Platinum-based alloy baffle material for airspace engine

Abstract

The invention discloses a platinum-based alloy baffle material for an airspace engine, and belongs to the technical field of precious metal alloy materials. By optimizing alloy components and the preparation method, the problems that platinum-based alloy is insufficient in high-temperature mechanical property, rare earth elements are seriously burnt and the like are successfully solved, and a new-generation platinum-based high-temperature structural material with excellent high-temperature mechanical property and oxidation resistance is developed. The material comprises the following components in percentage by mass: 25.0%-30.0% of Ir, 0.10%-1.00% of Sm, 0.10%-1.00% of Ce and the balance of Pt, the preparation method comprises the following steps: weighing a mixture of platinum, iridium, samarium and cerium metals, and sequentially carrying out pre-alloying, vacuum induction melting, pouring, solution treatment and aging treatment, thermoplastic processing, cutting and surface treatment to obtain the platinum-based alloy baffle material for the airspace engine. The tensile strength of the material reaches 48 MPa at the temperature of 1500 DEG C, and the lasting creep life exceeds 54 h under the stress of 50 MPa; under severe thermal shock and cavitation conditions, the surface of the alloy is kept intact, and the 10h oxidation weight gain is lower than 1.6 mg / cm < 2 >.

Description

Technical Field

[0001] The invention belongs to the technical field of precious metal alloy materials, and in particular relates to a platinum-based alloy baffle material for aerospace engines. Background Art

[0002] With the rapid development of aerospace technology, the new generation of "green" chemical propellants are increasingly used in aerospace engines. Compared with traditional hydrazine propellants, new propellants represented by ADN (ammonium dinitramide) and HAN (hydroxylamine nitrate) have the advantages of non-toxicity, low pollution, and high specific impulse, and therefore have become an important development direction for future aerospace engines. However, this type of propellant will release high-temperature, high-speed, and highly oxidizing combustion gases during the combustion process, which puts higher requirements on the wall materials of the engine combustion chamber, especially the catalyst baffle near the injection head, which needs to work for a long time in an extreme environment above 1500°C without failure.

[0003] At present, platinum-rhodium alloy is one of the main candidate materials for high-temperature components of aerospace engines. Platinum-rhodium alloy has excellent oxidation resistance and high melting point, and has good mechanical properties below 1500°C. It has been used in a variety of aerospace engines. For example, the use of Pt-30Rh (mass fraction, %) alloy to prepare key components such as injectors and combustion chambers can meet the use requirements of conventional chemical propellant engines. In order to further improve the high-temperature mechanical properties of platinum-rhodium alloy, some researchers have tried to strengthen the alloy matrix by adding rare earth elements (such as yttrium, samarium, etc.), and to improve the mechanical properties of platinum-rhodium alloy to a certain extent by forming a solid solution or a second phase.

[0004] However, traditional platinum-rhodium alloys still have many shortcomings in the combustion environment of new green propellants. On the one hand, the strong oxidizing properties produced by the combustion of propellants such as ADN and HAN far exceed those of hydrazine propellants. Platinum-rhodium alloys are prone to severe ablation and oxidation above 1500°C, resulting in premature failure of the combustion chamber and the injector head; on the other hand, the high-temperature strength and creep resistance of platinum-rhodium alloys are still difficult to meet the requirements of long-term work, and they are prone to softening and deformation under high heat loads, affecting the working stability of the engine. Traditional alloy strengthening methods, such as adding a small amount of rare earth elements, have very limited effects and are difficult to support the application of platinum-rhodium alloys in more demanding combustion environments. Therefore, it is urgent to develop a new platinum-based alloy system that has superior high-temperature comprehensive mechanical properties while maintaining excellent oxidation resistance. This has become a difficult problem that technicians in this field need to overcome urgently, and it is crucial for the development of a new generation of "green" chemical propellant aerospace engines. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention provides a platinum-based alloy baffle material for aerospace engines.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A platinum-based alloy baffle material for aerospace engines, which achieves the purpose of improving the low-temperature and high-temperature mechanical properties of the platinum-based alloy baffle material by optimizing the alloy composition and preparation method;

