Overview
The SIST EN ISO 2179:2016 standard defines the specifications and test methods for electroplated coatings of tin-nickel alloy (SnNi), specifically those with an approximate composition of 65% tin and 35% nickel by mass. This coating is recognized for its hardness, wear resistance, and corrosion protection properties. The standard supersedes the first edition (ISO 2179:1972) and is applicable for use on various ferrous and non-ferrous base metals, excluding certain components such as threaded parts, coil springs, and high tensile strength steels (>1000 MPa). This international standard aims to ensure consistent quality and performance of tin-nickel alloy electroplated coatings.
Key Topics
- Coating Composition: Specifies intermetallic SnNi alloy coatings with approx. 65% tin and 35% nickel.
- Scope Exclusions: Does not apply to threaded components, sheet/strip/wire in unfabricated form, coil springs, or steels with tensile strength exceeding 1000 MPa.
- Service Condition Classification:
- Class 1 (mild) - Indoor dry environments
- Class 2 (moderate) - Indoor with some condensation
- Class 3 (severe) - Typical outdoor temperate conditions
- Class 4 (exceptionally severe) - Very harsh outdoor conditions
- Thickness Requirements: Minimum coating thicknesses are classified by service conditions, ranging from 5 µm for mild to 25 µm for severe conditions.
- Undercoats: Use of undercoats (copper, nickel, bronze, or tin) is necessary for enhanced adhesion and corrosion resistance, particularly on ferrous substrates.
- Test Methods:
- Preparation and Heat Treatment:
- Recommendations for stress relief of cold-worked steels before plating.
- Hydrogen embrittlement relief precautions, noting the slow diffusion of hydrogen through SnNi coatings.
Applications
The SIST EN ISO 2179:2016 standard is essential for industries requiring durable and corrosion-resistant metal finishes. Typical applications include:
- Electronics: Protective coatings on printed circuit boards and associated components.
- Automotive and Machinery: Parts requiring wear and corrosion resistance, excluding those with threaded surfaces or high-tensile steel components.
- General Metal Finishing: Equipment and tools where SnNi coatings provide a hard, wear-resistant, and corrosion-protective layer.
- Engineering and Manufacturing: Ensures reliable coating quality, adhesion, thickness, and durability standards are met for components exposed to various environmental conditions.
Related Standards
Professionals working with SIST EN ISO 2179:2016 should also be familiar with complementary standards for metallic coatings and testing methodologies:
- ISO 1462: Accelerated corrosion tests for metallic coatings.
- ISO 1463: Microscopical methods for coating thickness measurement.
- ISO 2664: Definitions and conventions concerning coating thickness.
- ISO 2177: Coulometric method for measuring coating thickness.
- ISO 2819: Testing adhesion of metallic coatings by thermal shock.
- ISO 3497: X-ray spectrometric methods for coating thickness measurement.
- ISO 6988: Sulfur dioxide tests with condensation for corrosion resistance.
- ISO 2859 & ISO 4519: Sampling procedures and inspection methods for electroplated coatings.
Summary
SIST EN ISO 2179:2016 provides a comprehensive framework for specifying and testing electroplated tin-nickel alloy coatings, ensuring high-performance, consistent quality finishes that meet the demands of diverse industrial applications. With clear guidelines on composition, thickness, adhesion, and environmental suitability, this standard supports manufacturers and electroplaters in delivering durable and wear-resistant coatings tailored to specific service conditions. Adherence to EN ISO 2179 safeguards product longevity and reliability, enhancing protective metal finishing solutions globally.
