High-strength aluminum alloy for a metal mold and a manufacturing process thereof

Abstract

This invention relates to the field of aluminum alloy technology, and discloses a high-strength aluminum alloy for metal molds and its preparation process; including the following steps: Step 1: Cleaning and drying the aluminum alloy to obtain an aluminum alloy substrate; sequentially magnetron sputtering an AlTiN layer, a TiN layer, and a Ti layer onto the surface of the aluminum alloy substrate to obtain a pre-formed aluminum alloy substrate; Step 2: Placing the pre-formed aluminum alloy substrate in an electrolyte for anodic oxidation to form a porous titanium-based composite oxide layer, cleaning and drying, magnetron sputtering a TiB2 layer, and heat treatment to obtain a high-strength aluminum alloy. To form a TiB2 layer on the surface of the aluminum alloy to improve hardness; since the electrode potential difference between aluminum alloy and TiB2 is large, direct contact between the two will cause galvanic corrosion; therefore, in this solution, an AlTiN layer, a TiN layer, and a Ti layer are sequentially magnetron sputtered on the surface of the aluminum alloy; direct contact between the aluminum alloy substrate and the TiB2 layer is isolated, protecting the aluminum alloy substrate from damage.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, specifically a high-strength aluminum alloy for metal molds and its preparation process. Background Technology

[0002] As a core piece of equipment in modern manufacturing, the material properties of metal molds directly determine the mold's service life, molding accuracy, and production efficiency. They must simultaneously meet core requirements such as high strength and corrosion resistance.

[0003] Aluminum alloys are increasingly used in mold manufacturing due to their low density, excellent thermal conductivity, ease of processing, and controllable cost. However, conventional aluminum alloys have low strength and are prone to corrosion and other failures, limiting their application in medium- and high-load metal molds. Although existing high-strength aluminum alloy mold materials have been improved through alloying element doping, they still suffer from problems such as an imbalance between strength and toughness and low corrosion resistance.

[0004] In summary, the preparation of a high-strength aluminum alloy for metal molds is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a high-strength aluminum alloy for metal molds and its preparation process, so as to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A manufacturing process for a high-strength aluminum alloy for metal molds includes the following steps: Step 1: Clean and dry the aluminum alloy to obtain an aluminum alloy substrate; sequentially magnetron sputter AlTiN layer, TiN layer and Ti layer onto the surface of the aluminum alloy substrate to obtain a pre-fabricated aluminum alloy substrate; Step 2: Place the pre-made aluminum alloy substrate in an electrolyte for anodic oxidation to form a porous titanium-based composite oxide layer. Clean and dry the substrate, magnetron sputter the TiB2 layer, and heat treat it to obtain a high-strength aluminum alloy.

[0007] In a more optimized configuration, the thickness of the AlTiN layer is 0.5~1μm; the thickness of the TiN layer is 1.5~2μm; the thickness of the Ti layer is 2~3μm; the thickness of the porous titanium-based composite oxide layer is 1~2μm; and the thickness of the TiB2 layer is 1~1.5μm.

[0008] In the proposed scheme, the porosity of the porous titanium-based composite oxide layer is 18%~28%, and the pore size is 30~50nm.

[0009] In the proposed solution, the aluminum alloy is sequentially cleaned with acetone, then deionized water, and finally dried.

[0010] In a more optimized form, the electrolyte comprises the following components: 4~10 g / L HF, 8~12 g / L Na2SO4, 2~5 g / L modified nano-alumina, and 0.2~0.6 g / L polyvinylpyrrolidone.

[0011] A more optimized method for preparing the modified nano-alumina is as follows: (1) LaCl3, KBH4 and nano-alumina are ground and mixed, vacuum sintered, cooled to room temperature, and then added to dilute hydrochloric acid and deionized water for ultrasonic cleaning to form lanthanum hexaboride and obtain hydroxyl composite nano-alumina; (2) hydroxyl composite nano-alumina is ultrasonically dispersed in tetrahydrofuran, mixed with perfluorodecylphosphonic acid, heated to 40~60℃ and stirred for 4~6 hours, filtered, washed and dried to obtain modified nano-alumina.

