Interface-Driven Carbon Fiber Reinforcement in Graphite Packing Rings for Enhanced Service Stability

Area of Science:

• Materials Science
• Mechanical Engineering
• Tribology

Background:

• Flexible graphite packing is crucial for high-temperature/pressure valves due to lubricity and thermal stability.
• However, low mechanical strength, creep, and tribological instability limit its reliability under extreme conditions.

Purpose of the Study:

• To enhance the performance of graphite packing rings using surface-functionalized polyacrylonitrile-based carbon fibers (PAN-CFs).
• To investigate the effect of PAN-CF content on mechanical properties, thermal stability, friction, and durability.

Main Methods:

• Interface engineering strategy involving oxidative modification of PAN-CFs and high-temperature graphite expansion.
• Fabrication of a 3D reinforced graphite network with varying PAN-CF content (0-7 wt%).
• Systematic evaluation of compressive strength, thermal stability, friction coefficient, creep resistance, and long-term durability.

Main Results:

• Optimal performance achieved at 5 wt% PAN-CF, showing a ~58% increase in compressive strength.
• Stable friction coefficient (0.15-0.18) and enhanced creep resistance were observed.
• Over 78% of initial strength retained after 1000 h of sustained loading.

Conclusions:

• Surface-functionalized PAN-CF reinforcement significantly improves mechanical strength, tribological behavior, and creep resistance of graphite packing.
• Interfacial mechanical anchoring and load transfer are key mechanisms for performance enhancement.
• This approach offers a practical solution for improving the reliability of graphite sealing components in demanding industrial environments.