Production process of passivated aluminum alloy shielding tape

Abstract

The invention discloses a passivated aluminum alloy shielding tape production process, and belongs to the technical field of shielding tape production. The technical problems that a traditional production process is poor in shielding effect, and chromium-containing waste liquid is not environmentally friendly are solved. According to the technical scheme, the method is characterized by comprising the steps that firstly, an aluminum strip is immersed in NaOH electrolyte, and pulse high voltage is applied to conduct plasma electrolytic etching for plasma electrolytic etching pretreatment; 2, immersing the aluminum strip into a GO quantum dot solution, and applying an alternating electric field to carry out electrophoretic deposition for graphene oxide quantum dot deposition; 3, TiO-SiO mixed sol is sprayed, directional drying is carried out in a pulsed electric field, and the TiO-SiO mixed sol is used for electric field assisted sol self-assembly; 4, the sample obtained in the step 3 is placed in a microwave plasma reactor, N / O mixed gas is contained in the microwave plasma reactor to form a reaction environment, the microwave plasma reactor is used for microwave plasma in-situ ceramization, and the product has a high electromagnetic shielding effect.

Description

Technical Field

[0001] The invention relates to the technical field of metal shielding belt production, in particular to a production process of a passivated aluminum alloy shielding belt. Background Art

[0002] At present, a Chinese patent with the publication (announcement) number: CN113122833B discloses a method for passivation of aluminum alloys. The method includes the following processing steps: (1) heat treatment, mechanical polishing, degreasing, and activation of the aluminum alloy in sequence; (2) passivation solution treatment: the passivation solution is composed of fluorotitanic acid, fluorozirconic acid, manganese sulfate, tartaric acid, sodium fluoride, and sodium alkylbenzene sulfonate, and the treatment method is immersion; (3) ultrasonic cleaning; (4) ultra-high temperature water vapor treatment; the water vapor is composed of 3-5wt.% ethyl orthosilicate and distilled water, the ultra-high water vapor temperature is 110-120oC, and the injection method is pulse injection; the method can effectively improve the dense plating of the passivation film, and the thickness of the obtained passivation film is uniform, which is a yellow passivation film of 4-5μm, and the passivation film has strong corrosion resistance.

[0003] The above aluminum alloy passivation method is not applicable to the production of shielding tape. Shielding tape can be used in many fields, such as electronic products, aerospace, medical equipment, etc. According to its main function, it is electromagnetic shielding (metal shielding tape is used to prevent electromagnetic interference and improve equipment performance and stability in the fields of electronic products, aerospace and medical equipment. In the cable, the metal shielding tape limits the electric field within the insulation layer, prevents external electromagnetic interference from entering the cable, and prevents internal signal leakage), or anti-interference (the metal shielding layer protects the internal cable core from external force damage and provides grounding protection. It is used in instrumentation and analog signal circuits to shield external interference.)

[0004] Traditional aluminum alloy shielding tapes are mainly made of 1000 series or 8000 series aluminum alloys, prepared by hot rolling, cold rolling finishing, annealing, and surface treatment, and the surface treatment process is generally anodizing. However, the effect of this shielding tape on electromagnetic shielding is still poor. With the continuous advancement of nanotechnology, the requirements for electromagnetic shielding are getting higher and higher. The traditional production method can no longer meet the market demand for high precision and high shielding capabilities, and the traditional process needs to be improved. Summary of the invention

[0005] In order to solve the above technical problems and shortcomings: how to improve the electromagnetic shielding effect of metal shielding tapes, the present invention provides a production process for passivated aluminum alloy shielding tapes.

