NIST Standard Reference Database 30
Last Update to Data Content: 2002
"Investigation of Selected Si3N4 and SiC Ceramics," N.L. Hecht, D.E. McCullum, and G.A. Graves, Ceramic Materials and Components for Engines, pp. 806-816 (1988), edited by V.J. Tennery, published by American Ceramic Society.Language: English
Material #1: "Sohio - Hexoloy α-SiC, Cold formed (injection molded or isostatic pressing) and pressureless sintered α-SiC with additions of B and Al" Material #2: "GTE - PY6, Injection molded and hipped β Si3N4 with additions of Y2O3" Material #3: "Norton/TRW - NT154, Sintered and HIP'ed Si3N4"
Rectangular test bars, 51 mm x 6.4 mm x 3.2 mm, were used. The tensile surfaces were ground, and the long edges of the tensile surface were chamfered. The Instron Universal Testing Machine, Model 1123 was used. Measurements at 1300 °C and 1450 °C used an ATS #3320 high temperature furnace. For room temperature tests, the bend fixture was made of steel. For tests at 1300 °C and 1450 °C, the bend fixture was made of SiC. The four-point bend fixture had an outer span of 3.81 cm and an inner span of 1.90 cm. A Weibull analysis was performed with the Weibull modulus being determined using a maximum likelihood estimate.Transient impulse
Three specimens were measured, one at a time, in a Grindo-Sonic, Model MR3ST, Transient Impulse/Elastic modulus apparatus.Dilatometry
Measurements were made on four specimens, from 25 °C to 1450 °C, using a Theta Industries Dilatronic II, Model 6024, apparatus.Vickers indentation
Five representative specimens were used for each material in a Vickers microindentation hardness tester. No additional measurement details were noted.
| Amount of Element ( formula units ) |
Element ( no unit ) |
|---|---|
| 1 | Si |
| 1 | C |
| Sintering Aid ( no unit ) |
|---|
| B |
| Al |
| Temperature ( °C ) |
Density ( g cm-3 ) |
|---|---|
| 25 | 3.17 |
| Temperature ( °C ) |
Elastic Modulus ( GPa ) |
|---|---|
| 25 | 427 |
| Temperature ( °C ) |
Crosshead Speed ( cm/s ) |
Flexural Strength ( MPa ) |
|---|---|---|
| 25 | 0.0064 | 331 |
| 1300 | 0.0064 | 494 |
| 1450 | 0.0064 | 500 |
| 25 | 0.004 | 402 |
| 1000 | 0.004 | 416 |
| 1200 | 0.004 | 435 |
| 1400 | 0.004 | 436 |
| 1000 | 0.00004 | 412 |
| 1200 | 0.00004 | 441 |
| 1300 | 0.00004 | 500 |
| 1400 | 0.00004 | 390 |
| 1450 | 0.00004 | 455 |
Standard deviations ranged from 6 MPa to 90 MPa and tended to be about 50 MPa. Failures occurred at tensile surface and edge flaws.
| Temperature ( °C ) |
Fracture Toughness ( MPa m1/2 ) |
|---|---|
| 25 | 2.6 |
"The fracture toughness values measured by the microindent method are found to be considerably higher (greater than 20%) than those measured by the controlled flaw method."
| Temperature ( °C ) |
Hardness ( GPa ) |
|---|---|
| 25 | 25.1 |
| Temperature ( °C ) |
Thermal Expansion ( 10-6 K-1 ) |
|---|---|
| 25-1450 | 5 |
| Temperature ( °C ) |
Crosshead Speed ( cm/s ) |
Weibull Modulus ( no unit ) |
|---|---|---|
| 25 | 0.0064 | 9 |
| 1300 | 0.0064 | 8 |
| 1450 | 0.0064 | 10 |
| 25 | 0.004 | 9 |
| 1000 | 0.004 | 18 |
| 1200 | 0.004 | 9 |
| 1400 | 0.004 | 11 |
| 1000 | 0.00004 | 12 |
| 1200 | 0.00004 | 10 |
| 1300 | 0.00004 | 8 |
| 1400 | 0.00004 | 15 |
| 1450 | 0.00004 | 9 |
| Amount of Element ( formula units ) |
Element ( no unit ) |
|---|---|
| 3 | Si |
| 4 | N |
| Sintering Aid ( no unit ) |
|---|
| Y2O3 |
| Temperature ( °C ) |
Density ( g cm-3 ) |
|---|---|
| 25 | 3.24 |
| Temperature ( °C ) |
Elastic Modulus ( GPa ) |
|---|---|
| 25 | 293 |
| Temperature ( °C ) |
Crosshead Speed ( cm/s ) |
Flexural Strength ( MPa ) |
|---|---|---|
| 25 | 0.0064 | 641 |
| 1450 | 0.0064 | 393 |
| 1450 | 0.00004 | 241 |
Standard deviations were approximately 69 MPa. Specimens failed at tensile surface, edge, and subsurface flaws.
| Temperature ( °C ) |
Fracture Toughness ( MPa m1/2 ) |
|---|---|
| 25 | 6.1 |
| Temperature ( °C ) |
Hardness ( GPa ) |
|---|---|
| 25 | 14.3 |
| Temperature ( °C ) |
Thermal Expansion ( 10-6 K-1 ) |
|---|---|
| 25-1450 | 3.4 |
| Temperature ( °C ) |
Crosshead Speed ( cm/s ) |
Weibull Modulus ( no unit ) |
|---|---|---|
| 25 | 0.0064 | 11 |
| 1450 | 0.0064 | 8 |
| 1450 | 0.00004 | 7 |
| Amount of Element ( formula units ) |
Element ( no unit ) |
|---|---|
| 3 | Si |
| 4 | N |
| Temperature ( °C ) |
Density ( g cm-3 ) |
|---|---|
| 25 | 3.24 |
| Temperature ( °C ) |
Elastic Modulus ( GPa ) |
|---|---|
| 25 | 314 |
| Temperature ( °C ) |
Crosshead Speed ( cm/s ) |
Flexural Strength ( MPa ) |
|---|---|---|
| 25 | 0.0064 | 538 |
| 1300 | 0.0064 | 604 |
| 1450 | 0.0064 | 453 |
| 1300 | 0.00004 | 551 |
| 1450 | 0.00004 | 213 |
Standard deviations ranged from 12 to 97 MPa and averaged 60 MPa. Failures occurred primarily at tensile surface flaws, but also at edge flaws and subsurface inclusions.
| Temperature ( °C ) |
Fracture Toughness ( MPa m1/2 ) |
|---|---|
| 25 | 3.8 |
| Temperature ( °C ) |
Hardness ( GPa ) |
|---|---|
| 25 | 13.9 |
| Temperature ( °C ) |
Thermal Expansion ( 10-6 K-1 ) |
|---|---|
| 25-1450 | 3.4 |
| Temperature ( °C ) |
Crosshead Speed ( cm/s ) |
Weibull Modulus ( no unit ) |
|---|---|---|
| 25 | 0.0064 | 6 |
| 1300 | 0.0064 | 13 |
| 1450 | 0.0064 | 12 |
| 1300 | 0.00004 | 9 |
| 1450 | 0.00004 | 6 |