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VAMAS Round Robin on Fracture Toughness of Silicon Nitride
Author(s) -
Mizuno Mineo,
Okuda Hiroshi
Publication year - 1995
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1995.tb08891.x
Subject(s) - materials science , silicon nitride , fracture toughness , composite material , beam (structure) , chevron (anatomy) , enhanced data rates for gsm evolution , fracture (geology) , silicon , nitride , metallurgy , optics , layer (electronics) , paleontology , telecommunications , physics , computer science , biology
Eight laboratories in Germany, Japan, U.K., and U.S. participated in the VAMAS round robin. The fracture toughness of silicon nitride at room temperature and at 1200 deg; C was measured by three methods: the single‐edge V‐notched beam (SEVNB), single‐edge precracked beam (SEPB), and chevron notched beam (CNB). The obtained values show hardly any crosshead speed dependence, irrespective of test temperature and atmosphere. Results may have been influenced by a small amount of slow crack growth, but distinct R ‐curve behavior could not be detected within the scope of the tests. The values at 1200 deg; C in N 2 can be measured by the SEVNB and SEPB methods with small scatters. The oxidation of silicon nitride, caused by heating in air, increases the SEVNB and SEPB values. The CNB values are free from the effects of test temperature and atmosphere, but they show a large scatter between laboratories. However, the chevron V‐notched beam (CVNB) method, which is an improved CNB method, shows values with a small scatter, irrespective of the measurement conditions. The SEVNB and SEPB measurements in N 2 and the CVNB measurement under any conditions are recommended for the measurement of high‐temperature fracture toughness.