Ming-xue Shen

Antiwear Properties of Bonded MoS2 Solid Lubricant Coating under Dual-Rotary Fretting Conditions

ABSTRACT Bonded MoS2 solid lubricant coatings are widely used in tribology for their friction-reducing and antiwear properties. However, such coatings have been rarely investigated in complex fretting conditions, such as dual-rotary fretting (DRF). DRF is a complex fretting wear mode that combines torsional fretting with rotational fretting. In this work, the antiwear properties of bonded MoS2 solid lubricant coating under dual-rotary fretting conditions were studied. Results indicated that the MoS2 coating had better friction-reducing and antiwear properties than the substrate for alleviating DRF wear. The coating can greatly influence the fretting regimes and reduce the coefficient of friction. Furthermore, the service life of the coating was strongly dependent on the competition of the two fretting components and was reduced as the rotational fretting component increased.

Research on the Rotational Fretting Wear of Ti6Al4V Alloy against Silicon Nitride

The rotational fretting of Ti6Al4V titanium alloy flat against silicon nitride (Si3N4) ceramics ball has been investigated by using a special rotational fretting wear test rig. Under various parameters of normal load and angular displacement amplitude, three fretting regimes were observed (i.e. partial slip regime, mixed fretting regime, and slip regime), corresponding to the different evolutions of the running condition at the contact interface. The micro-examination of the wear scars revealed an accumulation of plastic deformation within the centre of the wear scars in the gross slip condition. The damage mechanisms in the different fretting regimes were analysed in detail. The results showed that the mechanisms were quite different in the different fretting regimes.

Thermohydrodynamic analysis on herringbone-grooved mechanical face seals with a quasi-3D model

A quasi-3D thermohydrodynamic model was introduced to analyze the seal performance of a herringbone-grooved mechanical face seal. In the model, the heat conduction equations of the seal rings and the energy equation of the lubrication film were solved simultaneously by the streamline upwind/Petrov–Galerkin finite element method. The Reynolds equation and the temperature equations were iteratively solved to obtain the liquid film pressure and the temperature distribution. A parameterized study was conducted to analyze the influence of the herringbone grooves’ geometry on the opening force, leakage rate, friction coefficient, and temperature rise. The results show that the hydrodynamic analysis overestimates the opening force because the viscous heat reduces the dynamic viscosity. The longer and narrower inner spiral groove gives the smaller leakage rate and the longer outer spiral groove with a smaller spiral angle shows the larger opening force.