NIST Structural Ceramics Database (SCD) Database

NIST Standard Reference Database 30

Last Update to Data Content: 2002

DOI: http://dx.doi.org/10.18434/T4F30D


SCD Citation Number: Z00038

Bibliographic Information

Reference:
"Effects of Ceramic Microstructures on Strength and Fracture Surface Energy," G.K. Bansal, Proceedings of the Sixth International Materials Symposium, pp. 860-871 (1976), edited by R.M. Fulrath and J.A. Pask, published by Westview Press (Boulder Colorado).
Language: English

General Materials Processing Notes

"...commercial polycrystalline ceramics, a sintered alumina, a hot pressed alumina, and a hot pressed silicon nitride, were investigated. ... The sintered alumina is made by isostatic pressing and sintering of spray-dried powder granules. The final product contains about 96% Al2O3, and is 95% dense. The grain size of the material is 5 µm. The hot-pressed alumina is 99.5% dense and contains about 99.8% Al2O3 and 0.2% of a grain growth inhibitor. The grain size of the material is about 2 µm. The hot pressed silicon nitride is prepared by hot pressing of high α-phase Si3N4 powder with about 2% MgO used as a densification aid. The material is pressed to nearly full density and possesses an average grain size of 1 µm to 2µm. Some SiO2 in the initial powder is believed to react with MgO to form a glassy grain boundary phase."

Measurement Methods

Three-point bend test
"Strengths were measured using 3-point bend tests on specimens having dimensions (2.54 mm x 5.08 mm x 38.1 mm = 0.1 x 0.2 x 1.5 in.). Specimens' surfaces were finish ground parallel to the tensile axis using a 320-grit (25-40 µm) diamond wheel. All tests were conducted on a (3.175 cm =1.25-in.) span, and in dry nitrogen at a stress rate of 100 MNm-2s-1 to restrict moisture-assisted subcritical crack growth. More than 10 specimens were tested for each material. Strengths of hot pressed Al2O3 specimens were measured in two directions: in each case, the fracture plane contained the hot pressing direction. In one, flaws propagated parallel to the pressing direction and, in the other, perpendicular to it. Strengths of the hot pressed Si3N4 specimens were measured with flaws moving parallel to the pressing direction only. The glass-ceramic and the sintered Al2O3 were found to be isotropic."
Toughness test
The author sites D.P. Williams et al., J. Testing and Evaluation, Vol. 1 (4) 264-270 (1973) and R.W. Davidge et al., Proc. Br. Ceram. Soc., Vol. 15, 47-60 (1970), and summarizes the procedure as follows. "Fracture surface energies were measured using two techniques: double torsion and notch bend. Four specimens of each material were used for determination by each technique."
Stress-strain measurement
"Young's moduli were determined both in uniaxial compression from measurements of strain as a function of applied load, and from 4-point bend tests. In the bend test, axial strains were measured as a function of applied moment using resistance strain gages on both the tension and the compression surfaces."

Index of Materials and Properties (Click on a selected Material Number to expand material properties menu)

Material Specification and Properties for Al2O3

Material number 1 of 3
in SCD Citation Number: Z00038
Chemical Class: Oxide
Chemical Family: Al-O
Formula: Al2O3
Informal Name: alumina
Structure Type: Polycrystalline
Manufacturer: 3M Company
Commercial Name: Alsimag 614
Process: Sintering

Al2O3

Material number 1 of 3
in SCD Citation Number: Z00038
Elemental Composition
Amount of
Element
( formula units )
Element
 
( no unit )
2 Al
3 O
Measurement Method: Reported Formula
Evaluation Status: Unevaluated

Al2O3

Material number 1 of 3
in SCD Citation Number: Z00038
Elastic Modulus
Temperature
 
( °C )
Elastic
Modulus
( GPa )
22 318
Measurement Method: Stress-strain measurement
Evaluation Status: Evaluated by acceptance criteria

Al2O3

Material number 1 of 3
in SCD Citation Number: Z00038
Flexural Strength
Temperature
 
