Characteristics of Graphite Products for Photovoltaic Industry

Density

2.26g/cm3 (graphite single crystal), 1.5-1.9g/cm3 (artificial graphite), 2.1g/cm3 (solid pyrolytic carbon)

Mechanical strength

Artificial graphite is different from most other materials. Its tensile, flexural, and compressive strength will increase with the increase in temperature. However, when it reaches 2200K, its strength will decrease. At 2200K, the strength of graphite is twice as high as that at room temperature.

The compressive strength of graphite materials generally used in semiconductor and photovoltaic industries reaches 90-150 MPa; The bending strength is 40-65 MPa.

Electrical conductivity

Unlike other metals, the resistance temperature coefficient of graphite is negative. Graphite has good electrical conductivity. Close to absolute zero, with only a few free electrons, it acts as an insulator in itself, and its conductivity increases as the temperature rises. The electrical conductivity of graphite is higher than that of many metals, and its value decreases with increasing temperature. The thermal conductivity of graphite varies with the degree of graphitization.

Thermal expansibility

3×10-6K-1, 1/4 of iron

Specific heat

The specific heat of graphite varies greatly in the temperature range of 500K-1500K, and it also increases greatly with the increase of temperature. And different grades of graphite, its specific heat change is very small.

Temperature resistance

Graphite does not melt, but it can withstand temperatures up to 750K (477°C) and even up to 3900K (3627°C). Graphite also has excellent thermal shock resistance, so it can handle rapid heating or cooling without any issues.

Machinability

Graphite is easy to process, and it has good edge strength and wear resistance. It can be used to obtain parts with complex structures and tight tolerances through finishing. Graphite also has good resistance to infiltration, as it will not be melted by glass or most metals.