A high-strength aluminum alloy material suitable for a humanoid robot skeleton and a method of manufacturing the same

Abstract

A high-strength aluminum alloy material suitable for humanoid robot skeletons and its preparation method relate to the field of humanoid robots. The material includes an aluminum matrix and modified zirconia dispersed within the aluminum matrix. The modified zirconia comprises hollow mesoporous zirconia, cerium oxide loaded within the pores of the hollow mesoporous zirconia, and a silica sealing layer covering the outer surface of the hollow mesoporous zirconia. This invention solves the problems of poor interfacial bonding and low plasticity in traditional ceramic / aluminum composite materials, producing an aluminum alloy with high strength, high toughness, and low density, perfectly meeting the stringent requirements of humanoid robot skeletons for high load-bearing capacity and high mobility.

Description

Technical Field

[0001] This invention relates to the field of humanoid robot technology, specifically to a high-strength aluminum alloy material suitable for humanoid robot skeletons and its preparation method. Background Technology

[0002] With the rapid development of artificial intelligence and precision manufacturing technologies, humanoid robots are gradually moving from laboratories into practical applications such as industrial production, home services, and disaster relief. As the physical support platform for robots, the skeletal system not only needs to bear its own weight and driving loads, but also needs to withstand complex alternating stresses and impact loads during dynamic operations such as walking, jumping, and grasping heavy objects. Therefore, the choice of skeletal materials for humanoid robots directly determines the robot's mobility, load-bearing capacity, and endurance.

[0003] Currently, structural materials used in robotics mainly include high-strength steel, titanium alloys, carbon fiber composites, and high-strength aluminum alloys. While high-strength steel boasts high strength, its excessive density increases the robot's weight, significantly consuming battery power and reducing its range. Titanium alloys, despite their high specific strength, are expensive and have poor processing performance, making them unsuitable for large-scale production. Carbon fiber composites, while lightweight and high-strength, exhibit significant anisotropy and are prone to interlaminar cracking at joints, resulting in relatively weak impact resistance. In contrast, high-strength aluminum alloys, with their low density, good processability, and high specific strength, have become the preferred material for humanoid robot skeletons.

[0004] However, traditional commercial high-strength aluminum alloys still exhibit the following shortcomings when facing the next generation of high-performance robots:

[0005] Insufficient modulus: The elastic modulus of aluminum alloy (about 70 GPa) is much lower than that of steel (about 210 GPa), which makes it prone to elastic deformation under heavy load conditions, affecting the positioning accuracy of robot joints;

[0006] Strength bottleneck: Traditional alloying methods (solution + aging) have reached their limit in improving strength, making it difficult to significantly increase load-bearing capacity while maintaining lightweight design;

[0007] Poor wear and heat resistance: During long-term high-frequency movement, the joints of the robot are prone to heat and wear, and the strength of traditional aluminum alloys decreases rapidly at high temperatures.

[0008] To overcome these bottlenecks, researchers attempted to introduce ceramic particles into aluminum alloys to prepare aluminum-based composites. Zirconia, due to its extremely high hardness, fracture toughness, and wear resistance, is considered an ideal reinforcing phase. However, directly adding commercially available solid zirconia particles into the aluminum matrix presents three main technical challenges:

[0009] Weight gain effect: The density of zirconium oxide (approximately 5.68 g / cm3) is much higher than that of aluminum (approximately 2.70 g / cm3). Adding solid particles will cause the density of the composite material to increase significantly, which violates the original design intention of "lightweight" robots.

[0010] Poor interfacial bonding: Zirconia is a chemically inert ceramic with poor wettability with aluminum, making it difficult to form a strong metallurgical bond between the two. Under stress, microcracks or particle debonding easily occur at the interface, resulting in a material that is "strong but not tough," with a sharp decrease in elongation after fracture, making it unable to withstand drops or impacts.

[0011] Agglomeration phenomenon: Micro- and nano-sized ceramic particles are prone to agglomeration during high-energy ball milling, forming large-size defect sources that severely disrupt the matrix structure.

[0012] Therefore, how to develop a lightweight, high-strength aluminum alloy material that can utilize the high hardness and high modulus properties of zirconium oxide, overcome its high-density defects, and solve the problem of bonding between ceramics and metals is a key technical problem that urgently needs to be solved in the field of humanoid robot skeleton materials. Summary of the Invention

[0013] In view of this, the present invention aims to propose a high-strength aluminum alloy material suitable for humanoid robot skeletons and its preparation method. By utilizing the in-situ reaction of the reinforcing phase surface to construct a strong and tough chemical interface, combined with the dispersed fine grain effect of cerium oxide inside, the strength and toughness of the material are significantly improved. At the same time, the intact hollow structure effectively offsets the weight gain of alloying, achieving lightweighting.

