Project Title:

Oxidation Resistant Ti/6Al/4V-SiC Composite Materials by Ion Implantation

04.01-6000
Oxidation Resistant Ti/6Al/4V-SiC Composite
	Materials by Ion Implantation
Spire Corporation
Patriots Park
Bedford, MA 01730
James K. Hirvonen  (617-275-6000)
LeRC -- NAS3-25326

Abstract:

	 Lifetime of silicon-carbide-reinforced, titanium-aluminum-vanadium composites at
high temperature is presently limited by oxidation and embrittlement to a few hours
or less. An oxidation inhibitor could increase this to more than 800 hours at temperature,
a time consistent with mission requirements for hypersonic vehicles such the National
Aerospace Plane. This project investigated the feasibility of extending the operating
temperature of these composites by ion implantation, which has previously been found
to significantly enhance the oxidation resistance of titanium. 
	The Phase I effort explored improving the oxidation resistance of Ti-6Al-4V alloy
at 540 C in air by ion implantation processing and using it in SiC-fiber, titanium
alloy composite structures. The plan was to use barium and other ions because previous
work by the principal investigator showed significantly improved oxidation resistance
in elemental Ti after implantation. These choices proved to be very difficult to
pursue due to the high secondary electron yield of Ba, which produced high-voltage
breakdown on the internal electrodes of the ion implanter.

Potential Commercial Application:

Potential Commercial Application: Extending the operating temperature of SiC-fiber-reinforced,
Ti-6Al-4V composites will open up a large number of applications such as aircraft
wing panels for hypersonic flight, compressor blades in advanced turbojet engines,
and turbine engine cases, spacers, and turbine disks.