Improvement of the Corrosion Resistance of Turbine Engine Bearings

Improved bearing corrosion resistance can be achieved with either the use of a new corrosion resistant alloy, or by surface treating, or coating state-of-the-art M50 with a protective covering. This two-phase program investigated all three methods; alloys, coatings, and surface treatments. Appropriate bearing materials, surface treatments, and coatings were identified. Screening tests were performed on the most promising candidates. Candidates with potential for improving bearing corrosion resistance included corrosion resistant alloys such as CRB7 (AMS5900), and BG42 (AMS5749), coatings such as the proprietary chrome plating process called Armoloy, and surface treatments such as nickel sputter-coated M50. This program was aimed at developing an alternate material, fabrication technique, or material treatment of turbine engine mainshaft bearings with improved corrosion resistance compared to state- of-the-art VIM-VAR-M50. During Phase I, five corrosion-resistance bearing candidates (Armoloy-coated M50, nickel sputter-coated M50, wrought CRB7, RSR565, and MRC2001) were identified as the most promising. These were subjected to rolling contact fatigue, corrosion, hot hardness, and wear screening tests. The phase concluded with selection of MRC2001 as the single most promising candidate for full-scale bearing fabrication and testing.