A method for preparing a wax material for producing a large-size gas turbine vane

Abstract

The present application relates to the field of precision casting, and discloses a wax material preparation method for large-size gas turbine blade production, which comprises the following steps: selecting and proportionally weighing full-refined paraffin wax, Fischer-Tropsch wax, stearic acid, petroleum resin, lignite wax, a modifier and an antioxidant, carrying out basic melting and mixing, high-temperature mixing and low-temperature mixing to form a wax material melting liquid, removing impurities and air bubbles through filtration, then forming and cooling to obtain blocky wax material, and sealing and storing the blocky wax material. Through optimization of the wax material ratio and step-by-step mixing process, the present application realizes the coordinated balance of the properties of the wax material, such as melting point, hardness, fluidity, shrinkage and ash content, effectively reduces wax mold deformation, damage and dewaxing residue, improves forming precision and surface quality, uses environmentally-friendly raw materials to reduce pollution and safety risks, and is simple and controllable in the preparation process, suitable for large-scale production, low in cost, and strong in adaptability, and suitable for high-quality manufacturing of large-size gas turbine blades.

Description

Technical Field

[0001] This invention relates to the field of precision casting technology, specifically a method for preparing wax materials for the production of large-size gas turbine blades. Background Technology

[0002] Large-size directional gas turbine blades, as core hot-end components of gas turbines, operate under harsh conditions of high temperature, high pressure, and high-speed rotation for extended periods. They must withstand enormous centrifugal forces and thermal stresses, and their dimensional accuracy, molding quality, and material purity directly determine the operating efficiency, service life, and operational safety of the gas turbine. Currently, the production of large-size directional gas turbine blades in China mainly adopts investment casting (lost-wax casting) technology. This technology is currently the only feasible and dominant technical path for manufacturing blades with complex geometries and high precision. Among these processes, wax pattern forming is the core link in the entire process chain. The quality of the wax pattern directly affects the implementation effect of subsequent processes such as shell manufacturing, dewaxing and firing, and directional solidification, thus determining the final dimensional accuracy, internal structure quality, and service reliability of the blade.

[0003] As the core raw material for wax modeling, the rationality of the wax material's formulation directly determines its key properties such as melting point, hardness, fluidity, shrinkage rate, and flexural strength, which is a crucial prerequisite for ensuring the quality of the wax model. Currently, the wax materials used in the production of large-size directional gas turbine blades in China mostly follow the formulation of ordinary aviation blade wax materials, failing to fully consider the unique structural characteristics of large-size blades (typically exceeding 500mm in length and 120mm in chord length)—complex curved surfaces, uneven thickness (the thinnest point can be as low as 1.60mm), internal hollow structures, and ceramic cores. This results in several prominent defects in the practical application of existing wax materials: First, the melting point range is unreasonable; either the melting point is too low, easily softening and deforming during wax model handling, assembly, and shell coating, affecting the accuracy of the wax model; or the melting point is too high, easily remaining inside the shell during dewaxing, causing shell cracks and leading to casting defects. Second, there is an imbalance between hardness and toughness; insufficient hardness makes the wax model prone to breakage and deformation. Excessive hardness increases the brittleness of the wax model, making it prone to cracking during demolding and unable to meet the complex structural molding requirements of large-sized blades. Secondly, poor fluidity makes it difficult to fully fill the fine structures and hollow areas of the mold, resulting in poor surface finish and large dimensional deviations in the wax model, leading to defects such as material shortages, burrs, and shrinkage cavities in subsequent castings. Thirdly, unstable shrinkage rates cause uneven shrinkage during the cooling process of large-sized blade wax models, resulting in dimensional accuracy that cannot meet the production requirements of CT4-level blades, thus affecting the dimensional consistency of the blades after directional solidification. Fourthly, some wax materials contain heavy metals such as lead or harmful additives, which not only pollute the production environment and endanger the health of operators but may also remain during dewaxing, affecting the purity of the blade material and reducing the high-temperature performance of the blades.

