Corrosion of high-temperature alloys in chloride-containing supercritical water oxidation systems
- Forschungszentrum Karlsruhe (Germany)
Supercritical water oxidation (SCWO) is a promising and effective method for the oxidation of organic wastes. Its high solubility for organic compounds and its special physical properties (i.e., density and viscosity) result in a key advantage over standard processes such as incineration. During oxidation of chlorine organics, severe corrosion attack of most of the materials have been observed as a result of the formation of hydrochloric acid (HCl). An investigation was conducted of corrosion of high-temperature alloys such as alloy 214 (UNS N07214), alloy 602CA (UNS N06602), alloy G-30 (UNS N06030), alloy 625 (UNS N06625), and alloy 686 (UNS N06686), exposed at 400 bar (40 MPa) and 420 C for 24 h in a dichloromethane (CH{sub 2}Cl{sub 2}) hydrogen peroxide (H{sub 2}O{sub 2}) mixture with {approximately}2,000 wppm chloride (Cl{sub 2}). Weight losses of all the samples varied between 1.3 mm/y for alloy G-30 and {approximately}31.6 mm/y for alloy 686. Alloy 214 showed increased corrosion for the preoxidized material, whereas the corrosion rate of alloy 602CA was reduced by a factor of three as a result of preoxidation at 900 C prior to SCWO exposure. Analysis revealed that alloy 686 lost most of its nickel down to a depth of {approximately}150 {micro}m. Alloy G-30 showed good corrosion behavior as a result of formation of a protective oxide layer during the exposure. The layer was homogeneous, with a thickness of {approximately}12 {micro}m, but slight nickel leaching was observed.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 305363
- Journal Information:
- Corrosion, Vol. 55, Issue 1; Other Information: DN: Paper presented at Corrosion/98, March 1998, San Diego, CA (US); PBD: Jan 1999
- Country of Publication:
- United States
- Language:
- English
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