[0012] In a more optimized configuration, the mass ratio of LaCl3, KBH4, and nano-alumina is 1:(1.3~1.5):(3.8~6); the mass ratio of the hydroxyl-based composite nano-alumina to perfluorodecylphosphonic acid is 10:(3~5); the nano-alumina includes one or both of α-alumina and γ-alumina; and the particle size of the nano-alumina is 30~60 nm.

[0013] In the procedure, lanthanum trichloride heptahydrate is dried at 175°C to remove the lanthanum trichloride, yielding LaCl3; potassium borohydride is weighed and then dried at 180°C for 1 hour to prevent the presence of water.

[0014] The optimized vacuum sintering process conditions are as follows: under a nitrogen atmosphere, the temperature is increased to 200-250°C at a rate of 1-2°C / min for 1-2 hours, and then increased to 900-920°C for 2-3 hours; the loading of lanthanum hexaboride in the hydroxyl composite nano alumina is 10-15 wt%.

[0015] The optimized process conditions for magnetron sputtering AlTiN layers are as follows: using titanium-aluminum alloy as the target material, nitrogen gas flow rate of 40~100 sccm, and current of 60~80 A; the process conditions for magnetron sputtering TiN layers include: nitrogen gas flow rate of 40~100 sccm, titanium as the target material, and current of 70~80 A. The process conditions for magnetron sputtering the Ti layer are: argon gas flow rate of 40~60 sccm, titanium as target material, and current of 60~70 A; the process conditions for magnetron sputtering the TiB2 layer are: TiB2 powder as target material, argon gas flow rate of 40~60 sccm, and current of 50~65 A.

[0016] The optimized anodizing process conditions are: voltage of 10~25V and time of 0.5~1.5 hours.

[0017] Compared with the prior art, the beneficial effects of the present invention are: In this solution, a TiB2 layer is formed on the surface of the aluminum alloy to improve hardness. However, due to the significant difference in electrode potential between the aluminum alloy and TiB2, direct contact between the two would lead to galvanic corrosion, which would damage the aluminum alloy substrate and affect the mold performance. Therefore, in this solution, a Ti layer, a TiN layer, and an AlTiN layer are sequentially magnetron sputtered onto the surface of the aluminum alloy. This isolates the aluminum alloy substrate from direct contact with the TiB2 layer, fundamentally preventing galvanic corrosion and protecting the aluminum alloy substrate from damage.

[0018] However, magnetron sputtering multilayers increases the density of the AlTiN layer, which reduces the adhesion of the redeposited TiB2 layer, making the TiB2 layer prone to detachment and affecting hardness.

[0019] To address this issue, the proposed solution involves sequentially magnetron sputtering AlTiN, TiN, and Ti layers onto the aluminum alloy surface; a porous titanium-based composite oxide layer is then formed on the Ti layer using HF. However, the pore size of the porous titanium-based composite oxide layer is too large, resulting in most of the pores remaining unfilled even after TiB2 deposition, thus affecting performance. To address this issue, the proposed solution involves adding modified nano-alumina to the electrolyte. Since nano-alumina is non-conductive and cannot fill the porous titanium-based composite oxide layer under an electric field, lanthanum hexaboride is coated onto its surface to obtain hydroxyl-based composite nano-alumina. This protects the nano-alumina from HF corrosion. However, lanthanum hexaboride contains other impurities during preparation, which are dissolved by dilute hydrochloric acid (2M) and deionized water, allowing conductive lanthanum hexaboride to be loaded in situ onto the alumina surface. Perfluorodecylphosphonic acid strongly chelates with the hydroxyl groups on the surface of the hydroxyl-based composite nano-alumina through PO bonds, forming a hydrophobic fluorocarbon protective layer that inhibits HF etching of the alumina and ensures the integrity of the particles in the electrolyte. However, the time spent in the HF electrolyte should not be too long, otherwise it will still corrode γ-alumina.