[0006] In order to achieve the above-mentioned purpose and other related purposes, the present invention adopts the following technical solutions:

[0007] A production process for a passivated aluminum alloy shielding tape, comprising:

[0008] Step 1: Immerse the aluminum strip in a NaOH electrolyte and apply a pulsed high voltage for plasma electrolytic etching for plasma electrolytic etching pretreatment;

[0009] Step 2: Immerse the aluminum strip in the GO quantum dot solution and apply an alternating electric field for electrophoretic deposition for graphene oxide quantum dot deposition;

[0010] Step 3: spraying TiO2-SiO2 mixed sol and performing directional drying under a pulsed electric field for electric field-assisted sol self-assembly;

[0011] Step 4: Place the sample obtained in step 3 in a microwave plasma reactor, which contains a N2 / O2 mixed gas to form a reaction environment, and the mixing ratio of the mixed gas is 8:2. The set power of the microwave plasma reactor is 800W for 15 minutes for microwave plasma in-situ ceramicization.

[0012] Preferably, in step 1, the applied pulse high voltage is set to 800V and 100μs pulse width.

[0013] Preferably, in step 2, the GO quantum dot solution is set to 0.1 mg / mL, pH=9; and the alternating electric field requirement is 10 V / cm.

[0014] Preferably, in step three, the solid content of the TiO2-SiO2 mixed sol is 20wt%, and the pulse electric field is set to 1 kV / cm.

[0015] Preferably, the method further comprises step five, defect treatment, treating with triethoxysilane vapor at 120° C. for 30 minutes, followed by vacuum annealing at 200° C.

[0016] Preferably, in step one: the NaOH electrolyte is 10wt%, 0.5mol / L tetramethylammonium chloride is used as an additive, the aluminum strip is made of aluminum alloy strip, the type is aluminum alloy 5052 or aluminum alloy 6061, the thickness is 0.1-0.3mm, the graphite cathode adopts a diameter of 50mm, the aluminum strip is ultrasonically cleaned with acetone for 15min and then dried, and loaded into the electrolytic cell as an anode with an inter-electrode spacing of 10mm, the pulse power supply equipment is started, the processing time is 30s, and the process is stopped when uniform micro-pits appear on the surface, and the strip is rinsed with deionized water and blown dry with nitrogen.

[0017] Preferably, in step 2, the aluminum strip is immersed in a 0.1 mg / mL GO dispersion, the pH is adjusted to 9.0, 10 mmol / L Tris-HCl is used as a buffer, an electric field strength of 10 V / cm is applied, the current density is controlled to be <0.5 mA / cm², the deposition time is 2 min, and after being taken out, it is rinsed with deionized water 3 times and dried at 80°C for 10 min.

[0018] Preferably, in step three, the sol is ultrasonically dispersed for 30 minutes and then loaded into a spray gun. The mixed sol is: TiO2 (P25, 30nm) + SiO2 (Ludox HS-40, 5nm), with a solid content of 20wt%, and the dispersion medium is anhydrous ethanol. A wet film is sprayed on the surface of the aluminum strip with a thickness of 10-15μm. A pulsed electric field is immediately applied, maintained for 10 minutes, and vacuum dried at 60°C for 2h.

[0019] Preferably, in step 4, the sample is placed in a quartz boat, the mixed gas is introduced for 10 minutes, the microwave source is started, the reflected power is kept <5W, the processing temperature is maintained at 280±10°C by infrared monitoring, and the sample is naturally cooled after the processing time of 15 minutes.

[0020] Preferably, in step five, the sample is placed in a vacuum box, TES vapor is introduced at a pressure of 50 Pa, and the temperature is maintained at 120° C. for 30 min, then vacuumed, transferred to an annealing furnace, annealed at 200° C. for 2 h, and cooled to room temperature in a N2 atmosphere.

[0021] In summary, the invention has at least one of the following beneficial technical effects:

[0022] This process breaks through the traditional chemical passivation or anodization ideas, and is based on the dual mechanisms of directional self-assembly of colloidal particles induced by local electric fields and in-situ ceramicization reactions. It uses pulsed electric fields to generate periodic electrostrictive vibrations on the surface of aluminum alloys, driving charged nanoceramic precursors (such as TiO2 / SiO2 sol particles) to be oriented in micron-sized grooves. Pre-deposited graphene oxide (GO) nanosheets are used as two-dimensional templates to guide the amorphous precursors to transform into crystalline ceramic phases under the action of electric fields, forming a nanocomposite passivation layer. The nanograin boundaries in the ceramic layer of the product produced by this process produce a synergistic effect with the graphene surface plasma resonance, converting electromagnetic wave energy into heat dissipation to achieve broadband shielding. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0024] The following is an explanation of the embodiments of the present invention by specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0025] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention. The illustrations only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0026] The specific implementation manner of the present invention will be further described below in conjunction with the accompanying drawings.

