Measurement of the fracture toughness of CVD-grown ZnS using a miniaturized disk-bend test

Journal Article · Sun Sep 01 04:00:00 EDT 1991 · Journal of Materials Research; (United States)

DOI:https://doi.org/10.1557/JMR.1991.1950· OSTI ID:5206436

Zhang, J; Ardell, A J ^[1]

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1. Department of Materials Science and Engineering, University of California, Los Angeles, California (USA)

Novel apparatus and methodology have been developed for measuring the fracture toughness of ceramics using small disk-shaped samples 3 mm in diameter. The method involves the Vickers indentation of specimens ranging in thickness from 300 to 700 {mu}m, and testing them in a ring-on-ring bending mode. Experiments on ZnS grown by chemical vapor deposition (CVD) have been used to evaluate the technique. The apparent fracture toughness of this material increases with crack length (R-curve behavior). This behavior is analyzed using established equations in conjunction with a new graphical method that obviates the need for measuring the apparent toughness of samples containing very large cracks. The fracture toughness at infinite'' crack length, 0.86{plus minus}0.08 MPa{center dot}m{sup 1/2}, is in very good agreement with the values obtained by conventional methods. The effect of sample size on the accuracy of the results is thoroughly discussed. The thickness, {ital t}, of the sample should exceed by a factor of ten the initial crack length produced by the indentation. Also, since samples are tested at various indentation loads, {ital P}, the ratio of their thicknesses should be chosen to satisfy the condition {ital t}{proportional to}{ital P}{sup 2/3}. The importance of several parameters in the design of the apparatus is also discussed.

• DOE Contract Number: FG03-86ER45264
• OSTI ID: 5206436
• Journal Information: Journal of Materials Research; (United States), Journal Name: Journal of Materials Research; (United States) Vol. 6:9; ISSN JMREE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ANALYTICAL SOLUTION
CHALCOGENIDES
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
CRACKS
DEPOSITION
EQUATIONS
FRACTURE PROPERTIES
INORGANIC PHOSPHORS
MECHANICAL PROPERTIES
PHOSPHORS
SULFIDES
SULFUR COMPOUNDS
SURFACE COATING
VICKERS HARDNESS
ZINC COMPOUNDS
ZINC SULFIDES