CRUD deposition in accelerated high-temperature water: Investigation on the effect of substrate material and water chemistry

摘要

Deposition of corrosion products (CRUD) on micro-orifice specimens under accelerated flow conditions was investigated in high-temperature water on several substrate materials (SS 304L, Titanium, Alloy 690, Zirlo and magnesia stabilised Zirconia) and water chemistries (0-2 ppm of Li, 0-2.5 ppm of H-2). Regardless of the substrate material, no significant differences in radial CRUD build-up were observed in high purity water (0 ppm of Li and either 0 or 2.5 ppm of H-2). Conversely, in lithiated water (2 ppm of lithium and 2.5 ppm of H-2), the CRUD surface build-up was dependent on the oxide electrical conductivity, which in turn depends on the substrate material. In fact, no build-up occurred on Zirconia and only a minor deposition on Zirlo. The deposition mechanism was ascribed to be dominated by particulate deposition at neutral pH where magnetite solubility is the highest. Conversely, crystalline build-up induced by electrokinetic activity played an important role at alkaline pH where oxide solubility was the lowest. (C) 2019 The Authors. Published by Elsevier B.V.