HIGH-TEMPERATURE OXIDATION-RESISTANT COATINGS FOR TANTALUM BASE ALLOYS. Third Quarterly Progress Report, May 1, 1962-July 31, 1962
Tests were made to determine optimum Sn--Al coating compositions on Ta-- 10 W and Ta--30 Nb--7/sup 1/2 V alloys. Coating losses were considerable during exposure to environments of 0.1 to 100 microns pressure at 2500 to 2800 deg F for one hour. Little improvement was obtained by preoxidation at various temperatures. Temperature gradient samples tested at a msximum of 3000 deg F showed significant differences in diffusion penetration behavior between the two alloys. Several techniques were used to obtain considerably thicker coatings and to minimize run-off of the Sn--Al during diffusion treatment. Pretitanizing prevented run-off but decreased oxidation resistance somewhat. Several new coatings were also investigated. Additions of yttrium to the Sn--Al slurries resulted in some coatings with unstable room temperature behavior and none of the coatings showed superior properties to those previously developed. Calorize- spray and calorize-hot dip Sn--Al coatings were found to be inferior in oxidation resistance to slurry coatings. The use of Sn--Si slurries was not successful. However, pack-siliciding over a titanized base gave coatings with good oxidation resistance to 2800 deg F, particularly on the Ta--10 W alloy. Maximum temperature capability of the Ti --Si coating is several hundred degrees below the Sn--Al coating. (auth)
- Research Organization:
- General Telephone and Electronics Labs., Inc., Bayside, N.Y.
- DOE Contract Number:
- AF 33(657)-7339
- NSA Number:
- NSA-16-029341
- OSTI ID:
- 4792314
- Report Number(s):
- NP-11990; TR 62-460.4
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-62
- Country of Publication:
- United States
- Language:
- English
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