Exploratory Development of Functionally Graded Nano-Composite (FGNC) for Gear Applications

The goal of this STTR program is to design and demonstrate a new carburized gear steel alloy that improves performance and power density for the V22 rotorcraft transmission compared to the incumbent carburized gear steel, X53. This STTR program is a collaborative effort among materials design engineers at QuesTek, gear and drive-train engineers from Bell Helicopter, and gear testing experts from the Gear Research Institute (GRI) at The Pennsylvania State University. The proposed Phase II program will consist of an 18-month base program followed by two consecutive 12-month options to finalize and test the carburized, secondary-hardening gear steel designed during the Phase I program using QuesTek's Materials by Designr technology. In the base program, static core properties, single tooth bending fatigue, and rolling/sliding fatigue tests will be conducted. During the first option program, spur gear tests will be conducted at GRI to evaluate the bending fatigue, contact fatigue, and scoring fatigue resistance in comparison with X53. Failure analysis studies will characterize the operating fracture mechanisms and associated microstructural features responsible for fatigue initiation. During the second option program, planetary gear tests on a helicopter transmission test rig will be conducted to develop design allowables for the invented alloy.