( °C )
Flaw
Direction
 
Flexural
Strength
( MPa )
22 -- 408 ± 12
Measurement Method: Three-point bend test
Evaluation Status: Evaluated by acceptance criteria

Al2O3

Material number 1 of 3
in SCD Citation Number: Z00038
Fracture Energy
Temperature
 
( °C )
Flaw
Direction
 
Fracture
Energy
( J m-2 )
22 -- 23.2 ± 1.2
Measurement Method: Toughness test
> Evaluation Status: Evaluated by acceptance criteria

Material Specification and Properties for Al2O3

Material number 2 of 3
in SCD Citation Number: Z00038
Chemical Class: Oxide
Chemical Family: Al-O
Formula: Al2O3
Informal Name: alumina
Structure Type: Polycrystalline
Manufacturer: Avco Co.
Process: Hot Pressing

Al2O3

Material number 2 of 3
in SCD Citation Number: Z00038
Elemental Composition
Amount of
Element
( formula units )
Element
 
( no unit )
2 Al
3 O
Measurement Method: Reported Formula
Evaluation Status: Unevaluated

Al2O3

Material number 2 of 3
in SCD Citation Number: Z00038
Elastic Modulus
Temperature
 
( °C )
Elastic
Modulus
( GPa )
22 413
Measurement Method: Stress-strain measurement
Evaluation Status: Evaluated by acceptance criteria

Al2O3

Material number 2 of 3
in SCD Citation Number: Z00038
Flexural Strength
Temperature
 
( °C )
Flaw
Direction
 
Flexural
Strength
( MPa )
22 parallel 915 ± 50
22 normal 843 ± 54
Measurement Method: Three-point bend test
Evaluation Status: Evaluated by acceptance criteria

Al2O3

Material number 2 of 3
in SCD Citation Number: Z00038
Fracture Energy
Temperature
 
( °C )
Flaw
Direction
 
Fracture
Energy
( J m-2 )
22 Parallel 42.2 ± 6.0
22 Normal 21.2 ± 2.1
Measurement Method: Toughness test
> Evaluation Status: Evaluated by acceptance criteria

Material Specification and Properties for Si3N4·xMgO

Material number 3 of 3
in SCD Citation Number: Z00038
Chemical Class: Nitride
Chemical Family: Si-N:MgO
Formula: Si3N4·xMgO
Informal Name: silicon nitride
Structure Type: Polycrystalline
Manufacturer: Norton Company
Commercial Name: NC-132
Process: Hot Pressing

Si3N4·xMgO

Material number 3 of 3
in SCD Citation Number: Z00038
Elemental Composition
Amount of
Element
( formula units )
Element
 
( no unit )
3 Si
4 N
Measurement Method: Reported Formula
Evaluation Status: Unevaluated

Si3N4·xMgO

Material number 3 of 3
in SCD Citation Number: Z00038
Sintering Aids
Sintering Aid
Mass Fraction
( % )
Sintering Aid
 
( no unit )
2 MgO
Measurement Method: Reported Formula
Evaluation Status: Unevaluated

Si3N4·xMgO

Material number 3 of 3
in SCD Citation Number: Z00038
Elastic Modulus
Temperature
 
( °C )
Elastic
Modulus
( GPa )
22 310
Measurement Method: Stress-strain measurement
Evaluation Status: Evaluated by acceptance criteria

Si3N4·xMgO

Material number 3 of 3
in SCD Citation Number: Z00038
Flexural Strength
Temperature
 
( °C )
Flaw
Direction
 
Flexural
Strength
( MPa )
22 parallel 960 ± 35
Measurement Method: Three-point bend test
Evaluation Status: Evaluated by acceptance criteria

Si3N4·xMgO

Material number 3 of 3
in SCD Citation Number: Z00038
Fracture Energy
Temperature
 
( °C )
Flaw
Direction
 
Fracture
Energy
( J m-2 )
22 Parallel 61.3 ± 5.3
22 Normal 42.2 ± 1.8
Measurement Method: Toughness test
> Evaluation Status: Evaluated by acceptance criteria