Die-cast Aluminum Passivation Before-and-after Comparison
For die-cast aluminum parts with darkening, uneven appearance, short-term oxidation and insufficient corrosion resistance after cleaning, Minghan established a degreasing, natural passivation and drying protection process to improve surface uniformity, oxidation resistance and handling stability.
Before passivation
After passivation
Case Overview
The customer’s die-cast aluminum housings and aluminum alloy structural parts were prone to surface darkening, uneven color, water marks and localized oxidation during handling, assembly and short-term storage after cleaning. Based on the porous surface condition of die-cast aluminum, complex contamination and natural appearance requirements, Minghan Chemical provided a degreasing and natural aluminum passivation process to improve surface stability and corrosion resistance while keeping the original aluminum appearance.
Customer Challenge
Die-cast aluminum surfaces often retain release agents, machining oil, dust and oxides. After standard cleaning, surface cleanliness may remain unstable, and the parts may darken, become uneven or develop localized oxidation spots during storage. The customer needed better natural appearance consistency and short-term anti-oxidation performance without obvious coloring or impact on assembly dimensions.
Solution
Minghan recommended a process of degreasing, rinsing, natural aluminum passivation, final rinsing and drying protection. Pretreatment removes release agents, machining oil and surface contaminants. The natural aluminum passivation agent forms a compact protective film on the aluminum surface, improving oxidation and corrosion resistance while maintaining the original die-cast aluminum appearance as much as possible.
Result
After treatment, surface darkening, uneven color and localized oxidation were visibly improved. The overall aluminum appearance became more uniform, while risks of water marks and handling discoloration were reduced. The natural passivation film improved short-term oxidation resistance and corrosion protection, helping reduce appearance rework and improve batch shipment stability.
Implementation Process
Sample review
Confirm die-cast aluminum material, surface oil, oxidation condition, appearance requirement and corrosion resistance target.
Degreasing cleaning
Remove release agents, machining oil, dust and surface contaminants before passivation.
Natural aluminum passivation
Match passivation concentration, treatment time and temperature to form a protective film.
Rinsing control
Rinse thoroughly to reduce residue, water marks and localized uneven appearance.
Drying protection
Dry promptly and use proper handling and packaging to reduce secondary contamination and short-term oxidation.
Case Information
Surface condition
Improved from darkening, uneven color and localized oxidation to a more uniform natural aluminum appearance
Oxidation resistance
Natural passivation film improves short-term anti-oxidation and corrosion resistance
Process compatibility
Suitable for die-cast aluminum housings, aluminum alloy structural parts and hardware components
Delivery value
Reduces appearance rework and handling discoloration risk, improving batch shipment stability
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Die-cast Aluminum Natural Passivation Case Brief
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