Evalution of Corrosion Resistance of Materials in Waste Incineration Environment by A. C. Impedance Method

Abstract

To investigate the corrosion behavior of materials of boiler tubes in simulated waste incineration environments, A. C. impedance measurements have been carried out for Alloy 625, SUS347H and STBA24 embedded in NaCl-KCl-K₂SO₄-Na₂SO₄-Al₂O₃ mixed synthetic ash at 823K. The evaluation of corrosion resistance was conducted by using 1/ΔR (the reciprocal of the difference of resistance at 10mHz and 20kHz). The HCl addition in the atmosphere accelerated the corrosion of all materials. On the other hand, the H₂O addition did not affect the corrosion of Alloy 625 significantly, but it accelerated the corrosion of SUS347H and STBA24. In all cases a good relation was obtained between the integrated value of 1/ΔR with time to tested period and real corrosion losses of materials after tests. This result reveals that A. C. impedance measurements can be a useful technique for monitoring the corrosion rate of materials in a waste incineration environment.