Introduction of Isotropic Pyrolytic Graphite (IPG) Materials

1. Background and needs

Isotropic pyrolytic graphite (IPG) material is a high-performance carbonaceous material prepared by chemical vapor deposition (CVD) method. It has a dense structure and small grain size, which overcomes the Graphite material has the weakness of anisotropy, and has the characteristics of high temperature resistance, lubrication, wear resistance, high strength, airtightness, ablation resistance, and excellent processability. It is the material with the best comprehensive performance among bulk carbon materials. The use of isotropic pyrolytic graphite as a key component of the mechanical seal device of an important equipment system is a major breakthrough in the development of carbon materials for mechanical seals in the world. It not only simplifies the impregnation of traditional carbon materials before they can be used in mechanical seals. The technical process, and the strength, sealing, wear resistance, ablation resistance and other properties of the material are significantly improved, which fully demonstrates the superiority of the single structure carbon material, and is the mechanical sealing material with the best comprehensive performance.

The isotropic pyrolytic graphite material is deposited on the surface of the substrate after high-temperature pyrolysis of hydrocarbons, and its preparation process is a chemical vapor deposition process. Commonly used raw materials include hydrocarbon gases such as methane, acetylene, propane, and ethylene. The chemical reaction equation is as follows:

CnHm → C (pyrolysis) + [C, H]

2. Main performance indicators

The main performance indicators of isotropic pyrolytic graphite materials are as follows:

1) Density: g/cm³ ≥1.8

2) Non-isotropic pyrolytic graphite impurities: None

3) Carbon black impurities: None

4) Thermal conductivity: W/m·K 30~50

5) Linear thermal expansion coefficient: (KTTP) K-1

293~1173K (5.0~8.5)×10^－6

6) Compressive strength: MPa ≥ 200

7) Bending strength: MPa ≥100

8) Tensile strength: MPa ≥ 40

9) Young's modulus: GPa 8-12

10) Impact toughness: J/m2 ≥44×10²

11) Microhardness: MPa 300~700

12) Shore hardness: ≥80

13) Resistivity: Ω·m (3.72±0.64)×10^-5

14) Maximum working temperature in oxidizing environment: ℃ 650

15) Open porosity: % ≤0.3

16) Good matching with the dual metal, no damage to the metal surface

17) Good machining performance

Comparing the performance indicators of carbon materials for mechanical seals, it can be found that isotropic pyrolytic graphite not only has high mechanical strength, but also has excellent properties such as high oxidation resistance and wear resistance, as well as higher processing accuracy and smaller open pores. Therefore, as the mechanical seal material with the best comprehensive performance, it will be successfully applied in aviation, aerospace, shipbuilding, metallurgy, petroleum, electronics and other fields.