24-10-2012, 02:24 PM
Foreign Object Damage in Flexure Bars of Two Gas-Turbine Grade Silicon Nitrides
ABSTRACT
Foreign object damage (FOD) behavior of two commercial gas-turbine grade silicon nitrides, AS800 and SN282, was
determined at ambient temperature through strength testing of flexure test specimens impacted by steel ball projectiles with
a diameter of 1.59 mm in a velocity range from 220 to 440 m/s. AS800 silicon nitride exhibited a greater FOD resistance than
SN282, primarily due to its greater value of fracture toughness (K(sub lc)). The use of an additional equiaxed, fine-grained
silicon nitride (NC132) showed that fracture toughness was a key material parameter affecting FOD resistance. The observed
damages generated by projectile impact were typically in the forms of well- or ill-developed ring and cone cracks with little
presence of radial cracks.
ABSTRACT
Foreign object damage (FOD) behavior of two commercial gas-turbine grade silicon nitrides, AS800 and SN282, was
determined at ambient temperature through strength testing of flexure test specimens impacted by steel ball projectiles with
a diameter of 1.59 mm in a velocity range from 220 to 440 m/s. AS800 silicon nitride exhibited a greater FOD resistance than
SN282, primarily due to its greater value of fracture toughness (K(sub lc)). The use of an additional equiaxed, fine-grained
silicon nitride (NC132) showed that fracture toughness was a key material parameter affecting FOD resistance. The observed
damages generated by projectile impact were typically in the forms of well- or ill-developed ring and cone cracks with little
presence of radial cracks.