Slow crack growth in sintered silicon nitrideThe strength and crack growth characteristics of a sintered silicon nitride were studied at 1000 C. Fractographic analysis of material failing in dynamic fatigue revealed the presence of slow crack growth (SCG) at stressing rates below 6 ksi/min. This material can sustain a 40-ksi flexural stress at 1000 C for 400 h or more but is susceptible to both SCG and creep deformation at higher stress levels. The crack velocity exponent (N) determined both from dynamic and static fatigue experiments lies in a range from 13 to 22. The subcritical crack growth and creep behavior at 1000 C is primarily controlled by the deformation of an intergranular glassy phase.
Document ID
19870061715
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Khandelwal, P. K. (General Motors Corp. Indianapolis, IN, United States)
Chang, J. (General Motors Corp. Indianapolis, IN, United States)
Heitman, P. W. (General Motors Corp. Allison Gas Turbine Div., Indianapolis, IN, United States)