Atmospheric corrosion test chambers

ASTM B 810, Test Method for Calibration of Atmospheric Corrosion Test Chambers by Change in Mass of Copper Coupons. 

In atmospheric corrosion testing, it is customary to perform tests in special climate chambers in addition to field tests. The tests are used for comparison but are also valuable for determining the behavior of anticorrosive films and coatings. The conditions used to obtain the appropriate atmospheres, constant or alternating condensed water climates, with and without the presence of such additional substances as sulfur dioxide and salt spray, and at various pH values, are specified in the standards (DIN 50 018 1978 DIN 50 021 1975 ASTM B 117-85 1985 ASTM G 87-84 1984 ASTM G 91-86 1986 ASTM G 85-85 1985). 

The salt spray test provides testing under atmospheric corrosion conditions. The sample is exposed to a continuously sprayed salt solution in a humidified, temperature-controlled closed chamber. The chamber is composed of an atomizing nozzle and a salt solution... 

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. 

Cabinet tests are the most commonly used laboratory tests in the automobile industry. These have been developed to simulate the effects of atmospheric corrosion 44. Normally, a test chamber is used and the desired environment is introduced under controlled conditions. A list of these tests is given in Table 6. The simplest of these is the humidity test whereby the temperature and relative humidity within a chamber are controlled. A condensing humidity chamber, which operates at 100 % relative humidity and 38°C, provides... 

ASTM B 808 Test Method for Monitoring of Atmospheric Corrosion Chambers by Quartz Cyrstal Microbalances... 

Following the run, the lower housing was removed, and the specimens and test chamber were heated with an electric air heater to prevent condensation of atmospheric moisture. The test specimens were usually removed from the apparatus as quickly as possible to minimize the possibility of corrosion. 

The cone calorimeter is also used to quantify the corrosivity of products of combustion as described in ASTM D 5485. The Cone Corrosimeter uses the same load cell, specimen holder, retainer frame, spark igniter, conical heater, and exhaust system as the cone calorimeter. A heated stainless steel sampling tube is connected to a funnel placed on top of the conical heater. A gas sample is continuously drawn from the tube at a rate of 4.5 L/min. The sampling tube is connected with silicone rubber tubing to the pump via an 11.2L exposure chamber, a filter, and a flow meter. A target is placed in the exposure chamber at the start of the test and exposed to the corrosive atmosphere of the gas sample for 60 min or until the specimen has lost 70% of its total mass loss, whichever occurs first. 

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