ISSN 2594-5327
49º Congresso anual — Vol. 49, Num. 1 (1994)
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Resumo
Amorphous alloys display remarkable properties such as corrosion resistance, mechanical hardness and special magnetic properties. Because they do not have crystalline interphases characteristic for conventional alloys, they should be more resistant to localized attack. With the aim of preparing protective coatings, the electrodeposition of ternary Co–W–B amorphous alloy was investigated. The amorphous layer was coated on a substrate from plating bath containing cobalt and tungsten salts in presence of boron phosphate, wetting agent, ammonium salt of a hydroxy-organic acid, with the pH adjusted in the range 7–10. Various parameters for quality of the deposit and for the efficiency of the process were studied. To get sound, smooth and thick amorphous deposits the optimum conditions for the system were found to be as follows: temperature 70–60 °C, current density 30–50 mA/cm², and pH 8.5–9.0. Analytical and cyclic voltammetric experiments performed on the deposited alloys showed that a passive layer of tungsten oxide or metatungstate in acidic medium, and of cobalt oxide in basic medium formed on the surface of the alloy protects it from the corrosion.
Palavras-chave
Co-W-B, amorphous alloys, electrodeposition, corrosion resistance, protective coatings
Como citar
Prasad, Shiva.
ELECTRODEPOSITION OF Co-W-B AMORPHOUS ALLOYS AND THEIR CORROSION RESISTANCE,
p. 5252-5263.
In: 49º Congresso anual,
Rio de Janeiro, Brasil,
1994.
ISSN: 2594-5327, DOI 10.5151/2594-5327-49v11-249-260
