Accession Number : AD0778651

Title :   Development of Fiber Reinforced Ceramic Matrix Composites.

Descriptive Note : Final rept. Mar 73-Mar 74,


Personal Author(s) : Brennan,John J.

Report Date : APR 1974

Pagination or Media Count : 58

Abstract : Tantalum wire reinforced Si3N4 has been found to increase the Charpy impact strength of Si3N4 by a factor of over 30 (0.5 ft-lbs to 16 ft-lbs) at temperatures from RT to 1300C. The mode of failure is also affected such that interfacial splitting along with ductile wire elongation occurs, resulting in very small fragments of matrix breaking off upon impact. This mode of fracture is desirable for use in gas turbine engines. The Ta-Si3N4 composite system has also been found to exhibit a threshold energy below which no damage occurs upon either Charpy or ballistic impact that is considerably higher than unreinforced Si3N4. This effect is prevalent at both RT and elevated temperatures (1300C). In addition, thermal fatigue of Ta-Si3N4 composites between 200C and 1300C for up to 100 cycles and thermal aging at 1300C for up to 1000 hrs does not significantly lower impact properties nor does it affect the mechanisms of failure of the composite. (Modified author abstract)

Descriptors :   *Fiber reinforced composites, Silicon nitrides, Tantalum, Matrix materials, Ceramic materials, Gas turbines, Wire, Impact strength, Thermal fatigue, Hot pressing

Subject Categories : Laminates and Composite Materials
      Jet and Gas Turbine Engines

Distribution Statement : APPROVED FOR PUBLIC RELEASE