Dynamic corrosion characteristics of metal materials in supercritical water

Abstract

The static and dynamic corrosion experimental platforms of supercritical fluid reactor were used for the static and dynamic corrosion test of Q235, 304, 316L, P91, N80 and 3Cr13 in the supercritical water pseudo-critical region (22.5 MPa, 375.6 ℃) and gas-like region (22.5 MPa, 407.6 ℃) for 72 h. The results show that the dynamic corrosion rate of materials in supercritical water environment is significantly higher than the static corrosion rate, and the flow accelerates the corrosion process, in which 304 is increased by more than 4 times; the strengthening effect of dynamic conditions on corrosion mass gain is weakened with the decrease of corrosion resistance. The factors that exacerbate corrosion under dynamic conditions are: flow shear force accelerates the movement of the corrosive medium in the supercritical fluid to the substrate surface, promoting the corrosion chemical reaction; the flow shear force scours the material surface, promotes the dissolution of Fe on the material surface, and accelerates the corrosion chemical reaction; the erosion effect of shear force promotes the detachment of corrosion product crystals during the formation process of the wall, accelerating the corrosion process.

Keywords

• supercritical water
• metal material
• dynamic corrosion
• corrosion mechanism