[0004] Furthermore, existing wax formulations largely rely on imported raw materials, resulting in high procurement costs and poor compatibility between their performance parameters and the production process requirements of large-size directional gas turbine blades in China (such as commonly used directional solidification process parameters and shell material properties), making it difficult to fully leverage the advantages of the process. Therefore, developing a wax formulation and preparation method that is suitable for the production of large-size directional gas turbine blades in China, with reasonable composition, excellent performance, controllable cost, and environmental safety, has become a pressing technical challenge in the domestic gas turbine blade manufacturing industry. This is of great significance for promoting the localization of domestic gas turbine blades and enhancing the core competitiveness of the industry. Summary of the Invention

[0005] To address the existing problems, this invention provides a method for preparing wax materials for the production of large-size gas turbine blades, which can effectively solve the problems mentioned in the background art.

[0006] To solve the above problems, the present invention adopts the following technical solution: A method for preparing wax material for the production of large-size gas turbine blades includes the following steps: S1. Select wax raw materials, weigh fully refined paraffin wax, Fischer-Tropsch wax, stearic acid, petroleum resin, lignite wax, modifier and antioxidant according to the mass percentage, and set aside. S2. Basic mixing of wax materials: Fully refined paraffin wax, Fischer-Tropsch wax and lignite wax are added to the reactor and heated to melt under stirring to obtain a homogeneous basic mixture. S3. High-temperature mixing of wax materials: Stearic acid and petroleum resin are added to the base mixture and stirred continuously at the set temperature to ensure that they are fully dissolved and uniformly mixed. S4. Low-temperature mixing of wax: Lower the temperature and add modifiers and antioxidants to the mixture, continue stirring to fully integrate the components and form a wax melt. S5. Filtration process: Filter the molten wax to remove impurities and air bubbles. S6. Molding and Cooling: Pour the filtered molten wax into a mold to cool and solidify, obtaining block-shaped wax. S7. Storage: Store the obtained block wax material in a sealed, dry environment.

[0007] As a further embodiment of the present invention: the components in step S1 are as follows by mass percentage: 35%-45% fully refined paraffin wax, 10%-18% Fischer-Tropsch wax, 22%-32% stearic acid, 8%-15% petroleum resin, 2%-6% lignite wax, 1%-3% modifier, and 0.3%-1% antioxidant.

[0008] As a further embodiment of the present invention: in step S2, the stirring rate is 60-80 r / min, the heating rate is 5-8℃ / min, and the heating temperature is 90-100℃.

[0009] As a further embodiment of the present invention: in step S3, the stirring temperature is 85-95°C, the stirring rate is 60-80 r / min, and the stirring time is 20-30 min.

[0010] As a further embodiment of the present invention: in step S4, the stirring temperature is 80-90°C, the stirring rate is 80-100 r / min, and the stirring time is 15-25 min.

[0011] As a further embodiment of the present invention: in step S5, a 200-300 mesh filter is used to filter the molten wax.

[0012] As a further aspect of the present invention: in step S6, natural cooling is used, and the material is demolded after cooling to 25±5℃.

[0013] As a further aspect of the present invention: in step S7, the storage temperature is controlled at 15-25°C, and direct sunlight and high temperature and humidity environments are avoided.

