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DEVELOPMENT OF PRODUCTION METHODS FOR HIGH-TEMPERATURE COATING OF LARGE TANTALUM PARTS.
SYLVANIA ELECTRIC PRODUCTS INC HICKSVILLE NY SYLCOR DIV
A Sn-27Al-5.5Mo slurry coating system previously developed for oxidation protection in the 1100-3300 F range was scaled up to coat tantalum structures 24x24x36 inches. Parts could be coated by dipping, spraying or brushing, andor combinations of each. A vacuum slurry dip process was also developed which is capable of coating faying surfaces and complex welded geometries. Run-off of the Sn-rich layer during diffusion treatment, previously inherent in Sn-Al-base coatings, was effectively eliminated for large part sizes through the use of a single-cycle coating of Sn-27.5Al-6.9Mo. Initial results indicate that this coating composition has improved resistance to oxidation under high mass-flow conditions such as would be experienced during reentry. Considerable progress was made in the area of coating repair. Techniques were developed for stripping and recoating of defective or oxidized parts. Production proof was demonstrated with 11 leading edge segments, 11 large corrugated heat shield panels, hundreds of smaller components, and several thousand samples which were reproducibly coated by processes developed in this program. The Sn-27Al-5.5Mo coating applied to the Martin leading edge segments successfully withstood several cycles of typical reentry profile. The effects of coating and processing on distortion of prototype hardware coated in this program were found to be minor. Author
Final technical rept. 1 Jun 63-1 Jun 65,