1. Scope
1.1This specification covers the basic requirements for non-electrolytically applied corrosion protective coating systems on fasteners. (See Note 1) Note 1: The coating systems do not contain hexavalent chromium, lead, cadmium, or mercury. 1.2This specification is intended for corrosion protection of ISO metric threaded fasteners and non-ISO metric threaded fasteners with nominal diameter M6.0 (0.236 inches) as well as for non-threaded fasteners such as clips, pins, washers, and brackets. 1.3This coating system may be specified to consist of a zinc-rich basecoat, or a zinc-rich basecoat and topcoat. (See Note 2) Note 2: For threaded fasteners, the coating system will typically consist of a zinc-rich basecoat and topcoat. 1.3.1The basecoat is a zinc-rich material containing aluminum flakes dispersed in a compatible liquid medium. The zinc-rich basecoat may be specified to contain integral lubricant. 1.3.2Topcoats may be organic or inorganic in composition depending upon the specified requirements. 1.3.2.1Organic topcoats consist of polymer resins, aluminum, dispersed pigments, and are colored in their applied state. 1.3.2.2Inorganic topcoats consist of water dispersed silicate compounds and are transparent in their applied state. 1.3.2.3Topcoats contain integral lubricants and are applied in conjunction with zinc-rich basecoats to form a coating system with enhanced performance attributes. 1.4These zinc-rich basecoats and topcoats are applied by conventional dip-spin, dip-drain, or spray methods to fasteners which can be handled through a cleaning, coating, and baking operation. The maximum baking temperature is 250C (482F). 1.5The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.6This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
The corrosion protection of fasteners and ferrous materials by means of zinc based coating systems is common, has applicability to multiple business sectors serviced by fastener suppliers and is acknowledged by ASTM Standards (Ref. ASTM F 1136). The adoption of this proposal will benefit the fastener industry utilizing ASTM Standards in several respects one of which is material sourcing. There are several primary sources (ie. global suppliers) of zinc based corrosion protection systems, however, ASTM Standards address the usage of materials from just one of the primary suppliers.
Keywords
Aluminum; basecoat; coating; corrosion; dip-drain; dip-spin; embrittlement; fasteners; friction; inorganic; non-electrolytically; organic; protection; resistance; rust; spray; topcoat; zinc.
The title and scope are in draft form and are under development within this ASTM Committee.
Citing ASTM Standards
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