TITLE:
Analytical Method to Monitor Industrial Pickling Baths Initially Constituted by HF, HNO3
AUTHORS:
Brigitte Dustou, Laure Latapie, Fabien Chauvet, Jean-Michel Bergerat, Theodore Tzedakis
KEYWORDS:
Pickling Bath Monitoring, Mix HF/HNO3 Titration, Fluoride-Metallic Cations Complexation, Titanium Alloys Pickling, Stainless Steel Alloys Pickling
JOURNAL NAME:
Journal of Analytical Sciences, Methods and Instrumentation,
Vol.7 No.4,
December
29,
2017
ABSTRACT: The present study couples the
acid/basis titration and the ICP analysis in order to monitor the
concentrations of nitric and hydrofluoric acids, and presents into baths used to pickle alloys of titanium or stainless steel,
largely employed in the aeronautic industry. The pickling of the alloys releases various metallic cations able to react with HF in order to lead to
metal-fluoride complexes and free H+, the last being able to react
with the basis. In this study, it was determined: the most significant correlations providing the number of
the protons released by the complexation of the metallic cation by the
fluoride. The proposed method based on: 1) these
correlations; 2) the titration pH = f(VKOH) curves; and 3) the
content of metallic cations determined by ICP, enables the monitoring of the
content of HNO3 and HF into the pickling bath. Assuming that one
bath was used for one type of alloy (alloys of Titanium for example, or alloys
of stainless steel), then the proposed method appears providing reliable
concentration values of both acids as well as metallic cations.