Properties of Columnar and Laminar Pyrolytic Graphites

The properties of pyrolytic graphite are summanzed in Table 7.2. The values listed were collected from the manufacturer s data sheets.P i i The spread in value may represent slightly different materials and differences in the degree of graphitization. It may also reflect variations in the test methods for instance, the measurement of mechanical properties may vary widely depending on the sample geometry and the test method (see Ch. 5, Sec. 2.1). 

Flexural strength tested in the c direction (across grain), MPa 80-170 

Tensile strength tested in the ab directions (with grain), MPa 110 

Mechanical Properties. The mechanical properties of pyrolytic graphite are like those of the ideal graphite crystal In the sense that they show a marked increase with increasing temperature as shown in Fig. 7 9 [iij[26i Above 2600°C, the strength drops sharply. 

Thermal Conductivity. As noted in Ch. 3, Sec. 4.3, the thermai conductivity of the ideal graphite crystal in the ab directions is high. It is far lower for the average pyrolytic graphite (up to 390 W/m K at 25°C) but still high enough for the material to be considered a good thermal conductor, similar to copper (385 W/m K at 25°C) (see Ch. 3, Table 3.6). 

---