Indentation fracture assessment of residual stress in Si{sub 3}N{sub 4}

Conference · Mon Dec 30 23:00:00 EST 1996

OSTI ID:567530

Wu, K H ^[1]; Liu, K C; Sentella, M ^[2]

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1. Florida International Univ., Miami, FL (United States)
2. Oak Ridge National Lab., TN (United States)

The measurement of residual stress in Si{sub 3}N{sub 4} ceramics was examined using the indentation technique while a bar specimen with a square cross-section was loaded in tension, and an indentation was created by means of a Vicker`s indenter. The stress applied to the specimen ranged from 0 to 98.8 MPa. The crack length and the shape of the crack were measured by both optical and scanning electron microscopes. Results of the tests indicate that the indentation fracture method can be used to accurately determine the residual stress existing in the material as well as to predict the K{sub c} value of the material. The indentation load must be higher than a critical value in order to develop a well-defined penny-shaped crack. For the Si{sub 3}N{sub 4} this critical load is approximately 3 kg. A geometric constant is an important factor for the calculation of the residual stress.

• DOE Contract Number: AC05-96OR22464
• OSTI ID: 567530
• Report Number(s): CONF-960106--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
MEASURING METHODS
RESIDUAL STRESSES
SILICON NITRIDES