Volume 9, Number 3 • May/June 2001

Pressure Sensors Developed for High Temperatures

A high-temperature pressure sensor for aircraft engine testing has been developed through a Small Business Innovation Research (SBIR) contract between NASA Glenn Research Center (GRC) and Kulite Semiconductor Products, Inc.

The silicon carbide (SiC) pressure sensor is designed for use at temperatures as high as 500 degrees Celsius, which is approximately 50 degrees higher than temperatures that can be withstood by currently available silicon pressure sensors. The sensor is capable of operating at 500 degrees Celsius for several hours. Silicon carbide exhibits excellent thermal and mechanical properties at high temperatures; further, it has large coefficients of piezoresistance. This combination of properties makes the material well suited for high-temperature electromechanical sensors.

“Engine companies have always been looking for pressure sensors capable of operating at higher temperatures,” said Dr. Glenn Beheim, instrumentation research engineer at GRC. “Kulite and other sensor manufacturers have been increasing the operating temperatures of silicon pressure sensors for some time, but they have pretty much reached the maximum temperature at which silicon can operate. For temperatures of 500 degrees Celsius and higher, silicon deforms plastically. Silicon carbide works quite well at 500 degrees Celsius and eventually will allow us to go to even higher temperatures.”

Silicon carbide microfabrication and high-temperature packaging technologies were developed under Phase II of the SBIR contract with Kulite. Under Phase III of the contract, Kulite will provide NASA Glenn with twelve prototype sensors. One of these prototypes was successfully tested in the compressor of a gas turbine engine in early fall of 2000 at Honeywell in Phoenix, Arizona.

In addition to use in aircraft engine development and testing, the sensors can also be used for fast response pressure measurements in the compressor hot section for aircraft stall detection and control. There is also potential for other high-temperature pressure measurement applications, including tank and ship engines, power plants and material-processing systems.

According to Beheim, eventual goals of the project are to produce pressure sensors with in-package temperature compensation and to increase the maximum operating temperature. In addition, tests with Pratt & Whitney, a unit of United Technologies Corporation of Hartford, Connecticut, are being discussed. Work on the sensors is being conducted with engine manufacturers through the Propulsion Instrumentation Working Group (PIWG), a consortium of engine companies and government agencies. PIWG has guided the design of the sensor to ensure that it meets the requirements of the engine manufacturers. PIWG is also coordinating the on-engine testing of the sensor.

Kulite designs, develops and manufactures solid-state semiconductor pressure sensors using piezoresistive technology.

The Advanced High Temperature Engine Material Technology Program (HITEMP) and Higher Operating Temperature Propulsion Components (HOTPC) Program provided funding for the project.

For more information, contact Glenn Beheim at NASA Glenn Research Center, 216/433-3847, beheim@grc.nasa.gov. Please mention you read about it in Innovation.