[0020] After adding modified nano-alumina to the electrolyte, HF erodes the Ti layer to form a porous titanium-based composite oxide layer; the modified nano-alumina fills the pores to prevent the pore size from being too large; and lanthanum hexaboride has a similar crystal structure to TiB2, thus reducing interfacial stress and improving the performance of the aluminum alloy. Detailed Implementation

[0021] 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. Example

[0022] Materials preparation: The preparation method of modified nano-alumina is as follows: (1) Weigh LaCl3, KBH4 and nano-α-alumina (particle size of 60nm) in a mass ratio of 1:1.4:4.2; grind and mix LaCl3, KBH4 and nano-α-alumina, vacuum sinter, cool to room temperature, add dilute hydrochloric acid (2M dilute hydrochloric acid) and deionized water in sequence for ultrasonic cleaning to form lanthanum hexaboride and obtain hydroxyl composite nano-alumina; (2) Weigh hydroxyl composite nano-alumina and perfluorodecylphosphonic acid ((1H,1H,2H,2H-heptafluorodecyl)phosphonic acid, CAS number 80220-63-9) in a mass ratio of 10:4; ultrasonically disperse hydroxyl composite nano-alumina in tetrahydrofuran, add perfluorodecylphosphonic acid and mix, heat to 50℃ and stir for 6 hours, filter, wash and dry to obtain modified nano-alumina; The vacuum sintering process conditions were as follows: under a nitrogen atmosphere, the temperature was increased to 250℃ for 2 hours at a rate of 2℃ / min, and then increased to 920℃ for 2 hours; the loading of lanthanum hexaboride in the hydroxyl composite nano-alumina was 12wt%. Step 1: Clean and dry the aluminum alloy to obtain an aluminum alloy substrate; sequentially magnetron sputter the surface of the aluminum alloy substrate to form an AlTiN layer with a thickness of 0.82 μm, a TiN layer with a thickness of 1.73 μm, and a Ti layer with a thickness of 2.2 μm to obtain a pre-fabricated aluminum alloy substrate; The process conditions for magnetron sputtering the AlTiN layer are as follows: using titanium-aluminum alloy as the target material, nitrogen flow rate is 90 sccm, and current is 80 A; the process conditions for magnetron sputtering the TiN layer include: nitrogen flow rate is 100 sccm, using titanium as the target material, and current is 80 A; the process conditions for magnetron sputtering the Ti layer are: argon flow rate is 60 sccm, using titanium as the target material, and current is 70 A. Step 2: The pre-made aluminum alloy substrate is placed in an electrolyte for anodizing (voltage is 25V, time is 0.75 hours) to form a porous titanium-based composite oxide layer with a thickness of 1.54μm. After cleaning and drying, a TiB2 layer with a thickness of 1.23μm is sputtered by magnetron sputtering and heat-treated at 160℃ for 2 hours to obtain a high-strength aluminum alloy. The electrolyte raw materials include the following components: 10 g / L HF, 8 g / L Na2SO4, 4 g / L modified nano alumina, and 0.4 g / L polyvinylpyrrolidone. The process conditions for magnetron sputtering TiB2 layers are as follows: TiB2 powder is used as the target material, argon gas flow rate is 60 sccm, and current is 65 A.

