Persona: Pascual Ferreiro, Jon
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Pascual Ferreiro
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Publicación Acceso Abierto Rapid α-Al2O3 Growth on an Iron Aluminide Coating at 600 °C in the Presence of O2, H2O, and KCl(ACS Publications, 2024-10-17) Agüero, Alina; Audigié, Pauline; Sergio, Rodríguez Catela; Gutiérrez del Olmo, Marcos; Pascual Ferreiro, Jon; Ssenteza, Vicent; Jonsson, Torbjörn; Johansson, Lars Gunnar; Agencia Estatal de Investigación (España); European CommissionIn this work, a slurry iron aluminide-coated ferritic steel SVM12 was subjected to a laboratory experiment mimicking superheater corrosion in a biomass-fired power boiler. The samples were exposed under model Cl-rich biomass conditions, in a KCl + O2 + H2O environment at 600 °C for 168, 2000, and 8000 h. The morphology of corrosion and the composition of the oxide scale and the coating were investigated by a combination of advanced analytical techniques such as FESEM/EDS, SEM/EBSD, and XRD. Even after short-term exposure, the coating developed a very fast-growing and up to 50 μm thick α-Al2O3 scale in contrast to the spontaneous formation of a protective, thin, dense, slow-growing, and very adhesive α-Al2O3 layer usually formed on metallic materials after high-temperature oxidation. In view of the literature on the formation of oxide scales on alloys and coatings, the formation of an α-Al2O3 scale at this relatively low temperature is very surprising in itself. The thick alumina scale was not protective as its formation resulted in fast degradation of the coating and rapid Fe2Al5 → FeAl phase transformation, which in turn generated porosity inside the coating. In all cases, the resulting thick Al2O3 scale was porous and consisted of both equiaxed α-Al2O3 grains and randomly oriented aggregated alumina whiskers. Potassium is concentrated in the outer part of the Al2O3 scale, while chlorine is concentrated close to the scale/aluminide interface. The unexpected formation of rapidly growing α-Al2O3 at relatively low temperature is attributed to the hydrolysis of aluminum chloride generated in the corrosion process.Publicación Acceso Abierto Modified high hardness steel coating for biomass corrosion protection(Springer Nature Link, 2025-09-13) Agüero, Alina; Gutiérrez del Olmo, Marcos; Audigié, Pauline; Sergio, Rodríguez Catela; Pascual Ferreiro, JonBiomass is a renewable and CO2-neutral energy source. However, the efficiency of biomass combustion plants remains lower than that of current fossil fuel-based systems. To minimize corrosion from aggressive species found in biomass combustion, these plants currently operate at a maximum temperature of 550 °C. The European project BELENUS explored new materials and coatings to raise the operating temperature to 600 °C, thereby improving plant efficiency. Among the coatings under investigation, a super high-hardness steel (SHS) modified with Al, applied by high velocity oxy-fuel (HVOF) thermal spray on ferritic steel SVM12, has demonstrated an improved performance in the laboratory, exposed to a model biomass environment containing KCl deposits for 8000 h at 600 °C. Microstructural analysis by field emission scanning electron microscopy (FESEM) and X-ray diffraction was conducted on the tested samples to examine the coating’s evolution in these environments, as well as the associated protection and degradation mechanisms. The presence of Al within the coating significantly enhanced its resistance to biomass corrosion when compared to uncoated SVM12 and the Al-free SHS coating. Possible reasons for the improved behaviour of the Al-modified coating are the reduction of porosity as well as the blocking effect of either intermetallic FeAl or Al oxide which forms at the splat boundaries prior to exposure to the corrosive atmosphere.
