NIST Standard Reference Database 30
Last Update to Data Content: 2002
"Effects of Oxidation and Oxidation Under Load on Strength Distributions of Si3N4," T.E. Easler, R.C. Bradt, and R.E. Tressler, Journal of the American Ceramic Society, Vol. 65 [6], pp. 317-320 (1982), published by American Ceramic Society.Language: English
"The sintered silicon nitride (SNW-1000, GTE Sylvania, Towanda, PA) contains both yttria and alumina as sintering aids and has a density of 3.00 g/cm3. The hot-pressed silicon nitride (NCX-34, Norton Co., Worcester, MA) has an 8% yttria addition and a density of 3.36 g/cm3. Specimens were cut from large billets, all of each type from a single billet, and then machined with a 600-grit diamond wheel to a final size of 0.25 cm by 0.25 cm by 3.0 cm. Grinding was always along the long dimension. The edges were not beveled."
"The as-machined strength distributions were determined by fracturing 50 specimens in a 4-point bend test geometry, over an outer span of 2.22 cm (1/3-point loading). All strength testing was carried out at a crosshead speed of 0.127 cm/min. Oxidation was performed at 1370 °C in air for various exposure times ...in an SiC resistance-heated furnace. Oxidation under static load was carried out at 1370 °C for 1 h. These specimens were loaded in 4-point bending over a span of 2.22 cm (1/4-point loading). For the static loading, a testing machine was used in the constant load mode after rapidly loading to the desired level. All specimens were fractured at room temperature for comparison with the as-machined strength distributions."Mechanical resonance
The authors cite S. Spinner et al., Proc. Am. Soc. Test. Mater., Vol. 61, 1121-1138 (1961), and summarize the procedure as follows. "The elastic modulus (was) determined using the mechanical resonance technique."Controlled Flaw
The authors cite P.L. Land et al., J. Mater. Sci., Vol. 12 (7), 1421-1425 (1977), and summarize the procedure as follows. "The controlled microflaw technique yielded a fracture toughness."
| Amount of Element ( formula units ) |
Element ( no unit ) |
|---|---|
| 3 | Si |
| 4 | N |
| Temperature ( °C ) |
Elastic Modulus ( GPa ) |
|---|---|
| 22 | 240 |
| Oxidation Time ( h ) |
Number of Samples |
Static Load ( MPa ) |
Flexural Strength ( MPa ) |
|---|---|---|---|
| 0.0 | 50 | 0 | 420 |
| 0.5 | 10 | 0 | 465 |
| 1.0 | 53 | 0 | 375 |
| 12.0 | 11 | 0 | 325 |
| 20.0 | 11 | 0 | 305 |
| 50.0 | 10 | 0 | 260 |
| 1.0 | 15 | 23 | 515 |
| 1.0 | 15 | 45 | 435 |
| Temperature ( °C ) |
Fracture Toughness ( MPa m1/2 ) |
|---|---|
| 22 | 4.0 |
| Oxidation Time ( h ) |
Static Load ( MPa ) |
Weibull Modulus ( no unit ) |
|---|---|---|
| 0.0 | 0 | 8.2 |
| 0.5 | 0 | 7.7 |
| 1.0 | 0 | 10.9 |
| 12.0 | 0 | 17.2 |
| 20.0 | 0 | 8.3 |
| 50.0 | 0 | 19.6 |
| 1.0 | 23 | 10.2 |
| 1.0 | 45 | 7.0 |
| Amount of Element ( formula units ) |
Element ( no unit ) |
|---|---|
| 3 | Si |
| 4 | N |
| Temperature ( °C ) |
Elastic Modulus ( GPa ) |
|---|---|
| 22 | 320 |
| Oxidation Time ( h ) |
Number of Samples |
Static Load ( MPa ) |
Flexural Strength ( MPa ) |
|---|---|---|---|
| 0.0 | 53 | 0 | 810 |
| 0.5 | 10 | 0 | 825 |
| 1.0 | 54 | 0 | 705 |
| 12.0 | 11 | 0 | 590 |
| 20.0 | 12 | 0 | 605 |
| 50.0 | 12 | 0 | 625 |
| 1.0 | 14 | 45 | 650 |
| 1.0 | 13 | 158 | 545 |
| Temperature ( °C ) |
Fracture Toughness ( MPa m1/2 ) |
|---|---|
| 22 | 4.2 |
| Oxidation Time ( h ) |
Static Load ( MPa ) |
Weibull Modulus ( no unit ) |
|---|---|---|
| 0.5 | 0 | 7.0 |
| 1.0 | 0 | 14.1 |
| 12.0 | 0 | 7.0 |
| 20.0 | 0 | 14.3 |
| 50.0 | 0 | 7.6 |
| 1.0 | 45 | 9.7 |
| 1.0 | 158 | 7.9 |