handbook of carbon, graphite, diamond and fullerenes

102 Carbon, Graphite, Diamond, and Fullerenes
.1500
Refractory Alloys
Sic
Graphite -
400 1000 2000 3000
Temperature °C
Figure 5.7. Specific strength as a function of temperature of graphite and other
high-temperature materials. I 12 '
The room-temperature transverse (flexural) strength of molded-graphite
grades varies between 10 and 100 MPa and its Young's modulus (also at room
temperature) is between 5 and 10 GPa. These large variations are due to
differences in raw materials and processing techniques. Flexural testing is
described in detail in the test procedures listed in Table 5.3. In the more
common three-point loading test, typical test specimens have a square cross
section, 5.08 mm (0.200 in) or 3.18 mm (0.125 in) on the side. The support span
is 3.05 mm (1.20 in) or 1.52 mm (0.60 in) for the larger and smaller test
specimens, respectively. The strength is given by the following formula:
where:
S =
S = flexural strength
P = load at rupture
L = support span
b = specimen width
d = specimen thickness! 2 !