2205 Duplex Stainless Steel Cathode
High-Strength Permanent Cathode for Copper Electrowinning & Electrorefining
In copper electrowinning and electrorefining operations, chloride ions in electrolytes are one of the main causes of cathode plate corrosion and premature failure. Standard 304 and 316L austenitic stainless steels often struggle to maintain long-term stability in such environments.
Our 2205 duplex stainless steel permanent cathodes are engineered for moderately to highly aggressive electrolysis conditions. With a nearly 50/50 balanced austenite-ferrite dual-phase microstructure, it combines high mechanical strength with excellent chloride corrosion resistance. It delivers reliable long-term performance and better return on investment than standard austenitic steel grades, and is fully compatible with both ISA and OK process systems.
Material Properties & Microstructure Advantage
2205 (UNS S32205 / S31803) is the most widely used standard duplex stainless steel for permanent cathodes. Its excellent comprehensive performance comes from the synergy of the two phases:
The ferrite phase brings high mechanical strength and outstanding resistance to chloride stress corrosion cracking.
The austenite phase provides good toughness and uniform overall corrosion resistance.
Key Alloy Composition
- Chromium (21–23%): Provides basic corrosion resistance for long-term immersion in sulfuric acid electrolytes
- Nickel (4.5–6.5%): Stabilizes the austenite phase and improves material toughness
- Molybdenum (2.5–3.5%): Significantly enhances pitting and crevice corrosion resistance
- Nitrogen (0.08–0.2%): Boosts overall strength and improves localized corrosion resistance
Core Performance Indicators
- Tensile strength: ≥ 620 MPa (nearly double that of 316L)
- Yield strength: ≥ 450 MPa
- Typical Pitting Resistance Equivalent Number (PREN): 32 – 38
- Excellent resistance to chloride stress corrosion cracking
Structural Design
A complete 2205 duplex stainless steel cathode assembly consists of:
- Stainless Steel Plate Body
Precision-cut 2205 duplex steel plate with polished surface, serving as the substrate for copper electrodeposition. - Copper-Stainless Steel Composite Conductive Beam
Copper core for high conductivity, clad with stainless steel for corrosion resistance, metallurgically bonded to the cathode plate body. - Hanging Lugs
Two lifting lugs on both ends of the conductive beam, for crane handling and positioning on cell busbars. - Edge Insulation Strip
Polypropylene or PVDF insulation strips on both side edges and bottom edge, preventing copper deposition on edges and facilitating stripping.
Technical Specifications
| Item | Standard Parameter |
|---|---|
| Base Material | 2205 duplex stainless steel (UNS S32205 / S31803, TISCO origin) |
| Plate Thickness | 3.0 – 6.0 mm (customizable) |
| Effective Deposition Area | Fully customized to match cell dimensions |
| Edge Insulation | PP / PVDF strips |
| Matching Conductive Beam | Stainless steel clad copper, metallurgical bonding |
| Applicable Current Density | 200 – 400 A/m² |
| Applicable Medium | Sulfuric acid system copper electrolyte |
| Design Service Life | 8 – 12 years under normal operation |
| Compatible Processes | ISA process, OK process |
Core Performance Advantages
1. Industry-leading Chloride Corrosion Resistance
This is the most significant advantage of 2205 over 316L and economy duplex grades.
- With a PREN of 32 – 38, it far outperforms 316L (PREN ~24) in pitting and crevice corrosion resistance.
- The ferrite phase effectively blocks crack propagation, greatly reducing the risk of chloride stress corrosion cracking - a common failure mode for 316L in harsh electrolytes.
- Its critical pitting temperature is typically above 60°C, maintaining stable performance in warm chloride electrolytes below 60 – 80°C.
2. High Mechanical Strength & Anti-Deformation
Nearly double the yield strength of 316L allows for a thinner plate design while maintaining structural rigidity. It better resists bending and distortion during repeated crane handling and stripping operations, reducing plate damage rates and maintenance downtime.
3. Extended Service Life & Lower Total Cost
Under normal operating conditions, 2205 cathodes last 2 – 3 times longer than ordinary 304 stainless steel cathodes. Fewer replacements reduce long-term procurement costs and production interruption risks, delivering excellent long-term return on investment.
2205 vs LDX 2101: Grade Selection Reference
| Feature | 2205 (Standard Duplex) | LDX 2101 (Economy Duplex) |
|---|---|---|
| Core Positioning | High-performance solution for chloride-rich harsh environments | Cost-effective upgrade from 304/316L for mild conditions |
| Key Alloy Difference | Contains ~3% molybdenum and higher nitrogen content | Low or no molybdenum, designed to reduce nickel/molybdenum cost |
| Typical PREN | 32 – 38 | 24 – 26 |
| Chloride Resistance | Excellent pitting, crevice and SCC resistance | Similar to 316L; better SCC resistance than austenitic grades |
| Critical Pitting Temperature | Typically > 60°C | Approximately 22°C |
| Ideal Application | Higher chloride levels, warmer electrolytes, electrorefining scenarios | Low chlorides, near-ambient temperature, general EW use |
Free Drawings:
We provide AutoCAD drawings for free. Customization and optimization are available based on your requirements and our expertise. Drawings are confirmed before entering the commercial negotiation stage.
Lead Time:
Fast delivery guaranteed. For example, 5000 cathode plates can be manufactured within 90 days.
Payment Terms:
50% T/T in advance; balance to be paid before shipment. Bank guarantees can be arranged upon request.
After-sales Service:
Quick response within 24 hours. Both remote support and on-site technical guidance are available.
Packaging & Shipping
Export Experience
Extensive export experience with efficient handling of documentation and Certificates of Origin.
Packaging
The product is securely packed in steel-frame packaging, ensuring each cathode plate is protected from mechanical damage during port handling.
Transportation Options
Shipped by container. If purchased together with electrowinning cells, cathodes can be stacked within the cells to reduce space and shipping costs. Shipping options include sea freight, land transport, and rail logistics depending on the project location.
Frequently Asked Questions (FAQ)
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