[0014] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0015] A high-strength aluminum alloy material suitable for humanoid robot skeletons includes an aluminum matrix and modified zirconia dispersed in the aluminum matrix; the modified zirconia includes hollow mesoporous zirconia, cerium oxide loaded in the pores of the hollow mesoporous zirconia, and a silica sealing layer covering the outer surface of the hollow mesoporous zirconia.

[0016] In some embodiments, the aluminum matrix is ​​made from the following raw materials by weight percentage: 0.6–1.2% Si, 0.05–0.2% Fe, 0.5–1.1% Cu, 0.8–1.4% Mg, 0.05–0.32% Cr, 0.05–0.25% Zn, 0.05–0.15% Ti, 1.2–2.4% Ni, 0.4–1.0% Co, with the balance being Al.

[0017] In some embodiments, the modified zirconium oxide is 1.2 to 3.6% by mass.

[0018] A method for preparing the above-mentioned high-strength aluminum alloy material suitable for humanoid robot skeletons includes the following steps: preparing modified zirconia: obtaining hollow mesoporous zirconia by etching a silica template; impregnating and calcining cerium salt into the pores of the hollow mesoporous zirconia to form cerium-loaded zirconia; coating the surface of the loaded zirconia with silica sol and dehydrating and condensing it to form a silica sealing layer to obtain modified zirconia; preparing composite material: mixing aluminum matrix raw material powder with modified zirconia, molding, sintering and heat treating to obtain high-strength aluminum alloy material.

[0019] In some embodiments, the steps for preparing modified zirconia are as follows: a silica template, anhydrous ethanol, acetonitrile, and ammonia are mixed and dropped into a zirconium source solution to carry out a hydrolysis-condensation reaction, thereby coating a zirconia layer on the silica surface. The silica template is then removed with an alkaline etching solution to obtain hollow mesoporous zirconia. The hollow mesoporous zirconia is mixed with a cerium salt solution under vacuum conditions, and then dried and calcined at high temperature to thermally decompose the cerium salt into cerium oxide, which is then loaded into the pores to obtain loaded zirconia. The loaded zirconia is mixed with silica sol, and then stirred and dried to dehydrate and condense the silica sol to form a silica sealing layer, thereby obtaining modified zirconia.

[0020] In some embodiments, the zirconium source is selected from at least one of zirconium propoxide, zirconium butoxide, or zirconium oxychloride; the alkaline etching solution is a sodium hydroxide solution or a potassium hydroxide solution; the cerium salt is cerium nitrate, and its solution is a cerium nitrate ethanol solution; the solid content of the silica sol is 10–30 wt%.

[0021] In some embodiments, the steps for preparing the composite material include: high-energy ball milling of aluminum matrix raw material powder (excluding modified zirconium oxide) to obtain matrix alloy powder; low-energy ball milling of modified zirconium oxide into the matrix alloy powder to obtain composite powder; pressing the composite powder into a green compact; sintering the green compact under vacuum or a protective atmosphere to obtain a sintered alloy; and performing solid solution and aging treatment on the sintered alloy.

[0022] In some embodiments, the high-energy ball mill has a rotation speed of 300–600 r / min, a ball-to-material ratio of 5–10:1, and a milling time of 10–20 h; the low-energy ball mill has a rotation speed of 50–150 r / min, a ball-to-material ratio of 1–3:1, and a milling time of 1–3 h.

[0023] In some embodiments, the sintering temperature is 560–620°C, and the holding time is 1–3 hours.

[0024] In some embodiments, the heating rate of high-temperature calcination is 2-5°C / min, the calcination temperature is 400-600°C, and the holding time is 3-5h. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0026] Figure 1 This is a schematic diagram of the aluminum alloy material prepared in Example 1 of the present invention and the distribution of its Vickers hardness measurement sampling points. Detailed Implementation

[0027] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings and embodiments. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The following is for reference. Figure 1 The high-strength aluminum alloy material suitable for humanoid robot skeletons and its preparation method are described in conjunction with embodiments of the present invention.

[0029] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0030] The raw material information used in this invention is as follows:

[0031] Aluminum powder (Al): average particle size 20~50μm, purity ≥99.9%; Silicon powder (Si): average particle size 5~10μm, purity ≥99.9%; Magnesium powder (Mg): average particle size 40~70μm, purity ≥99.9%; Copper powder (Cu), Nickel powder (Ni), Cobalt powder (Co), Iron powder (Fe), Chromium powder (Cr), Titanium powder (Ti), Zinc powder (Zn): all are atomized spherical powders with an average particle size of 10~30μm, purity ≥99.5%.

