Formation of Robust Polydimethylsiloxane Coatings on the Flexspline Material and Mechanism of the Tribological Property Improvement.

Flexspline frictional degradation causes failure of harmonic drives. This study focused on the improvement of the flexspline tribological properties. Flexspline material 40Cr was modified with a robust polydimethylsiloxane (PDMS) coating. Etched and chemically modified films were utilized to enhance the organic PDMS coating-substrate link strength. Comparing modified and unmodified 40Cr, the surface friction coefficient decreased by 82.2%. Moreover, the modified 40Cr exhibited excellent load-bearing properties. The effects of speed and lubricant-coating interaction on the tribological properties were verified. This study provides an essential theoretical basis for improving the tribological performance of harmonic drives via soft coating modification.