[0008] The platinum-based alloy baffle material for aerospace engines includes the following components: Ir, Sm, Ce, and Pt;

[0009] The method for preparing the platinum-based alloy baffle material for aerospace engines comprises the following steps:

[0010] (1) weighing platinum, iridium, samarium, and cerium metal raw materials and mixing them uniformly to obtain a mixed material;

[0011] (2) placing the mixed material in a non-consumable vacuum arc furnace for pre-alloying to obtain a pre-alloyed ingot;

[0012] (3) then subjecting the pre-alloyed ingot to vacuum induction melting to obtain a molten alloy;

[0013] (4) filtering the alloy liquid and pouring it into a metal mold under protective gas at a cooling rate of 50-200K / s to obtain a casting;

[0014] (5) subjecting the casting to solution treatment and aging treatment in a protective gas, and then to thermoplastic processing;

[0015] (6) Cutting the alloy material after thermoplastic processing, and finally performing surface treatment to obtain a platinum-based alloy baffle material for aerospace engines.

[0016] As a preferred embodiment of the present invention, the platinum-based alloy baffle material for aerospace engines includes the following components in percentage by mass: 25.0% to 30.0% Ir, 0.10% to 1.00% Sm, 0.10% to 1.00% Ce, and the balance is Pt.

[0017] As a preferred embodiment of the present invention, the pre-alloying specifically includes: evacuating a non-consumable vacuum arc furnace, filling it with nitrogen, and then arc melting the mixture 4 to 6 times using direct current, each arc melting time is 3 to 5 minutes, and the arc distance from the melt surface is controlled to be 2 to 5 mm, and finally cooling to room temperature with the furnace.

[0018] As a preferred embodiment of the present invention, the vacuum degree in the furnace is 2.0×10 -3 Pa, and then fill with nitrogen to 0.4-0.6 atmospheres.

[0019] As a preferred embodiment of the present invention, the electric current of the arc melting is 400-500A.

[0020] As a preferred embodiment of the present invention, the vacuum degree of the vacuum induction melting is 5.0×10 -3 Pa, temperature is 1550-1600℃, time is 30-45min.

[0021] As a preferred embodiment of the present invention, in the step (3), a crucible pouring method or a top pouring method is adopted, the pouring height is 200-500 mm, the metal mold preheating temperature is 900-1000°C, the pouring temperature is 1500-1550°C, and the demolding temperature is lower than 200°C.

[0022] As a preferred embodiment of the present invention, the heating rate of the solution treatment is 10-20°C / min, the solution treatment temperature is 1250-1300°C, and the holding time is 120-180min.

[0023] As a preferred embodiment of the present invention, the temperature of the aging treatment is 1000-1100° C., and the time is 240-300 min.

[0024] As a preferred embodiment of the present invention, after the solution treatment, the temperature is lowered to the aging temperature at a rate of 5 to 10°C / min, and after the aging treatment, the temperature is cooled to room temperature at a rate of 10 to 20°C / min.

[0025] As a preferred embodiment of the present invention, the thermoplastic processing specifically includes: thermoplastic processing the aging treated casting at 1100-1150°C by die forging, free forging or rolling, the cumulative deformation of the thermoplastic processing is not less than 60%, the deformation of each pass is 20%-30%, and recrystallization annealing is performed after each pass. As a preferred embodiment of the present invention, the recrystallization annealing is to heat to 1100-1150°C and keep the temperature for 60-120 minutes, and then air cool.

[0026] As a preferred embodiment of the present invention, in step (6), the alloy material obtained by hot plastic processing is cut into a desired shape and size by plasma arc cutting, laser cutting or wire cutting; the cutting process is carried out in an annealed state, and the cut surface roughness Ra ≤ 3.2 μm. If necessary, the cut blank can be machined, ground or other finishing processes.

[0027] As a preferred embodiment of the present invention, in the step (6), the cut baffle blank is subjected to pickling and polishing surface treatment.

[0028] As a preferred embodiment of the present invention, the pickling solution in the pickling is a 10% to 20% hydrochloric acid solution, the soaking time is 5 to 15 minutes, and the temperature is room temperature.

