Soon after the Space Shuttle Columbia broke up on descent from orbit in February 2003, material scientists and engineers at a GE plant in Newark, Delaware, started building a set of repair kits long thought impossible.
Columbia suffered a crack in its left wing when it was hit by a briefcase-size insulating foam fragment that fell from a fuel tank during take-off. During her return, superheated air entered the spacecraft through the wound and ripped the shuttle apart 15 minutes before touchdown.
The GE team, in collaboration with NASA and industry partners, helped design and fabricate unique patches future crews could use to repair similar damage in space.
Space Shuttle Discovery returned to flight in July 2005. It was the first shuttle to fly after the Columbia disaster. It carried two wing and body repair kits made from a ceramic composite material developed by GE scientists.
The team designed the patches from a special ceramic composite material that could survive wild temperature swings, from minus 250 degrees Fahrenheit in orbit to 3,000 degrees during descent.
“You could bolt it on the wing’s leading edge in space and cover the damaged portion,” says Robert Klacka, technology marketing manager at GE Ceramic Composite Products. “The repair kit had 30 different patches that could cover a hole located on over 80 percent of the wing leading edge surface. The thin, flexible panels used a high temperature toggle bolt to attach it through the hole in the wing. Thankfully, we never had to use them.”
That’s not entirely true. NASA retired the shuttle fleet last year, but the a class of the materials, called ceramic matrix composites (CMCs), lives on inside the LEAP jet engine and other technology. Related applications include steering components for ballistic missile defense systems, and as rocket motor thrusters for new commercial space transportation aircraft.
Ordinary ceramics can take a lot of heat but are notoriously fragile. Scientists at GE Aviation, GE Global Research and at Klacka’s Delaware plant have spent the last two decades developing ceramic composites that are tough, light and heat-resistant. The extra heat allows engines like the LEAP to extract more power and become more efficient.
GE makes two types of ceramic composites: ceramics strengthened with carbon fibers handle over 3,000 degrees Fahrenheit and serve as hot gas valves and thrusters inside of rocket systems and heat shields for hypersonic aircraft and re-entry vehicles in the aerospace industry.
The second group includes CMCs, which are reinforced with ceramic fibers and operate at 2,400 degrees. They are more durable and have applications as turbine tip shrouds, combustor liners, blades, and fairings in turbinesand jet engines.
GE workers in Delaware make the composite parts from specially engineered fiber tapes that are shapd into turbine engine components, infiltrated with silicon and converted into ceramic. “I’ve seen a lot of different materials,” says Klacka, who has been in the composites business for over 25 years. “Our materials have the strength, durability and manufacturability that other ceramic composites lack. That’s why they work.”