ASTM D2803-09(R2020) pdf free download

ASTM D2803-09(R2020) pdf free download.Standard Guide for Testing Filiform Corrosion Resistance of Organic Coatings on Metal
1. Scope
1.1 This guide covers three procedures for determining the susceptibility of organic-coated metal substrates to formation of filiform corrosion. 1.2 This guide is limited to the determination of whether filiform corrosion will occur between the organic coating and substrate. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. N OTE 1—Procedure B of this standard is equivalent to ISO 4623. 1.4 This 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Summary of Method
4.1 Coated metal specimens are scribed and placed in a corrosive atmosphere to initiate corrosion. The specimens are then exposed to controlled temperature and humidity condi- tions known to be conducive to filiform corrosion.4.2 In Procedure A, panels are subjected to a preliminary exposure in the salt spray cabinet to initiate corrosion, rinsed, and placed in a humidity cabinet. In Procedure B, based on ISO 4623, panels are either exposed to salt spray or dipped in a salt solution but not rinsed before placing in the humidity cabinet operated at a higher temperature than in Procedure A. In Procedure C, specimens are exposed as in Procedure A except the humidity cabinet is operated at a higher temperature. 4.3 The procedures contained in this guide differ signifi- cantly in method of initiation, and or temperature, or both, and humidity of exposure and therefore may not yield comparable results.
9. Procedure A
9.1 Expose the test specimens to the salt-fog atmosphere in accordance with Practice B117 for at least 4 h and not more than 24 h, or as agreed upon between the producer and user. 9.2 Remove from the salt-fog cabinet and thoroughly rinse with distilled or demineralized water. Do not permit specimens to dry before placing in the humidity cabinet. 9.3 Place the specimens in the humidity cabinet so that they are no closer together than 40 mm (1.5 in.) and not in contact with any metal. Set the cabinet to operate at 25°C (77°F) and 85 % relative humidity unless otherwise agreed upon between the producer and user. The allowed operational limits are 62°C (63.5°F) and 610 % relative humidity. N OTE 6—The recommended means ofmaintaining the specified relative humidity is to utilize trays of saturated potassium chromate solution (650 g/L). Practice E104 describes other methods for maintaining relative humidity, but they may affect the degree and rate of filiform corrosion. 9.4 Inspect the specimens at intervals of approximately 168 h for development of threadlike filaments from the scribe. Exercise care to maintain wetness of specimens during inspection, since drying stops the original pattern of filiform corrosion. New filiform may develop on continued exposure but at different points. 9.4.1 Filiform corrosion will be noted as threadlike fila- ments (see Note 7), initiating at the scribe. A standard method ofrating failure due to filiform is not available. The uniformity of filament growth in direction, width, height and frequency precludes a precise rating system. Photographs of filiform failure are preferred for recording test results. Otherwise, a briefdescription ofthe filament growth and their frequency can be made. ISO 4628–10 provides a method for the measurement of filiform filaments. Filiform corrosion may continue to develop after specimens are removed from the humidity cabinet. N OTE 7—The nature of grinding and grain direction on panels can influence the direction of filiform growth.