Study of Erosion-Corrosion and Corrosion Behavior of Commercially Pure-Ti During Slurry Erosion

摘要

The erosion-corrosion (EC) and pure erosion of commercially pure titanium have been investigated in a 3.5% sodium chloride solution containing 10, 30, and 60 g/l SiO2 particles with an average size of 318 mu m. The tests were performed at impact velocities of 4, 6. and 9 mls under two impact angles of 40 deg and 90 deg. Polarization technique was used to study corrosion behavior of the material during erosion-corrosion. The eroded .surfaces were examined by a scanning electron microscope (SEM) and a surface profilometer. The pure erosion, corrosion, and erosion-corrosion rates increased as impact velocity and sand concentration increased. The corrosion rates of the eroding surfaces under a normal impact were lower than those at an impact angle of 40 deg. The SIT ratio, i.e., the ratio of synergy to erosion-corrosion rates was about 80% at an impact velocity of 4 mls, which indicated the high effect of the electrochemical corrosion on the degradation of CP-Ti at low velocity. The SIT ratio decreased to 30% and 15% at the impact velocities of 6 and 9 mls, respectively. The SIT ratio was also decreased with increasing sand concentration indicating a greater role of mechanical degradation upon the erosion-corrosion rate in the concentrated slurries.