ASTM B825-13
Standard Test Method for Coulometric Reduction of Surface Films on Metallic Test Samples

Standard No.

ASTM B825-13

Release Date

2013

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM B825-19

Latest

ASTM B825-19

Scope

4.1 The present trend in environmental testing of materials with electrically conductive surfaces is to produce, under accelerated laboratory conditions, corrosion and film-forming reactions that are similar to those that cause failures in service environments. In many of these procedures the parts under test are exposed for days or weeks to controlled quantities of both water vapor and pollutant gases, which may be present in extremely dilute concentrations.

Note 2—Descriptions of such tests can be found in Practice B827.

4.2 Many of these environmental test methods require monitoring of the conditions within the chamber during the test in order to confirm that the intended environmentally related reactions are actually taking place. The most common type of monitor consists of copper, silver, or other thin metallic coupons of a few square centimeters that are placed within the test chamber and that react with the corrosive environment in much the same way as the significant surfaces of the parts under test.

4.3 In practice, a minimum number of control coupons are placed in each specified location (see Test Method B810) within the chamber for a specified exposure time, depending upon the severity of the test environment. At the end of this time interval, the metal samples are removed and analyzed by the coulometric reduction procedure.

4.4 Other corrosion film evaluation techniques for metallic coupons are also available. The most common of these is mass gain, which is nondestructive to the surface films, but is limited to the determination of the total amount of additional mass acquired by the metal as a result of the environmental attack. The most common is weighing using high performance microbalances or for purposes of real-time monitoring, quartz crystal microbalances (see Specification B808).

Note 3—Detailed instructions for conducting such weighings, as well as coupon cleaning and surface preparation procedures, are included as part of Test Method B810.

Note 4—Some surface analytical techniques (such as X-ray methods) can provide nondestructive identification of some compounds in the films, but such methods, for example, X-ray diffraction, can miss amorphous compounds and compounds present in quantities less than 58201;% of the tarnish film volume.

4.5 With the coulometric technique, it is possible to resolve the complex total film into a number of individual components (Fig. 1) so that comparisons can be made. This resolving power provides a fingerprint capability for identifying significant deviations from intended ......

ASTM B825-13 Referenced Document

• ASTM B808 Standard Test Method for Monitoring of Atmospheric Corrosion Chambers by Quartz Crystal Microbalances
• ASTM B809 Standard Test Method for Porosity in Metallic Coatings by Humid Sulfur Vapor ("Flowers-of-Sulfur")*， 2024-04-20 Update
• ASTM B810 Standard Test Method for Calibration of Atmospheric Corrosion Test Chambers by Change in Mass of Copper Coupons
• ASTM B827 Standard Practice for Conducting Mixed Flowing Gas (MFG) Environmental Tests
• ASTM D1193 Standard Specification for Reagent Water

ASTM B825-13 history

• 2019 ASTM B825-19 Standard Test Method for Coulometric Reduction of Surface Films on Metallic Test Samples
• 2013 ASTM B825-13 Standard Test Method for Coulometric Reduction of Surface Films on Metallic Test Samples
• 2002 ASTM B825-02(2008) Standard Test Method for Coulometric Reduction of Surface Films on Metallic Test Samples
• 2002 ASTM B825-02 Standard Test Method for Coulometric Reduction of Surface Films on Metallic Test Samples
• 1997 ASTM B825-97 Standard Test Method for Coulometric Reduction of Surface Films on Metallic Test Samples