THE DISCOVERY OF NON-CHROMATE CORROSION INHIBITORS FOR AEROSPACE ALLOYS USING HIGH-THROUGHPUT SCREENING METHODS

摘要

New corrosion inhibitors to replace chromate must be discovered and characterized via experimentation. One approach to accelerate the discovery and characterization process of experimentally determined products is through the use of high throughput screening (HTS) methods. This paper presents three methods for the rapid screening of potential corrosion inhibitors and their synergistic combinations for AA2024. Inhibition characteristics of 100 separate chemistries could be assessed simultaneously within hours using polarization methods along with a multiple-electrode testing system. Methods examined include DC polarization, cyclic voltammetry characterization of re-deposited copper, and fluorometric detection of Al~(3+). Tests were conducted on single and binary combinations of the following inhibitors: cerium chloride, yttrium chloride, sodium metatungstate, sodium metavanadate, lanthanum chloride, sodium molybdate, sodium metasilicate, potassium phosphate, sodium phosphate, and barium metaborate. Testing was performed at 3.4 mM total inhibitor concentration in 0.6M NaCl. Comparison of HTS results to target electrochemical impedance results previously acquired over 10 days of testing yielded a high correlation (R~2=0.86) Testing of the inhibitor combinations revealed both synergistic and antagonistic pairings. These experimental approaches provide an avenue for the rapid discovery and performance characterization of effective corrosion inhibitors in an array of conditions using combinatorial methods.