[0032] This invention provides a high-strength aluminum alloy material suitable for humanoid robot skeletons, comprising an aluminum matrix and modified zirconium oxide dispersed in the aluminum matrix. The aluminum matrix, by mass percentage, is made from the following raw materials: 0.6~1.2% Si, 0.05~0.2% Fe, 0.5~1.1% Cu, 0.8~1.4% Mg, 0.05~0.32% Cr, 0.05~0.25% Zn, 0.05~0.15% Ti, 1.2~2.4% Ni, 0.4~1.0% Co, with the balance being Al. The modified zirconium oxide comprises 1.2~3.6% by mass. The modified zirconium oxide has a unique core-shell structure, specifically comprising hollow mesoporous zirconium oxide, cerium oxide loaded within the pores of the hollow mesoporous zirconium oxide, and a silica sealing layer covering the outer surface of the hollow mesoporous zirconium oxide.

[0033] The present invention also provides a method for preparing the above-mentioned high-strength aluminum alloy material, which mainly includes two core parts: the preparation of modified zirconium oxide and the preparation of composite materials.

[0034] I. Preparation of Modified Zirconia

[0035] The modified zirconia was prepared by a three-step method of "template etching - vacuum impregnation - sol sealing", the specific steps of which are as follows:

[0036] (1) Preparation of hollow mesoporous zirconia (template etching method)

[0037] This step aims to construct a hollow carrier with lightweight and energy-absorbing properties.

[0038] First, prepare the dispersion: Mix the silica template (hard template), anhydrous ethanol, acetonitrile and ammonia water in a mass ratio of 1:15~25:5~10:2~5 until homogeneous.

[0039] Next, hydrolysis-condensation coating is performed: Under stirring conditions, an alcoholic solution of the zirconium source is slowly added dropwise to the above dispersion, controlling the mass ratio of zirconium source to silica to be 0.5~2.0:1. The zirconium source is selected from at least one of zirconium propoxide, zirconium butoxide, or zirconium oxychloride. After the addition is complete, the reaction is carried out for 6~8 hours to allow the zirconium oxide precursor generated by hydrolysis to uniformly coat the surface of the silica template.

[0040] Finally, etching is performed to create pores: the product is collected and dried, then placed in an alkaline etching solution (sodium hydroxide or potassium hydroxide solution) at a temperature of 70~90℃ and a concentration of 0.5~2mol / L, and reacted for 6~8h to completely remove the internal silica template. After washing and drying, hollow mesoporous zirconia is obtained.

[0041] (2) Preparation of supported zirconia (vacuum impregnation and conversion)

[0042] This step aims to utilize hollow channels to load rare earth elements to strengthen the matrix grain boundaries.

[0043] First, mixing and impregnation: The hollow mesoporous zirconium oxide prepared in step (1) is immersed in a cerium nitrate ethanol solution with a concentration of 0.1~0.5 mol / L, and the mass-to-volume ratio of hollow mesoporous zirconium oxide to the solution is controlled at 1 g: 10~20 mL. To ensure that the cerium salt fully enters the micropores, the mixing process must be carried out under ultrasonic dispersion and vacuum conditions below 2.0 kPa.

[0044] Secondly, thermal decomposition and conversion: The impregnated powder is dried to remove the solvent, and then placed in a high-temperature furnace for calcination. The calcination process is controlled as follows: heating rate 2~5℃ / min, calcination temperature 400~600℃, and holding time 3~5h. During this process, cerium nitrate entering the pores undergoes in-situ thermal decomposition into cerium oxide nanoparticles, which adhere to the inner wall of the hollow mesoporous zirconia, thus obtaining supported zirconia.

[0045] (3) Preparation of modified zirconia (sol-sealing modification)

[0046] This step aims to construct a surface-active layer and seal the hollow structure.

[0047] The supported zirconia prepared in step (2) is mixed with silica sol with a solid content of 10~30wt%, and the mass ratio of supported zirconia to silica sol is controlled to be 1:5~10.

[0048] Subsequently, a dehydration condensation reaction was carried out: the mixture was stirred at a constant temperature of 200-300 r / min and 80-90℃ for 2-4 hours to allow the silica sol to cross-link and solidify on the surface and pores of the supported zirconia, forming a silica sealing layer. After the reaction was completed, the mixture was dried at 100-120℃ for 1-2 hours to obtain the final core-shell structure modified zirconia.

[0049] II. Preparation of High-Strength Aluminum Alloy Materials (Two-Step Ball Milling and Reaction Sintering)

[0050] This step introduces the modified zirconium oxide into the alloy system and prepares the finished product through a specific powder metallurgy process.

[0051] (1) Ingredients: Weigh 0.6~1.2% Si, 0.05~0.2% Fe, 0.5~1.1% Cu, 0.8~1.4% Mg, 0.05~0.32% Cr, 0.05~0.25% Zn, 0.05~0.15% Ti, 1.2~2.4% Ni, 0.4~1.0% Co and 1.2~3.6% of the modified zirconia prepared in step (I) by mass percentage, with the balance being Al.