[0027] Example:

[0028] The invention discloses a production process of a passivated aluminum alloy shielding tape.

[0029] Specifically,

[0030] Step 1: Implementation of plasma electrolytic etching pretreatment.

[0031] Ingredients:

[0032] Electrolyte: NaOH (10wt%) + 0.5mol / L tetramethylammonium chloride (additive);

[0033] Substrate: aluminum alloy strip (5052 or 6061, thickness 0.1-0.3mm);

[0034] Electrode: graphite cathode (diameter 50mm);

[0035] equipment:

[0036] Pulse power supply (output parameters: 800V peak voltage, 100μs pulse width, 1kHz frequency);

[0037] Electrolytic cell (with circulating cooling system, temperature controlled at 25±2℃);

[0038] Ultrasonic cleaning machine (pretreatment degreasing);

[0039] How to do it:

[0040] Step 11, the aluminum strip is ultrasonically cleaned with acetone for 15 minutes and then dried;

[0041] Step 12, loading into the electrolytic cell as an anode, with an inter-electrode distance of 10 mm;

[0042] Step 13, start the pulse power supply, and process for 30 seconds (stop when uniform micro-pits appear on the surface);

[0043] Step 14, rinsing with deionized water and drying with nitrogen;

[0044] The finished effect is as follows:

[0045] 1. Crater-like micro-pits (diameter 5-20 μm, depth 2-5 μm) are formed on the sample surface;

[0046] 2. Roughness Ra = 1.5 ± 0.3 μm;

[0047] 3. Contact angle <5°, surface energy >70mJ / m²;

[0048] Step 2: Implementation of graphene oxide quantum dots deposition.

[0049] Ingredients:

[0050] GO quantum dot dispersion: 0.1 mg / mL (pH adjusted to 9.0);

[0051] Buffer: Tris-HCl (10mmol / L);

[0052] equipment:

[0053] Electrophoretic deposition apparatus (parallel plate electrodes, 2 cm spacing);

[0054] DC power supply (0-30V adjustable, with current monitoring);

[0055] Constant temperature magnetic stirrer;

[0056] How to do it:

[0057] Step 21, immersing the aluminum strip in the GO dispersion and applying an electric field strength of 10 V / cm;

[0058] Step 22, controlling the current density to <0.5 mA / cm² and the deposition time to 2 min;

[0059] Step 23, after taking out, rinse with deionized water 3 times;

[0060] Step 24: Dry at 80°C for 10 min.

[0061] The finished effect is as follows:

[0062] 1. The surface is covered with a continuous GO quantum dot layer (thickness 5-8nm);

[0063] 2. Surface resistance 80±10Ω / sq;

[0064] 3. Raman spectrum shows that the D / G peak intensity ratio is <0.8 (low defect density).

[0065] Step 3: Electric field-assisted sol-gel self-assembly is achieved as follows.

[0066] Ingredients:

[0067] Mixed sol: TiO2 (P25, 30nm) + SiO2 (Ludox HS-40, 5nm);

[0068] Solid content 20wt%, dispersion medium is anhydrous ethanol;

[0069] equipment:

[0070] Electrostatic spray gun (with high voltage module, 0-30kV adjustable);

[0071] Pulsed electric field generator (1 kV / cm field strength, 50% duty cycle);

[0072] Vacuum drying oven.