[0029] In the polishing surface treatment, the chemical polishing liquid includes 200 ml / L sulfuric acid, 200 ml / L phosphoric acid, 50 ml / L nitric acid and 50 g / L oxalic acid, the polishing temperature is 50-75° C., the polarization potential is 1.5-3.0 V, and the polishing time is 10-30 min.

[0030] As a preferred embodiment of the present invention, the surface roughness Ra of the platinum-based alloy baffle material for aerospace engines after surface treatment is ≤ 0.2 μm.

[0031] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention adds Sm and Ce to the Pt-Ir alloy. Compared with the conventional method of adding Sm or Ce alone, the synergistic addition of Sm and Ce achieves a strengthening effect through multiple mechanisms, including particle strengthening, solid solution strengthening and grain boundary passivation. The enriched phases of Sm and Ce can effectively hinder dislocation movement and reduce grain boundary cracking caused by oxidation, thereby comprehensively improving the high-temperature oxidation resistance and mechanical properties of the material. This synergistic effect makes the material performance significantly better than the case of adding either element alone.

[0032] (2) The inventors have adopted a combination of pre-alloying and rapid solidification processes to address the problem that rare earth elements are easily burned during the smelting process. Pre-alloying is first used to avoid the loss of a large amount of rare earth elements; vacuum induction melting is then used to obtain a liquid alloy with uniform composition and structure, and the alloy structure is refined and homogenized through a rapid solidification process. Compared with ordinary casting processes, the alloy obtained by rapid solidification has a finer grain size (ASTM grade 8 or above) and a lower degree of component segregation, which is not only conducive to the strengthening effect of rare earth elements, but also can significantly improve the isotropy and stability of the alloy. At the same time, combined with the use of the "high temperature deformation + solution aging" hot working process, while obtaining a uniform fine grain structure, the second phase particles can be dispersed and precipitated, and a good coherent interface can be formed with the matrix, thereby improving the high temperature strength and softening resistance of the alloy. After surface polishing and pickling, the alloy surface is smooth and defect-free, and the high temperature oxidation resistance is further improved.

[0033] (3) The present invention combines alloy composition with preparation method, successfully overcomes the technical difficulties of insufficient high-temperature mechanical properties of existing platinum-based alloys and serious burnout of rare earth elements, and develops a new generation of platinum-based high-temperature structural materials with excellent high-temperature mechanical properties and oxidation resistance, which demonstrates significant technical advantages and application value in the preparation of key parts for aerospace engines (such as combustion chamber walls, injection heads, etc.). This is of great strategic significance for enhancing the core competitiveness of my country's aerospace propulsion technology and promoting the industrialization and application of "green" chemical propellants. DETAILED DESCRIPTION

[0034] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0035] Example 1

[0036] A platinum-based alloy baffle material for aerospace engines comprises the following components in percentage by mass: 28.0% Ir, 0.5% Sm, 0.6% Ce, and the balance Pt.

[0037] A method for preparing a platinum-based alloy baffle material for an aerospace engine comprises the following steps:

[0038] (1) Weigh platinum, iridium, samarium, and cerium metal raw materials and mix them evenly to obtain a mixture, which is then placed in a clean alumina crucible. The volume of the crucible should be no less than 5 times the total volume of the raw materials to prevent the alloy liquid from overflowing during smelting.

[0039] (2) Place the crucible containing the mixed material into a non-consumable vacuum arc furnace and evacuate the furnace until the vacuum degree reaches 2.0×10 -3 Pa or more, and then high-purity argon (purity ≥ 99.999%) is filled to 0.6 atmospheres. A DC power supply is used to arc-melt the mixture. The melting process is carried out in 4 times, and each melting time is 4 minutes. During the melting process, the copper crucible is rotated to fully stir the melt, and the arc is controlled to be 3mm away from the melt surface. After the melting is completed, the furnace is cooled to room temperature to obtain a pre-alloyed ingot.

[0040] (3) Place the pre-alloyed ingot into an alumina crucible in a vacuum induction melting furnace and evacuate the furnace to a vacuum degree of 5.0×10 -3 Pa. Fill with high-purity argon gas that has been dehydrated and deoxygenated to normal pressure, heat to 1550℃, and keep warm for 45 minutes to fully melt and homogenize the alloy. During the smelting process, the induced current frequency is adjusted to control the melt temperature fluctuation range within ±10℃.

