Abstract
This study was carried out to evaluate a series of ceramic coatings in a sulfidation atmosphere containing 99% synthetic air and 1% H2S (vol.%) under a flow rate of 50 mL/min. The study was carried out at 773.15 K for 336 hours (heating rate 278.15 K/min). Chemically resistant glass enamels based on SiO2-B2O3-TiO2-Na2O compounds were deposited on the surface of 16Mo3 (16M) low-alloyed steel. Kinetic data were recorded periodically every 168 hours; macro- and microanalyses using scanning electron microscopy (SEM), phase analyses using x-ray diffractometry (XRD) and chemical composition using energy-dispersive x-ray spectrometry along with EDS x-ray mappings were carried out to observe the degradation process of the sulfidized coatings. The results indicated that some of the ceramic coatings exposed in the harsh atmosphere at 773.15 K for 336 hours showed a high degree of protection.
Highlights
Thermodynamic efficiency in the ultra-supercritical (USC) plants is achieved by increasing the operating temperatures and pressures, which lowers fuel consumption and subsequently the emissions (Ref 1)
The other coatings showed a decent corrosion resistance in the sulfide atmosphere, and despite this, some of the coatings showed some porosity and hole formation during preparation. These holes and subsequent levels of porosity showed no big influence on the overall corrosion resistance of the applied ceramic coatings; the coatings with a higher concentration of holes and porosity indicated poorer sulfidation resistance
The results presented clearly show that exposure of ceramic coatings to a 99% synthetic air–1%H2S gas mixture indicates a relatively low mass gain; three out of four coatings showed similar results, where mass gain after 336 hours at 773.15 K/min reached around 1.9 mg/cm[2]
Summary
Thermodynamic efficiency in the ultra-supercritical (USC) plants is achieved by increasing the operating temperatures and pressures, which lowers fuel consumption and subsequently the emissions (Ref 1). The European goal of decreased CO2 emissions is a clear-cut requirement, which marks a historical turnover whereby Europe shall become fully neutral by 2050 (Ref 2) This can only be achieved by maximizing the efficiency of the plants and using biomass, which is considered carbon neutral. Very little is known about the effects of the conditions in ultra-supercritical (USC) plants and the effects impurities from biomass may have on the corrosion resistance of the hot components in power plants (boiler walls, superheaters (SH), re-heaters (RH)) These components are already operating at the limit of their tolerance in less critical plants, and a radical step forward will be needed in materials technology to ensure the durability of components in such aggressive environments. There are many different types of thermal spray coating systems including plasma, wire, flame and kinetic; the most popularly used ones include high-velocity oxy-fuel (HVOF) or air, atmospheric plasma spray (APS) and others (Ref 6-10)
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