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: Z00617

Bibliographic Information

Reference:
"Hardness Anisotropy of α-Si3N4 Crystal," K. Niihara and T. Hirai, Journal of Materials Science, Vol. 13, pp. 2276-2278 (1978), published by Chapman and Hall.
Language: English

General Materials Processing Notes

The authors cite K. Niihara et al., J. Mater. Sci., Vol. 11, 593 (1976), and summarize the procedure as follows. "Single crystals of α-Si3N4 for hardness measurements were needle-like crystals along the [0001] or [2-1-10] directions (up to 15 mm long, 1.5 mm2 in cross-section) and pyramidal crystals with large (11-20) or (10-10) planes (up to 3.5 mm2 area), which were prepared by pyrolysis of a NH3 and H2-carried SiCl4 mixture on a heated graphite substrate. The preparation conditions were as follows: the substrate temperature, 1500 °C to 1700 °C; the total gas pressure, (1.33 kPa to 6.67 kPa = 10 to 50 Torr), the flow rates of NH3, SiCl4 and H2, 60, 0.8 (in liquid) and 700 cm3 min-1, respectively."

Measurement Methods

Indentation method
"The single crystals were embedded in resin so as to make the (0001), (10-10) and (11-20) planes parallel to the resin surface, followed by polishing with a fine diamond paste (0.25 µm). ... Vickers microhardness (VMH) and Knoop microhardness (KMH) tests were carried out using an AKASHI diamond hardness tester (Model: MVK, Type: D). Indenter loads of 25 g to 300 g were used... For the KMH measurements, the long axis of indentations was adjusted to be parallel and perpendicular to the [10-10] and [11-20] directions on the (0001) plane and to the c-axis on the (10-10) and (11-20) planes."

Index of Materials and Properties

Material Number 1: Si3N4

Material Specification and Properties for Si3N4

Material number 1 of 1
in SCD Citation Number: Z00617
Chemical Class: Nitride
Chemical Family: Si-N
Formula: Si3N4
Informal Name: silicon nitride
Structure Type: Single Crystal
Manufacturer: In-House
Process: Crystal Growth

Si3N4

Material number 1 of 1
in SCD Citation Number: Z00617
Hardness
Test Type
 
 
Load
 
( g )
Plane
 
 
Orientation
 
 
Hardness
 
( GPa )
Vickers 25 (10-10) --- 47
Vickers 50 (10-10) --- 41
Vickers 100 (10-10) --- 34
Vickers 200 (10-10) --- 31
Vickers 300 (10-10) --- 27
Vickers 100 (0001) --- 28 ± 1
Vickers 100 (10-10) --- 35 ± 1
Vickers 100 (11-20) --- 36 ± 1
Knoop 100 (0001) [10-10] 27.3 ± 0.5
Knoop 100 (0001) [11-20] 25.7 ± 0.4
Knoop 100 (0001) [1-100] 27.4 ± 0.3
Knoop 100 (0001) [1-210] 25.4 ± 0.1
Knoop 100 (10-10) [0001] 34.2 ± 0.5
Knoop 100 (10-10) [1-210] 30.9 ± 0.4
Knoop 100 (11-20) [0001] 34.1 ± 0.4
Knoop 100 (11-20) [1-100] 31.7 ± 0.7

Measurement Method: Indentation method
Evaluation Status: Evaluated by acceptance criteria
Cautions:
Vickers data versus load were digitized from Fig. 1 of the reference.