[0014] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides a wax material formula suitable for large-size directional gas turbine blades in China, uses readily available domestic raw materials, optimizes the component ratio to replace imported wax materials, improves compatibility with existing processes and equipment, reduces raw material costs and production inputs, and achieves optimal balance of key properties such as melting point, hardness, fluidity, shrinkage rate, and ash content through precise control of the wax material formula. This solves the problems of wax mold deformation, breakage, poor dimensional accuracy, and excessive dewaxing residue, ensuring the quality and dimensional accuracy of blade forming. By selecting environmentally friendly raw materials free of heavy metals and harmful additives, ash and pollutant emissions are reduced, production process pollution is reduced, and operator health is protected, meeting green manufacturing requirements. By providing a simple, controllable, and environmentally friendly preparation process, stable and uniform wax material performance can be guaranteed without complex equipment, making it suitable for large-scale production, lowering production thresholds and scrap rates, and improving production efficiency. The produced wax material has strong versatility and practicality, and can be adapted to the production of various large-size directional gas turbine blades. This helps break the foreign technology monopoly, improve the level of self-control and core competitiveness of the domestic industrial chain, and promote the upgrading of the gas turbine blade manufacturing industry. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0016] This embodiment provides a method for preparing wax material for the production of large-size gas turbine blades, including the following steps: S1. Select wax raw materials and weigh out fully refined paraffin wax, Fischer-Tropsch wax, stearic acid, petroleum resin, lignite wax, modifier, and antioxidant by mass percentage. Set aside. Specifically, the wax ratio by mass percentage includes 35%-45% fully refined paraffin wax, 10%-18% Fischer-Tropsch wax, 22%-32% stearic acid, 8%-15% petroleum resin, 2%-6% lignite wax, 1%-3% modifier, and 0.3%-1% antioxidant. The sum of the mass percentages of each component is 100%. Accuracy must be ensured during the weighing process, with the error controlled within ±0.1% to avoid fluctuations in wax performance due to ratio deviations and to ensure the stability of wax performance, adapting to the high-precision production requirements of large-size directional gas turbine blades. S2. Basic mixing of wax: Add the weighed fully refined paraffin wax, Fischer-Tropsch wax, and lignite wax to the reactor. Turn on the stirring device and control the stirring speed at 60-80 r / min. At the same time, heat slowly at a heating rate of 5-8℃ / min until the temperature reaches 90-100℃, until the three components are completely melted to form a homogeneous basic mixture. The method of slow heating and uniform stirring can avoid local overheating and oxidation of the components, ensure that the components are fully melted, reduce air bubbles in the basic mixture, improve the uniformity of the wax, lay the foundation for subsequent component mixing, and at the same time prevent the wax from oxidizing and deteriorating, thus ensuring the performance of the wax. S3. High-temperature mixing of wax materials: Maintain the reactor temperature at 85-95℃ and keep the stirring rate constant. Add stearic acid and petroleum resin to the basic mixture while stirring. After the addition is complete, continue stirring for 20-30 minutes to ensure that the stearic acid and petroleum resin are completely dissolved and uniformly mixed with the mixture. Controlling the temperature at 85-95℃ can ensure that the stearic acid and petroleum resin dissolve quickly and avoid oxidation of components due to excessive temperature. At the same time, uniform stirring can ensure that the components are fully mixed, avoid component separation, improve the stability of wax material performance, and adapt to the performance requirements of wax materials for large-size directional gas turbine blades. S4. Low-temperature mixing of wax: Maintain the reactor temperature at 80-90℃, adjust the stirring speed to 80-100r / min, and add modifier and antioxidant to the mixture. Continue stirring for 15-25min to fully integrate the components and form a wax melt. Adjusting the stirring speed can promote the uniform dispersion of modifier and antioxidant, avoid local concentrations that are too high or too low, and ensure consistent performance of all parts of the wax. At the same time, controlling the temperature can prevent the decomposition of modifier and the failure of antioxidant, ensuring the fluidity, toughness and antioxidant properties of the wax, and adapting to the production requirements of large-size directional gas turbine blades. S5. Filtration treatment: The molten wax is filtered using a 200-300 mesh filter to remove impurities and air bubbles, ensuring the purity and uniformity of the wax. Filtration effectively removes impurities from the wax, preventing them from affecting the quality of the wax mold and subsequent blades. At the same time, it removes air bubbles, preventing defects such as porosity and shrinkage cavities in the wax mold, improving the surface smoothness and dimensional accuracy of the wax mold, and adapting to the high-precision production requirements of large-size directional gas turbine blades. S6. Molding and Cooling: Pour the filtered molten wax into the mold and cool it to room temperature (25±5℃) to obtain block wax material, which is the wax material for the production of large-size directional gas turbine blades. Natural cooling can ensure that the wax material shrinks slowly, avoiding defects such as cracks and delamination caused by excessive cooling, thus improving the molding quality and performance stability of the wax material. The block wax material obtained after demolding can be directly used for wax mold injection molding, which is suitable for the large-scale production needs of large-size directional gas turbine blade wax molds and reduces the complexity of the production process and production costs. S7. Storage: Place the prepared block wax material into a sealed container and store it in a cool, dry place. The storage temperature should be controlled at 15-25℃. Avoid direct sunlight and high temperature and humidity environments to prevent the wax material from oxidizing, softening or clumping, and ensure that the wax material performance is stable for a long time. This will help meet the needs of large-scale production of large-size directional gas turbine blades, reduce raw material loss and lower production costs.