[0052] (2) High-energy ball milling of the matrix: All metal powders except modified zirconium oxide are mixed and subjected to high-energy ball milling to achieve mechanical alloying. The process conditions are: rotation speed 300~600 r / min, ball-to-material ratio 5~10:1, ball milling time 10~20 h, to obtain matrix alloy powder.

[0053] (3) Low-energy dispersion composite: Modified zirconia is added to the matrix alloy powder and subjected to low-energy ball milling or low-speed mixing to achieve uniform dispersion without damaging the hollow structure. The process conditions are: rotation speed 50~150 r / min, ball-to-powder ratio 1~3:1, time 1~3 h, to obtain composite powder.

[0054] (4) Molding and Sintering: The composite powder is pressed into a green body under cold isostatic pressing or molding conditions; then sintered under vacuum or protective atmosphere at a temperature of 560~620℃ for 1~3h. During this stage, the silica layer on the modified zirconia surface reacts in situ with the aluminum substrate (4Al+3SiO2→2Al2O3+3Si) to form an interfacial bonding layer and release silicon.

[0055] (5) Heat treatment: The sintered alloy is subjected to solution treatment and aging treatment (T6) to precipitate alloying elements and strengthen it, thus obtaining the finished product.

[0056] The present invention will be further described below through specific embodiments.

[0057] Example 1

[0058] A method for preparing a high-strength aluminum alloy material suitable for humanoid robot skeletons includes the following steps:

[0059] (1) The silica template, anhydrous ethanol, acetonitrile, and ammonia were mixed evenly in a mass ratio of 1:25:10:5. Under stirring conditions, the alcohol solution of zirconium propoxide was slowly added dropwise to the above dispersion, and the mass ratio of zirconium source to silica was controlled at 2.0:1. After the addition was completed, the reaction was carried out for 8 hours. The product was collected and dried, and then put into a sodium hydroxide solution with a temperature of 80℃ and a concentration of 1.5mol / L. The reaction was carried out for 8 hours to completely remove the internal silica template. After washing and drying, hollow mesoporous zirconium oxide was obtained.

[0060] (2) Hollow mesoporous zirconia was immersed in a 0.5 mol / L cerium nitrate ethanol solution, and the mass-volume ratio of hollow mesoporous zirconia to the solution was controlled at 1 g: 10 mL. The mixture was then mixed under ultrasonic dispersion and a vacuum of 1.0 kPa. The impregnated powder was dried to remove the solvent and then placed in a high-temperature furnace for calcination. The calcination process was controlled as follows: heating rate 3℃ / min, calcination temperature 500℃, and holding time 4h to obtain loaded zirconia.

[0061] (3) The supported zirconium oxide was mixed with silica sol with a solid content of 20wt%, and the mass ratio of the supported zirconium oxide to silica sol was controlled to be 1:10. The mixture was stirred at a constant temperature of 250r / min and 90℃ for 2h to form a silica sealing layer. After the reaction was completed, the mixture was dried at 110℃ for 1.5h to obtain modified zirconium oxide.

[0062] (4) Weigh out 1.2% Si, 0.2% Fe, 1.1% Cu, 1.4% Mg, 0.32% Cr, 0.25% Zn, 0.15% Ti, 2.4% Ni, 1.0% Co, and 3.6% modified zirconium oxide by mass percentage, with the balance being Al; mix all metal powders except modified zirconium oxide, and ball mill at 500 r / min and a ball-to-powder ratio of 8:1 for 15 h to obtain a matrix alloy powder; add modified zirconium oxide to the matrix alloy powder, and ball mill at 100 r / min and a ball-to-powder ratio of 2:1 for 2 h to obtain a composite powder; press the composite powder into a green blank under molding conditions, and then sinter it under vacuum at a sintering temperature of 600℃ and a holding time of 2 h. Perform solid solution and aging treatment (T6) on the sintered alloy to precipitate and strengthen the alloy elements, thereby obtaining the high-strength aluminum alloy material suitable for humanoid robot skeletons, such as... Figure 1 As shown.

[0063] Example 2

[0064] A method for preparing a high-strength aluminum alloy material suitable for humanoid robot skeletons includes the following steps:

[0065] (1) The silica template, anhydrous ethanol, acetonitrile, and ammonia were mixed evenly in a mass ratio of 1:20:8:3. Under stirring, the alcohol solution of zirconium propoxide was slowly added dropwise to the above dispersion, and the mass ratio of zirconium source to silica was controlled to be 1.5:1. After the addition was completed, the reaction was allowed to proceed for 7 hours. The product was collected and dried, and then placed in a sodium hydroxide solution with a temperature of 80°C and a concentration of 1.5 mol / L. The reaction was allowed to proceed for 7 hours to completely remove the internal silica template. After washing and drying, hollow mesoporous zirconium oxide was obtained.