[0073] How to do it:

[0074] Step 31, after ultrasonic dispersion of the sol for 30 minutes, the sol is loaded into a spray gun;

[0075] Step 32, spraying a wet film (thickness 10-15 μm) on the surface of the aluminum strip;

[0076] Step 33, immediately apply a pulse electric field and maintain for 10 minutes;

[0077] Step 34: vacuum drying at 60°C for 2h.

[0078] The finished effect is as follows:

[0079] 1. Form a bimodal pore structure (2-5nm micropores account for 60%, 20-50nm mesopores account for 40%);

[0080] 2. Specific surface area 180±20m² / g;

[0081] 3. XRD shows that amorphous SiO2 encapsulates TiO2 nanocrystal cores;

[0082] Step 4: Implementation of microwave plasma in-situ ceramicization.

[0083] Ingredients:

[0084] Process gas: N2 / O2 mixed gas (8:2 volume ratio);

[0085] Gas flow rate: 200sccm.

[0086] equipment:

[0087] Microwave plasma CVD system (2.45GHz, 800W);

[0088] Quartz tube reactor (diameter 50 mm);

[0089] Infrared thermometer.

[0090] How to do it:

[0091] Step 41, placing the sample in a quartz boat (quartz tube reactor) and introducing the mixed gas for 10 minutes;

[0092] Step 42, start the microwave source and keep the reflected power <5W;

[0093] Step 43, the processing temperature is maintained at 280±10°C through infrared monitoring;

[0094] Step 44: Cool naturally after processing for 15 minutes.

[0095] The finished effect is as follows:

[0096] 1. TiO2 anatase phase crystallization (grain size 3-5nm);

[0097] 2. Nano hardness 800±50HV.

[0098] 3. XPS shows that the Si-O-Al bonding ratio reaches 23%.

[0099] Step 5: Implementation of defect handling.

[0100] Ingredients:

[0101] Triethoxysilane (TES) vapor;

[0102] Catalyst: dibutyltin dilaurate (0.5wt%);

[0103] equipment:

[0104] Vacuum steam treatment box (with TES evaporation source);

[0105] Tubular annealing furnace (N2 protection, temperature control accuracy ±2℃).

[0106] How to do it:

[0107] Step 51, placing the sample in a vacuum box, and introducing TES steam (pressure 50Pa);

[0108] Step 52, maintain at 120°C for 30 min and then evacuate;

[0109] Step 53, transfer to an annealing furnace, anneal at 200°C for 2h;

[0110] Step 54: Cool the N2 atmosphere to room temperature.

[0111] Finished effect:

[0112] 1. Salt spray test (ASTM B117) 2000h without red rust;

[0113] 2. Shielding effectiveness (SE) reaches 85±3dB in the range of 1-18GHz;

[0114] 3. TGA shows that the mass loss before 300°C is <1%.

[0115] Quantitative comparison of process advantages:

[0116] index Traditional anodizing This process Processing temperature 60-80℃ 25-200℃ Coating thickness 8-15μm 3-5μm Shielding effectiveness 60dB@1GHz 85dB@1GHz Bending durability Cracks after 50 times No cracks after 200 times Environmental protection Chromium-containing wastewater Chromium-free wastewater

[0117] This process uses electric field to precisely control the formation of nanostructures and realize atomic-level interface engineering of materials. It is particularly suitable for flexible electronic shielding and extreme environment applications. It can be used for shielding tape of 5G base station filter housing. This process reduces the product thickness from 0.3mm to 0.15mm and reduces the weight by 40%. In the 30GHz frequency band, the reflection loss is <-20dB, and the corrosion resistance life is many times longer than that of traditional anodizing process. This process realizes the integrated design of the structure and function of the passivation layer through the synergistic effect of electric field regulation and self-assembly of nanomaterials.

