using ProCAST finite element simulation software to perform temperature field and CAFE crystal growth simulation analysis on crystal selector structure parts with different technical parameters at a drawing speed of 6 mm/min; and finally, selecting crystal selector structural parameters with small crystal orientation deviation and short process time to design the crystal selector according to the crystal orientation angle deviation and the process time of the simulation result.

3. The method of claim 1, wherein the method comprises: and in the second step, the crystal selector interface structure is a concave-convex matching structure.

4. The method of claim 1, wherein the method comprises: and in the fourth step, the 3D printed crystal selector prototype and the blade wax mold are mechanically combined through an interface structure, and 40% of polyethylene wax emulsion is coated at the interface to enable the interface to be smooth.

5. The method of claim 1, wherein the method comprises: and step five, the concrete method for roasting the ceramic formwork comprises the following steps of firstly putting the dewaxed formwork into industrial alcohol, enabling the liquid level of the industrial alcohol to be lower than a 3D printed resin crystal selector, soaking for 10 minutes to enable the industrial alcohol to be slightly softened, then placing the formwork in a drying oven, preserving the temperature for 30-60 minutes within the temperature range of 40-50 ℃ to enable the residual industrial alcohol to volatilize, and finally preserving the temperature for 2-4 hours in a high-temperature sintering furnace at the temperature of 500-1000 ℃ to completely remove the resin and sinter the formwork.

Technical Field

The invention belongs to the technical field of precision casting application, and particularly relates to a preparation method of a ceramic mould shell of a single crystal high-temperature alloy turbine blade.

Background

High temperature alloys are widely used as hot end parts of aircraft engines and heavy duty gas turbines, and among them, single crystal high temperature alloys are used for manufacturing hot end key parts, i.e., turbine blades, due to their excellent temperature-bearing capability. The monocrystalline high-temperature alloy turbine blade is generally formed by directional solidification investment casting, the ceramic mould shell adopted by the investment casting of the monocrystalline turbine blade mainly comprises a pouring system, a middle column, a blade casting mould and a crystal selector, and the manufacturing process mainly comprises the steps of core manufacturing, wax mould manufacturing, mould assembling, slurry coating and sand pouring, dewaxing, roasting and the like. Early production preparation works such as blade and crystal selector wax mold metal mold preparation are involved in the manufacturing process of the ceramic mold shell; the three-dimensional structures of the blade and the crystal selector are complex, and the difficulty in manufacturing the die is high; therefore, the method has long production preparation period and high cost, and cannot realize quick response to the research requirement in the process of blade process development. At present, the combination of additive manufacturing technology (3D printing) and precision casting is a novel process route for solving the problem of casting and forming of parts with complex structures.

The additive manufacturing technology is an advanced manufacturing technology developed by integrating multiple disciplines such as information, materials, machinery and the like, solid parts are formed by accumulating the materials layer by layer, the additive manufacturing technology is suitable for small-batch production of parts with complex structures, and the preparation time and the cost for mass production can be saved. The resin or plastic prototype printed by 3D printing can be used for manufacturing a wax pattern for precision casting, and when the resin or plastic prototype printed by 3D printing is used as the wax pattern for investment casting, the resin or plastic prototype cannot be removed by a conventional steam dewaxing method and needs high-temperature burn-out, and in the process, the expansion and the crack of a ceramic shell can be caused in the burn-out process because the thermal expansion coefficient of the resin or the plastic is larger than that of the ceramic shell material.

For a common casting, the requirement on the heat dissipation of the mold shell is not high, the strength of the mold shell can be improved by increasing the thickness of the ceramic mold shell, however, the monocrystalline high-temperature alloy turbine blade needs to accurately control the metallurgical structure, and requires a smaller mold shell wall thickness to enhance the heat dissipation and improve the deformability of the mold shell. In addition, the dimensional accuracy and the surface quality of the wax pattern for 3D printing are generally not the same as those of the wax pattern for the traditional wax pressing process, and the overall quality of a casting is seriously influenced, so that the resin or plastic prototype formed by 3D printing can be directly used as the wax pattern for investment casting, and cannot be widely applied to the production of the single crystal blade at present.

