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Dissolution behavior of 304 stainless steel in HNO3/HF mixtures.

Authors
Covino-BS Jr.; Scalera-JV; Driscoll-TJ; Carter-JP
Source
Metall Trans, A, Phys Metall Mater Sci 1986 Jan; 17A:137-149
NIOSHTIC No.
10004974
Abstract
The dissolution behavior of type 304 stainless steel was studied in typical pickling environments in an effort to reduce the loss of the critical metals Ni and Cr during the pickling process. Dissolution rates were determined for a 90-minute exposure to HNO3/HF solutions ranging from 0.8 M to 3.5 M HNO3 and 0.5 M to 2.6 M HF at 30 deg, 50 deg, 70 deg, and 90 deg C and containing 0 to 0.21 M dissolved Fe, Cr, or Ni. Dissolution rates increased with increasing HNO3 concentration from 0.4 M to 1.5 M HNO3, decreased at higher HNO3 concentrations, and increased with increasing HF concentration. A lower activation energy was found for solutions with higher HNO3 concentrations. Dissolved Fe and Cr decreased the dissolution rate of 304 stainless steel while Ni had essentially no effect. Auger electron spectroscopy and x-ray photoelectron spectroscopy studies of films resulting from exposure to HNO3/HF solutions indicated that the fluoride did not penetrate the thin nonprotective films but remained on the outer surface of the film. Scanning auger microscopy studies indicated that the fluoride was uniformly distributed over the surface. Both the dissolution and surface studies are consistent with a dissolution process that is controlled by reactions occurring either in solution or at the film-solution interface.
CODEN
MTTABN
Publication Date
19860101
Document Type
OP; Journal Article
Fiscal Year
1986
NTIS Accession No.
NTIS Price
Identifying No.
OP 29-86
ISSN
0360-2133
NIOSH Division
AVRC
Source Name
Metallurgical Transactions. A. Physical Metallurgy and Materials Science
State
MD
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