GE is commercializing new silicon carbide ceramic matrix composite (CMC) materials—combining the high temperature resistance of ceramics with the mechanical toughness normally associated with metals—developed by scientists at GE Global Research, GE Aviation and GE Energy. The new materials could significantly enhance the efficiency of aircraft engines and gas turbines, while reducing emissions.
To produce the CMC materials, silicon carbide fibers are used to reinforce a silicon carbide matrix through a melt infiltration process. Careful engineering of the bonding between the fibers and matrix yields a CMC material that is many times tougher than traditional ceramics. The composite can withstand ballistic impact testing—a test which shatters a conventional silicon carbide ceramic material.
A pair of videos embedded in a post on the GE Global Research blog shows the catastrophic failure of the silicon carbide material compared to the resilience of the CMC material.
The CMC material is able to operate at temperatures exceeding 2,000 °F (1,093 °C)—well above the capability of current nickel alloys typically used as high temperature structural materials in gas turbines—with a lifetime of some 48,000 hours (about 5.5 years). The ceramic composite is also 1/3 the density of nickel, giving a significant weight advantage for aviation applications.
...we believe GE’s CMCs are going to redefine what is possible in the world of aviation and energy.—Greg Corman and Dan Dunn, GE Research
Over the past several years, the process for making this CMC has been transitioned from the GE Global Research Center to GE Ceramic Composite Products, LLC, GE’s production facility in Newark Delaware, where it is manufactured under the HiPerComp name for application in turbine vanes, blades, shrouds and liners.
GE is also actively developing and testing several types of turbine components made of CMC. GE Energy has field-tested CMC shrouds in a 7FA engine (170 MW simple cycle) for more than 5,000 hours. A GE CMC combustor liner has also run for >12,000 hours in a 5 MW Solar Turbines engine. GE Aviation has run a CMC combustor liner and CMC blades in a government demonstrator engine. CMC low-pressure turbine vanes are being used in the GE - Rolls Royce F136 development engine for the Joint Strike Fighter. Flight-testing of this engine will begin in 2010, and this CMC vane could be the first production application of HiPerComp.