Definition: Metal degradation occurs via chemical or electrochemical reactions with surrounding media. Approximately one-tenth of steel materials are lost annually due to corrosion.

Rail clamps are permanently exposed to outdoor conditions, high humidity, dust, industrial acid and alkaline environments. Severe metal corrosion greatly impairs their load-bearing stability and service life.

Chemical Corrosion: A pure chemical reaction without current generation, only causing surface corrosion.

Electrochemical Corrosion: Corrosion accompanied by current flow, affecting both surface and internal structure. It is the primary cause of steel corrosion, as well as the main reason for base metal deterioration of rail clamps.

Corrosion Origin: Metals tend to revert to their natural mineral forms, such as oxides and carbonates.

Material Selection & Structural Design: Select materials adaptable to corrosive media, avoid direct contact of dissimilar potential metals, and prevent stress concentration. Structural anti-corrosion design is optimized according to the load-bearing characteristics of rail clamps.

Chemical Treatment: Bluing and phosphating, which form dense protective films on metal surfaces.

Electrochemical Protection: Cathodic protection by sacrificing active metals including zinc, aluminum and magnesium to protect steel substrates.

Coating Protection: Metallic coatings (electroplating, hot-dip galvanizing, cladding) and non-metallic coatings (paint coatings, anti-rust oil).

Among all methods, hot-dip galvanizing delivers the best comprehensive anti-corrosion performance, and is the preferred surface treatment process for heavy-industry rail clamps at present.

Physical Protection: The dense zinc layer isolates corrosive media, blocking moisture, acid and alkali erosion on rail clamp substrates.

Electrochemical Protection: With lower electrode potential, zinc corrodes preferentially once the coating is damaged, thus protecting the internal steel substrate and significantly extending the overall service life of rail clamps.

Standard Process:

Degreasing → Water Washing → Pickling → Water Washing → Flux Treatment → Drying → Hot-Dip Galvanizing → Finishing → Cooling → Passivation → Rinsing → Drying → Inspection

Process: Hot-dip galvanizing relies on physical and chemical reactions in molten zinc, while electro-galvanizing is based on electrode reaction.

Performance: Hot-dip galvanizing forms thick coatings (over 35μm) with long anti-rust service life. Electro-galvanizing produces thin coatings which are prone to rusting with only several years of service life, failing to meet long-term outdoor application requirements of rail clamps.

Coating Formation Sequence: Steel substrate → Zinc-iron solid solution → Zinc-iron alloy layer → Pure zinc layer, with zinc dross as by-product.

Applicable Standards: GB/T 13912, ISO 1461, ASTM A123, JIS H 8641 and other international and national standards. Galvanized rail clamps are manufactured and inspected in strict accordance with the above standards.

Coating Thickness Requirements: Classified by steel material thickness. Thicker steel requires higher average and local coating thickness.

Inspection Items: Adhesion (scratch test and hammer test), uniformity (copper sulfate dip test). Coating performance directly determines the durability of finished rail clamp products.

Main Defects: Dull coating, missing plating, zinc dross particles, air bubbles, white rust, etc. These defects may also occur on hot-dip galvanized rail clamp products.

Treatment Principles: Large-area missing plating shall be rejected or repaired. Most other defects have little impact on corrosion resistance and are judged per prior agreements. Defect grades of rail clamps are strictly controlled in accordance with heavy industry application requirements.

Causes: High humidity, sealed environment and poor ventilation form oxygen concentration cells, resulting in white zinc hydroxide (Zn(OH)₂). Dense stacking and humid transportation conditions easily cause white rust on rail clamps.

Prevention Measures: Passivation treatment, dry and ventilated storage, reasonable overhead stacking, and desiccant addition in packaging. Standardized warehouse management effectively avoids white rust on finished rail clamps.

Treatment Methods: Slight white rust can be naturally air-dried; moderate white rust shall be removed with hard brushes; severe white rust requires repair or re-galvanising. Products can be delivered for track installation only after qualified reprocessing.