The variety of conditions in which corrosion appears and its various forms makes corrosion analysis a complex process. Because of the variety of corrosion forms and conditions, there is no universal corrosion test for all situations.

Examples of the types of problems:

• Stress Corrosion Cracking
• Pitting
• Galvanic Reactions
• Intergranular
• Microbiological Attack
• Electric Current Loops
• Erosion
• Hydrogen Embrittlement
• Oxidation
• Dezincification
• Sensitization
• Metal dusting
• Stray current fields

A method, for measuring the parameters of cathodic protection of the structures which are protected by electrolysis or by sacrificial anodes, comprises fixed programs for executing data acquisition and processing, measurement steps with high speed data sampling and digitizing in the passive and active modes of operation, generating a constant current pulse being sourced into or sunk from electrolyte containing said structures while in a measurement step, and generating a forced off-state condition in the vicinity of a test point of said structures. And, an active corrosion analyzer, (for implementing said method for measuring the polarized potential, the IR-drop, the depletion region capacitance, the coating capacitance, the equivalent voltage, and the equivalent resistance), comprises a microcontroller, a precision timing generator, a non-volatile memory, a random access memory, an analog to digital converter, constant current generators, and control elements.

X-ray powder diffraction (XRD) represents the method of choice for the analysis of corrosion products, as it is the only analysis method that readily provides information about the phase-composition of solid materials. For example, a mixture of Fe₃O₄ (magnetite), α-FeO(OH) (goethite) and Fe₅O₇(OH)x4H₂O (ferrihydrite) can be identified and quantified as such, while other analysis methods will only reveal that the corrosion product is Fe-based. Furthermore, XRD can readily distinguish between different crystallographic modifications of phases that have the same chemical formula. For example, the ferrous corrosion products goethite, lepidocrocite, feroxyhyte and akaganeite can be distinguished from each other, even though they all have the chemical formula FeO(OH).
From- http://www.freepatentsonline.com/; http://camet-lab.com/; etc.