NIST Standard Reference Database 30
Last Update to Data Content: 2002
"Fracture Phenomenology of a Sintered Silicon Nitride Containing Oxide Additives," R.K. Govila, Journal of Materials Science, Vol. 23, pp. 1141-1150 (1988), published by Chapman and Hall.Language: English
The authors cite K. Matsuhiro et al., US Patent 4535063 (1985), and summarize the procedure as follows. "The material used in this study was sintered silicon nitride commercially known as SN-73 (NGK Insulators Ltd, Nagoya, Japan) obtained in the form of a cylinder (length = 138 mm, inside and outside diameters 80 mm and 100 mm, respectively). The sintered silicon nitride contained various oxide additives (CeO2, MgO, ZrO2 and SrO) as sintering aids, and had a density of 3.26 g cm-3. ... The test component (cylinder) was isostatically pressed and contained an organic binder. The burnout of the component was carried out at 150 °C to 225 °C in a nitrogen gas environment and finally pressureless sintered at 1700 °C."
The author cites R.K. Govila, J. Mater. Sci., Vol. 20, 4345 (1985), and summarizes the procedure as follows. "Flexural test specimens (approximately 32 mm long x 6 mm wide x 3 mm thick) were machined from the cylinder (test component) wall. All faces were ground lengthwise using 320 grit diamond wheels; the edges were chamfered (lengthwise) to prevent notch effects. ... (Some specimens) were precracked using the Vickers diamond pyramid and Knoop microhardness indenters. ... For various indentation loads used, the corresponding surface crack lengths as seen optically were measured. ... specimens were tested in four-point bending..." A self-aligning, hot-pressed SiC fixture with an outer span of 19 mm and an inner span of 9.5 mm was used with a crosshead speed of 0.5 mm/min.
| Amount of Element ( formula units ) | Element ( no unit ) |
|---|---|
| 3 | Si |
| 4 | N |
| Temperature ( °C ) | Indentation Load ( g ) | Indenter Type | Flexural Strength ( MPa ) |
|---|---|---|---|
| 20 | -- | -- | 790 ± 60 |
| 800 | -- | -- | 860 ± 65 |
| 900 | -- | -- | 655 ± 30 |
| 1000 | -- | -- | 440 ± 45 |
| 1100 | -- | -- | 395 ± 20 |
| 1200 | -- | -- | 345 ± 20 |
| 20 | 1000 | Knoop | 599 ± 8 |
| 20 | 2000 | Knoop | 460 ± 50 |
| 20 | 4000 | Knoop | 358 ± 10 |
| 1200 | 1000 | Knoop | 323 |
| 1200 | 2000 | Knoop | 323 |
| 1200 | 4000 | Knoop | 336 |
| 20 | 1000 | Vickers | 655 ± 10 |
| 20 | 2000 | Vickers | 549 ± 6 |
| 20 | 4000 | Vickers | 424 ± 30 |
| 1000 | 4000 | Vickers | 413 |
| 1200 | 4000 | Vickers | 331 |
Digitized data were obtained from Figure 4 or derived from Table II of the paper.