Atmospheric corrosion chambers

Schubert, R., "A Second Generation Accelerated Atmospheric Corrosion Chamber, Degradation of Metals in the Atmosphere, ASTM STP 965, ASTM International, West Conshohocken, PA, 1988, pp. 374-384. 

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

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 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). 

Salts present on the surface due to pollution reduce the saturation vapor pressure. They also increase the ionic conductivity of the electrolyte that forms on the metal surface, thus favoring corrosion even more. Table 8.11 gives the relative humidity in equilibrium with solutions of different salts at their saturation concentration. The given values demonstrate that in presence of certain salts condensation can take place at quite low values of relative humidity. In the laboratory, one uses this effect to control the relative humidity during atmospheric corrosion experiments one exposes the sample to air in a chamber that contains a salt solution of known concentration. The saturation vapor pressure then determines the humidity of the atmosphere for any given temperature. 

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. 

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

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... 

Influence ofNOi on Atmospheric Corrosion OF Zinc Exposed in a Climate Chamber... 

Ion Plating film thickness not limited to simple housing designs. not field repairable specialized application equipment vacuum chamber size a limiting factor requires specialized knowledge subject to corrosion in humid atmosphere unless protected. 

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. 

Combustion Chemical Vapor Deposition (CCVD) allows deposition of thin films that confer special electronic, catalytic, or optical properties, corrosion and oxidation resistance. The CCVD process is a novel, open-atmosphere process that is environmentally friendly and does not require expensive reaction/vacuum chambers. Often coatings are of equal or better quality than those obtained by vacuum-based methods. Coating costs are significantly lower than for more traditional processes such as Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD). Equally important, this novel technology can be implemented in a production-line environment, thus enabling uninterrupted processing. To date over 70 different inorganic materials have been deposited onto a variety... 

Steam methane reforming is performed in a high-temperature, high-pressure reaction chamber typically operating between 1,250 to 1,575°C at pressures of 20 to 100 atmospheres. Materials issues are the same as those of high-temperature, high-pressure vessels where creep of corrosion-resistant materials is important for the containment vessel and durability of alumina, chromia, or SiC refractory lining materials is critical to the performance of the system. 

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