[0023] Example 2 is based on Example 1, except that nano-α-alumina is replaced with γ-alumina; the remaining operation steps are the same. Materials preparation: The preparation method of modified nano alumina is as follows: (1) LaCl3, KBH4 and nano γ-alumina (particle size of 60nm) are weighed in a mass ratio of 1:1.4:4.2; LaCl3, KBH4 and nano γ-alumina are ground and mixed, vacuum sintered, cooled to room temperature, and then added to dilute hydrochloric acid and deionized water for ultrasonic cleaning to form lanthanum hexaboride and obtain hydroxyl composite nano alumina; (2) Hydroxyl composite nano alumina and perfluorodecylphosphonic acid ((1H,1H,2H,2H-heptafluorodecyl)phosphonic acid, CAS number 80220-63-9) are weighed in a mass ratio of 10:4; hydroxyl composite nano alumina is ultrasonically dispersed in tetrahydrofuran, perfluorodecylphosphonic acid is added and mixed, heated to 50℃ and stirred for 6 hours, filtered, washed and dried to obtain modified nano alumina; The vacuum sintering process conditions were as follows: under a nitrogen atmosphere, the temperature was increased to 250℃ for 2 hours at a rate of 2℃ / min, and then increased to 920℃ for 2 hours; the loading of lanthanum hexaboride in the hydroxyl composite nano-alumina was 12wt%. Step 1: Clean and dry the aluminum alloy to obtain an aluminum alloy substrate; sequentially magnetron sputter the surface of the aluminum alloy substrate to form an AlTiN layer with a thickness of 0.82 μm, a TiN layer with a thickness of 1.73 μm, and a Ti layer with a thickness of 2.2 μm to obtain a pre-fabricated aluminum alloy substrate; The process conditions for magnetron sputtering the AlTiN layer are as follows: using titanium-aluminum alloy as the target material, nitrogen flow rate is 90 sccm, and current is 80 A; the process conditions for magnetron sputtering the TiN layer include: nitrogen flow rate is 100 sccm, using titanium as the target material, and current is 80 A; the process conditions for magnetron sputtering the Ti layer are: argon flow rate is 60 sccm, using titanium as the target material, and current is 70 A. Step 2: The pre-made aluminum alloy substrate is placed in an electrolyte for anodizing (voltage is 25V, time is 0.75 hours) to form a porous titanium-based composite oxide layer with a thickness of 1.52μm. After cleaning and drying, a TiB2 layer with a thickness of 1.23μm is sputtered by magnetron sputtering and heat-treated at 160℃ for 2 hours to obtain a high-strength aluminum alloy. The electrolyte raw materials include the following components: 10 g / L HF, 8 g / L Na2SO4, 4 g / L modified nano alumina, and 0.4 g / L polyvinylpyrrolidone. The process conditions for magnetron sputtering TiB2 layers are as follows: TiB2 powder is used as the target material, argon gas flow rate is 60 sccm, and current is 65 A.

[0024] Example 3 is based on Example 2, except that the amount of modified nano-alumina added is 2 g / L; the remaining operation steps are the same. Materials preparation: The preparation method of modified nano-alumina is as follows: (1) Weigh LaCl3, KBH4 and nano-alumina in a mass ratio of 1:1.4:4.2; grind and mix LaCl3, KBH4 and nano-α-alumina, vacuum sinter, cool to room temperature, add to dilute hydrochloric acid and deionized water in sequence and ultrasonically clean to form lanthanum hexaboride, and obtain hydroxyl composite nano-alumina; (2) Weigh hydroxyl composite nano-alumina and perfluorodecylphosphonic acid in a mass ratio of 10:4; ultrasonically disperse hydroxyl composite nano-alumina in tetrahydrofuran, add perfluorodecylphosphonic acid and mix, heat to 50℃ and stir for 6 hours, filter, wash and dry to obtain modified nano-alumina; The vacuum sintering process conditions were as follows: under a nitrogen atmosphere, the temperature was increased to 250℃ for 2 hours at a rate of 2℃ / min, and then increased to 920℃ for 2 hours; the loading of lanthanum hexaboride in the hydroxyl composite nano-alumina was 12wt%. Step 1: Clean and dry the aluminum alloy to obtain an aluminum alloy substrate; sequentially magnetron sputter the surface of the aluminum alloy substrate to form an AlTiN layer with a thickness of 0.82 μm, a TiN layer with a thickness of 1.73 μm, and a Ti layer with a thickness of 2.2 μm to obtain a pre-fabricated aluminum alloy substrate; The process conditions for magnetron sputtering the AlTiN layer are as follows: using titanium-aluminum alloy as the target material, nitrogen flow rate is 90 sccm, and current is 80 A; the process conditions for magnetron sputtering the TiN layer include: nitrogen flow rate is 100 sccm, using titanium as the target material, and current is 80 A; the process conditions for magnetron sputtering the Ti layer are: argon flow rate is 60 sccm, using titanium as the target material, and current is 70 A. Step 2: Place the pre-made aluminum alloy substrate in an electrolyte for anodizing (voltage 25V, time 0.75 hours) to form a porous titanium-based composite oxide layer with a thickness of 1.55μm. Clean and dry, magnetron sputter a TiB2 layer with a thickness of 1.23μm, and heat treat at 160℃ for 2 hours to obtain a high-strength aluminum alloy. The electrolyte raw materials include the following components: 10 g / L HF, 8 g / L Na2SO4, 3 g / L modified nano alumina, and 0.4 g / L polyvinylpyrrolidone. The process conditions for magnetron sputtering TiB2 layers are as follows: TiB2 powder is used as the target material, argon gas flow rate is 60 sccm, and current is 65 A.

