Corrosion of Stellite Alloys and WC ‐Based Cemented Ceramics Exposed to Oxygen‐Containing Molten Pb at 600°C and 700°C

Liquid metals such as molten lead (Pb) are attractive heat transfer fluids for high-temperature thermal energy storage systems. Although extensive research is performed on the corrosion behavior of structural steels and Fe-based alloys in liquid Pb, the corrosion resistance of materials with high wear resistance in such environments is less explored. In order to expand the knowledge on the compatibility of wear-resistant materials with molten Pb in a temperature range relevant for high-temperature thermal energy storage systems, the current study investigates for the first time Pb corrosion of the two commercial Co-Cr-based alloys Stellite 21 and Stellite 6 and of two commercial tungsten carbide (WC) ceramics, one with Co binder and the other with Ni/Cr binder, in the temperature range from 600°C to 700°C. Static exposure tests in molten Pb containing 2 × 10$^{−7}$ wt.% dissolved oxygen are performed for up to 5000 h. The results reveal the formation of Cr-rich oxides on the surfaces of all materials, though an oxide scale with protective properties is found for Stellite 6 at 700°C only. Here, the scale is composed of an outer Cr-rich oxide layer and an inner Si-rich oxide. ... mehrIn all other cases, dissolution of alloying elements (Co-Cr-based alloys) and of the binder phase (WC-based ceramics) is observed to various extents, which gives first indications for the service life of respective components exposed to liquid Pb environments.