Materials Research for Advanced Inertial Instrumentation. Task 2. Gas Bearing Material Development by Surface Modification of Beryllium.
Technical rept. no. 1, 30 Sep 77-30 Jun 78,
CHARLES STARK DRAPER LAB INC CAMBRIDGE MA
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Beryllium surfaces, such as used in inertial instrument gas bearings, are to be modified for improved friction and wear performance by case hardening with boron. Techniques being investigated are 1 high temperature reactive diffusion of the elements, and 2 low temperature ion implantation of boron into beryllium. Diffusion experiments to date have consisted of heating the solid elements in contact with each other under inert atmosphere at temperatures predicted by the Be-B phase diagram to avoid undesirable eutectic reactions. Of the two elements, beryllium has been used as a bulk solid and boron has been applied to its surface from a powder slurry, sputtered film, or bulk solid. Preliminary experiments have been done with CVD of boron from a commerical boronizing compound during induction heating under argon. Results indicate that a vapor source of boron may react differently as compared to a solid boron source with a beryllium substrate in that adherent compounds are formed. Ion implantation of boron into beryllium has been attempted. Initial beryllium flat specimens have had a concentration of 10 atomic percent boron implanted to a depth of approximately a micron. Annealing these specimens up to 650 C appears to have increased microhardness and resulted in a metallographic change resembling precipitation of a second phase. Analysis of this reaction is in progress. Higher concentrations of implanted boron 30 atomic percent are planned. Author
- Metallurgy and Metallography
- Fabrication Metallurgy
- Machinery and Tools