Salt water immersion testing

The salt water immersion test (SWI) and the standard salt spray (fog) test (SS) were conducted for both ISPCs and control baking enamels applied on bare CRS, iron phosphated B-1000, and BD+P60 panels. The painted coupons of about 1.0 mil dry film thickness cured at 163 C for 15 minutes were X-cut through the film to the substrate and then either immersed in a 3% NaCI solution (SWI test) or subjected to a continuous salt-solution spray in a test chamber (SS test). After a specified duration of testing, the specimens were removed from the salt solution, and the coated surface was immediately dried. A DUCK brand tape (Manco, Inc., Westlake, OH) was applied over the X-cut and then removed, and the protective performance was... 

Minford also studied the effects of four different phosphoric acid processing conditions under stress and intermittent salt-water immersion testing of 6061-T6 aluminum alloys. None of the joints pretreated by varying phosphoric acid anodizing conditions failed after 480 days exposure, even... 

Organic coatings are commonly evaluated using salt water immersion, salt fog or spray, modified salt exposure tests (e.g., salt fog with added SO2), and various cyclic exposure tests. Humidity exposure and water immersion, and, for many applications, physical resistance tests (adhesion, impact resistance, etc.) are widely used preliminary tests. Standard methods for most of these tests are given in compilations of standard tests such as the Annual Book of ASTM Standards (16). Test methods have been extensively reviewed (e.g., 17-23). 

Nonelectrochemical Methods. Nonelectrochemical methods of studying corrosion include exposure tests of performance and primary film property measurements. Standard exposure tests include salt water immersion (3-5% aq. NaCl, usually at room temperature, sometimes oxygen saturated) cyclic immersion (e.g., salt water immersion alternated with drying periods) salt fog or spray (5% aq. NaCl fog,... 

Figure 5.37 shows the elfects of the water immersion test (distilled and salt water) on peel strength of NR and CR rubbers for 30 days at ambient temperature. The result is then compared with the dry sample of NR and CR rubbers. Within the 30-day period there is no sign of deterioration of the peel strength. The amount of water absorbed is relatively negligible and for this reason the peel strength is relatively unalfected. This is consistent with the findings of Ab-Malek et al.f who reported that the rubber tyre had absorbed about 5% of sea water after 42 years of immersion. 

The salt-water corrosion test is used to evaluate submarine splice closures. For this test a spUce closure tuid its outer housing are immersed in aerated 3.5 % sodium chloride solution for 180 days. The test is described in TA-TSY-041 [17]. The same closures are also exposed to a similar test using artificial fresh water (ASTM D 2570, Method for Simulated Service Corrosion Testing of Engine Coolants). 

Alternate Immersion in 3.5% NoCl. Exposure to 3.5% sodium chloride or to substitute ocean water (ASTM D 1141) by alternate immosion (ASTM G 44) (see Table 1) is a widely used procedure for testing smooth specimens of aluminum alloys. Aeration of the specimens, achieved by the alternate immersion, enhances the corrosion potential (Ref 26) and produces more rapid SCC of most aluminum alloys than continuous immersion. The ASTM G 44 standard practice consists of a 1 h cycle that includes a 10 min soak in the aqueous solution followed by a SO min period out of solution in air at 27 °C (80 °F) and 45% relative humidity, during which time the specimens are air dried, lliis 1 h cycle is repeated continuously for the total number of days recommended for the particular alloy being tested. IVpically, aluminum alloys are exposed from 10 to 90 days, depending on the resistance of the alloy to corrosion by salt water. This test ntethod is widely used for testing most types of aluminum alloys with all types of smooth specimens. 

Reference to Table 4.19 will show that greatly superior corrosion rates of the high-purity alloys are only in evidence in the more severe conditions of test by immersion in salt water, and that in less drastic conditions, and especially in industrial atmospheric exposure, there is little to choose between the alloys. 

In considering the corrosion of magnesium and its alloys it is important to examine the methods available for assessing corrosion tendencies and particularly those known as accelerated tests. Tests carried out by immersion in salt water or by spraying specimens regularly with sea-water are worthless as a means of determining the resistance of magnesium alloys under any other than the particular test conditions. Extrapolation to less corrosive conditions is not valid and even the assessment of the value of protective measures by such means is hardly possible. The reason is to be found in the fact that corrosion behaviour is directly related to the formation of insoluble... 

A useful spot test utilizes the fact that a suspension of red nickel dimethylglyoxime in water when treated with a neutral or acetic acid solution of a palladium salt yields the yellow palladium dimethylglyoxime, which is sparingly soluble in dilute acids. The test is best performed with dimethylglyoxime paper the latter is prepared as follows. Immerse drop-reaction paper in a 1 per cent alcoholic solution of dimethylglyoxime, dry, then immerse again in a solution of 05m nickel chloride rendered barely ammoniacal. The nickel complex precipitates wash thoroughly with water, immerse in alcohol and dry. 

In an effort to confirm the performance of Hypalon liners in concentrated brine solutions at high temperatures, immersion tests were set up. Potable grade Hypalon, which was used in the brine pits as well as in the New Mexico salt gradient pond was compared to a new grade of Hypalon - Industrial grade, which shows less water swell at elevated temperatures. Both materials were tested in distilled water as a control and in 20%... 

Immersion tests in distilled water, tap water, and seawater have shown that chromized steels exhibit high corrosion resistance to these solntions. After 8 h testing in a salt spray fog at 35°C, chromized steel was less affected than alnminized steel, galvanized steel, or a 17% Cr steel. 

Minford has shown the exceptional strength retention of nitrile-phenolics, such as FM-61, on aluminum after extended salt spray, water immersion, and other long-term exposure tests. It is probably true that no other adhesive type exceeds the ability the nitrile-phenolics to maintain good strength on steel or aluminum after extended exposure to water, salts, or other corrosive media, and to prevent undercutting through corrosion of the metal substrate. ... 

The test consists of immersing rubber-to-metal bonded test-pieces in distilled water and salt water for 30 days at ambient temperature. The changes in weight before and after the test are noted. 

Tables are available in American Society for Metal, (1984, p. 283) that summarize filler alloy selection recommended for welding various combinations of base metal alloys to obtain maximum properties, including corrosion resistance. Care must be taken not to extrapolate the corrosion performance ratings indiscriminately. Corrosion behavior ratings generally pertain only to the particular environment tested, usually rated in continuous or alternate immersion in fresh or salt water.

---