[0017] It is worth noting that fully refined food-grade paraffin wax is selected, which has high purity and low ash content. Tests have verified that its ash content is ≤0.015%, far lower than that of ordinary paraffin wax (ash content ≤0.05%), which can effectively reduce dewaxing residue. PEG-4000 or EVA is selected as a modifier, and both have excellent compatibility with other components. Tests show that adding 2% PEG-4000 can improve the fluidity of the wax by more than 20% and the impact resistance by more than 15%. BHT is selected as an antioxidant, and its antioxidant effect is stable, which can extend the shelf life of the wax to more than 12 months and prevent the wax from oxidizing and deteriorating.

[0018] During the preparation process, the stirring rate is controlled at 60~80 r / min (melting stage) and 80~100 r / min (mixing stage). This rate can avoid local overheating and oxidation of the components, while ensuring uniform mixing of each component and reducing the generation of bubbles. The heating rate is controlled at 5~8℃ / min to avoid local overheating and decomposition of the wax and to ensure that the components are fully melted. A 200~300 mesh filter is selected, which can effectively remove impurities and bubbles, while avoiding excessive wax loss.

[0019] All performance indicators of the wax material are tested in accordance with the domestic industry standard for investment casting of gas turbine blades (GB / T 14226-2019). Among them, the dimensional accuracy refers to the CT4 level standard, the surface roughness refers to the Ra≤0.8μm standard, and the ash content refers to the GB / T2549-2017 standard to ensure that the performance of the wax material meets the industry production requirements.

[0020] After testing, the prepared wax material has a melting point of 75~85℃, a hardness of 25~35D, and a shrinkage rate of 0.55%~0.65%, achieving a balance between melting point and fluidity, hardness and toughness, and shrinkage rate and dimensional accuracy, thus solving the problem of performance imbalance in existing wax materials. At the same time, the ash content is controlled to ≤0.02%, ensuring environmental friendliness and the purity of the blade material.

[0021] In the wax preparation process, there is no need to modify the existing production equipment. It can be directly used for the production of wax molds for large-size directional gas turbine blades in China. It is compatible with domestic directional solidification process parameters and shell material characteristics. At the same time, it has versatility and can be adapted to large-size blades of different specifications, thus improving practicality.

[0022] The working principle of this invention is as follows: By precisely optimizing the wax composition ratio, selecting domestically readily available environmentally friendly raw materials, and achieving synergistic effects among the components, this invention solves the problems of poor compatibility and reliance on imports in existing similar solutions, thus improving the compatibility of wax materials with the domestic production process of large-size directional gas turbine blades. By precisely controlling key performance indicators such as the melting point, hardness, and shrinkage rate of the wax material, this invention achieves optimal balance of various performances, solving the problems of performance imbalance and poor wax mold quality in existing solutions, and improving the molding accuracy and surface quality of wax molds. By selecting environmentally friendly raw materials free of heavy metals and low in ash, and optimizing the preparation process to reduce pollution, this invention solves the problem of insufficient environmental safety in existing solutions, and improves the environmental friendliness of the production process and the safety of operators. By designing a simple and controllable preparation process that does not require complex equipment, and precisely controlling each process parameter, this invention solves the problems of complex preparation processes and difficulty in scaling up existing solutions, thus improving the production efficiency and quality stability of wax materials. By improving the versatility and compatibility of wax materials, this invention reduces production costs and production barriers, solving the problems of poor practicality and difficulty in promotion in existing solutions, and improving the manufacturing quality and localization level of high-end gas turbine blades.