[0118] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, any equivalent changes made to the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A production process for passivated aluminum alloy shielding tape, characterized in that: include: Step 1: Immerse the aluminum strip in a NaOH electrolyte and apply a pulsed high voltage for plasma electrolytic etching for plasma electrolytic etching pretreatment; Step 2: Immerse the aluminum strip in the GO quantum dot solution and apply an alternating electric field for electrophoretic deposition for graphene oxide quantum dot deposition; Step 3: spraying TiO2-SiO2 mixed sol and performing directional drying under a pulsed electric field for electric field-assisted sol self-assembly; Step 4: Place the sample obtained in step 3 in a microwave plasma reactor, which contains a N2 / O2 mixed gas to form a reaction environment, and the mixing ratio of the mixed gas is 8:

2. The set power of the microwave plasma reactor is 800W for 15 minutes for microwave plasma in-situ ceramicization.

2. A production process for a passivated aluminum alloy shielding tape according to claim 1, characterized in that: In step 1, the applied pulse high voltage is set to 800V and 100μs pulse width.

3. The production process of a passivated aluminum alloy shielding tape according to claim 1, characterized in that: In step 2, the GO quantum dot solution is set to 0.1 mg / mL, pH=9; the alternating electric field requirement is 10 V / cm.

4. A process for producing a passivated aluminum alloy shielding tape according to claim 1, characterized in that: In step three, the solid content of the TiO2-SiO2 mixed sol is 20wt%, and the pulse electric field is set to 1 kV / cm.

5. The production process of a passivated aluminum alloy shielding tape according to claim 1, characterized in that: The method further includes step five, defect treatment, which includes treating with triethoxysilane vapor at 120° C. for 30 minutes, followed by vacuum annealing at 200° C.

6. The production process of a passivated aluminum alloy shielding tape according to claim 1, characterized in that: In step 1: the NaOH electrolyte is 10wt%, 0.5mol / L tetramethylammonium chloride is used as an additive, the aluminum strip is made of aluminum alloy strip, the type is aluminum alloy 5052 or aluminum alloy 6061, the thickness is 0.1-0.3mm, the graphite cathode is 50mm in diameter, the aluminum strip is ultrasonically cleaned with acetone for 15min and then dried, and loaded into the electrolytic cell as an anode with an inter-electrode distance of 10mm. The pulse power supply equipment is started, the processing time is 30s, and the process is stopped when uniform micro-pits appear on the surface, and the strip is rinsed with deionized water and blown dry with nitrogen.

7. The production process of a passivated aluminum alloy shielding tape according to claim 1, characterized in that: In step 2, the aluminum strip was immersed in 0.1 mg / mL GO dispersion, the pH was adjusted to 9.0, 10 mmol / L Tris-HCl was used as a buffer, an electric field strength of 10 V / cm was applied, the current density was controlled to be <0.5 mA / cm², the deposition time was 2 min, and after being taken out, it was rinsed with deionized water 3 times and dried at 80 °C for 10 min.

8. The production process of a passivated aluminum alloy shielding tape according to claim 1, characterized in that: In step three, the sol is ultrasonically dispersed for 30 minutes and then loaded into a spray gun. The mixed sol is: TiO2 (P25, 30nm) + SiO2 (Ludox HS-40, 5nm), with a solid content of 20wt%, and the dispersion medium is anhydrous ethanol. A wet film is sprayed on the surface of the aluminum strip with a thickness of 10-15μm. A pulsed electric field is immediately applied and maintained for 10 minutes, and then vacuum dried at 60℃ for 2h.

9. The production process of a passivated aluminum alloy shielding tape according to claim 1, characterized in that: In step 4, the sample is placed in a quartz boat, the mixed gas is introduced for 10 minutes, the microwave source is started, the reflected power is kept <5W, the processing temperature is maintained at 280±10°C through infrared monitoring, and the sample is naturally cooled after the processing time of 15 minutes.

10. A process for producing a passivated aluminum alloy shielding tape according to claim 5, characterized in that: In step five, the sample is placed in a vacuum box, TES vapor is introduced at a pressure of 50Pa, and the sample is kept at 120°C for 30 minutes, then vacuumed and transferred to an annealing furnace, annealed at 200°C for 2 hours, and cooled to room temperature in a N2 atmosphere.

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