BS EN ISO 2082:2008 Metallic coatings. Electroplated coatings of cadmium with supplementary treatments on iron or steel
BS EN ISO 2082 specifies the requirements of electroplated coatings of cadmium with supplementary treatments on iron and steel. It includes information that is to be supplied by the purchaser to the electroplater, and describes coating requirements, including those for heat treatment before and after electroplating.
It is not applicable to coatings applied:
- To sheet, strip or wire in the non-fabricated form
- To close-coiled springs
- For purposes other than protective, intrinsic lubricity, ductility, electrical conductivity and low contact resistance use.
BS EN ISO 2082 does not specify the requirements for the surface condition of the basis metal prior to electrodeposition with cadmium.
The coating thickness that can be applied to threaded components can be limited by dimensional requirements, including class or fit.
Electrodeposits of cadmium are used to protect iron and steel from corrosion. Cadmium is anodic and corrodes sacrificially, thus protecting ferrous basis metals even when exposed through pores or pits in the cadmium. Electrodeposited cadmium coatings have traditionally been applied to iron or steel from alkaline cyanide solutions, but in recent years, environmental concerns and regulations have led to increased use of acid sulphate, neutral chloride and acid fluoborate cadmium solutions.
Because the appearance and serviceability of electroplated cadmium coatings are influenced by the surface condition of the basis metal, agreement should be reached between the interested parties that the surface of the basis metal is satisfactory for electroplating.
Cadmium is highly toxic and health, safety and environmental concerns are eliminating its non-essential uses.
There remain, nevertheless, critical applications, often aerospace-related, where the unique properties of electrodeposited cadmium coatings, for example, their corrosion resistance, intrinsic lubricity, ductility, electrical conductivity and low contact resistance, make continued use of cadmium coatings necessary.
The corrosion resistance of electroplated cadmium coatings and their tendency to tarnish when handled can be improved by applying chromate conversion and other supplementary coatings.
Chemical conversion coatings that do not contain hexavalent chromium are commercially available and their use is becoming more and more popular. The appearance of these substitutes may be different from those produced with hexavalent chromium. Other conversion coatings that are chromium-free are also available.
Substitutes are required to satisfy the corrosion requirements given in this International Standard.
Contents of BS EN ISO 2082 include:
- Scope
- Normative references
- Terms, definitions, abbreviated terms and symbols
- Terms and definitions
- Abbreviated terms
- Symbols
- Information to be supplied by the purchaser to the electroplater
- Essential information
- Additional information
- Designation
- Designation specification
- Designation of heat treatment requirements
- Examples
- Requirements
- Appearance
- Thickness
- Conversion coatings and other supplementary treatments
- Adhesion of cadmium and chromate coatings
- Accelerated corrosion testing
- Stress relief heat treatment before cleaning and metal deposition
- Hydrogen-embrittlement-relief heat treatment 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
BS EN ISO 2082:2008 replaces BS EN 12330:2000 which has been withdrawn