Coatings evaluation

Panels of high strength aluminum alloy (7075-T6) were used in this study. The panels were approximately 10 x 3 x 0.032 inch (25 x 7.5 x 0.08 cm) in size. The test environments for coating evaluation were (1) a 5% NaCl spray (fog) chamber according to ASTM Standard Method of Salt Spray (Fog) Testing (B117-73), and (2) a modified 5% NaCl/S02 spray (fog) chamber with SO gas introduced periodically - ASTM Standard Practice for Modified Salt Spray (Fog) Testing (G85-84(A4)). In the latter case, a constant spray of 5% NaCl was maintained in the chamber and SO2 was introduced for one hour four tines a day (every 6 hours)( ). Coated test panels were examined for corrosion after one- and two- eek exposure periods. 

Electrochemical Noise Methods for Organic Coating Evaluation... 

Drip Test Titanium/coating evaluation Resistance to hydraulic fluid of coating and substrate at various temperatures (usually 450°F) Bare 6A1-4V titanium specimen... 

CIPS (close interval potential survey) Enables detection of defects of coatings, evaluation of cathodic protection effectiveness, CP station current is used. Localization of area with insufficient protection, localization of coating defects, indication of defect size. Requires inspection of whole pipeline, may not show coating disbonding, does not determine corrosion. 

Ken Carlson and co-workers, from the U.S. Department of Agriculture, have reported that "vernonia" coatings can be obtained directly from vernonia oil by a standard baking procedure at 150< C for 30 minutes in the presence of different drier systems.Our initial goal is determination of the drying mechanism and compatibility of vernonia oil with alkyd and other resins, characterization of these "vernonia" coatings, evaluation of different drier systems, and eventually, improvement of their properties. 

Leakage current is the parameter used for the material evaluation in both cases and usually an investigation of the material condition is performed by using appropriate methods (contact angle, ESCA, FTIR, etc.). In the field, leakage current and material analysis methods are also incorporated for the coating evaluation. 

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