Case 1 – CVI expertise provides unique friction
Parker Hannifin Corporation, Aircraft Wheel and Brake Division
approached the Pyrogenics Group to collaborate towards creating a new coating
material to support the V-22 Osprey revolutionary new tiltrotor aircraft.
The V-22 is a fixed-wing plane with rotors that tilt so the
aircraft can take off and land like a helicopter. A tiltrotor combines the
speed, range and fuel efficiency normally associated with turboprop aircraft
with the vertical take-off/landing and hover capabilities of helicopters. The
tiltrotor aircraft represents a major technological breakthrough in aviation
that meets long standing military needs.
The tiltrotor brake pad and system must stand some of the
harshest design criteria faced for an aircraft including hold and takeoff in
support of mission operations and maneuvers on aircraft carriers and assault
ships. The brake material must stand up to highly resistant wear, heat and
fracture specifications and have a very high and uniform friction coefficient
across ranges of operation.
The Challenge: Develop a cost effective
material coating that can withstand the severe operational conditions and
longevity requirements of the mission planners for the V22 Osprey.
The Pyrogenics Group worked closely with Parker Hannifin in
developing a special SiC coating that satisfied the quality, performance, and
schedule requirements set by the mission planners. This cost effective coating
bonds to a carbon-carbon preform and under high temperature furnace conditions.
Unlike superalloys and ceramics, the resultant brake material is light weight,
self lubricating, and retains its strength at high temperatures. In addition, it
possesses a very low coefficient of thermal expansion (CTE), low residue, and
withstands the thermal shock of the mission profile. The extremely wear
resistant material makes it ideal for this application, and with a friction
coefficient as high as 0.70, is an ideal friction material for high performance
clutches and other brake applications.
On September 29, 2005 United States Defense Department for
Full Rate Production (FRP) of the Bell Boeing V-22 Osprey tiltrotor aircraft.
Case 2 – Pyrolytic Graphite Provides Optimum
Erosion in MoCVD
MoCVD System photo courtesy
Johannes Keppler University
A leading electronics manufacturer of Metal Organic Chemical
Vapor Deposition (MoCVD) in looking to increase productivity has used SiC coated
graphite and solid SiC susceptors.
In MoCVD, a laminar carrier gas with precursor molecules of
metal-organic compounds flow over a wafer placed on hot graphite based susceptor
inside a reactor vessel. The atoms are deposited by decomposing the
metal-organic molecules while passing over the hot substrate. The undesired
remnants are removed or deposited on the walls of the reactor.
The Challenge: Test materials to determine the best selection
for new resistance to ammonium offering material stability and consistent long
The manufacturer undertook a detailed duration test under
temperature (800 °C) for 40 hours with GaN cleaning media under a N2 and
0.3-0.5% levels of CL2 and HCl at flow rates of 0.33 to 1.095 SLM.
The results indicated that Pyroid® pyrolytic graphite provided
the most erosion resistance of all the materials (2.5X times that of CVD SiC and
8X greater than SiC coated graphite).