RESEARCH ON GAS PLATED REFRACTORY METAL COATINGS FOR LIQUID METAL COMPATIBILITY INVESTIGATION
Technical summary rept. 1 Nov 1964-1 Nov 1965
SAN FERNANDO LABS PACOIMA CA
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Techniques were developed for depositing Cb-1 Zr metal corrosion barrier coatings on the internal surfaces of type 316 SS tubing assemblies. Shapes approximating various parts of the SNAP 50SPUR space nuclear auxiliary power generation system were coated with uniform and adherent deposits of Cb-1 Zr ranging in thickness from 0.002 to 0.006 in. Deposition chemistry was investigated. A chemical system employing the hydrogen reduction of mixed chlorides at reduced pressure proved to be most suitable. Efforts to minimize interstitial contamination of the deposits resulted in impurity levels of 150 ppm C, 10 ppm H2, 50 ppm O2, and 50 ppm N2. About 100 trial depositions were made on the inner and outer surfaces of tubular 316 SS specimens. A bond was not attained directly between Cb-1 Zr alloy and 316 SS. However, a diffusion bond was attained between columbium and 316 SS, and it was demonstrated that plating Cb-1 Zr over a 5-to-10 micron interlayer of Cb gave adherent coatings. The integrity of the bonding was demonstrated in comprehensive physical tests.
- Metallurgy and Metallography