DEVELOPMENT OF A HIGH-PERFORMANCE TIAL EXHAUST VALVE

A new high-performance and lightweight TiAl intermetallic compound exhaust valve has been developed. The TiAl valve can improve power output and fuel economy by contributing higher engine speeds and a reduction in valve train friction. It was achieved by developing A Ti-33.5Al-0.5Si-1Nb-0.5Cr (mass %) intermetallic compound, a precision casting method for TiAl that provides a low-cost, high-quality process, and a plasma carburizing technique for assuring good wear resistance on the valve stem end, stem and face.