In:
Materials and Corrosion, Wiley, Vol. 39, No. 11 ( 1988-11), p. 525-533
Abstract:
Effects of Mo, V, Nb, Ti, Zr and their carbides on the corrosion and hydrogen uptake of iron in sulphuric acid The effects of Mo, V, Nb, Ti, Zr and their carbides on the corrosion and hydrogen uptake of iron in 1 M H 2 SO 4 /N 2 /25°C were investigated by electrochemical and surface analytical methods using binary and ternary Fe‐Me alloys with about 0.2 at.‐%Me. Due to the experimental conditions, no protective surface layers formed. The transition metals were enriched at the iron surface only as a carbide or oxicarbide. Mo or Zr were not markedly enriched. The corrosion current density and the hydrogen activity were decreased only by Mo or Zr. Hydrogen permeation measurements were analysed in terms of the trapping theory. The average binding energy of shallow traps for hydrogen increases with increasing atomic radius of the substituted alloying elements in the order V, Mo, Ti, Nb and Zr. Correspondingly, the hydrogen diffusion coefficient (after saturation of the deep traps) decreases and the hydrogen solubility increases. The steadystate hydrogen permeation rate remains almost unaffected. The total hydrogen content is determined by the density of deep traps and thus mostly independent of the external hydrogen activity. The trapping effect of iron is strongly increased by dissolved Zr or Nb or in the presence of fine dispersed carbides as VC x . The effect of coarse carbide particles at a lower density is small.
Type of Medium:
Online Resource
ISSN:
0947-5117
,
1521-4176
DOI:
10.1002/maco.19880391108
Language:
English
Publisher:
Wiley
Publication Date:
1988
detail.hit.zdb_id:
1481051-7
detail.hit.zdb_id:
1224916-6
detail.hit.zdb_id:
202688-0
