Advanced ceramics in the international aerospace industry

Ceramics used in NASA’s space shuttles for many years are increasingly being applied in commercial and military aircraft.

These materials, generally lighter than metals, have a low mass that make them highly appealing to the aerospace industry. However, the cost of working with advanced ceramic materials requires a clear advantage to justify using it. Once an advantage has been identified for a product or system, such as being able to run at a higher temperature or increased electrical activity, various ceramics are available.
 

Electrical applications

Advanced ceramics underpin electronics, and the average aircraft is packed full of electronics. These electrical components, such as sensors, antennas, capacitors, and resistors, are getting smaller and more capable, creating a major area of development for advanced ceramics.

The design team of the Concorde supersonic airliner selected Macor, the glass ceramic developed by Corning Inc., because it needed a lightweight and electrically insulating technical material for the engine control and management system. Corning engineers developed Macor as a material stable at high temperatures that could be machined like plastic.
 

Structural applications

Structural ceramics, crystalline inorganic non-metals, are used in aerospace as thermal barrier coatings (TBCs) in the hot part of the engine, as reinforcement, or as matrix such as ceramic matrix composites (CMCs). Engineers need to assess how a composite will perform at an elevated temperature in an air atmosphere and what impact erosion will have on the system and at what rate.

Lighter than most metals and stable at temperatures substantially hotter than high-grade technical plastics, structural ceramics have applications that include thermal protection systems in rocket exhaust cones, missile nose cones, and engine components.

The U.S. space shuttle orbiter used Macor machinable glass ceramic at hinge points, windows, and doors. Also, large pieces of the Corning glass ceramic have been used in a NASA space borne gamma radiation detector.
 

Turbine applications

Using technical ceramics for various parts of the engine have been considered for the past 30 to 40 years. Currently, there is a focus on developing silicon carbide (SiC/SiC composites) for use in jet engine turbines, mainly for turbine blades. The main driver is fuel efficiency, as engineers seek to run the jet engine without cooling channels that currently stop the metal alloy blades from melting. If the blades were made of ceramic composites, which could deal with 1,500°C to 1,600°C, the engine could run at higher temperatures. Energy efficiency would increase, therefore the engine would use less fuel, and the airplane could fly further.

Ceramics facilitate the drive toward more powerful, yet smaller electrical devices. Structural ceramics also offer huge potential for transforming aircraft engine capabilities.

Corning Inc.
www.corning.com

About the Author: Franck de Lorgeril is the product line, marketing, and sales manager at Corning Specialty Glass. He can be reached at delorgerf@corning.com.