Thin Dense Chrome Bearing Insertion Program; Pyrowear 675 and Cronidur Wear Testing

This portion of the Thin Dense Chrome Insertion Program evaluated two new corrosion-resistant materials for use in F101 and F110 main shaft bearings Cronidur 30 and Pyrowear 675. Contamination, wear, and corrosion resistance were assessed through selected subscale and full-scale tests. Subscale tests evaluated the wear characteristics and corrosion resistance. Full-scale tests demonstrated contamination resistance at normal F110-GE-129 operating conditions with exposure to abnormal aluminum oxide contamination levels. Cronidur 30 demonstrated improved corrosion resistance relative to M50 in salt water and tap water in subscale corrosion testing. Pyrowear 675 also demonstrated improved corrosion resistance relative to M50 but was not as good as Cronidur 30. Both Cronidur 30 and Pyrowear 675 demonstrated reduced wear resistance relative to M50 material in subscale testing. In full-scale testing, both materials exhibited outer race shoulder and cage pocket wear greater than M50. Based on these results, both new bearing materials were deemed to be too great of risk for immediate application to the F101 and F110 engines. Possibly, bearing alloy development or race treatments can be used to improve wear resistance, but such assessment was beyond the scope of this contract.