[0066] (2) Hollow mesoporous zirconia was immersed in a 0.3 mol / L cerium nitrate ethanol solution, and the mass-volume ratio of hollow mesoporous zirconia to the solution was controlled at 1 g: 15 mL. The mixture was then mixed under ultrasonic dispersion and a vacuum of 1.0 kPa. The impregnated powder was dried to remove the solvent and then placed in a high-temperature furnace for calcination. The calcination process was controlled as follows: heating rate 3 °C / min, calcination temperature 500 °C, and holding time 4 h to obtain loaded zirconia.

[0067] (3) The supported zirconium oxide was mixed with silica sol with a solid content of 20wt%, and the mass ratio of the supported zirconium oxide to silica sol was controlled to be 1:8. The mixture was stirred at a constant temperature of 250r / min and 85℃ for 3h to form a silica sealing layer. After the reaction was completed, the mixture was dried at 110℃ for 1.5h to obtain the modified zirconium oxide.

[0068] (4) Weigh 0.9% Si, 0.15% Fe, 0.8% Cu, 1.1% Mg, 0.18% Cr, 0.15% Zn, 0.10% Ti, 1.8% Ni, 0.7% Co and 2.4% modified zirconium oxide by mass percentage, with the balance being Al; mix all metal powders except modified zirconium oxide and ball mill at 500 r / min and a ball-to-powder ratio of 8:1 for 15 h to obtain matrix alloy powder; add modified zirconium oxide to matrix alloy powder and ball mill at 100 r / min and a ball-to-powder ratio of 2:1 for 2 h to obtain composite powder; press the composite powder into a green blank under molding conditions, and then sinter it under vacuum at a sintering temperature of 600℃ and a holding time of 2 h. Perform solid solution and aging treatment (T6) on the sintered alloy to precipitate and strengthen the alloy elements, and obtain the high-strength aluminum alloy material suitable for humanoid robot skeletons.

[0069] Example 3

[0070] A method for preparing a high-strength aluminum alloy material suitable for humanoid robot skeletons includes the following steps:

[0071] (1) The silica template, anhydrous ethanol, acetonitrile and ammonia were mixed evenly in a mass ratio of 1:15:5:2. Under stirring, the alcohol solution of zirconium propoxide was slowly added dropwise to the above dispersion, and the mass ratio of zirconium source to silica was controlled at 0.5:1. After the addition was completed, the reaction was carried out for 6 hours. The product was collected and dried, and then put into a sodium hydroxide solution with a temperature of 80℃ and a concentration of 1.5mol / L. The reaction was carried out for 7 hours to completely remove the internal silica template. After washing and drying, hollow mesoporous zirconium oxide was obtained.

[0072] (2) Hollow mesoporous zirconia was immersed in a 0.1 mol / L cerium nitrate ethanol solution, and the mass-volume ratio of hollow mesoporous zirconia to the solution was controlled at 1 g: 10 mL. The mixture was then mixed under ultrasonic dispersion and a vacuum of 1.0 kPa. The impregnated powder was dried to remove the solvent and then placed in a high-temperature furnace for calcination. The calcination process was controlled as follows: heating rate 3 °C / min, calcination temperature 500 °C, and holding time 4 h to obtain loaded zirconia.

[0073] (3) The supported zirconium oxide was mixed with silica sol with a solid content of 20wt%, and the mass ratio of the supported zirconium oxide to silica sol was controlled to be 1:5. The mixture was stirred at a constant temperature of 250r / min and 80℃ for 4h to form a silica sealing layer. After the reaction was completed, the mixture was dried at 110℃ for 1.5h to obtain modified zirconium oxide.

[0074] (4) Weigh 0.6% Si, 0.05% Fe, 0.5% Cu, 0.8% Mg, 0.05% Cr, 0.05% Zn, 0.05% Ti, 1.2% Ni, 0.4% Co and 1.2% modified zirconium oxide by mass percentage, with the balance being Al; mix all metal powders except modified zirconium oxide and ball mill at 500 r / min and a ball-to-powder ratio of 8:1 for 15 h to obtain matrix alloy powder; add modified zirconium oxide to matrix alloy powder and ball mill at 100 r / min and a ball-to-powder ratio of 2:1 for 2 h to obtain composite powder; press the composite powder into a green blank under molding conditions, and then sinter it under vacuum at a sintering temperature of 600℃ and a holding time of 2 h. Perform solid solution and aging treatment (T6) on the sintered alloy to precipitate and strengthen the alloy elements, and obtain the high-strength aluminum alloy material suitable for humanoid robot skeletons.

[0075] Comparative Example 1

[0076] A method for preparing an aluminum alloy material includes the following steps:

[0077] (1) The silica template, anhydrous ethanol, acetonitrile, and ammonia were mixed evenly in a mass ratio of 1:25:10:5. Under stirring conditions, the alcohol solution of zirconium propoxide was slowly added dropwise to the above dispersion, and the mass ratio of zirconium source to silica was controlled at 2.0:1. After the addition was completed, the reaction was carried out for 8 hours. The product was collected and dried, and then put into a sodium hydroxide solution with a temperature of 80℃ and a concentration of 1.5mol / L. The reaction was carried out for 7 hours to completely remove the internal silica template. After washing and drying, hollow mesoporous zirconium oxide was obtained.

