![]() ![]() ![]() It is not recommended to use ASS or CASS test cabinets for NSS tests, since a thorough cleaning of the cabinet after ASS or CASS test is very difficult. Other solutions are acetic acid (ASS test) and acetic acid with copper chloride (CASS test), each one chosen for the evaluation of decorative coatings, such as electroplated copper-nickel-chromium, electroplated copper-nickel or anodized aluminium. Results are represented generally as testing hours in NSS without appearance of corrosion products (e.g. Tests performed with a solution of NaCl are known as NSS (neutral salt spray). ![]() Typical volumes of these chambers are of 400 L, but they can be constructed larger. This produces a corroding environment in the chamber and thus, parts in it are attacked under this severe corroding atmosphere. The apparatus for testing consists of a closed testing chamber, where a salted solution (mainly, a solution of sodium chloride) is sprayed by means of a nozzle. Nevertheless, salt spray test is widely used in the industrial sector for the evaluation of corrosion resistance of finished surfaces or parts. There is no correlation between the duration in salt spray test and the expected life of a coating, since corrosion is a very complicated process and can be influenced by many external factors. Test duration depends of the corrosion resistance of the coating the more corrosion resistant the coating is, the longer the period in testing without showing signs of corrosion. ![]() The appearance of corrosion products (oxides) is evaluated after a period of time. Salt spray test is an accelerated corrosion test that produces a corrosive attack to the coated samples in order to predict its suitability in use as a protective finish. Since coatings can provide a high corrosion resistance through the intended life of the part in use, it is necessary to check corrosion resistance by other means. Coatings provide corrosion resistance to metallic parts made of steel, zamak or brass. Salt spray test is a standardized test method used to check corrosion resistance of coated samples. ![]()
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