Dacromet Coating for Carbon Steel Fasteners
Introduction to Dacromet Coating for Fasteners
Dacromet coating for fasteners is a highly effective surface treatment widely used in the fastening industry, particularly on carbon steel materials. It involves a non-electrolytic process using a proprietary blend of metal oxides, chromates, and other chemicals to provide a highly corrosion-resistant, environmentally friendly coating.
This technology, introduced in the 1970s, has since become a preferred method for high-performance applications that demand superior anti-corrosion characteristics without sacrificing strength. Dacromet coating for fasteners has earned a solid reputation due to its proven performance in extreme environments including heavy industrial, automotive, and aerospace sectors.
Common Uses and Applicability
Dacromet-coated carbon steel fasteners are suitable for a wide range of fastener types and applications. Here’s a breakdown:
| Fastener Types | Common Application Industries |
|---|---|
| Bolts, Screws, Nuts, Sealing Washers, etc. | Automotive, Construction, Marine, Railway, Aerospace, Agriculture, Energy |
This coating is particularly advantageous for fasteners used in corrosive environments, where standard finishes like electro-zinc plating would degrade quickly. It’s highly suitable for external structural applications, engine compartments, and marine components.
Unique Characteristics of Dacromet Coating
| Feature | Description |
|---|---|
| Corrosion Resistance | Excellent salt spray resistance (up to 1000 hours per ASTM B117) |
| Appearance | Silver-gray matte finish, uniform coating, smooth adhesion |
| Surface Hardness | Enhances wear resistance, although not as hard as thermal treatments |
| Conductivity | Semi-conductive, allowing limited use in grounded systems |
| Temperature Resistance | Performs well under high-temperature environments up to 300°C |
Dacromet Surface Treatment Process Steps
The Dacromet application process involves several non-electrolytic steps to ensure optimal adhesion and performance:
- Pre-Treatment / Surface Preparation
- Degreasing
- Rinsing
- Acid pickling or blasting (if needed) to remove scale or rust
- Coating Application
- Immersion or spray application of Dacromet slurry
- Controlled drying phase
- Baking in industrial ovens to cure at 300–320°C
- Post-Treatment
- Optional topcoats for added durability
- Torque-tension control sealants
- Drying and packaging
Key Advantages and Limitations
Advantages
- ⚙️ Superior corrosion resistance without the use of toxic heavy metals
- 🌿 Environmentally friendly and RoHS compliant (no hexavalent chromium)
- 🔩 Uniform coating without hydrogen embrittlement—ideal for high-torque applications
- 🔧 Low-friction finish helps in tightening torque consistency
Limitations
- 💰 Initial cost is higher compared to standard electroplating
- 🧪 Requires specialized application processes and equipment
- 🚫 Not suitable for decorative applications—it has an industrial visual finish
Dacromet vs. Other Surface Treatments
| Feature | Dacromet Coating | Zinc Plating | Black Oxide | Phosphate Coating |
|---|---|---|---|---|
| Corrosion Resistance | ★★★★★ | ★★ | ★ | ★★ |
| Appearance | Silver-gray | Bright silver | Black | Gray |
| Electrical Conductivity | Moderate | High | High | Low |
| Temperature Stability | High | Moderate | Low | Moderate |
This comparison highlights why Dacromet coating for fasteners is often chosen where long-term durability, salt spray resistance, and environmental compliance are required.
International Standards & Certifications
Dacromet-coated fasteners often comply with several global standards, including but not limited to:
- ASTM B117 (Salt Spray Testing)
- ISO 10683
- RoHS and ELV European directives
- GMW3044 (General Motors standard for Zn-Al coatings)
Environmental & Safety Impact
A notable benefit of Dacromet coating is its environmental compliance:
- ✅ Chromium VI free (eco-friendly)
- ✅ No hydrogen embrittlement risk—making it ideal for high tensile carbon steel
- ✅ Safe handling due to the absence of electroplating chemicals
Cost Efficiency & Performance
Though the upfront application cost may be higher, Dacromet’s longevity reduces the total lifecycle cost by:
- Minimizing replacement due to corrosion
- Maintaining fastening integrity for longer durations
- Reducing surface prep in secondary manufacturing steps
Choose Flybear Fastener for Your Surface Coated Solutions
At Flybear Fastener, we provide a full range of Dacromet-coated carbon steel fastener products designed to meet the toughest industry standards. We tailor our products to meet the needs of sectors including automotive, construction, and energy infrastructure.
We always follow the principle “Quality First, Customer Foremost,” delivering end-to-end fastener solutions for high-performance applications. Explore our capabilities, and don’t hesitate to contact us for custom quotes or technical consultation.
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