[0078] (2) Hollow mesoporous zirconia was immersed in a 0.5 mol / L cerium nitrate ethanol solution, and the mass-volume ratio of hollow mesoporous zirconia to the solution was controlled at 1 g: 10 mL. The mixture was then mixed under ultrasonic dispersion and a vacuum of 1.0 kPa. The impregnated powder was dried to remove the solvent and then placed in a high-temperature furnace for calcination. The calcination process was controlled as follows: heating rate 3℃ / min, calcination temperature 500℃, and holding time 4h to obtain loaded zirconia.

[0079] (3) Weigh out the following components by mass percentage: 1.2% Si, 0.2% Fe, 1.1% Cu, 1.4% Mg, 0.32% Cr, 0.25% Zn, 0.15% Ti, 2.4% Ni, 1.0% Co, and 1.2% Mg. The alloy consists of supported zirconium oxide, 2.4% nano-silica, and the balance being Al. All metal powders except for the supported zirconium oxide and nano-silica are mixed and ball-milled at 500 r / min and a ball-to-powder ratio of 8:1 for 15 h to obtain a matrix alloy powder. The supported zirconium oxide and nano-silica are added to the matrix alloy powder and ball-milled at 100 r / min and a ball-to-powder ratio of 2:1 for 2 h to obtain a composite powder. The composite powder is pressed into a green compact under molding conditions and then sintered under vacuum at a temperature of 600 °C for 2 h. The sintered alloy is then subjected to solution treatment and aging treatment (T6) to strengthen the alloy by precipitation of alloying elements, thus obtaining the aluminum alloy material.

[0080] Comparative Example 2

[0081] A method for preparing an aluminum alloy material includes the following steps:

[0082] (1) The silica template, anhydrous ethanol, acetonitrile, and ammonia were mixed evenly in a mass ratio of 1:25:10:5. Under stirring conditions, the alcohol solution of zirconium propoxide was slowly added dropwise to the above dispersion, and the mass ratio of zirconium source to silica was controlled at 2.0:1. After the addition was completed, the reaction was carried out for 8 hours. The product was collected and dried, and then put into a sodium hydroxide solution with a temperature of 80℃ and a concentration of 1.5mol / L. The reaction was carried out for 7 hours to completely remove the internal silica template. After washing and drying, hollow mesoporous zirconium oxide was obtained.

[0083] (2) Hollow mesoporous zirconia was mixed with silica sol with a solid content of 20wt%, and the mass ratio of the loaded zirconia to the silica sol was controlled to be 1:10. The mixture was stirred at a constant temperature of 250r / min and 90℃ for 2h to form a silica sealing layer. After the reaction was completed, the mixture was dried at 110℃ for 1.5h to obtain modified zirconia.

[0084] (3) Weigh out the following components by mass percentage: 1.2% Si, 0.2% Fe, 1.1% Cu, 1.4% Mg, 0.32% Cr, 0.25% Zn, 0.15% Ti, 2.4% Ni, 1.0% Co, and 3.05% Mg. Modified zirconium oxide, 0.55% nano-cerium oxide, and the balance being Al were used to prepare a matrix alloy powder. All metal powders except modified zirconium oxide and nano-cerium oxide were mixed and ball-milled at 500 r / min and a ball-to-material ratio of 8:1 for 15 h. Modified zirconium oxide and nano-cerium oxide were added to the matrix alloy powder and ball-milled at 100 r / min and a ball-to-material ratio of 2:1 for 2 h to prepare a composite powder. The composite powder was pressed into a green blank under molding conditions and then sintered under vacuum at a sintering temperature of 600℃ and a holding time of 2 h. The sintered alloy was subjected to solution treatment and aging treatment (T6) to strengthen the alloy by precipitation, thereby obtaining the aluminum alloy material.

[0085] Performance testing

[0086] The aluminum alloy materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests. According to the national standard GB / T 228.1-2021 "Metallic materials, tensile testing—Part 1: Test methods at room temperature," tests were conducted using an electronic universal testing machine at a tensile rate of 1 mm / min. Tensile strength, yield strength, and elongation after fracture were recorded. Five parallel samples were tested for each group, and the average value was taken. According to the national standard GB / T 4340.1-2024 "Metallic materials, Vickers hardness testing—Part 1: Test methods," Vickers hardness was measured using a Vickers hardness tester with a load of 5 kg and a holding time of 15 s. The average value of five points was taken (the sampling point distribution is shown in the figure). The density was measured using the Archimedes displacement method. Specific data are shown in Table 1.