[0041] (4) After filtering, the vacuum induction melted alloy liquid is poured into a metal mold preheated to 1000°C under argon protection. The mold is made of high-purity graphite or high-strength alumina ceramic, and its shape is adapted to the shape of the casting, and the surface roughness of the inner cavity is Ra≤1.6μm. The pouring process adopts the crucible pouring method or top pouring method, the pouring height is 300mm, the pouring temperature is 1530°C, and the cooling rate of the casting in the mold is controlled at 100K / s to obtain a fine and uniform solidification structure. The demolding temperature is lower than 200°C to obtain the casting.

[0042] (5) Place the casting in a vacuum heat treatment furnace and evacuate to 2.0×10 -3Pa or above, and then fill with high-purity argon to normal pressure. The heating rate is 150℃ / min, the solution treatment temperature is 1280℃, the holding time is 150min, and after the solution treatment is completed, the aging temperature is reduced to 1050℃ at a rate of 7℃ / min, the aging temperature is kept for 280min, and then cooled to room temperature at a rate of 15℃ / min. This heat treatment process can fully dissolve the components in the alloy and precipitate fine dispersed second phase particles, thereby strengthening the matrix.

[0043] (6) The solution-aged casting is subjected to hot plastic processing at 1120°C. The cumulative deformation is not less than 60% by die forging, free forging or rolling. The deformation of each pass is 25%. After each deformation, recrystallization annealing is required, that is, heating to 1120°C for 90 minutes and then air cooling. After 3 cycles, a uniform and fine equiaxed crystal structure can be obtained, and the grain size is above ASTM grade 8.

[0044] (7) The alloy material obtained by hot plastic processing is cut into the required shape and size by plasma arc cutting. The cutting is carried out in the annealed state, and the cut surface roughness Ra ≤ 3.2 μm. If necessary, the cut blank can be machined, ground, etc. for finishing.

[0045] (8) The baffle blank after cutting and forming is pickled and polished. The pickling solution is a 15% hydrochloric acid solution, the immersion time is 10 minutes, and the temperature is room temperature. The chemical polishing liquid formula is: 200ml / L sulfuric acid, 200ml / L phosphoric acid, 50ml / L nitric acid and 50g / L oxalic acid; the polishing temperature is 65°C, the polarization potential is 2.0V, and the polishing time is 20 minutes. The surface roughness Ra after surface treatment is ≤0.2μm.

[0046] Example 2

[0047] A platinum-based alloy baffle material for aerospace engines comprises the following components in percentage by mass: 25.0% Ir, 0.1% Sm, 1.0% Ce, and the balance Pt.

[0048] A method for preparing a platinum-based alloy baffle material for an aerospace engine comprises the following steps:

[0049] (1) Weigh platinum, iridium, samarium, and cerium metal raw materials and mix them evenly to obtain a mixture, which is then placed in a clean alumina crucible. The volume of the crucible should be no less than 5 times the total volume of the raw materials to prevent the alloy liquid from overflowing during smelting.

[0050] (2) Place the crucible containing the mixed material into a non-consumable vacuum arc furnace and evacuate the furnace until the vacuum degree reaches 2.0×10 -3Pa or more, and then high-purity argon (purity ≥ 99.999%) is filled to 0.4 atmospheres. A DC power supply is used to perform arc melting on the mixture. The melting process is divided into 4 times, and each melting time is 3 minutes. During the melting process, the copper crucible is rotated to fully stir the melt, and the arc is controlled to be 5mm away from the melt surface. After the melting is completed, the furnace is cooled to room temperature to obtain a pre-alloyed ingot.

[0051] (3) Place the pre-alloyed ingot into an alumina crucible in a vacuum induction melting furnace and evacuate the furnace to a vacuum degree of 5.0×10 -3 Pa. Fill with high-purity argon gas that has been dehydrated and deoxygenated to normal pressure, heat to 1550℃, and keep warm for 30 minutes to fully melt and homogenize the alloy. During the smelting process, the induced current frequency is adjusted to control the melt temperature fluctuation range within ±10℃.

