Immersion testing cleaning specimens

The EC test was developed by Saur and Basco for decorative Cu (optional) -I- Ni -I- Cr electrodeposits. After an appropriate area is masked off and cleaned with a slurry of MgO, the specimen is immersed in test solution Aor B (Table 19.2). It is held by means of a potentiostat at -I-0-3 V (v5. S.C.E.) and taken through cycles of 1 min anodically polarised, 2 min unpolarised. 

All specimens anodlcally phosphated were Initially polished to 600 grit, cleaned and Immersed In the phosphatlng solution Oxy-Plus 84 DRS, before applying a potential of +0.8V/SCE. This potential corresponds to the passive zone In the cyclovoltammogram obtained for the test steel In the phosphatlng solution. ... 

The ASTM Corrosion Test procedure by Total Immersion Method requires that all specimens in a test series should have the same dimensions when comparisons are to be made. In these experiments, carbon steel was used representing the pipeline material. The coupons were cleaned, polished and weighed. Coal-water slurry, 10 to 40 weight percent, was used in the corrosion tests. For the coal-water slurry the intitial pH of the medium varied from 2.3 to 2.6 and the test series containing the nutrient media, the microorganisms and the inhibitors the pH varied from 2 to 2.5. Specimens were immersed in the reaction vessel maintained at a constant temperature of 86°F for 72 hours or the specified time. The coupons were removed, washed with deionized water, dried and weighed. The loss in weight of the specimen, before and after the test was attributed to corrosion. 

The simplest uniform corrosion tests are those based on coupon immersion and mass loss tests. The tests provide data on the uniform metallic corrosion rate most often expressed in English units as mils per year (mpy) or in metric units as millimeters per year (mm/y). While there are various standards for such tests, the predominant methods are those prescribed by ASTM G 1, "Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens. This standard contains a comprehensive reference list of other ASTM standards that also apply, depending on the type of tests of interest to the investigator. 

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