This paper reports interactions between corrosion and solid particles erosion in slurry conditions.
The materials tested in this investigation are intended to be used as hardfacing protective overlays in
critical areas of the hydrotransport process in the oilsands industry, where erosion-corrosion can
dramatically reduce the pumping and piping equipment lifetime. The materials under investigation
were: two Ni-based and one Fe-based metal matrix composites (MMCs) with tungsten carbide (WC)
as the reinforcing phase. The microstructure of the overlays was analyzed and mainly comprised a
matrix phase with the presence of embedded intermetallics and the WC reinforcing phase grains. The
corrosion behavior is assessed as a function of temperature, the Ni-based MMCs showed a pseudopassive
behavior at low temperature; however at high temperature their corrosion resistance was
dramatically reduced. In contrast, the Fe-based MMC showed active corrosion behavior. The
erosion- corrosion degradation mechanisms were assessed as a function of sand loading and aqueous
environment. It was found that the presence of intermetallics in the matrix phase and around the WC
grains played an important role in the erosion-corrosion performance of the MMCs overlays. At low
sand loading and high temperature, the corrosion behavior of the MMCs dramatically affected their
erosion-corrosion performance, whereas at high solid loading and low solution corrosivity, the
microstructural features and matrix microhardness of the overlays determined their erosion-corrosion
performance.
Keywords: Erosion-corrosion, plasma transferred arc welding, metal matrix composites, oilsands