1.1This specification covers the basic requirements for non-electrolytically applied zinc-flake composite corrosion protective coating systems for 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 metric and inch series threaded fasteners with nominal diameters of 6 mm (0.236 inches) and larger as well as for non-threaded fasteners such as washers and pins. 1.3This coating system may be specified to consist of a zinc-flake basecoat, or a zinc-flake basecoat and topcoat (See Note 2). Note 2: For threaded fasteners, the coating system will typically consist of a zinc-flake basecoat and topcoat. 1.3.1The basecoat is a zinc-rich material containing aluminum flakes dispersed in a compatible liquid medium. The zinc-flake basecoat may be specified to contain integral lubricant. 1.3.2Topcoats may be organic or inorganic in composition depending upon the specified requirements. 188.8.131.52Organic topcoats consist of polymer resins, aluminum, dispersed pigments, and are colored in their applied state. 184.108.40.206Inorganic topcoats consist of water-dispersed silicate compounds and are transparent in their applied state. 220.127.116.11Topcoats contain integral lubricants and are applied in conjunction with zinc-flake basecoats to form a coating system with enhanced performance attributes such as increased corrosion resistance, total coefficient of friction properties, chemical resistance, and color. 1.4These zinc-flake 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 curing operation. The maximum curing temperature is 250C (482F). 1.5The friction properties of the coating system may be determined by a standard test to verify process control or by a part specific test which requires the purchaser to establish and communicate technical criteria. 1.6The values stated in either inch-pound units or SI units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.7This 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.
KeywordsBasecoat; coating; corrosion; dip-drain; dip-spin; embrittlement; fasteners; flake; 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.Back to Top
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