[0052] (4) After filtering, the vacuum induction melted alloy liquid is poured into a metal mold preheated to 900°C under argon protection. The mold is made of high-purity graphite or high-strength alumina ceramic, and its shape is adapted to the shape of the casting, and the surface roughness of the inner cavity is Ra≤1.6μm. The pouring process adopts the crucible pouring method or top pouring method, the pouring height is 500mm, the pouring temperature is 1500°C, and the cooling rate of the casting in the mold is controlled at 200K / s to obtain a fine and uniform solidification structure. The demolding temperature is lower than 200°C to obtain the casting.

[0053] (5) Place the casting in a vacuum heat treatment furnace and evacuate to 2.0×10 -3 Pa, and then fill with high-purity argon to normal pressure. The heating rate is 10℃ / min, the solution treatment temperature is 1300℃, the holding time is 180min, and after the solution treatment is completed, the temperature is reduced to 1000℃ at a rate of 5℃ / min, the aging temperature is kept for 240min, and then cooled to room temperature at a rate of 20℃ / min. This heat treatment process can fully dissolve the components in the alloy and precipitate fine dispersed second phase particles, thereby strengthening the matrix.

[0054] (6) The solution-aged casting is subjected to hot plastic processing at 1150°C. The cumulative deformation is not less than 60% by die forging, free forging or rolling. The deformation of each pass is 20%. After each deformation, recrystallization annealing is required, that is, heating to 1100°C for 60 minutes and then air cooling. After 3 cycles, a uniform and fine equiaxed crystal structure can be obtained, and the grain size is above ASTM grade 8.

[0055] (7) The alloy material obtained by hot plastic processing is cut into the required shape and size by plasma arc cutting. The cutting is carried out in the annealed state, and the cut surface roughness Ra ≤ 3.2 μm. If necessary, the cut blank can be machined, ground, etc. for finishing.

[0056] (8) The baffle blank after cutting and forming is pickled and polished. The pickling solution is a 20% hydrochloric acid solution, the immersion time is 5 minutes, and the temperature is room temperature. The chemical polishing liquid formula is: sulfuric acid 200ml / L, phosphoric acid 200ml / L, nitric acid 50ml / L and oxalic acid 50g / L; the polishing temperature is 75°C, the polarization potential is 1.5V, and the polishing time is 30 minutes. The surface roughness Ra after surface treatment is ≤0.2μm.

[0057] Example 3

[0058] A platinum-based alloy baffle material for aerospace engines comprises the following components in percentage by mass: 30.0% Ir, 1.0% Sm, 0.1% Ce, and the balance Pt.

[0059] A method for preparing a platinum-based alloy baffle material for an aerospace engine comprises the following steps:

[0060] (1) Weigh platinum, iridium, samarium, and cerium metal raw materials and mix them evenly to obtain a mixture, which is then placed in a clean alumina crucible. The volume of the crucible should be no less than 5 times the total volume of the raw materials to prevent the alloy liquid from overflowing during smelting.

[0061] (2) Place the crucible containing the mixed material into a non-consumable vacuum arc furnace and evacuate the furnace until the vacuum degree reaches 2.0×10 -3 Pa or more, and then high-purity argon (purity ≥ 99.999%) is filled to 0.5 atmospheres. A DC power supply is used to arc-melt the mixture. The melting process is divided into 4 times, and each melting time is 5 minutes. During the melting process, the copper crucible is rotated to fully stir the melt, and the arc is controlled to be 2mm away from the melt surface. After the melting is completed, the furnace is cooled to room temperature to obtain a pre-alloyed ingot.

[0062] (3) Place the pre-alloyed ingot into an alumina crucible in a vacuum induction melting furnace and evacuate the furnace to a vacuum degree of 5.0×10 -3 Pa. Fill with high-purity argon gas that has been dehydrated and deoxygenated to normal pressure, heat to 1600℃, and keep warm for 45 minutes to fully melt and homogenize the alloy. During the smelting process, the induced current frequency is adjusted to control the melt temperature fluctuation range within ±10℃.

