Diffusion Effect on the Anodic Reactions of Tungsten

Mustafa ANIK; Tuba CANSIZOĞLU and Sinem ÇEVİK

Makale detayları

Diffusion Effect on the Anodic Reactions of Tungsten

Yazarlar:

Mustafa ANIK | Tuba CANSIZOĞLU and Sinem ÇEVİK

Yayıncı:

TUBITAK

Dergi:

Turkish Journal of Chemistry 2004 Vol.28 Issue 4, pp.425-440

Belge Tipi:

Makale

Yayın Tarihi:

3/2004

Belge Dili:

Türkçe

Document ID (Org No.):

2000729285

Sıklık:

İki Aylık

eISSN:

1303-6130

pISSN:

1300-0527

Özet:

 

Potentiodynamic and potentiostatic polarizations, and a  rotating disk electrode technique were used to study the influence of  diffusion on the anodic reactions of tungsten (W) in a broad pH range  (\sim 0.3--13.5) in H3PO4 buffered solutions.  The anodic current  was controlled totally by the kinetics of H+ -assisted dissolution  below pH 1 (Region A).  At around pH 2.5 (Region B), in addition to  the kinetics of H2O-assisted dissolution, specimen rotation had an  effect on the current.  This observation was attributed mainly to the  physical damage to an oxide phase by hydrodynamic effects and partly  to the diffusion of surface H2WO4(aq) species.  The anodic current  was under the mixed control of the kinetics of OH--assisted  dissolution and slow diffusion of surface WO42- ions between pH  4 and 7 (Region C).  The kinetics of the H2WO4(s) solubilization  and slow diffusion of surface WO42- ions were observed to  influence the anodic current between pH 7.5 and 11.5 (Region D).  In  highly alkaline solutions (pH > 12; Region E), however, W anodic  current was controlled totally by the slow diffusion of bulk OH-  ions to the electrode surface.

 

Potentiodynamic and potentiostatic polarizations, and a  rotating disk electrode technique were used to study the influence of  diffusion on the anodic reactions of tungsten (W) in a broad pH range  (\sim 0.3--13.5) in H3PO4 buffered solutions.  The anodic current  was controlled totally by the kinetics of H+ -assisted dissolution  below pH 1 (Region A).  At around pH 2.5 (Region B), in addition to  the kinetics of H2O-assisted dissolution, specimen rotation had an  effect on the current.  This observation was attributed mainly to the  physical damage to an oxide phase by hydrodynamic effects and partly  to the diffusion of surface H2WO4(aq) species.  The anodic current  was under the mixed control of the kinetics of OH--assisted  dissolution and slow diffusion of surface WO42- ions between pH  4 and 7 (Region C).  The kinetics of the H2WO4(s) solubilization  and slow diffusion of surface WO42- ions were observed to  influence the anodic current between pH 7.5 and 11.5 (Region D).  In  highly alkaline solutions (pH > 12; Region E), however, W anodic  current was controlled totally by the slow diffusion of bulk OH-  ions to the electrode surface.

Makale detayları

Diffusion Effect on the Anodic Reactions of Tungsten

Yazarlar: Mustafa ANIK | Tuba CANSIZOĞLU and Sinem ÇEVİK

Yayıncı: TUBITAK

Dergi: Turkish Journal of Chemistry 2004 Vol.28 Issue 4, pp.425-440

Belge Tipi: Makale

Yayın Tarihi: 3/2004

Belge Dili: Türkçe

Document ID (Org No.): 2000729285

Sıklık: İki Aylık

eISSN: 1303-6130

pISSN: 1300-0527

Sayı

Yazarlar:

Mustafa ANIK | Tuba CANSIZOĞLU and Sinem ÇEVİK

Yayıncı:

TUBITAK

Dergi:

Turkish Journal of Chemistry 2004 Vol.28 Issue 4, pp.425-440

Belge Tipi:

Makale

Yayın Tarihi:

3/2004

Belge Dili:

Türkçe

Document ID (Org No.):

2000729285

Sıklık:

İki Aylık

eISSN:

1303-6130

pISSN:

1300-0527