Corrosion reduces structural integrity and can ultimately lead to part failure. Furthermore, both scale and corrosion products can result in blockages, necessitating costly downtime and repairs. Powder x-ray diffraction (XRD) is a powerful technique that allows rapid identification of scale and corrosion products. While chemical analysis methods can be used to determine elemental composition, they cannot identify what phases are present in scale and corrosion products. In addition, powder XRD can also distinguish between polymorphic phases with the same chemical composition.
For example, calcium carbonate (CaCO₃), a common scale product, is mainly found in the form of calcite; however, it is also found as other polymorphs, such as aragonite or vaterite, depending on the environmental conditions present during formation. Iron-based corrosion products (e.g., rust) are perhaps the most common type of corrosion products analyzed. Iron(III) oxide-hydroxides can also be found in various polymorphic types such as lepidocrocite, feroxyhyte, and ferrihydrite, which can only be identified using XRD.
XRD allows for phase identification of crystalline materials by comparing a collected diffraction pattern with a reference pattern of a known material in a database, such as the ICDD Powder Diffraction File (PDF). Quantitative multiphase analysis can be performed by using Rietveld analysis on an x-ray diffraction pattern with sophisticated XRD analysis software.
Through the use of our economical AXRD Benchtop unit coupled with powerful XRD analysis software, one can perform quantitative phase analysis utilizing Rietveld refinement to determine the composition of various types of corrosion and scale products.
