The corrosion of a dense TiB2 material (hot pressed with 1.5 wt.% Ni as sintering aid) in 3.5% NaCl aqueous solution was studied at T=25°C, T=45°C, T=65°C for exposure times up to 30 days. Results revealed by polarization curves, polarization resistance measurements and potentiostatic tests, coupled with microstructure analyses of the sample surface and chemical analyses of the solutions after the corrosion tests, allowed us to asses that TiB2 behaves like a passive metal at 25°C and 45°C as a rather protective hydrated titanium oxide film forms, the film protectivity is markedly reduced at 65°C, the corrosion attack is preferentially localized on a Ni-rich grain boundary phase, besides electrochemical corrosion, chemical corrosion also occurs, which plays an important role in the whole corrosion process as long as passive conditions are maintained.
Corrosion behaviour of titanium diboride in neutral chloride solutions
MONTICELLI, Cecilia;FRIGNANI, Alessandro;BRUNORO, Giancarlo;TRABANELLI, Giordano
2001
Abstract
The corrosion of a dense TiB2 material (hot pressed with 1.5 wt.% Ni as sintering aid) in 3.5% NaCl aqueous solution was studied at T=25°C, T=45°C, T=65°C for exposure times up to 30 days. Results revealed by polarization curves, polarization resistance measurements and potentiostatic tests, coupled with microstructure analyses of the sample surface and chemical analyses of the solutions after the corrosion tests, allowed us to asses that TiB2 behaves like a passive metal at 25°C and 45°C as a rather protective hydrated titanium oxide film forms, the film protectivity is markedly reduced at 65°C, the corrosion attack is preferentially localized on a Ni-rich grain boundary phase, besides electrochemical corrosion, chemical corrosion also occurs, which plays an important role in the whole corrosion process as long as passive conditions are maintained.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