[0063] (4) After filtering, the vacuum induction melted alloy liquid is poured into a metal mold preheated to 1000°C under argon protection. The mold is made of high-purity graphite or high-strength alumina ceramic, and its shape is adapted to the shape of the casting, and the surface roughness of the inner cavity is Ra≤1.6μm. The pouring process adopts the crucible pouring method or top pouring method, the pouring height is 200mm, the pouring temperature is 1550°C, and the cooling rate of the casting in the mold is controlled at 50K / s to obtain a fine and uniform solidification structure. The demolding temperature is lower than 200°C to obtain the casting.

[0064] (5) Place the casting in a vacuum heat treatment furnace and evacuate to 2.0×10 -3 Pa, and then fill with high-purity argon to normal pressure. The heating rate is 20℃ / min, the solution treatment temperature is 1250℃, the holding time is 120min, and after the solution treatment is completed, the temperature is reduced to 1100℃ at a rate of 10℃ / min, the aging temperature is kept for 300min, and then cooled to room temperature at a rate of 10℃ / min. This heat treatment process can fully dissolve the components in the alloy and precipitate fine dispersed second phase particles, thereby strengthening the matrix.

[0065] (6) The solution-aged casting is subjected to hot plastic processing at 1100°C. The cumulative deformation is not less than 60% by die forging, free forging or rolling. The deformation of each pass is 30%. After each deformation, recrystallization annealing is required, that is, heating to 1150°C for 120 minutes and then air cooling. After 2 cycles, a uniform and fine equiaxed crystal structure can be obtained, and the grain size is above ASTM grade 8.

[0066] (7) The alloy material obtained by hot plastic processing is cut into the required shape and size by plasma arc cutting. The cutting is carried out in the annealed state, and the cut surface roughness Ra ≤ 3.2 μm. If necessary, the cut blank can be machined, ground, etc. for finishing.

[0067] (8) The baffle blank after cutting and forming is pickled and polished. The pickling solution is a 10% hydrochloric acid solution, the immersion time is 15 minutes, and the temperature is room temperature. The chemical polishing liquid formula is: 200ml / L sulfuric acid, 200ml / L phosphoric acid, 50ml / L nitric acid and 50g / L oxalic acid; the polishing temperature is 50°C, the polarization potential is 3.0V, and the polishing time is 10 minutes. The surface roughness Ra after surface treatment is ≤0.2μm.

[0068] Comparative Example 1

[0069] The only difference between the preparation method of the platinum-based alloy baffle material for aerospace engines described in this comparative example and that in Example 1 is that the mixed material is directly subjected to vacuum induction melting without pre-alloying treatment.

[0070] Comparative Example 2

[0071] The only difference between the preparation method of the platinum-based alloy baffle material for aerospace engines described in this comparative example and that in Example 1 is that in step (4), the cooling rate of the casting in the mold is controlled at 40K / s.

[0072] Comparative Example 3

[0073] The only difference between the preparation method of the platinum-based alloy baffle material for aerospace engines described in this comparative example and that in Example 1 is that in step (4), the cooling rate of the casting in the mold is controlled at 240K / s.

[0074] Comparative Example 4

[0075] The platinum-based alloy baffle material for aerospace engines described in this comparative example includes the following components in percentage by mass: 28.0% Ir and the balance Pt.

[0076] The preparation method of the platinum-based alloy baffle material for aerospace engines described in this comparative example is the same as that in Example 1.

[0077] Comparative Example 5

[0078] The platinum-based alloy baffle material for aerospace engines described in this comparative example includes the following components in percentage by mass: 28.0% Ir, 1.0% Ce, and the balance Pt.

[0079] The preparation method of the platinum-based alloy baffle material for aerospace engines described in this comparative example is the same as that in Example 1.

[0080] Comparative Example 6

[0081] The platinum-based alloy baffle material for aerospace engines described in this comparative example includes the following components in percentage by mass: 28.0% Ir, 1.0% Sm, and the balance Pt.

[0082] The preparation method of the platinum-based alloy baffle material for aerospace engines described in this comparative example is the same as that in Example 1.

