Erosion-enhanced corrosion behaviour of X-65 carbon steel and UNS S32750 superduplex stainless steel was investigated by electrochemical cyclic polarisation. The tests were performed using a jet slurry device coupled with a potentio-galvanostat at various jet velocities of 4, 6.5 and 9 m s −1 and impingement angles of 30 and 90˚in a 3.5 wt-% NaCl water containing 6 wt-% silica sand particles. The results showed that increasing the jet velocity and impingement angle increased the corrosion rate of both alloys. Negative hysteresis and greater E rp than OCP were observed for superduplex stainless steel in all erosion-corrosion conditions that indicated the pitting resistance of the alloy. However, the low resistance of carbon steel against pitting during erosion-corrosion was demonstrated by positive hysteresis in the cyclic polarisation curves as well as SEM images of the eroded surfaces.

A slurry impingement rig containing 6 wt.% SiO2 particles was used to investigate synergistic erosion–corrosion behavior of X-65 carbon steel at various impingement angles. Maximum erosion–corrosion and erosion rates occurred at impingement angles of about 25 deg and 40–55 deg, respectively. The synergy value highly depended on the impingement angle. The formation of patches of porous corrosion product followed by the formation of corrosion pits led to a positive synergy under impingement angle of 25 deg. At higher impingement angles, the absence of pits probably due to the formation of a more durable tribocorrosion layer resulted in a negative synergy.

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A number of aluminide coatings have been developed which are modified by additional elements (noble metals, Cr and reactive elements such as Y and Hf). This results in a marked improvement in their corrosion resistance. In the present paper, aluminide coatings are reviewed. The hot corrosion and oxidation resistance of these coatings in laboratory and field tests under different conditions are studied. SE/S291