Accelerated tests method

An extensive survey of accelerated test methods for anticorrosive coating performance which emphasizes the need to develop more meaningful methods of testing has been pubUshed (129). The most powerful tool available is the accumulated material in data banks correlating substrate, composition, apphcation conditions, and specifics of exposure environments with performance. 

Portland cement is susceptible to corrosion by CO2 and H2S. The chemical attack by CO2 is called carbonation. A microsample technique has been developed to study the CO2 corrosion in cements, because the corrosion is difficult to monitor with common test procedures [264]. This technique is also advantageous as an accelerated testing method. A polymer-modified cement has been tested in field studies [694]. The addition of silica also improves chemical resistance [146], in particular brine corrosion. 

It might be interesting to note how far the results of accelerated test methods agree with full-length outdoor exposure and the effect of natural daylight. The correlation between outdoor or daylight exposure, including factors such as location,... 

In a search for reliable accelerated test methods for determining coating performance, electrochemical techniques have often been explored. The corrosion resistance of a coated steel panel is a composite of the steel quality, its surface finish and the quality of the coating. For this reason. Bonderite 40 coated steel panels were included in our work. They were employed primarily to aid in the interpretation of the electrical measurements for the nitrile-based photocured samples. 

Before heginning a series of experiments to measure corrosion rates or to study some other aspect of corrosion, it is important to determine clearly what the goal of the work is. Usually, such studies require the use of an accelerated test method to provide answers to problems quickly. Exposure testing in the service environment is an important tool in corrosion engineering, hut the time frame for exposure tests is often too long for timely decisions on design. 

B.S. Skerry, C.H. Simpson, Accelerated test method for assessing corrosion and weathering of paints for atmospheric corrosion control. Corrosion 49 (1993) 663—674. 

A quick check of extrusion properties of ceramic compounds can be made using a simplified capillary-rheometric method. A one-point or two-point determination can, for example, make it possible to quickly select promising compound compositions. The accelerated test method was used in the development of a compound from aluminium oxide for making catalyst supports. Two criteria were here taken into account ... 

Attempts to support such estimates simply by using laboratory data and accelerated testing methods, with high temperatures and so on, have not been particularly successful. To quote Nagae and Otsuka [33],. . many researchers have investigated the corrosion behaviour of GRP [glass rein-... 

Develop time- and geometry-based scaling techniques to relate laboratory tests to the real performance of a structure, and accelerated test methods for simulating long-term ageing. 

Figure 2.14 Hands-on accelerated testing method for long-term thermo-oxidative degradation.

Devalapura, R. K., M. E. Greenwood, J. V. Gauchel and T. J. Humphrey (1998). Evaluation of GERP performance using accelerated test methods. First International Conference on Durability of Fiber Reinforced Polymer Composites for Construction, Sherbrooke, Quebec, Canada, pp. 107-116. 

The described mechanisms of atmospheric corrosion demonstrate the importance of pollutants and of humidity cycles. Unfortunately, the complexity of the underlying phenomena, makes it difficult to predict atmospheric corrosion behavior Irom accelerated testing. Outdoor exposure tests, which generally require several years, therefore remain popular. Different norms and recommended practices fix in detail the conditions to be applied in atmospheric corrosion tests. The following accelerated test methods are most commonly used in the laboratory ... 

Current accelerated testing methods are empirically correlated with field performance, and acceleration factors are often deduced firom relative differences in the evolution of damage over time. However, there is often little understanding of why a given method succeeds or whether it will be effective on another coating, material, or in another environment, because the rules that determine its applicability to other situations are not understood. The uncertainty surrounding... 

Gray RL (1990) Accelerated Testing Method for Evaluating Polyolefin Stability. In Koemer RM (ed) (leosynthetic Testing for Waste Ckmtainment Applications ASTM special technical Publication 1081. American Society for Testing and Materials (ASTM), West Conshohocken, pp 57-74... 

It has been shown that an accelerated test method (the automatic boil test—ASTM D-3434) is convenient for evaluating adhesive performance and for predicting durability for exterior applications. Samples are subjected to 800 cycles, which corresponds to approximately 16 years of exterior exposure for a good wood adhesive. Figure 6 compares the perform-... 

Accelerated test methods using artificial light sources reduce the time span of a test, but outdoor exposure is the only real means of obtaining reliable information. Most manufacturers use data based on trials in Florida, USA. Outdoor exposure data are reported in klloLangleys - a unit of energy irradiation (1 kLy = 1 kcal cm ). On average, 140 kLy relate to one year of exposure in Florida and 190 kLy to one year in Arizona. 

The number of available cyclic corrosion tests are too many to outline. ASTM Subcommittee D 01.27, Accelerated Test Methods, has formalized a document on laboratory corrosion tests that is published as ASTM D 6899. 

Lifka, B. W. and Sprowls, D. O., Relationship of Accelerated Test Methods for Exfoliation Resistance in 7XXX Series Aluminum Alloys with Exposure to a Seacoast Atmosphere, Corrosion in Natural Environments, ASTM STP 558, ASTM International, West Conshohocken, PA, 1974, pp. 306-333. 

The slow strain-rate test method (10 s" to 10" s" ) is an accelerated test method when compared with a sustained-load test method. The slow strain-rate test provides an "accelerated test for measuring the threshold when compared with the 5000 hours required by ASTM E 1681, for steels at a hardness of 50-52 HRC. 

Johnson, D. A., Miltenberger, M. A, and Ahny, S. L., "Determining Chloride Diffusion Coefficients for Concrete Using Accelerated Test Methods, Third CANMET/ACI International Conference on Concrete in Marine Enviromnent, St. Andrews by-the-Sea, New Brunswick, Canada, August 4-9, 1996, Supplementary Papers, pp. 95-114. 

If the goal is a mechtinistic/kinetic investigation of the corrosion process, ag lin examination of samples after field exposure in the enviromnent of interest may be the ideM. When this is not possible or practical, accelerated test methods should be used. If possible, these accelerated methods should have been previously verified to result in the same extent and mechtuiism of degradation as actutd field exposure. ElectrochemiceJ methods can often provide important mechanistic/kinetic information about a corrosion process. Surface m j3rtical, metcJlographic, or spectroscopic methods, or a combination thereof, can also be important components of 2my mechanistic study of metallic corrosion. 

Appleman, B. R., Survey of Accelerated Test Methods for Anticorrosive Coating Performance," Journal of Coatings Technology, Vol. 62, No. 787, August 1990, pp. 57-67. 

S] Appleman, B. R., "Survey of Accelerated Test Methods for Anti-Corrosive Coating Performance, Monograph prepared for Corrosion Committee of Federation of Societies for Coatings Technology, June 1990, available from FSCT, Blue Bell, PA. 

Test methods Standardization of test methods Relation between properties of specimens and of a material in a structure Testing of structures in natural scale Accelerated test methods and evaluation of durability New test methods computer image analysis, tomography, micro-indentation, etc. 

Table 1.3. General accelerated test methods in PEM fuel cell lifetime analysis...

In the mid-1980s experiences with field failures in electronic equipment made it clear that existing accelerated test methods were inadequate for discovering failure processes caused by fine particle deposition. A method was needed to apply a realistic layer of particles on circuit boards or test substrates to answer questions such as ... 

In addition, the usefulness of each mechanism depends on the service environment. Guruviah studied corrosion of coated panels under various accelerated test methods with and without sodium chloride (salt). Where salt was present, electrolytic resistance of the coatings was the dominant factor in predicting performance. However, in a generally similar method with no sodium chloride, oxygen permeation was the rate-controlling factor for the same coatings [2]. 

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