[0025] Comparative Example 1 is based on Example 2, with the AlTiN layer as the outermost layer; the remaining operation steps are the same. Materials preparation: The preparation method of modified nano-alumina is as follows: (1) LaCl3, KBH4 and nano-γ-alumina are weighed in a mass ratio of 1:1.4:4.2; LaCl3, KBH4 and nano-γ-alumina are ground and mixed, vacuum sintered, cooled to room temperature, and then added to dilute hydrochloric acid and deionized water for ultrasonic cleaning to form lanthanum hexaboride and obtain hydroxyl composite nano-alumina; (2) Hydroxyl composite nano-alumina and perfluorodecylphosphonic acid are weighed in a mass ratio of 10:4; hydroxyl composite nano-alumina is ultrasonically dispersed in tetrahydrofuran, perfluorodecylphosphonic acid is added and mixed, heated to 50℃ and stirred for 6 hours, filtered, washed and dried to obtain modified nano-alumina; The vacuum sintering process conditions were as follows: under a nitrogen atmosphere, the temperature was increased to 250℃ for 2 hours at a rate of 2℃ / min, and then increased to 920℃ for 2 hours; the loading of lanthanum hexaboride in the hydroxyl composite nano-alumina was 12wt%. Step 1: Clean and dry the aluminum alloy to obtain an aluminum alloy substrate; sequentially magnetron sputter the surface of the aluminum alloy substrate to form a Ti layer with a thickness of 2.2 μm, a TiN layer with a thickness of 1.73 μm, and an AlTiN layer with a thickness of 0.82 μm to obtain a pre-fabricated aluminum alloy substrate; The process conditions for magnetron sputtering the AlTiN layer are as follows: using titanium-aluminum alloy as the target material, nitrogen flow rate is 90 sccm, and current is 80 A; the process conditions for magnetron sputtering the TiN layer include: nitrogen flow rate is 100 sccm, using titanium as the target material, and current is 80 A; the process conditions for magnetron sputtering the Ti layer are: argon flow rate is 60 sccm, using titanium as the target material, and current is 70 A. Step 2: The pre-made aluminum alloy substrate is placed in an electrolyte for anodizing (voltage is 25V, time is 0.75 hours) to form a porous titanium-based composite oxide layer with a thickness of 1.52μm. After cleaning and drying, a TiB2 layer with a thickness of 1.23μm is sputtered by magnetron sputtering and heat-treated at 160℃ for 2 hours to obtain a high-strength aluminum alloy. The electrolyte raw materials include the following components: 10 g / L HF, 8 g / L Na2SO4, 4 g / L modified nano alumina, and 0.4 g / L polyvinylpyrrolidone. The process conditions for magnetron sputtering TiB2 layers are as follows: TiB2 powder is used as the target material, argon gas flow rate is 60 sccm, and current is 65 A.

[0026] Comparative Example 2 is based on Example 2, but without the addition of modified nano-alumina to the electrolyte; the remaining operating steps are the same. Materials preparation: Step 1: Clean and dry the aluminum alloy to obtain an aluminum alloy substrate; sequentially magnetron sputter the surface of the aluminum alloy substrate to form an AlTiN layer with a thickness of 0.82 μm, a TiN layer with a thickness of 1.73 μm, and a Ti layer with a thickness of 2.2 μm to obtain a pre-fabricated aluminum alloy substrate; The process conditions for magnetron sputtering the AlTiN layer are as follows: using titanium-aluminum alloy as the target material, nitrogen flow rate is 90 sccm, and current is 80 A; the process conditions for magnetron sputtering the TiN layer include: nitrogen flow rate is 100 sccm, using titanium as the target material, and current is 80 A; the process conditions for magnetron sputtering the Ti layer are: argon flow rate is 60 sccm, using titanium as the target material, and current is 70 A. Step 2: The pre-made aluminum alloy substrate is placed in an electrolyte for anodizing (voltage is 25V, time is 0.75 hours) to form a porous titanium-based composite oxide layer with a thickness of 1.52μm. After cleaning and drying, a TiB2 layer with a thickness of 1.23μm is sputtered by magnetron sputtering and heat-treated at 160℃ for 2 hours to obtain a high-strength aluminum alloy. The electrolyte raw materials include the following components: 10 g / L HF, 8 g / L Na2SO4; the porous titanium-based composite oxide layer has a pore size of 232 nm. The process conditions for magnetron sputtering TiB2 layers are as follows: TiB2 powder is used as the target material, argon gas flow rate is 60 sccm, and current is 65 A.

