STUDY OF GRAPHENE COATING EFFECTIVENESS FOR MITIGATING LOW-TEMPERATURE HOT CORROSION IN SS630 STAINLESS STEEL

In this work, the hot corrosion behavior of stainless steel 630 (17-4 PH) with and without a graphene nanoplatelet covering is examined during cyclic thermal exposure in both salt-free and salt-laden conditions. Prior to testing, SS 630 specimens were selected due to their exceptional strength and resistance to corrosion and were ultrasonically cleaned, mirror polished and precisely machined. To improve adhesion, a controlled dip coating method was used to apply a stable graphene dispersion made in ethanol, which was then thermally cured. A 1:1 combination of sodium sulfate (Na2SO4) and vanadium pentoxide (V2O5) was utilized to mimic harsh combustion conditions for salt exposure. Three temperatures, 300, 350 and 400 °C, were used for hot corrosion testing with 50 heat cycles per condition. Surface analysis and weight increase measures were used to gauge the extent of deterioration. The findings showed that corrosion rose with temperature, particularly when exposed to salt. The largest weight gain for uncoated specimens in a salt environment was 0.32 g/cm2 at 400 °C. This was considerably lessened by graphene coverings, which decreased the weight growth by up to 52 % in salt-free and 45.6 % in salt-rich environments. Graphene-coated specimens consistently showed 40–55 % less weight increase than uncoated ones across all test conditions, according to comparative analysis. SEM examination confirmed that coated samples had better surface integrity, less oxide spallation, and less scale formation. These results demonstrate graphene’s promise as a strong corrosion barrier for applications involving low temperatures. According to the study, components in heat exchangers, boilers, low-pressure stream turbines and other industrial systems subjected to corrosive and thermal stressors might have their service lives greatly increased by graphene coatings.