Tribological Properties of Nitrate Graphite Foils

Area of Science:

• Materials Science
• Tribology
• Nanotechnology

Background:

• Graphite foils (GF) are utilized in various applications requiring specific tribological and mechanical properties.
• Understanding the influence of raw material characteristics (particle size) and processing parameters (density, cold rolling) is crucial for optimizing GF performance.
• Previous research has explored GF properties, but a comprehensive analysis linking particle size, density, and tribological behavior under varying conditions is needed.

Purpose of the Study:

• To investigate the tribological properties of graphite foils (GF) produced from natural graphite with varying particle sizes and densities.
• To analyze the effects of static and dynamic friction testing on surface roughness, friction coefficient, and microstructural changes.
• To correlate mechanical properties, such as Young's modulus and stress-strain behavior, with particle size and density.

Main Methods:

• Graphite foils were prepared using purified natural graphite with particle sizes of 40-80 μm, 160-200 μm, and >500 μm, and densities of 1.0, 1.3, and 1.6 g/cm³.
• Surface roughness was measured after cold rolling and friction tests under static (0.001 mm/s) and dynamic (0.1 Hz, 1 Hz) conditions.
• Friction coefficients, Young's modulus, stress-strain states, microstrains, and residual macrostresses were determined. Structural analyses included measurements of coherent-scattering region size and misorientation angles.

Main Results:

• Dynamic friction tests significantly increased surface roughness compared to static tests.
• The friction coefficient decreased with higher sliding speeds, with GF made from 40-80 μm particles showing the lowest values (0.13-0.15).
• Young's modulus increased with density and decreased with particle size. Greater plastic deformation and microstrain accumulation were observed in GF with smaller particles.

Conclusions:

• Particle size is a critical factor influencing the tribological performance and mechanical properties of graphite foils.
• Smaller graphite particles (40-80 μm) lead to lower friction coefficients and enhanced plastic deformation, suggesting improved wear resistance.
• Density plays a role in modifying friction and mechanical properties, especially for larger particle fractions, and accumulated deformation correlates with friction behavior.