Salt spray testing ASTM

Corrosion Testing. Salt spray testing (ASTM-B-117-52,54) was used to determine durability of adhesive bond in corrosive environment. Lap shear samples were exposed to salt spray for 14 days and then immediately tested for lap shear strength. 

Magnesium and its alloys Salt spray test ASTM... 

The Copper-Accelerated Salt Spray Test, ASTM B 368, commonly known as the CASS test, is typically used for testing copper-nickel chrome products. It was developed by the American Electroplaters Society as AES Research Project 15 [12], along with the Corrodkote Test (ASTM B 380) and incorporated into ASTM in 1965. 

The current salt spray test, in which the plated specimen is exposed to a spray or fog of sodium chloride solution, is the most widely used accelerated corrosion test for coatings, and various procedures have acceptance tests in standard specifications in numerous countries. Over the years, the procedure has employed sodium chloride solutions of concentrations between 3 and 20 %, sometimes with the addition of hydrochloric acid or hydrogen peroxide. The salt spray test [ASTM B 117, Test Method of Salt Spray (Fog) Testing] has largely fallen into disrepute because of the recognition that its reproducibility and correlation with outdoor exj>osure were often poor. Cyclic salt spray testing as well as alternate electrolytes such as the "prohesion test solution have been found to produce more realistic results. 

It was reported that the early salt spray tests (ASTM B 117) did not yield useful results when applied to chromium-plated brass specimens, while the results of a hydrochloric acid spray test were claimed to be in good agreement with the behavior of this material during weathering [10. ... 

Applicable test methods include [28] Continuous Salt Spray Tests (ASTM B 117), Neutral Salt Spray Test (ASTM B 117), Acetic Acid Salt Spray Test, Copper-Accelerated Salt Spray Test (CASS) (ASTM B 368), Cyclic Salt Spray Tests, the Copper Development Association (CDA) Test, the Hitachi Salt Spray Test, Climate Tests, The Humidity Test, The International Electrotechnical Commission/Intemational Organization for Standardization (lEC/ISO) Test and Mud Test. 

The basic in vitro tests derived from teehnieal applications are the salt spray test (ASTM B-117) and the submersion test, performed in saline solutions (3.5% NaCl, ASTM G31-72 (2004) Standard Practice for Laboratory Immersion Corrosion Testing of Metals). Both tests are conducted at room temperature. By such tests the mass loss ean be determined according to equation (10.5). The mass loss is calculated after removing the corrosion products with chromic acid, which at the same time removes the corrosion products and inhibits further corrosion (Forking, 1964), which is suitable for technical applications but may raise problems in biological environments. 

The most widely used accelerated tests are based on salt spray, and are covered by several Government Specifications. BS 1391 1952 (recently withdrawn) gives details of a hand-atomiser salt-spray test which employs synthetic sea-water and also of a sulphur-dioxide corrosion test. A continuous salt-spray test is described in ASTM B 117-61 and BS AU 148 Part 2(1969). Phosphate coatings are occasionally tested by continuous salt spray without a sealing oil film and are expected to withstand one or two hours spray without showing signs of rust the value of such a test in cases where sealing is normally undertaken is extremely doubtful. 

For the salt fog test, ASTM-B117, panels were placed on a rack in a salt fog spray for 500 or 1000 hours at a... 

Coated specimens were placed in an electrochemical cell. After 4 hours of temperature, open-circuit potentials were measurements were made on duplicate samples, in a salt spray test cabinet (ASTM B117-73) for 1, 17 and 96 hours respectively and their surfaces photographed in order to calculate the percentage of surface covered by corroded spots and blisters (ASTM D610-68). 

Figure 7. Paint adhesion loss in salt spray exposure (ASTM B117) as a function of ester content for chain-extended epoxy-amine and epoxy-ester resin based coatings. All coatings applied at 20-25 urn film thickness to SAE 1010 steel test panels, baked, scribed and exposed for 24 hours to salt spray conditions.

Figure 8. Zinc dust paints based on an epoxy ester after a 168-h salt spray test in accordance with DIN 50 021 and ASTM B 117-64 left, control paint right, paint containing 2% Aerosil R 972 related to zinc dust mass.

One of the most common accelerated exposure tests is the salt spray or salt fog test described in ASTM B117 [84]. In this test, samples are exposed to a spray or fog of 5% NaCl solution at 30 C. Several US military specifications require salt fog testing, and many corrosion engineers have considerable experience with this test. It is therefore of use as a qualification procedure to evaluate materials. However, the results of salt spray testing do not always correlate with other types of exposure, and considerable variability in test results is not uncommon. 

ASTM G85 describes modified versions of salt spray testing in which the spray solution is acidified with acetic acid, SO2 is added, or the test conditions are cycled. These modifications result in a more corrosive environment than the standard salt spray test. 

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