Fracture Studies of High Temperature Ceramics.

Abstract

A high-temperature isothermal instrumented impact testing apparatus was designed and built and utilized to test a variety of high performance ceramic materials at temperatures up to 1500 C. Test specimens were held on an anvil in the furnace and heated rapidly to the test temperature. An impacter broke the samples in 3-point bending, and high speed digital recorders stored the outputs of force and velocity transducers. The controlled flaw technique was utilized to obtain the critical stress intensity factor, K sub IC. Hot-pressed silicon nitride materials containing MgO, CeO2 or ZrO2 sintering aids showed a decrease in K sub IC as the temperature exceeded 1300 C. Hot-pressed silicon carbide containing alumina sintering aid showed a similar decrease. Sintered alpha-SiC, on the other hand, showed a gradual increase in K sub IC at temperatures up to 1500 C. Reaction bonded SiC failed to break at the controlled flaw, but exhibited a drop in impact fracture force at temperatures approaching the melting point of silicon. (Author)

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Document Details

Document Type
Technical Report
Publication Date
May 01, 1980
Accession Number
ADA086653

Entities

People

  • D. Lynn Johnson

Organizations

  • Northwestern University

Tags

Communities of Interest

  • Advanced Electronics

DTIC Thesaurus Topics

  • Aluminum Oxides
  • Ceramic Materials
  • Chemical Synthesis
  • Chemistry
  • Composite Materials
  • Materials
  • Materials Science
  • Materials Testing
  • Measurement
  • Mechanical Properties
  • Mechanical Working
  • Mechanics
  • Residual Stress
  • Silicon Carbide
  • Stress Intensity Factors
  • Stresses
  • Test And Evaluation

Readers

  • Materials Science and Engineering.
  • Mathematics or Statistics
  • Reinforced Composite Materials