STP1201: Creep Behavior of Silicon Nitride Determined From Curvature and Neutral Axis Shift Measurements in Flexure Tests

    Salem, JA
    Materials Research Engineer, NASA LeRC, Cleveland, OH

    Choi, SR
    Resident Research Associate, Cleveland State University, Cleveland, OH

    Pages: 15    Published: Jan 1994


    Abstract

    The creep behavior of a hot-pressed silicon nitride was determined in flexure in air at 1200 and 1300°C by monitoring the creep deflection, the specimen curvature and the position of the neutral axis. The resulting data was used to evaluate the steady-state creep rate from the conventional elastic solution, curvature-moment relations and a model accounting for neutral axis shift. Fractography and measurements of specimen compliance before and after testing indicated bulk cracking and a loss of stiffness. The validity of flexural data to determine creep life parameters was considered.

    Keywords:

    silicon nitride, creep, tension, compression, bending, flexure, neutral axis, cracking, stiffness


    Paper ID: STP12776S

    Committee/Subcommittee: C28.01

    DOI: 10.1520/STP12776S


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