PRELIMINARY EVALUATION OF COATED CB-10 W-10 HF COLUMBIUM ALLOY.
MCDONNELL AIRCRAFT CORP ST LOUIS MO
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A new columbium alloy was produced by the Wah Chang Corporation. This alloy Cb-10W-10Hf, designated as C-129, has high strength at elevated temperatures in a vacuum. Such an alloy requires an oxidation protective coating in order to make it applicable for use in aerospace structures. Four of the coupons were coated at McDonnell with LB-2 coating four were coated by Tapco and two were not coated. Six of the coated specimens, three of each kind, were oxidation tested by repeated exposures to high temperatures in an air atmosphere. The duration of each exposure was 30 minuteeees, followed by subsequent cooling to room temperature. The temperature for the first exposure was 2000F, folloooowed by four additional expoooxposureres at 2500F. The ten coupons were also tested for bendd ductility beforrore and after coang and a after oxidation testing. The coupons were bent around a radius of 0.094-in. through an angle of 130 degrees. Microhardness determinations were also made across the thickness of the bend specimens. The Tapco coating provides greater oxidation protection than the LB-2 coating. Author