Investigation of aqueous slurry erosion-corrosion behaviour of Tantalum in different pH solutions

Erosion-corrosion behaviour of pure Tantalum (Ta) was investigated using corrosive slurry solutions (pH 4, 7, and 10) containing 7 wt% SiC as erodent particles. Tests were carried out using an impinging jet erosion-corrosion apparatus with a jet velocity of 5 ms−1 and at two impact angles (30° and 90°). Under particle bombardment conditions, a marked reduction in corrosion resistance offered by Ta was observed amid a significant cathodic shift in the ECorr values for all pH values investigated. Results showed that interaction between erosion and corrosion was higher under 30° impact leading to a higher rate of material removal. On the contrary, negative synergism was observed for experimental conditions of normal impact for pH 7 and pH 10. Scanning electron microscopy studies revealed typical ductile erosion mechanisms of material removal which consisted of dominating micro-cutting for 30° and plastic deformation resulting in lip formation for normal impact angle. These appeared to be assisted by dissolution of weakened areas and passive layer removal as corrosion mechanisms. Potentiostatic erosion-corrosion experiments were utilised for calculation of synergistic and antagonistic effects and have been presented in the paper.

Erosion-Corrosion of Tantalum in Different pH Solutions

The study investigates the effect of pH and impact angle on the erosion-corrosion behavior of pure Tantalum using corrosive slurry solutions containing 7 wt% SiC as erodent particles. Tests were conducted using an impinging jet erosion-corrosion apparatus. Results show that there is a marked reduction in corrosion resistance and a significant cathodic shift in the E Corr values for all pH values under particle bombardment conditions. The erosion-corrosion rate was higher at 30° impact angle compared to 90° and was also higher at pH 4 compared to pH 7 and pH 10. The study concludes that there is a diminution in the E Corr values and hence in the corrosion resistance of Ta under particle bombardment conditions.

The research on the erosion-corrosion behavior of pure Tantalum (Ta) is important because Tantalum is a material commonly used in spallation targets for neutron scattering facilities. However, these targets are experiencing premature failures, which significantly reduce their operation life. This study aims to investigate the effect of pH and impact angles on the slurry erosion-corrosion behavior of pure Tantalum, which can help understand the reasons behind the premature failures.

Key Takeaways:

1. The corrosion resistance of Ta was markedly diminished under particle bombardment conditions.

2. The erosion-corrosion rate was higher at 30° impact angle than at 90° impact angle, and the rate was higher at pH 4 than at pH 7 and pH 10.

3. The study found typical ductile erosion mechanisms of material removal, consisting of micro-cutting and plastic deformation resulting in lip formation.