[0083] Comparative Example 7

[0084] The platinum-based alloy baffle material for aerospace engines described in this comparative example includes the following components in percentage by mass: 28.0% Ir, 0.5% Sm, 0.6% La, and the balance Pt.

[0085] The preparation method of the platinum-based alloy baffle material for aerospace engines described in this comparative example is the same as that in Example 1.

[0086] Comparative Example 8

[0087] The platinum-based alloy baffle material for aerospace engines described in this comparative example includes the following components in percentage by mass: 28.0% Ir, 0.5% Ce, 0.6% Y, and the balance Pt.

[0088] The preparation method of the platinum-based alloy baffle material for aerospace engines described in this comparative example is the same as that in Example 1.

[0089] Effect example

[0090] The mechanical properties and high-temperature oxidation resistance of the prepared alloy baffle material were tested and evaluated, and the main technical indicators are shown in Table 1.

[0091] Table 1

[0092]

[0093]

[0094] According to Example 1 and Comparative Example 1, pre-alloying can improve the mechanical property stability of the alloy at room temperature and at 1500°C. In addition, pre-alloying can also improve the machinability of the alloy, reduce the formation of casting defects and cracks, and improve the comprehensive mechanical properties and oxidation resistance of the alloy. The alloy lacking the pre-alloying step exhibits microstructural defects, resulting in a decrease in mechanical properties and oxidation resistance.

[0095] According to Example 1 and Comparative Examples 2 and 3, it can be seen that the reasonable control of solidification rate is crucial in platinum-based alloys, affecting the microstructure and overall performance of the alloy: a moderate solidification rate can refine the grains and evenly distribute the dispersed phase formed by the rare earth elements Sm and Ce, thereby improving the high-temperature mechanical properties of the material such as tensile strength and creep resistance, while reducing the burning loss of rare earth elements. On the contrary, a too slow solidification rate will lead to grain coarsening and component segregation, reduce mechanical properties and oxidation resistance, and increase the burning loss of rare earth elements, while a too fast solidification rate will lead to the formation of internal defects such as shrinkage cavities and cracks, weakening the mechanical properties and oxidation resistance of the material.

[0096] According to the data of Examples 1-3 and Comparative Examples 4-6, the lack of one or both of Sm and Ce will lead to a decrease in the high-temperature mechanical properties of the alloy, while improving the oxidation resistance.

[0097] According to Examples 1-3 and Comparative Examples 7 and 8, Sm, Ce, Ir, and Pt interact with each other and produce synergistic effects. When La replaces one of the rare earth elements, although the yield strength of the material at room temperature is improved, the tensile strength at room temperature is reduced, and the oxidation resistance at high temperature is reduced, which is manifested as an increase in oxidation weight loss and a decrease in mechanical properties. When Y replaces one of the rare earth elements, the yield strength of the material at room temperature does not decrease significantly, but its tensile strength at room temperature, mechanical properties at high temperature, and oxidation resistance are all reduced.

[0098] According to the comparison between Example 1 and platinum-rhodium alloy and niobium-silicon alloy, it can be seen that although the yield strength and high-temperature oxidation resistance of the PtIr alloy with the addition of Sm and Ce at room temperature are not as good as those of the platinum-rhodium alloy and the niobium-silicon alloy, the room temperature tensile strength is higher, and the mechanical properties at high temperature are better than those of the platinum-rhodium alloy and the niobium-silicon alloy.

[0099] Therefore, the room temperature and high temperature mechanical properties of the platinum-based alloy baffle material for aerospace engines prepared by the preparation method of the platinum-based alloy baffle material for aerospace engines of the present invention are as follows: room temperature tensile strength ≥ 900 MPa, yield strength ≥ 670 MPa; tensile strength at 1500°C ≥ 39 MPa, creep life of 5 MPa at 1500°C ≥ 52 h, endurance strength at 1500°C 10 h ≥ 10 MPa, oxidation weight gain at 1500°C 10 h less than 1.72 mg / cm 2 .

