Evaluation of Hydroxyethane Diphosphonic Acid (HEDPA) as Metal Cleaning Agent Using Chemical and Electrochemical Test Methods: Part 2
Abstract
In order to evaluate the adaptability of hydroxyethane diphosphonic acid (HEDPA) as an environmentally benign alternative rust removal agent, a systematic investigation is being carried out. The effectiveness of HEDPA was thoroughly investigated as a function of acid concentration in the range 2 - 100 vol% and at different temperatures in the temperature range 27 - 60 deg C. The results suggest that the acid HEDPA is very effective in the rust removal process. The rate of rust removal by HEDPA is strongly dependent on the acid concentration and the solution temperature. Once an optimum threshold is reached further increase in either the acid concentration and/or temperature has a negative effect on the reaction kinetics. Chemical treatment of rusted steel samples with concentrated HEDPA solution (concentration range 5 - 100 vol.% HEDPA) has produced rust free steel samples with very rough surface topography. Prolonged treatment of samples with HEDPA allows the re-deposition of the reaction products onto the cleaned sample surface. The reaction product contains a mixture of various higher order iron phosphates.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1998
- Accession Number
- ADA353718
Entities
People
- A. S. Rao
- J. N. Murray
Organizations
- Naval Surface Warfare Center Carderock Division