Aluminum alloy for raised floor and preparation method thereof

Abstract

The invention relates to the technical field of aluminum alloy materials, in particular to an aluminum alloy for a raised floor and a preparation method thereof.The aluminum alloy for the raised floor comprises, by weight, 8.5%-10.5% of Si, 0.8%-1.2% of Mg, 0.8%-1.5% of Cu, 0.4%-0.8% of Mn, 0.6%-0.9% of Fe, 0.1%-0.3% of Zr, 0.02%-0.05% of Ti, smaller than or equal to 0.2% of Zn and the balance Al and inevitable impurities, and the mass ratio of Mn to Fe is (0.8-1.2): 1. The method comprises the following steps: S1, smelting and refining; s2, vacuum die casting; s3, heat treatment; and S4, surface treatment. Through alloy component optimization and preparation process innovation, the product strength and corrosion resistance can be improved, no corrosion is generated in a salt spray test for more than or equal to 2000 hours, meanwhile, the gas content of a mold cavity can be reduced, and the die-casting porosity is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy materials, in particular to an aluminum alloy for elevated floors and a preparation method thereof. Background Art

[0002] Aluminum alloy materials in raised floor systems are widely used in data centers, clean rooms, laboratories and other places with high requirements for load-bearing capacity, anti-static properties or wiring flexibility due to their lightweight, high strength and corrosion resistance.

[0003] Ordinary aluminum alloys have the following problems: insufficient strength, unable to meet high load-bearing requirements, and increasing thickness to improve strength leads to excessive weight; poor corrosion resistance, with corrosion occurring after 500-800 hours in a salt spray test; and high die-cast porosity. In the Chinese Patent Literature Library, application number 202310134554.X discloses a high-hardness aluminum alloy and its production process. Although the strength is improved by adding rare earth elements, there are problems such as high cost and poor die-casting fluidity. Summary of the Invention

[0004] The object of the present invention is to provide an aluminum alloy for elevated floors and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solution: an aluminum alloy for raised floors, wherein the components of the aluminum alloy for raised floors include, by weight percentage: Si: 8.5-10.5%, Mg: 0.8-1.2%, Cu: 0.8-1.5%, Mn: 0.4-0.8%, Fe: 0.6-0.9%, Zr: 0.1-0.3%, Ti: 0.02-0.05%, Zn: ≤0.2%, and the rest are Al and unavoidable impurities, and the Mn / Fe mass ratio is 0.8-1.2:1.

[0006] Furthermore, the mass ratio of Zr to Ti is 4 to 6:1.

[0007] A method for preparing an aluminum alloy for an elevated floor comprises the following steps:

[0008] S1. Melting and refining;

[0009] S2. Vacuum die casting;

[0010] S3. Heat treatment;

[0011] S4. Surface treatment.

[0012] Furthermore, the S1 smelting and refining includes:

[0013] The raw materials were melted at 720-750°C, using electromagnetic stirring at a frequency of 15-20 Hz;

[0014] Argon with a purity of ≥99.99% is introduced for refining, with a gas flow rate of 1.5-2.5 L / (min·kg) of aluminum liquid and a refining time of 15-20 minutes;

[0015] Online monitoring was performed to control the hydrogen content to ≤0.12ml / 100g Al.

[0016] Furthermore, the S2 vacuum die-casting includes:

[0017] S21. Preheat the mold to 200±10℃. Use a mold temperature controller to control the temperature in different zones. The temperature difference between each zone should be ≤5℃. The mold temperature control accuracy should be ±3℃.

[0018] S22. Die casting is carried out under vacuum ≤ 50 mbar. The injection process consists of three stages:

[0019] Slow stage: injection speed 0.2~0.5m / s, stroke 100~150mm;

[0020] Rapid stage: injection speed 4~6m / s;

[0021] Pressurization stage: pressure 80~120MPa, holding time 5~8 seconds.

[0022] Furthermore, the S3 heat treatment includes:

[0023] S31. The die casting was placed in a controlled atmosphere heat treatment furnace and kept at 535±5°C for 2 hours;

[0024] S32. Quench in hot water at 80±5°C, with a quenching transfer time ≤ 15 seconds and a cooling rate ≥ 100°C / s;

[0025] For step aging treatment, first keep the temperature at 120±2℃ for 2 hours with a wind speed of 1-2m / s in the furnace, then raise the temperature to 185±3℃ at a rate of ≤2℃ / min and keep the temperature for 4 hours. After aging, air cool to room temperature with a cooling rate of ≤5℃ / min.

[0026] Furthermore, the oxygen content of the controlled atmosphere heat treatment furnace in S31 is ≤100 ppm; and 0.1% to 0.3% of polyvinyl alcohol is added to the quenching hot water in S32 as a cooling medium modifier.

[0027] Furthermore, the S4 surface treatment includes:

[0028] S41. Pre-treatment of the workpiece by sandblasting after aging, with a sand particle size of 80 to 120 mesh and an air pressure of 0.4 to 0.6 MPa;

[0029] S42. Micro-arc oxidation treatment: electrolyte temperature 20 ~ 30 ℃, pulse power supply, positive and negative current density ratio of 1:0.3 ~ 0.5, treatment time 25-35 minutes;

[0030] S43. After forming a 30-50 μm ceramic layer, dry it at 100-120° C. for 30-60 minutes.