[0027] Comparative Example 3 was based on Example 2, but without the introduction of perfluorodecylphosphonic acid; the remaining operating steps were the same. Materials preparation: The preparation method of hydroxyl composite nano-alumina is as follows: LaCl3, KBH4 and nano-γ-alumina are weighed in a mass ratio of 1:1.4:4.2; LaCl3, KBH4 and nano-γ-alumina are ground and mixed, vacuum sintered, cooled to room temperature, and then added to dilute hydrochloric acid and deionized water for ultrasonic cleaning to form lanthanum hexaboride, thus obtaining hydroxyl composite nano-alumina; The vacuum sintering process conditions were as follows: under a nitrogen atmosphere, the temperature was increased to 250℃ for 2 hours at a rate of 2℃ / min, and then increased to 920℃ for 2 hours; the loading of lanthanum hexaboride in the hydroxyl composite nano-alumina was 12wt%. Step 1: Clean and dry the aluminum alloy to obtain an aluminum alloy substrate; sequentially magnetron sputter the surface of the aluminum alloy substrate to form an AlTiN layer with a thickness of 0.82 μm, a TiN layer with a thickness of 1.73 μm, and a Ti layer with a thickness of 2.2 μm to obtain a pre-fabricated aluminum alloy substrate; The process conditions for magnetron sputtering the AlTiN layer are as follows: using titanium-aluminum alloy as the target material, nitrogen flow rate is 90 sccm, and current is 80 A; the process conditions for magnetron sputtering the TiN layer include: nitrogen flow rate is 100 sccm, using titanium as the target material, and current is 80 A; the process conditions for magnetron sputtering the Ti layer are: argon flow rate is 60 sccm, using titanium as the target material, and current is 70 A. Step 2: The pre-made aluminum alloy substrate is placed in an electrolyte for anodizing (voltage is 25V, time is 0.75 hours) to form a porous titanium-based composite oxide layer with a thickness of 1.52μm. After cleaning and drying, a TiB2 layer with a thickness of 1.23μm is sputtered by magnetron sputtering and heat-treated at 160℃ for 2 hours to obtain a high-strength aluminum alloy. The electrolyte raw materials include the following components: 10 g / L HF, 8 g / L Na2SO4, 4 g / L hydroxyl-containing composite nano-alumina, and 0.4 g / L polyvinylpyrrolidone. The process conditions for magnetron sputtering TiB2 layers are as follows: TiB2 powder is used as the target material, argon gas flow rate is 60 sccm, and current is 65 A.

[0028] Performance Test 1: Impact toughness test: Cut the high-strength aluminum alloy specimens prepared in Examples 1 to 3 into specimens of the same size (55mm×10mm×5mm), fix them on the impact testing machine, release the impact energy of the specimens at the highest point of the impact testing machine, calculate the impact strength, and take the average value of each specimen 5 times; the weight of the impact hammer is 10kg.

[0029] Table 1

[0030] Conclusion: The crystal form and amount of alumina added affect the impact toughness of high-strength aluminum alloys.

[0031] Performance Test 2: The corrosion resistance of the high-strength aluminum alloys prepared in Example 2 and Comparative Examples 1-3 was tested according to ASTM B117 NSS standard; conditions: 35°C, corrosive medium was 5±0.1wt% sodium chloride aqueous solution, 80cm... 2 Salt spray deposition rate of 1.5 mL per hour; observe the corrosion of high-strength aluminum alloy surface; Table 2

[0032] Conclusions: Comparative Example 1, based on Example 2, used the AlTiN layer as the outermost layer, which led to a decrease in the interfacial bonding of the TiB2 layer and a reduction in corrosion resistance. Comparative Example 2, based on Example 2, did not add modified nano-alumina to the electrolyte, resulting in larger pore sizes and thus affecting the performance of the aluminum alloy. Comparative Example 3, based on Example 2, did not introduce perfluorodecylphosphonic acid, which led to the corrosion of γ-alumina. The main component of the modified nano-alumina was lanthanum hexaboride, which resulted in a decrease in pore-blocking properties. However, lanthanum hexaboride has good corrosion resistance, so the impact was relatively small.

