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VAMAS TWA #3
Project #12: Fracture Toughness of Ceramics by the SEVNB Method Round Robin
Fracture Toughness V
Organized as a joint VAMAS/ESIS project by the Swiss Federal Laboratories for Materials Testing and Research, Switzerland (Mr. Kübler)

Objective

Evaluate the Single-edged V-notched beam (SEVNB) test method.

Approach

All participants received 10 specimens of coarse-grained alumina (A) and silicon nitride (C). 5 specimens each by SEVNB and 1 other test method of participant's choice.
A common steel razor blade with diamond paste was used to create a very sharp notched beam.
Razor polishing of notches done either by hand or machine.
Participants also had the option of testing 5 specimens of fine-grained alumina (B), sintered silicon carbide (D), or yttria-stabilized zirconia (E).

Status

A very popular project. Specimens distributed: June 1997.
32 of 36 laboratories completed their testing by late 1998.
Round Robin completed. Final report in preparation.

Principal Findings
  • Within-lab and between-lab precisions were very good for the silicon nitride provided that notch tip radii were less than 30 µm. Results concurred with SEPB, CN, IS and IF data.
  • Notch tip radii less than 10 µm are necessary for the Y-PSZ.
  • SEVNB results may better represent short crack R-curve behavior than SEPB results.
Standards Impact
  • This method is a leading candidate for a draft CEN standard in TC 184 in 1999.
Publications
  1. J. Kübler, "Fracture Toughness of Ceramics Using the SEVNB Method: Initial Results for Si3N4 of a Joint VAMAS/ESIS Round Robin," presented at the 9th CIMTEC Conference, Florence, Italy, June 14-19, 1998.
  2. J. Kübler, "Fracture Toughness of Ceramics Using the SENVB Method: Initial Results of a Joint VAMAS/ESIS Round Robin," to be publ. Ceram. Eng. and Sci. Proc. 1999.
For more information or copies of the reports, contact:
Mr. J. Kübler, EMPA, Uberlandstrasse 129, CH 8600 Dubendorf, Switzerland, Tel: (+41) 1 823 5511, email: jakob.kuebler@empa.ch


The VAMAS TWA #3 Round Robins Between 1987 and 1999.

Click on the numbered projects in the image below for round robin details.



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