Geomet is one of the world’s most advanced, eco-friendly coating technologies for rust and corrosion protection. It is a surface treatment solution promoted by Nippon Dacro Shamrock. In recent years, rising global environmental concerns have driven stricter regulations on hazardous substances. Hexavalent chromium compounds, long widely used for metal anti-corrosion finishes, have faced growing restrictions across Europe and North America under environmental legislation.
Against this backdrop, Nippon Dacro Shamrock, Metal Coatings International Inc. (MCII) of the United States and DACRAL of France carried out years of joint R&D based on the established Dacromet technology. The collaboration resulted in Geomet, a fully chromium-free surface treatment innovation.
Geomet is a state-of-the-art eco-friendly inorganic coating for metal substrates. Its core performance is defined by three key dimensions: environmental compliance, corrosion resistance, and process characteristics.
Environmental Compliance
- Chromium-free formulation: Zero chromium throughout the treatment, fully compliant with EU RoHS directives.
- Closed-loop processing: Adopts a zero-discharge closed system. Process emissions consist primarily of water vapor, with no hazardous waste discharge.
Corrosion Resistance
- Salt spray testing: Delivers reliable anti-corrosion performance exceeding 480 hours, with maximum performance up to 2000 hours. It maintains stable performance for up to 40 cycles in cyclic corrosion tests.
- Broad material compatibility: Suitable for stainless steel, aluminum, and other metal substrates, eliminating the risk of hydrogen embrittlement.
Process Characteristics
- Coating structure: Formulated from zinc and aluminum flakes bound by inorganic binders with zero chromium content. It forms an ultra-thin protective layer above 6 μm, combining electrochemical protection and physical barrier defence.
- Hardness: Finished coating achieves 600–1000 HV, offering superior wear resistance compared with conventional finishing processes.
Key Advantages of Geomet
- Water-based treatment solution for environmental protection. The fully water-soluble system is harmless to both the natural environment and workshop operating conditions.
- 100% chromium-free. No chromium compounds are used during processing or present in the final coating, complying with global end-of-life vehicle regulatory requirements.
- Closed-loop, zero-effluent processing system. Exhaust from the coating spraying stage is mostly water vapor and contains no regulated hazardous substances.
- Exceptional corrosion resistance, proven in both salt spray and cyclic corrosion testing.
- Prevents galvanic corrosion between dissimilar metals when paired with aluminum. When iron or stainless steel fasteners are assembled with aluminum components, Geomet finishing on fasteners stops electrochemical corrosion. This feature makes the technology widely adopted in the automotive industry.
- Excellent adhesion. The coating can be applied to the inner surface of tubes and pipes, reaching internal areas that electro-galvanizing cannot easily cover.
- No hydrogen embrittlement risk. Materials treated with Geomet will not suffer hydrogen embrittlement.
- Compatible with overcoating. Geomet-finished surfaces can be further painted. Testing confirms reliable adhesion for both solvent-borne melamine resin coatings and powder coatings.