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A platinum-based alloy baffle material for aerospace engines, characterized in that: By optimizing the alloy composition and preparation method, the low-temperature and high-temperature mechanical properties of the platinum-based alloy baffle material are improved; The invention comprises the following components in percentage by mass: 25.0% to 30.0% Ir, 0.10% to 1.00% Sm, 0.10% to 1.00% Ce and the balance Pt; The method for preparing the platinum-based alloy baffle material for aerospace engines comprises the following steps: (1) weighing platinum, iridium, samarium, and cerium metal raw materials and mixing them uniformly to obtain a mixed material; (2) placing the mixed material in a non-consumable vacuum arc furnace for pre-alloying to obtain a pre-alloyed ingot; (3) then subjecting the pre-alloyed ingot to vacuum induction melting to obtain a molten alloy; (4) filtering the alloy liquid and pouring it into a metal mold under protective gas at a cooling rate of 50-200K / s to obtain a casting; (5) subjecting the casting to solution treatment and aging treatment in a protective gas, and then to thermoplastic processing; (6) Cutting the alloy material after thermoplastic processing, and finally performing surface treatment to obtain a platinum-based alloy baffle material for aerospace engines.

2. The platinum-based alloy baffle material for aerospace engines as claimed in claim 1, characterized in that: The pre-alloying specifically includes: evacuating a non-consumable vacuum arc furnace, filling it with nitrogen, and then arc melting the mixture 4 to 6 times using a direct current of 400 to 500A, each arc melting time is 3 to 5 minutes, and the arc distance is controlled to be 2 to 5 mm from the melt surface, and finally cooling to room temperature with the furnace.

3. The platinum-based alloy baffle material for aerospace engines as claimed in claim 1, characterized in that: The vacuum degree of the vacuum induction melting is 5.0×10 -3 Pa or above, the temperature is 1550-1600℃, and the time is 30-45min.

4. The platinum-based alloy baffle material for aerospace engines as claimed in claim 1, characterized in that: In the step (4), the casting is performed by a crucible pouring method or a top pouring method, the casting height is 200-500 mm, the metal mold preheating temperature is 900-1000° C., the casting temperature is 1500-1550° C., and the demoulding temperature is lower than 200° C.

5. The platinum-based alloy baffle material for aerospace engines as claimed in claim 1, characterized in that: The heating rate of the solution treatment is 10-20°C / min, the solution treatment temperature is 1250-1300°C, and the holding time is 120-180min; the aging treatment temperature is 1000-1100°C, and the holding time is 240-300min.

6. The platinum-based alloy baffle material for aerospace engines as claimed in claim 1, characterized in that: The thermoplastic processing specifically includes: performing thermoplastic processing on the aging treated casting at 1100-1150°C by die forging, free forging or rolling, wherein the cumulative deformation of the thermoplastic processing is not less than 60%, the deformation of each pass is 20%-30%, and recrystallization annealing is performed after each pass.

7. The platinum-based alloy baffle material for aerospace engines as claimed in claim 6, characterized in that: The recrystallization annealing is performed by heating the temperature to 1100-1150° C. and keeping the temperature for 60-120 minutes, and then air cooling.

8. The platinum-based alloy baffle material for aerospace engines as claimed in claim 1, characterized in that: In the step (6), the alloy material obtained by hot plastic processing is cut into a desired shape and size by plasma arc cutting, laser cutting or wire cutting; the cutting process is carried out at 1100° C. and solution annealing for 2 hours, and the cut surface roughness Ra is ≤3.2 μm.

9. The platinum-based alloy baffle material for aerospace engines as claimed in claim 1, characterized in that: In the step (6), the cut baffle blank is pickled and then subjected to a surface polishing treatment.

10. The platinum-based alloy baffle material for aerospace engines as claimed in claim 9, characterized in that: The pickling solution in the pickling is a 10% to 20% hydrochloric acid solution, the immersion time is 5 to 15 minutes, and the temperature is room temperature; in the polishing surface treatment, the chemical polishing solution includes 200ml / L sulfuric acid, 200ml / L phosphoric acid, 50ml / L nitric acid and 50g / L oxalic acid, the polishing temperature is 50 to 75°C, the polarization potential is 1.5 to 3.0V, and the polishing time is 10 to 30 minutes.

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