[0087] Table 1 Test Results of Aluminum Alloy Material Properties

[0088]

[0089] As shown in Table 1, the modified zirconia-reinforced aluminum alloy materials prepared in this invention (Examples 1-3) all exhibit excellent mechanical properties. Among them, Example 1 shows a tensile strength as high as 345 MPa while maintaining a good elongation of 8.5%. This indicates that with the optimization of the alloying degree and the reasonable matching of the modified zirconia addition amount, the material achieves a good balance between strength and toughness. In particular, the low density (2.71 g / cm³), thanks to the introduction of hollow mesoporous zirconia, makes it very suitable for the manufacture of humanoid robot skeletons with extremely high lightweight requirements.

[0090] The tensile strength of Example 1 was 31.7% higher than that of Comparative Example 1 (345 MPa vs 262 MPa), and the elongation after fracture was more than twice that of Comparative Example 1 (8.5% vs 4.2%). In Comparative Example 1, although equal amounts of nano-silica and supported zirconium oxide were added, the silica was unevenly dispersed due to the simple physical mixing, failing to form a silica sealing layer on the zirconium oxide surface. During sintering, an effective core-shell-matrix gradient transition layer could not be formed, resulting in weak interfacial bonding between the ceramic phase and the aluminum matrix. Under stress, microcracks easily formed and propagated rapidly (manifested as a significant decrease in elongation).

[0091] In Example 1, the silica sealing layer tightly coats the zirconia surface, not only acting as a reactant to react in situ with the aluminum matrix to generate a strong and tough alumina interface layer, but also effectively repairing defects on the surface of the hollow spheres. In contrast, Comparative Example 1 lacks this protective layer, and the hollow zirconia is prone to stress concentration and breakage during ball milling and forming, thus losing its hollow, toughening, and weight-reducing effects (the increased density of Comparative Example 1 to 2.78 g / cm³ further confirms this).

[0092] Compared to Comparative Example 2, Example 1 showed a 21.5% increase in tensile strength and a significant improvement in Vickers hardness. Comparative Example 2 involved directly mixing in nano-cerium oxide. Due to the extremely large specific surface area of ​​nanoparticles, they readily agglomerate within the aluminum matrix, becoming defect sources in the microstructure and leading to premature material fracture. Example 1 used a vacuum impregnation method to "anchor" cerium oxide within the pores of hollow mesoporous zirconia. On one hand, the cerium oxide particles within the pores acted as "internal support," improving the hollow spheres' resistance to isostatic pressing pressure. On the other hand, during sintering and heat treatment, cerium slowly diffused from the pores to the matrix grain boundaries, resulting in more uniform grain refinement and grain boundary pinning, thereby significantly improving the material's strength and hardness.

[0093] Compared with existing technologies, the high-strength aluminum alloy material and its preparation method suitable for humanoid robot skeletons of the present invention have the following advantages:

[0094] 1. This invention constructs a multi-phase synergistically strengthened alloy system through precise composition design, which perfectly meets the stringent requirements of humanoid robot skeletons for lightweight materials, high modulus, and long cycle fatigue life. Specifically, (1) Matrix strengthening: By adjusting the ratio of Mg and Si and introducing an appropriate amount of Cu into the matrix, high-density Mg2Si and Q phases (Al5Cu2Mg8Si6) can be precipitated after aging treatment, significantly improving the yield strength of the matrix; (2) Rigidity enhancement: The uniquely introduced Ni and Co elements form dispersed high-modulus intermetallic compounds (such as Al3Ni and Al9Co2) with the aluminum matrix, effectively improving the elastic modulus of the alloy and ensuring that the skeleton does not undergo elastic deformation when the robot walks under load; (3) Strength and toughness balance: The Fe content is strictly controlled to be below 0.2%, avoiding the coarse needle-like Al3Fe phase from cutting the matrix, greatly improving the fracture toughness and fatigue resistance of the material; (4) Grain refinement: The addition of trace amounts of Ti and Cr inhibits grain growth during recrystallization, and with the pinning effect of modified zirconia, a fine and uniform grain structure is obtained, further improving the comprehensive mechanical properties.