[0031] Furthermore, after S4, S5 nano-sealing treatment is also included:

[0032] S51. The workpiece after micro-arc oxidation is immersed in a nano-SiO2 sol, SiO2 particle size 10 to 20 nm, concentration 5% to 8%;

[0033] S52. Immersing temperature 40-50°C, time 20-30 minutes;

[0034] S53. After taking out, cure at 150-180°C for 1-2 hours.

[0035] Furthermore, 0.5% to 1% of silane coupling agent KH-550 is added to the nano-SiO2 sol.

[0036] Compared with the existing technology, the beneficial effects of the present invention are: the aluminum alloy for elevated floors and its preparation method can improve product strength and corrosion resistance through alloy composition optimization and preparation process innovation, and there is no corrosion in the salt spray test for ≥2000 hours. At the same time, it can reduce the gas content in the mold cavity and reduce the die-casting porosity. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0038] Example 1. An aluminum alloy for a raised floor. The aluminum alloy comprises, by weight, 9.5% Si, 1.0% Mg, 1.2% Cu, 0.6% Mn, 0.7% Fe, 0.2% Zr, 0.04% Ti, and 0.15% Zn, with the remainder being Al and unavoidable impurities. The Mn / Fe ratio is 0.86:1, and the Zr / Ti ratio is 5:1.

[0039] Based on the same inventive concept, this embodiment also provides a method for preparing an aluminum alloy for an elevated floor, comprising the following steps:

[0040] S1. Melting and Refining: Melt the raw materials at 735°C with electromagnetic stirring at a frequency of 15-20 Hz. Refining is performed by introducing argon gas with a purity of ≥99.99% at a gas flow rate of 2.2 L / (min·kg) of molten aluminum for 15-20 minutes. Online monitoring is used to control the hydrogen content to 0.08 ml / 100 g Al.

[0041] S2. Vacuum die casting:

[0042] S21. Preheat the mold to 200±10℃. Use a mold temperature controller to control the temperature in different zones. The temperature difference between each zone should be ≤5℃. The mold temperature control accuracy should be ±3℃.

[0043] S22. Die casting is performed under a vacuum of 40 mbar. The injection process includes three stages: a slow stage with an injection speed of 0.2 to 0.5 m / s and a stroke of 100 to 150 mm; a fast stage with an injection speed of 4 to 6 m / s; and a pressurization stage with a pressure of 80 to 120 MPa and a holding time of 5 to 8 seconds.

[0044] S3. Heat treatment:

[0045] S31 The die casting is placed in a controlled atmosphere heat treatment furnace and kept at 535 ℃ for 2 hours. The oxygen content of the controlled atmosphere heat treatment furnace is ≤100ppm;

[0046] S32. Using 80 ° C hot water quenching, adding 0.1% to 0.3% polyvinyl alcohol as a cooling medium modifier to the quenching hot water, quenching transfer time ≤ 15 seconds, cooling rate ≥ 100 ° C / s;

[0047] S33. Step aging treatment: first, keep the temperature at 120℃ for 2 hours, with the wind speed in the furnace 1-2m / s, then raise the temperature to 185℃ at a rate of ≤2℃ / min and keep it at this temperature for 4 hours. After aging, air cool to room temperature at a cooling rate of ≤5℃ / min.

[0048] S4.Surface treatment:

[0049] S41. Pre-treatment of the workpiece by sandblasting after aging, with a sand particle size of 80 to 120 mesh and an air pressure of 0.4 to 0.6 MPa;

[0050] S42. Micro-arc oxidation treatment: electrolyte temperature 20-30°C, pulse power supply, positive-to-negative current density ratio of 1:0.3-0.5, treatment time 30 min;

[0051] S43. After forming a 40 μm ceramic layer, dry it at 100-120° C. for 30-60 minutes.

[0052] S5 nano-sealing treatment:

[0053] S51. The workpiece after micro-arc oxidation is immersed in a nano-SiO2 sol, SiO2 particle size 10 to 20 nm, concentration 7%, and 1% silane coupling agent KH-550 is added to the nano-SiO2 sol;

[0054] S52. Immersing temperature 40-50°C, time 20-30 minutes;

[0055] S53. After taking out, cure at 150-180°C for 1-2 hours.

[0056] Example 2: This example differs from Example 1 in that the aluminum alloy composition for the elevated floor comprises 0.75% Mn, 0.65% Fe, and Mn / Fe = 1.15:1.

[0057] Example 3: This example differs from Example 1 in that the aluminum alloy composition for the elevated floor includes Zr: 0.18%, Ti: 0.03%, and Zr / Ti = 6:1.

[0058] Example 4: This example differs from Example 1 in that the micro-arc oxidation time in S42 is extended to 35 min, and the concentration of nano-SiO2 in S51 is increased to 8%.

