BS EN ISO 2081 is the international standard that specifies the requirements for electroplated coatings of zinc with supplementary treatments on iron or steel. It includes information to be supplied by the purchaser to the electroplater, and the requirements for heat treatment before and after electroplating.
It is not applicable to zinc coatings applied:
- To sheet, strip or wire in the non-fabricated form
- To close-coiled springs
- For purposes other than protective or decorative.
BS EN ISO 208 does not specify the requirements for the surface condition of the basis metal prior to electroplating with zinc. However, defects in the surface of the basis metal can adversely affect the appearance and performance of the coating.
The coating thickness that can be applied to threaded components can be limited by dimensional requirements, including class or fit.
Zinc coatings are applied to iron or steel articles for protective and decorative purposes by electrodeposition from acid zinc chloride, alkaline non-cyanide zinc, and alkaline zinc cyanide solutions. Electroplated, bright zinc coatings are popular and the processes for preparing bright zinc coatings are widely used.
The ability of a zinc coating to prevent corrosion is a function of its thickness and the type of service conditions to which it is exposed. For example, the rate of corrosion of zinc will generally be greater in industrial exposures than in rural ones. The type of service condition should be taken into consideration when specifying the minimum coating thickness. Chromate conversion coatings and other supplementary treatments enhance the corrosion resistance of electrodeposited zinc coatings and are commonly applied after electroplating.
Because the appearance and serviceability of zinc coatings depends on the surface condition of the basis metal, agreement should be reached between the interested parties that the surface finish of the basis metal is satisfactory for electroplating.
Chromate conversion coatings are omitted, or replaced by other conversion coatings, at the specific request of the purchaser. BS EN ISO 2081 provides the codes for all types of chromate conversion and other supplementary coatings.
Chemical conversion coatings that do not contain hexavalent chromium or are chromium-free, conforming to BS EN ISO 2081, are commercially available. The appearance of these substitutes may be different from those produced with hexavalent chromium. All forms of chromate conversion coatings, alternative conversion coatings or substitutes, with the exception of phosphate coatings, can be used and are required to satisfy the corrosion requirements given in BS EN ISO 2081.
Standard designations for metals and alloys can be found in the Bibliography.
Contents of BS EN ISO 2081 include:
- Introduction
- Scope
- Normative references
- Terms, definitions, abbreviated terms and symbols
- Symbols
- Information to be supplied by the purchaser to the electroplater
- Essential information
- Additional information
- Designation specification
- Designation of the basis material
- Designation of heat treatment requirements
- Examples
- Requirements
- Appearance
- Thickness
- Conversion coatings and other supplementary treatments
- Adhesion of zinc and chromate coatings
- Accelerated corrosion testing
- Stress relief heat treatments before cleaning and metal deposition
- Hydrogen-embrittlement-relief heat treatments after electroplating
- Sampling
- Designation of chromate conversion coatings and other supplementary treatments
- Measurement of average thickness of coating on small articles
- Additional information on corrosion resistance, rinsing and drying, processing parts in bulk and dyeing of chromate conversion coatings
- Bibliography
This international standard may not be compliant with some countries’ health, safety and environmental legislations and calls for the use of substances and/or procedures that may be injurious to health if adequate safety measures are not taken. BS EN ISO 2081 does not address any health hazards, safety or environmental matters and legislations associated with its use.
It is the responsibility of the producers, purchasers and/or user of BS EN ISO 2081 to establish appropriate health, safety and environmentally acceptable practices and take appropriate actions to comply with any national, regional and/or international rules and regulations. Compliance with BS EN ISO 2081 does not, of itself, confer immunity from legal obligations.