Surface modification and effects on tribology by laser texturing in Al₂O₃

Area of Science:

• Materials Science
• Surface Engineering
• Tribology

Background:

• Surface properties significantly influence material performance, especially in tribological applications.
• Laser texturing offers a precise method for modifying material surfaces.
• Understanding microstructure evolution is key to optimizing laser surface treatments.

Purpose of the Study:

• To investigate the effects of laser texturing on the microstructure of aluminum oxide (Al2O3).
• To evaluate the impact of these surface modifications on tribological performance.
• To elucidate the mechanisms behind changes in friction coefficients under different conditions.

Main Methods:

• Laser texturing was applied to Al2O3 surfaces.
• Microstructure evolution was analyzed using scanning electron microscopy (SEM).
• Phase analysis was performed using X-ray diffraction (XRD).
• Chemical composition was examined using X-ray photoelectron spectroscopy (XPS).
• Tribological performance was assessed through wear tests measuring coefficients of friction (COF).

Main Results:

• Three distinct microstructural morphologies were observed: dense microfeatures, "coral" dendritic structures, and coarse grains.
• No metastable phases were formed in the nanosecond laser regime.
• Aluminum nitride (AlN) compounds formed in laser-treated regions.
• Laser texturing significantly improved COF in dry friction.
• Laser texturing decreased COF in wet friction due to abrasive particle storage and hydrodynamic film formation.

Conclusions:

• Laser texturing effectively modifies Al2O3 surface microstructure without forming undesirable phases.
• The created surface textures enhance dry friction performance.
• In wet conditions, laser texturing aids in lubricant film formation, reducing friction.