Evaluation of high‐temperature corrosion life using temperature gradient corrosion test with thermal cycle component in waste combustion environments

Abstract In energy conversion facilities such as boilers and pyrolysis reactors that burn waste, fossil fuel, biomass and other materials, many corrosion factors, such as gas temperature and fluctuations in gas temperature, the condition of deposits, and gas composition, influence the high‐temperature corrosion rate of materials in a complex manner. In order to evaluate the corrosion behavior and corrosion life time of materials rapidly and accurately, a temperature gradient corrosion test (TGT) was developed and applied to waste incineration environments. The TGT with thermal cycle was carried out without corrosive deposits in order to investigate the basic effect of gas temperature and fluctuation on corrosion behavior, especially in terms of the stability of protective oxide layers. As a result, it was clarified that gas temperature enhances the environmental factors such as the deposition rate of ash and penetration of corrosive species, while thermal cycle mainly enhances material factors such as the breakdown of protective scales. Furthermore, three application case studies of TGTs for corrosion life estimation were carried out with a comparison between TGT and field corrosion data. From these studies, a good correspondence of corrosion rates between TGTs and field tests was obtained. This correspondence of corrosion rate was explained by the breakdown of the protective oxide layer and the penetration of corrosive species in a corrosion front. The reproducibility and applicability of TGTs in the evaluation of the corrosion life time of materials were clarified based on the consideration of various corrosion mechanisms.