However, combining additive manufacturing techniques with conventional wax pattern techniques in part may provide a possible technical approach for high quality blade castings. Generally, the metallurgical structure of the single crystal blade is obtained by controlling the growth of the crystal by a crystal selection method in the process of directional solidification. During the growth of the metal crystal, after the special process structure of the crystal selector, a single crystal with a specific orientation is grown on the blade part, and the metal of the crystal selector part is cut off in the subsequent processing process. In the process experiment process, the structure and the process of the crystal selector need to be adjusted to a certain extent, and if the crystal selector wax mold is prepared by adopting the traditional wax pressing method, a plurality of sets of crystal selector wax mold dies are needed, so that the problems of high production cost and long period exist. Therefore, the 3D printed prototype can be only used for manufacturing the special structure of the crystal part, the method can avoid the problem of shell expansion crack caused by directly and completely using the 3D printed prototype, and the precision and the surface quality of the blade casting can be ensured to meet the requirements of the conventional process. The method can greatly simplify the preparation process of the single crystal blade crystal selector, shorten the process development period and further accelerate the trial production efficiency of the blade.

Based on the problems, the invention provides a preparation method of a ceramic mould shell of a single-crystal high-temperature alloy turbine blade.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a preparation method of a ceramic mould shell of a single crystal high-temperature alloy turbine blade, which utilizes the advantage of rapid forming of a complex structure by a 3D printing technology to prepare a crystal selector structure of a wax mould of the single crystal blade, combines the traditional wax mould method to prepare the ceramic mould shell, is used for developing the single crystal high-temperature alloy turbine blade, reduces the research and development cost and shortens the research and development period.

The technical scheme is as follows: the invention provides a preparation method of a ceramic mould shell of a single crystal high-temperature alloy turbine blade, which comprises the following steps: step one, designing a three-dimensional digital model of a crystal selector structure according to casting process requirements. And step two, designing the chassis of the casting wax mold, the blade casting and the interface of the crystal selector structure according to the crystal selector structure. And step three, firstly converting the three-dimensional model in the step one into an STL format, processing the STL format file, wherein the layering thickness is not more than 100-120 mu m, carrying out shell extraction processing on the crystal selector structure, the shell extraction thickness is 2-4 mm, then adding a support structure and determining the placing position of the prototype in a forming machine to obtain data for a photocuring 3D printer, finally carrying out 3D printing forming on the crystal selector structure by using a photocuring 3D printer based on a surface exposure method and adopting casting special photosensitive resin, and spraying 35 mass fractions of polyethylene wax emulsion on the surface of the prepared crystal selector structure by adopting an ultrasonic atomization film coating method. And step four, combining the wax mold of the pouring system, the crystal selector prototype printed by the 3D printing and the blade wax mold. And fifthly, dewaxing, roasting, deashing and checking cracks of the wax mold combined in the fourth step to obtain the ceramic mold shell of the single-crystal high-temperature alloy turbine blade.

Firstly, selecting a C-shaped crystal selector with the overall length of a blade casting below 100mm, and selecting a spiral crystal selector with the overall length of more than 100mm, wherein the main structural parameter of the C-shaped crystal selector is a screw pitch, the main structural parameter of the spiral crystal selector is a spiral lead angle, the screw pitch selection range of the C-shaped crystal selector is 15-40 degrees, and the spiral lead angle selection range of the spiral crystal selector is 15-40 degrees; then determining basic parameters of a formwork overall structure, a pouring system, a crystal selection system and a casting mold wall thickness according to casting process requirements, modeling a casting by using three-dimensional CAD modeling software, and analyzing by using ProCAST finite element simulation software to perform temperature field and CAFE crystal growth simulation analysis on crystal selector structure parts with different technical parameters at a drawing speed of 6 mm/min; and finally, selecting crystal selector structural parameters with small crystal orientation deviation and short process time to design the crystal selector according to the crystal orientation angle deviation and the process time of the simulation result.

According to the technical scheme, the interface structure of the crystal selector in the second step is a concave-convex matching structure.

According to the technical scheme, the crystal selector prototype printed in the step four in the 3D mode is mechanically combined with the blade wax mold through the interface structure, and 40% of polyethylene wax emulsion in mass fraction is coated at the interface, so that the interface is smooth.

The concrete method for roasting the ceramic formwork in the fifth step comprises the following steps of firstly putting the dewaxed formwork into industrial alcohol, enabling the liquid level of the industrial alcohol to be lower than a 3D printed resin crystal selector, soaking for 10 minutes to enable the industrial alcohol to be slightly softened, then putting the formwork into a drying oven, preserving heat for 30-60 minutes within the temperature range of 40-50 ℃ to enable residual industrial alcohol to volatilize, finally preserving heat for 2-4 hours in a high-temperature sintering furnace at the temperature of 500-1000 ℃ to completely remove resin and sinter the formwork.