[0033] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A manufacturing process for a high-strength aluminum alloy for metal molds, characterized in that: The following steps are included: Step 1: Clean and dry the aluminum alloy to obtain an aluminum alloy substrate; sequentially magnetron sputter AlTiN layer, TiN layer and Ti layer onto the surface of the aluminum alloy substrate to obtain a pre-fabricated aluminum alloy substrate; Step 2: Place the pre-made aluminum alloy substrate in an electrolyte for anodic oxidation to form a porous titanium-based composite oxide layer. Clean and dry the substrate, magnetron sputter the TiB2 layer, and heat treat it to obtain a high-strength aluminum alloy.

2. The manufacturing process of a high-strength aluminum alloy for metal molds according to claim 1, characterized in that: The thickness of the AlTiN layer is 0.5~1μm; the thickness of the TiN layer is 1.5~2μm; the thickness of the Ti layer is 2~3μm; the thickness of the porous titanium-based composite oxide layer is 1~2μm; and the thickness of the TiB2 layer is 1~1.5μm.

3. The manufacturing process of a high-strength aluminum alloy for metal molds according to claim 1, characterized in that: The electrolyte comprises the following components: 4~10 g / L HF, 8~12 g / L Na2SO4, 2~5 g / L modified nano alumina, and 0.2~0.6 g / L polyvinylpyrrolidone.

4. The manufacturing process of a high-strength aluminum alloy for metal molds according to claim 3, characterized in that: The modified nano-alumina is prepared by: (1) grinding and mixing LaCl3, KBH4 and nano-α-alumina, vacuum sintering, cooling to room temperature, and then adding them to dilute hydrochloric acid and deionized water for ultrasonic cleaning to form lanthanum hexaboride and obtain hydroxyl composite nano-alumina; (2) ultrasonically dispersing the hydroxyl composite nano-alumina in tetrahydrofuran, adding perfluorodecylphosphonic acid and mixing, heating to 40~60℃ and stirring for 4~6 hours, filtering, washing and drying to obtain modified nano-alumina.

5. The manufacturing process of a high-strength aluminum alloy for metal molds according to claim 4, characterized in that: The mass ratio of LaCl3, KBH4, and nano-alumina is 1:(1.3~1.5):(3.8~5); the mass ratio of the hydroxyl-based composite nano-alumina to perfluorodecylphosphonic acid is 10:(3~5); the nano-alumina includes one or both of α-alumina and γ-alumina.

6. The manufacturing process of a high-strength aluminum alloy for metal molds according to claim 4, characterized in that: The vacuum sintering process conditions are as follows: under a nitrogen atmosphere, the temperature is increased to 200-250℃ at a rate of 1-2℃ / min and heated for 1-2 hours, and then increased to 900-920℃ and heated for 2-3 hours; the loading of lanthanum hexaboride in the hydroxyl composite nano alumina is 10-15wt%.

7. The manufacturing process of a high-strength aluminum alloy for metal molds according to claim 1, characterized in that: The process conditions for magnetron sputtering AlTiN layers are as follows: using titanium-aluminum alloy as the target material, nitrogen gas flow rate is 40~100 sccm, and current is 60~80 A; the process conditions for magnetron sputtering TiN layers include: nitrogen gas flow rate is 40~100 sccm, using titanium as the target material, and current is 70~80 A. The process conditions for magnetron sputtering the Ti layer are: argon gas flow rate of 40~60 sccm, titanium as target material, and current of 60~70 A; the process conditions for magnetron sputtering the TiB2 layer are: TiB2 powder as target material, argon gas flow rate of 40~60 sccm, and current of 50~65 A.

8. The manufacturing process of a high-strength aluminum alloy for metal molds according to claim 1, characterized in that: The anodizing process conditions are: voltage of 10~25V and time of 0.5~2 hours; the heat treatment process conditions are: temperature of 180~200℃ and time of 1~3 hours.

9. A high-strength aluminum alloy is prepared by a process according to any one of claims 1 to 8.

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