[0059] Example 5: The difference between this example and example 1 is that the vacuum degree in S22 is increased to 20mbar and the mold temperature control accuracy is ±2℃.

[0060] The product parameters measured in each embodiment 3 are shown in the table below:

[0061]

[0062] As described in the above embodiments and comparative examples, the present invention eliminates harmful Fe phases and forms nano-scale Al3 (Zr, Ti) strengthening phases through Mn / Fe ratio control and Zr / Ti microalloying, which can effectively improve the strength of the material. Through micro-arc oxidation treatment and nano-sealing treatment, the porosity of the ceramic layer is less than 5%, and SiO2 sol fills the micropores, which can improve the corrosion resistance of the product. Through vacuum die-casting and precise control of mold temperature, the gas content in the mold cavity can be reduced, and the die-casting porosity can be reduced.

[0063] The present invention is further described above with the aid of specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the essence and scope of the present invention. Various modifications made to the above embodiments by ordinary technicians in this field after reading this specification are all within the scope of protection of the present invention.

Claims

1. An aluminum alloy for raised floor, characterized in that: Measured by weight percentage, the aluminum alloy composition for the elevated floor includes: Si: 8.5-10.5%, Mg: 0.8-1.2%, Cu: 0.8-1.5%, Mn: 0.4-0.8%, Fe: 0.6-0.9%, Zr: 0.1-0.3%, Ti: 0.02-0.05%, Zn: ≤0.2%, and the rest are Al and unavoidable impurities, and the Mn / Fe mass ratio is 0.8-1.2:

1.

2. The aluminum alloy for raised floor according to claim 1, characterized in that: The mass ratio of Zr to Ti is 4 to 6:

1.

3. A method for preparing the aluminum alloy for elevated flooring according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Melting and refining; S2. Vacuum die casting; S3. Heat treatment; S4. Surface treatment.

4. The method for preparing an aluminum alloy for elevated floor according to claim 3, characterized in that: The S1 smelting and refining includes: The raw materials were melted at 720-750°C, using electromagnetic stirring at a frequency of 15-20 Hz; Argon with a purity of ≥99.99% is introduced for refining, with a gas flow rate of 1.5-2.5 L / (min·kg) of aluminum liquid and a refining time of 15-20 minutes; Online monitoring was performed to control the hydrogen content to ≤0.12ml / 100g Al.

5. The method for preparing aluminum alloy for elevated floor according to claim 3, characterized in that: The S2 vacuum die casting includes: S21. Preheat the mold to 200±10℃. Use a mold temperature controller to control the temperature in different zones. The temperature difference between each zone should be ≤5℃. The mold temperature control accuracy should be ±3℃. S22. Die casting is carried out under vacuum ≤ 50 mbar. The injection process consists of three stages: Slow stage: injection speed 0.2~0.5m / s, stroke 100~150mm; Rapid stage: injection speed 4~6m / s; Pressurization stage: pressure 80~120MPa, holding time 5~8 seconds.

6. The method for preparing an aluminum alloy for an elevated floor according to claim 3, wherein: The S3 heat treatment includes: S31. The die casting was placed in a controlled atmosphere heat treatment furnace and kept at 535±5°C for 2 hours; S32. Quench in hot water at 80±5°C, with a quenching transfer time ≤ 15 seconds and a cooling rate ≥ 100°C / s; For step aging treatment, first keep the temperature at 120±2℃ for 2 hours with a wind speed of 1-2m / s in the furnace, then raise the temperature to 185±3℃ at a rate of ≤2℃ / min and keep the temperature for 4 hours. After aging, air cool to room temperature with a cooling rate of ≤5℃ / min.

7. The method for preparing an aluminum alloy for an elevated floor according to claim 6, wherein: The oxygen content of the controlled atmosphere heat treatment furnace in S31 is ≤100 ppm; and 0.1% to 0.3% polyvinyl alcohol is added to the quenching hot water in S32 as a cooling medium modifier.

8. The method for preparing aluminum alloy for elevated floor according to claim 3, characterized in that: The S4 surface treatment includes: S41. Pre-treatment of the workpiece by sandblasting after aging, with a sand particle size of 80 to 120 mesh and an air pressure of 0.4 to 0.6 MPa; S42. Micro-arc oxidation treatment: electrolyte temperature 20 ~ 30 ℃, pulse power supply, positive and negative current density ratio of 1:0.3 ~ 0.5, treatment time 25-35 minutes; S43. After forming a 30-50 μm ceramic layer, dry it at 100-120° C. for 30-60 minutes.

9. The method for preparing an aluminum alloy for an elevated floor according to claim 3, wherein: After S4, S5 nano-sealing treatment is also included: S51. The workpiece after micro-arc oxidation is immersed in a nano-SiO2 sol, SiO2 particle size 10 to 20 nm, concentration 5% to 8%; S52. Immersing temperature 40-50°C, time 20-30 minutes; S53. After taking out, cure at 150-180°C for 1-2 hours.

10. The method for preparing aluminum alloy for elevated floor according to claim 9, characterized in that: 0.5% to 1% of silane coupling agent KH-550 is added to the nano-SiO2 sol.

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