Corrosion and Oxidation

The annual cost of corrosion worldwide is estimated to be a whopping $2.3 trillion. So, it is imperative to carry out substantial research in this field to avoid the undesirable and sudden catastrophic failures of the components suffering from severe corrosion attacks. Our group primarily deals with the sensitization phenomena, intergranular corrosion, and pitting corrosion in various steels and Ni-based superalloys which serve as potential candidates in applications such as gas turbines, nuclear power plants, aerospace, chemical and oil, and gas industries. Additionally, we also aim to comprehend the corrosion taking place at higher temperatures (in a temperature range of 800°C -1000°C), popularly known as high-temperature hot corrosion (HTHC) phenomenon. Several conventional approaches such as lowering carbon content, addition of nonchromium carbide-forming elements (i.e., Ti, V, Nb,etc.), addition of suitable elements like Cr, Mo, N etc., inhibitors, and cathodic/anodic protection, use of appropriate coatings, frequent washing of hot components to remove the adhered salts/contaminants and installation of high-efficiency air filters, have been previously adopted to combat aqueous, pitting as well as hot corrosion phenomenon. However, all of these routes generally alter the mechanical properties and in essence, add to the cost. In this context, the microstructural engineering approach i.e. grain boundary engineering (GBE) and grain boundary serrations (GBS) has evolved as one of the most promising approaches over the conventional methods since it does not invoke on changing the chemical composition of the materials. GBE primarily focuses on enhancing the resistance against the interfacial degradation phenomenon (in this case corrosion) by optimizing the grain boundary character distribution (GBCD).The GBCD is optimized by introducing a large proportion of the low Ʃ (Ʃ⩽29) coincident site lattice (CSL) boundaries that effectively disrupt the random high angle grain boundaries (RHAGBs) network. We have already established the effect of GBS on the HTHC behavior and it is the ‘first-of-its-kind’ of study. Oxidation is also a crucial problem for the proposed materials at high-temperature applications. Recently, we have established a set-up to carry out oxidation studies on certain alloys that are prone to oxidation. Currently, we are trying to understand the underlying mechanism behind oxidation phenomena and in finding efficient ways to model and enhance the oxidation resistance of materials.

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