This study systematically presents the corrosion performance of plasma transferred arc(PTA)cladding,twin wire arc spraying(TWAS)and high-velocity oxygen-fuel(HVOF)spraying coatings through field trials in a 400 t/d wa...This study systematically presents the corrosion performance of plasma transferred arc(PTA)cladding,twin wire arc spraying(TWAS)and high-velocity oxygen-fuel(HVOF)spraying coatings through field trials in a 400 t/d waste-to-energy plant.The results revealed that the high-temperature superheater(HTS)tube exhibited significantly more severe corrosion than the low-temperature superheater(LTS)tube did,primarily due to the higher Cl content in its deposits and elevated tube wall temperature,which promoted the formation of volatile metal chlorides rather than protective oxides.The 2700 h field trial showed that the PTA-NiCr1 coating can be used in both the LTS and HTS areas.The HVOF-NiCr1 coating was competent in the LTS area and performed well on the HTS tube only in the first 900 h,whereas the TWAS-NiCr1 coating was not suitable even in the less corrosive LTS area.Based on microstructure characterization and thermodynamic calculations,the mechanism by which the preparation technique affects the corrosion resistance of the three coatings was further elucidated.The PTA-NiCr1 coating formed a dense dual-layer oxide with a Ni-rich outer layer and Cr-rich inner layer,contributing to the superior corrosion resistance.The Cr oxides formed in the HVOF-NiCr1 coating reacted with NaCl and KCl vapors to generate non-protective chromates,leading to reduced corrosion resistance.The low density of the TWAS-NiCr1 coating enabled the penetration of Cl2 and O_(2) gases into its interior,inducing Fe oxidation in the substrate and thereby increasing the risk of coating delamination.展开更多
基金support provided by the National Natural Science Foundation of China(No.52206143).
文摘This study systematically presents the corrosion performance of plasma transferred arc(PTA)cladding,twin wire arc spraying(TWAS)and high-velocity oxygen-fuel(HVOF)spraying coatings through field trials in a 400 t/d waste-to-energy plant.The results revealed that the high-temperature superheater(HTS)tube exhibited significantly more severe corrosion than the low-temperature superheater(LTS)tube did,primarily due to the higher Cl content in its deposits and elevated tube wall temperature,which promoted the formation of volatile metal chlorides rather than protective oxides.The 2700 h field trial showed that the PTA-NiCr1 coating can be used in both the LTS and HTS areas.The HVOF-NiCr1 coating was competent in the LTS area and performed well on the HTS tube only in the first 900 h,whereas the TWAS-NiCr1 coating was not suitable even in the less corrosive LTS area.Based on microstructure characterization and thermodynamic calculations,the mechanism by which the preparation technique affects the corrosion resistance of the three coatings was further elucidated.The PTA-NiCr1 coating formed a dense dual-layer oxide with a Ni-rich outer layer and Cr-rich inner layer,contributing to the superior corrosion resistance.The Cr oxides formed in the HVOF-NiCr1 coating reacted with NaCl and KCl vapors to generate non-protective chromates,leading to reduced corrosion resistance.The low density of the TWAS-NiCr1 coating enabled the penetration of Cl2 and O_(2) gases into its interior,inducing Fe oxidation in the substrate and thereby increasing the risk of coating delamination.
