HALOGEN PASSIVATION STUDIES
Quarterly rept. 1 Feb-30 Apr 1967
DOUGLAS AIRCRAFT CO INC NEWPORT BEACH CA ASTROPOWER LAB
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During this time experiments were carried out to further define the reactions of typical system organic contaminants on metal panels with fluorine in the passivation process. Tests with fluorine at 50 psig showed greater reaction than at 15 psig but complete removal did not occur. All residues from passivation treatment of organic contaminants are impact sensitive in LF2 some react spontaneously and violently with LF2. Dye penetrant residues in porous cast aluminum are impact sensitive, and are not removed by usual cleaning techniques. Addition of a vacuum bake-out step in the cleaning procedure followed by GF2 passivation does render the residues insensitive to impact in LF2. Tungsten-contaminated aluminum simulating tungsten inclusions in welds is impact sensitive in LF2. GF2 passivation reduces the sensitivity to apparently safe levels, but the optimum passivation conditions have not been determined. Secondary corrosion of F2-passivated metals in a high-humidity atmosphere containing a low level of HF is greater than corrosion of unpassivated specimens of the same metals. Gases adsorbed in the passive film on metals are being studied by analysing products desorbed under various conditions. Fluorine, hydrogen fluoride, oxygen and nitrogen are prominent. Conditions for complete desorption have not been defined.
- Properties of Metals and Alloys