To investigate the corrosion behavior and mechanism of candidate alloy for advanced ultra supercritical units firing typical coals in China

the Haynes 282

a candidate nickel-base alloy for key components of 700 ℃advanced ultra-supercritical(A-USC) boilers

was taken as the research object to carry out flue gas corrosion test in simulated flue gas/ash environments firing domestic high sulfur content coal at 650 ℃

700 ℃and 750 ℃. Through the corrosion kinetic curves

X-ray diffraction(XRD)

scanning electron microscope(SEM) and X-ray energy spectrum(EDS)

the corrosion behaviour and products formation mechanism of the Haynes 282 were investigated. The results indicat that

the corrosion rate was the lowest at 650 ℃

high temperature oxidation mainly occurred at this temperature and the major corrosion product was Cr2 O3. Type-Ⅱ sulfate hot corrosion occurred at 700 and 750 ℃ ℃. The corrosion product's double-corrosion-layer structure was observed

with O

Ni

Co rich in the outer layer and O

Cr

S

Mo rich in the inner layer. The corrosion rate was the highest at 700 ℃.The corrosion rate at 750 was lower due to the ℃ intensing volatilization of eutectic salts withlow melting point.