Compared with the prior art, the preparation method of the ceramic mould shell of the monocrystalline high-temperature alloy turbine blade has the beneficial effects that: 1. the crystal selector is manufactured by adopting a 3D printing technology, and the blade wax mould and other components of the wax pattern are manufactured by combining the traditional wax mould technology, so that a high-precision ceramic mould shell meeting the requirements can be directly prepared, the process development period is shortened, and the process flow is simplified; 2. the 3D printing technology is adopted to manufacture the crystal selector structure, the design flexibility of the crystal selector is improved, the selection range of the crystal selector is widened, the structural parameters of the crystal selector can be selected according to the solidification process, and the customization of the crystal selectors with different blades can be realized.

Drawings

FIG. 1 is a schematic structural diagram of a turbine blade ceramic mold shell wax pattern produced by the method for preparing a single crystal superalloy turbine blade ceramic mold shell of the present invention.

Detailed Description

The invention is further elucidated with reference to the drawings and the embodiments.

The invention discloses a preparation method of a ceramic mould shell of a single crystal high-temperature alloy turbine blade, which comprises the following steps: step one, designing a three-dimensional digital model of a crystal selector structure according to casting process requirements. And step two, designing the chassis of the casting wax mold, the blade casting and the interface of the crystal selector structure according to the crystal selector structure. And step three, firstly converting the three-dimensional model in the step one into an STL format, processing the STL format file, wherein the layering thickness is not more than 100-120 mu m, carrying out shell extraction processing on the crystal selector structure, the shell extraction thickness is 2-4 mm, then adding a support structure and determining the placing position of the prototype in a forming machine to obtain data for a photocuring 3D printer, finally carrying out 3D printing forming on the crystal selector structure by using a photocuring 3D printer based on a surface exposure method and adopting casting special photosensitive resin, and spraying 35 mass fractions of polyethylene wax emulsion on the surface of the prepared crystal selector structure by adopting an ultrasonic atomization film coating method. And step four, combining the wax mold of the pouring system, the crystal selector prototype printed by the 3D printing and the blade wax mold. And fifthly, dewaxing, roasting, deashing and checking cracks of the wax mold combined in the fourth step to obtain the ceramic mold shell of the single-crystal high-temperature alloy turbine blade.

Preferably, the specific method for designing the crystal selector structure in the first step includes that firstly, for a selected C-type crystal selector with the overall length of the blade casting below 100mm and a selected spiral crystal selector with the overall length greater than 100mm, the main structural parameter of the C-type crystal selector is a screw pitch, the main structural parameter of the spiral crystal selector is a helix lead angle, the screw pitch selection range of the C-type crystal selector is 15-40 degrees, and the helix lead angle selection range of the spiral crystal selector is 15-40 degrees; then determining basic parameters of a formwork overall structure, a pouring system, a crystal selection system and a casting mold wall thickness according to casting process requirements, modeling a casting by using three-dimensional CAD modeling software, and analyzing by using ProCAST finite element simulation software to perform temperature field and CAFE crystal growth simulation analysis on crystal selector structure parts with different technical parameters at a drawing speed of 6 mm/min; and finally, selecting crystal selector structural parameters with small crystal orientation deviation and short process time to design the crystal selector according to the crystal orientation angle deviation and the process time of the simulation result. And the interface structure of the crystal selector in the second step is a concave-convex matching structure. And mechanically combining the crystal selector prototype printed by the 3D printing in the fourth step with the blade wax mold through an interface structure, and coating 40% of polyethylene wax emulsion on the interface to ensure that the interface is smooth. And the concrete method for roasting the ceramic mould shell in the fifth step comprises the following steps of firstly putting the mould shell subjected to dewaxing into industrial alcohol, enabling the liquid level of the industrial alcohol to be lower than a 3D printed resin crystal selector, soaking for 10 minutes to enable the mould shell to be slightly softened, then placing the mould shell in a drying oven, preserving the temperature for 30-60 minutes within the temperature range of 40-50 ℃ to enable residual industrial alcohol to volatilize, and finally preserving the temperature for 2-4 hours in a high-temperature sintering furnace at the temperature of 500-1000 ℃ to completely remove the resin and sinter the mould shell.

FIG. 1 is a schematic structural diagram of a turbine blade ceramic mold shell wax pattern produced by a method for preparing a single crystal superalloy turbine blade ceramic mold shell, wherein 1 is a casting head, 2 is a runner of a casting system, 3 is a casting part, 4 is a crystal selector part, 5 is a bottom plate, and 6 is a center pillar.

The foregoing is only a preferred embodiment of this invention and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the invention and these modifications should also be considered as the protection scope of the invention.