Corrosion features initial conditions

As mentioned earlier, the measured system should be stationary and should not evolve with time. In practice, such conditions cannot always be met. For example, corrosion processes may continue during the experiment and change the measured impedance. Such measurements should be carried out quickly. However, very often the most interesting features are observed at low frequencies and the experiment may take hours. In such cases it is possible to follow the evolution of impedances with time at one frequency and then repeat the experiment many times at different frequencies. In order to use such a method, the initial conditions must always... 

As in the case of corrosion failures, the sequence of steps involved in analyzing wear failures are initial examination of the failed component including service conditions to establish the mode or combination of modes of wear failure, metallographic examination to check if the microstructure of the worn part met the specification, both in the base material and in the hardened case or applied surface coatings, existence of localized phase transformations, shear or cold worked surfaces, macroscopic and microscopic hardness testing to determine the proper heat treatment, X-ray and electron diffraction analysis to determine the composition of abrasives, wear debris, surface elements and microstructural features such as retained austenite, chemical analysis of wear debris surface films and physical properties such as viscosity and infrared spectral determination of the integrity of lubricants and abrasive characteristics of soils or minerals in the cases of wear failures of tillage tools. 

The choice of material of construction will influence the extent of possible corrosion and may affect the retention of other deposits, for instance corrosion resistant titanium tubes have been known to foul more rapidly than some stainless steel alloys under similar conditions. It is unlikely in large cooling water systems, e.g. power station condensers, that treatment of the heat exchange surfaces will be considered as a feature for the reduction of fouling, due to the relatively high costs involved including initial cost and maintenance. 

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