VAMAS round robin on fracture toughness of silicon nitride

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1995.tb08891.x· OSTI ID:103611

Mizuno, Mineo; Okuda, Hiroshi ^[1]

---

1. Japan Fine Ceramics Center, Nagoya (Japan). R and D Lab.

Eight laboratories in Germany, Japan, U.K., and US participated in the VAMAS round robin. The fracture toughness of silicon nitride at room temperature and at 12090 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 1,200 C in N{sub 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{sub 2} and the CVNB measurement under any conditions are recommended for the measurement of high-temperature fracture toughness.

• Sponsoring Organization: USDOE
• OSTI ID: 103611
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 7 Vol. 78; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AIR
BULK DENSITY
CRACK PROPAGATION
FLEXURAL STRENGTH
FRACTURE MECHANICS
FRACTURE PROPERTIES
HARDNESS
MATERIALS TESTING
NITROGEN
NOTCHES
SAMPLE PREPARATION
SILICON NITRIDES