1.Pretreatment stage Surface cleaning Use alkaline degreasing agent to remove grease and dirt on the aluminum surface, and use ultrasonic cleaning if necessary to ensure the cleanliness of the substrate.
After cleaning, wash with water until neutral to avoid residual chemical reagents interfering with subsequent reactions.
Pickling activation Immerse in 10-15% sulfuric acid solution or phosphoric acid mixture to remove the natural oxide layer and microscopic impurities and activate the metal surface.
Control the pickling time (usually 2-5 minutes) to avoid over-corrosion and rough surface.
Alkali etching optimization (optional) NaOH solution alkaline etching is used for precision parts to eliminate extrusion lines and improve the uniformity of the oxide film.
2. Anodizing core process Electrolyte configuration Mainstream electrolyte: 15-20% sulfuric acid solution (temperature 18-22℃), with strong adaptability and low cost.
Oxalic acid, chromic acid or mixed acid system can be used for special demand scenarios, such as low-temperature oxalic acid solution for hard oxidation.
Oxidation reaction process
Aluminum is used as the anode, lead/graphite plate is used as the cathode, and 1-2 A/dm² DC is passed through, with a voltage of 12-20V.
The anode reaction generates a dense Al₂O₃ oxide film, and the thickness is positively correlated with time (conventional oxidation forms a 10-25μm film in 20-40 minutes).
Hydrogen is precipitated at the cathode, and the bubble emission needs to be controlled to prevent local uneven concentration.
Parameter precise control
The electrolyte temperature fluctuation needs to be <±1℃ to avoid loose film layer.
High current density can accelerate film formation, but it needs to be combined with a forced cooling system to prevent "ablation".
3. Post-treatment enhancement
Sealing treatment
Boiling water sealing: 98-100℃ deionized water immersion for 20-30 minutes, hydrolyzing the micropores of the oxide film to improve corrosion resistance.
Nickel salt sealing: Nickel ion solution fills micropores, suitable for parts that need to be conductive or subsequently sprayed.
Surface dyeing/decoration
Use the porous characteristics of the oxide film to adsorb organic/inorganic dyes to achieve customized colors such as black, red, and blue.
The bright/matte effect is achieved by adjusting the electrolyte composition and polishing process.
4. Key to performance improvement
Film performance indicators
Hardness: Conventional oxide film hardness HV 400-600, hard oxidation can reach HV 800 or above46.
Salt spray resistance: Neutral salt spray resistance test after sealing > 1000 hours (unoxidized substrate only 200-300 hours).
Material adaptation optimization
Anodizing after T6 heat treatment can simultaneously improve the substrate strength (tensile strength > 300MPa) and surface protection.
The welding area requires secondary oxidation treatment to compensate for the performance loss of the heat-affected zone.
Through standardized process flow and parameter control, 6061 aluminum anodizing can meet diversified needs such as industrial protection, electronic heat dissipation, and high-end decoration.
Raw Material Loading
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Degreasing
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Water Rinse 1
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Water Rinse 2
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Alkaline Etching
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Water Rinse 1
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Desmutting
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Water Rinse 1
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Anodizing
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Water Rinse 1
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Water Rinse 2
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Electrolytic Coloring
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Water Rinse 1
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Water Rinse 2
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Neutralization
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Dyeing
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Hot Water Rinse
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Electrolytic Dye Rinse
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Pure Water Rinse
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Sealing
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Water Rinse 1
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Post-Sealing Cooling
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Solidification
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Material Unloading
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Water Rinse 2
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Packaging