[0095] 2. The present invention uses a three-step process of "template etching - vacuum impregnation - sol sealing" to prepare modified zirconia with internal support and external protection structure. This unique structure cleverly solves the industry problem of "difficult dispersion and poor bonding" of ceramic reinforcing phase in metal matrix, and introduces a variety of beneficial elements. (1) The silica hard shell formed by silica sol dehydration condensation provides physical protection for hollow spheres. Combined with the dispersion process of low-energy ball milling, the modified zirconia can maintain a high degree of spherical integrity during the preparation process. The retained hollow structure not only significantly reduces the material density, but also absorbs the impact energy by utilizing the micro-closed-pore structure of the sphere to undergo controlled local deformation when the robot falls or is impacted, thus acting as a "micro-airbag" buffer; (2) The cerium salt introduced into the pores is transformed into cerium oxide nanoparticles, which are attached to the inner wall of the zirconium oxide, thus playing a role in physical reinforcement and preventing the hollow sphere from becoming unstable and collapsing during isostatic pressing; it can also act as a rare earth source to slowly release into the matrix during sintering, refine the matrix grains, and improve heat resistance; (3) The outer silica sealing layer plays the role of a "sacrificial layer" during the high-temperature sintering stage. It reacts in situ with the aluminum matrix to form a strong chemical bond, which "welds" the ceramic sphere to the matrix like an anchor point, thus completely solving the problem of poor interface bonding; at the same time, the released active Si atoms compensate for the strengthening elements required by the matrix in situ, avoiding the silicon-poor softening zone caused by the interface reaction.

[0096] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0097] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0098] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0099] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-strength aluminum alloy material suitable for humanoid robot skeletons, characterized in that, The invention comprises an aluminum matrix and modified zirconium oxide dispersed in the aluminum matrix; the modified zirconium oxide comprises hollow mesoporous zirconium oxide, cerium oxide loaded in the pores of the hollow mesoporous zirconium oxide, and a silica sealing layer covering the outer surface of the hollow mesoporous zirconium oxide.

2. The high-strength aluminum alloy material suitable for humanoid robot skeletons according to claim 1, characterized in that, The aluminum matrix is ​​made from the following raw materials by weight percentage: 0.6-1.2% Si, 0.05-0.2% Fe, 0.5-1.1% Cu, 0.8-1.4% Mg, 0.05-0.32% Cr, 0.05-0.25% Zn, 0.05-0.15% Ti, 1.2-2.4% Ni, 0.4-1.0% Co, with the balance being Al.

3. The high-strength aluminum alloy material suitable for humanoid robot skeletons according to claim 1, characterized in that, The modified zirconium oxide has a mass percentage of 1.2% to 3.6%.

4. A method for preparing a high-strength aluminum alloy material suitable for humanoid robot skeletons as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Preparation of modified zirconia: Hollow mesoporous zirconia is obtained by etching a silica template; cerium salt is impregnated and calcined in the pores of the hollow mesoporous zirconia to form cerium-loaded zirconia; silica sol is coated on the surface of the loaded zirconia and dehydrated and condensed to form a silica sealing layer to obtain modified zirconia. Preparation of composite material: The aluminum matrix raw material powder is mixed with the modified zirconium oxide, shaped, sintered and heat-treated to obtain the high-strength aluminum alloy material.

5. The preparation method according to claim 4, characterized in that, The specific steps for preparing modified zirconia are as follows: a silica template, anhydrous ethanol, acetonitrile, and ammonia are mixed and dropped into a zirconium source solution to carry out a hydrolysis and condensation reaction, thereby coating a zirconia layer on the silica surface. The silica template is then removed with an alkaline etching solution to obtain hollow mesoporous zirconia. The hollow mesoporous zirconia is mixed with a cerium salt solution under vacuum conditions, and then dried and calcined at high temperature to thermally decompose the cerium salt into cerium oxide, which is then loaded into the pores to obtain supported zirconia. The supported zirconia is mixed with silica sol, stirred, and dried to dehydrate and condense the silica sol to form a silica sealing layer, thereby obtaining modified zirconia.

6. The preparation method according to claim 5, characterized in that, The zirconium source is selected from at least one of zirconium propoxide, zirconium butoxide, or zirconium oxychloride; the alkaline etching solution is a sodium hydroxide solution or a potassium hydroxide solution; the cerium salt is cerium nitrate, and its solution is a cerium nitrate ethanol solution; the solid content of the silica sol is 10-30 wt%.

7. The preparation method according to claim 4, characterized in that, The steps for preparing the composite material include: high-energy ball milling of aluminum matrix raw material powder (excluding modified zirconium oxide) to obtain matrix alloy powder; low-energy ball milling of the modified zirconium oxide into the matrix alloy powder to obtain composite powder; pressing the composite powder into a green compact; sintering the green compact under vacuum or a protective atmosphere to obtain a sintered alloy; and performing solution treatment and aging treatment on the sintered alloy.

8. The preparation method according to claim 7, characterized in that, The high-energy ball mill operates at a rotation speed of 300–600 r / min, a ball-to-material ratio of 5–10:1, and a milling time of 10–20 h; the low-energy ball mill operates at a rotation speed of 50–150 r / min, a ball-to-material ratio of 1–3:1, and a milling time of 1–3 h.

9. The preparation method according to claim 7, characterized in that, The sintering temperature is 560–620℃, and the holding time is 1–3 hours.

10. The preparation method according to claim 5, characterized in that, The heating rate of the high-temperature calcination is 2-5℃ / min, the calcination temperature is 400-600℃, and the holding time is 3-5h.

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