What is Dacromet?
Dacromet is a leading-edge surface treatment technology consisting primarily of ultra-fine zinc and aluminum flakes bonded by an inorganic silicate matrix. It is renowned for providing exceptional corrosion protection, particularly for high-strength steel parts where traditional electroplating risks structural failure.
1. Core Components & Process
Composition: A blend of ultra-fine flake zinc, flake aluminum, organic solvents (e.g., ethylene glycol), and a chromic acid binder.
The Process:
Pre-treatment: Thorough cleaning (solvent or alkaline) followed by shot blasting or sandblasting to achieve a roughness of Ra 6.3~12.5μm. Unlike traditional plating, acid pickling is avoided to prevent hydrogen absorption.
Coating: Applied via dip-spinning, spraying, or brushing. Thickness is controlled by viscosity and the number of cycles (1-coat for 2-5μm; 3-coats for 8-13μm for heavy industrial use).
Curing: A two-stage thermal process. Pre-heating (80-120°C) removes moisture, followed by high-temperature curing (300-320°C) to form a dense, ceramic-like inorganic coating.
Post-treatment: Optional sealing with epoxy or silane to push salt spray resistance beyond 1000 hours.
2. Anti-Corrosion Mechanism
Dacromet protects steel through a three-fold defense system:
Barrier Effect: Overlapping metallic flakes create a physical "maze" that prevents moisture and oxygen from reaching the substrate.
Passivation: Chromic acid reacts with the metal powders and the substrate to form a stable chemical passivation film.
Cathodic Protection: Like galvanizing, the zinc and aluminum act as sacrificial anodes, protecting the iron base even if the coating is scratched.
3. Key Advantages
Superior Heat Resistance: Unlike traditional zinc plating which fails above 70°C, Dacromet remains stable at 300°C.
Zero Hydrogen Embrittlement: The absence of acid pickling and electrolysis makes it the safest choice for Grade 10.9 and 12.9 high-strength bolts.
High Salt Spray Resistance: Offers 7–10 times the protection of traditional galvanizing.
Excellent Penetration: Effectively coats complex geometries, blind holes, and tight gaps in springs and tubes.
Eco-Friendly: A "Green Electroplating" alternative with a closed-loop system and minimal harmful emissions.
Conclusion
Whether for automotive, marine, or renewable energy applications, Dacromet provides a durable, matte silver-grey finish that withstands the harshest environments.
