Copper-accelerated salt spray test

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. 

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. 

CASS test See copper-accelerated salt-spray test. 

Copper-accelerated salt-spray (CASS) test... 

Acetic acid salt spray test (ASS test) Copper-accelerated acetic acid salt spray test (CASS test)... 

Copper accelerated acetic acid salt spray test... 

Even though the exposure test in practical sites is stiU very important and useful, we StiU need laboratory tests. It would be very useful to accelerate the corrosion characteristics and to evaluate the results in a relatively short time. This category has some laboratory tests filling the gap between the exposure test and very fundamental electrochemical tests. To name a few, we can mention the salt spray test, a CASS (Copper accelerated acetic acid salt spray) test, and a combined cycle test [4],... 

On the other hand, the CASS test utilizes the sodium chloride - copper chloride mixed solution. The addition of copper ion accelerates corrosion much more than the salt spray testing. However, the results might not fit the real phenomenon so precisely in some cases. 

In a salt spray test the sample is brought in contact with a saline fog in a closed chamber for a certain number of hours. The fog is formed by atomizing a NaCl solution by means of a nozzle. The high corrosivity of the artificial fog simulates that of a marine atmosphere, but the method does not offer a realistic model of more general atmospheric corrosion conditions, because it involves neither the presence of SO2 nor humidity cycling. In order to accelerate the corrosion, acetic acid or copper chloride is sometimes added to the saline solution. 

Copper-Accelerated Acetic Acid Salt Spray Testing (CASS Test)... 

The addition of acetic acid to the salt solution used in the salt spray tests was introduced first in 1945 and is currently Annex A1 of ASTM G 85 [Practice for Modified Salt Spray (Fog) Testing]. The acidified test is much more corrosive than the normal salt spray test and is capable of producing a pattern of attack similar to that developed in outdoor service for decorative chromium plate on steel or zinc. It is much slower than the copper-accelerated acetic acid-salt spray (CASS) test in ASTM B 368 [Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test)], [77] which resembles it in effect. 

The most widely used cabinet test is the neutral salt spray (Fog) test (ASTM B 117), which consists of a fog of 5 % sodium chloride within the chamber at 35 C [46. Controversy exists over the validity of B 117 as a performance test because corrosion mechanisms are not always the same as those observed in automobile service. Also, not all materials can be successfully evaluated in the test. However, the value of the salt spray test as a quality assurance test is well documented [46]. Several modifications to the salt spray test have been developed including acetic acid salt spray (ASTM G 85, Annex 1), copper accelerated acetic acid salt spray (ASTM B 368), acidified synthetic seawater fog (ASTM G 43, Method of Acidified Synthetic Seawater (Fog) Testing), and modified salt spray (ASTM G 85). ASTM G 85 also includes cyclic tests. 

Table 7.7 provides a comparison between the CeCC (Bi-accelerated) and CrCC over a range of tests more appropriate for architectural applications. In most cases the CeCC is very similar to the CrCC under both polyester paint and a cathodic eCoat. Specifically, in the constant stress tests (filiform, acetic acid salt spray (AASS) and copper assisted salt spray (CASS)), the CeCC matches the CrCC with a few instances where the performance is poorer particularly in AASS and CASS. Perhaps the most important tests are the outdoor tests, which represent real test enviromnents and imder these conditions the CeCC matches the CrCC. 

The CASS Test. In the copper-accelerated acetic acid salt spray (CASS) test (42), the positioning of the test surface is restricted to 15 2°, and the salt fog corrosivity is increased by increasing temperature and acidity, pH about 3.2, along with the addition of cupric chloride dihydrate. The CASS test is used extensively by the U.S. automobile industry for decorative nickel—chromium deposits, but is not common for other deposits or industries. Exposure cycle requirements are usually 22 hours, rarely more than 44 hours. Another corrosion test, now decreasing in use, for decorative nickel—chromium finishes is the Corrodkote test (43). This test utilizes a specific corrosive paste combined with a warm humidity cabinet test. Test cycles are usually 20 hours. 

ASTM B368, Std. Methodfor Copper-Accelerated Acetic Acid Salt Spray (Fog) Testing (CASS Test), American Society for Testing and Materials, Philadelphia, Pa., 1990. 

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