[0023] The large-size directional gas turbine blade wax models produced using this wax material formulation and preparation method achieve optimal performance in all key indicators, with precise and controllable dimensional accuracy, surface finish, and molding stability. This allows the final wax model to perfectly replicate the complex structure of the blade, resulting in more uniform stress and a more rational temperature distribution in subsequent shell manufacturing and directional solidification processes. This not only significantly improves the blade product qualification rate but also substantially reduces raw material and production costs. Furthermore, this wax material solution effectively optimizes the domestic process system for investment casting of large-size directional gas turbine blades, enabling the wax models and subsequent castings to reach international advanced levels in terms of comprehensive performance, geometric dimensions, and overall quality. It has also successfully achieved import substitution and mass production application.

[0024] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0025] 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 method for preparing wax material for the production of large-size gas turbine blades, characterized in that, Includes the following steps: S1. Select wax raw materials, weigh fully refined paraffin wax, Fischer-Tropsch wax, stearic acid, petroleum resin, lignite wax, modifier and antioxidant according to the mass percentage, and set aside. S2. Basic mixing of wax materials: Fully refined paraffin wax, Fischer-Tropsch wax and lignite wax are added to the reactor and heated to melt under stirring to obtain a homogeneous basic mixture. S3. High-temperature mixing of wax materials: Stearic acid and petroleum resin are added to the base mixture and stirred continuously at the set temperature to ensure that they are fully dissolved and uniformly mixed. S4. Low-temperature mixing of wax: Lower the temperature and add modifiers and antioxidants to the mixture, continue stirring to fully integrate the components and form a wax melt. S5. Filtration process: Filter the molten wax to remove impurities and air bubbles. S6. Molding and Cooling: Pour the filtered molten wax into a mold to cool and solidify, obtaining block-shaped wax. S7. Storage: Store the obtained block wax material in a sealed, dry environment.

2. The method for preparing wax material for large-size gas turbine blades according to claim 1, characterized in that, The components in step S1, by mass percentage, are: 35%-45% fully refined paraffin wax, 10%-18% Fischer-Tropsch wax, 22%-32% stearic acid, 8%-15% petroleum resin, 2%-6% lignite wax, 1%-3% modifier, and 0.3%-1% antioxidant.

3. The method for preparing wax material for large-size gas turbine blades according to claim 1, characterized in that, In step S2, the stirring rate is 60-80 r / min, the heating rate is 5-8℃ / min, and the heating temperature is 90-100℃.

4. The method for preparing wax material for large-size gas turbine blades according to claim 1, characterized in that, In step S3, the stirring temperature is 85–95°C, the stirring rate is 60–80 r / min, and the stirring time is 20–30 min.

5. The method for preparing wax material for large-size gas turbine blades according to claim 1, characterized in that, In step S4, the stirring temperature is 80–90°C, the stirring rate is 80–100 r / min, and the stirring time is 15–25 min.

6. The method for preparing wax material for large-size gas turbine blades according to claim 1, characterized in that, In step S5, a 200-300 mesh filter is used to filter the molten wax.

7. The method for preparing wax material for large-size gas turbine blades according to claim 1, characterized in that, In step S6, natural cooling is used, and the material is demolded after cooling to 25±5℃.

8. The method for preparing wax material for large-size gas turbine blade production according to claim 1, characterized in that, In step S7, the storage temperature is controlled at 15-25°C, and direct sunlight and high temperature and humidity environments are avoided.