Analýza elastohydrodynamického mazání perfluoropolyetherových kapalin

Ehl traction analysis of perfluoropolyether fluids based on bulk modulus

journal article - other

en

Using three kinds of commercial perfluoropolyether (PFPE) fluids, the authors carried out high pressure density test at the pressure up to 1.2 GPa. Tangent bulk modulus and secant bulk modulus of the PFPE fluids were calculated by using the test results. Relationships of these moduli with pressure and temperature were examined. High pressure viscosity of each PFPE fluid was measured and the pressure viscosity coefficients of the PFPE fluids were obtained. In addition, the maximum traction coefficient and the limiting shear stress of each fluid were evaluated from the traction test employing a ball-on-disk testing machine. As a result, it was found that the maximum traction coefficient and the limiting shear stress are closely related to the tangent bulk modulus and the secant bulk modulus, respectively. The significant relationship of the maximum traction coefficient with the molecular packing parameter represented by the product of the pressure viscosity coefficient and the mean Hertzian pressure was also confirmed.

Perfluorpolyetherové (PFPE) kapaliny s vysokou hustotou jsou kapalné mazací oleje, které mají vynikající tepelnou stabilitu a extrémně nízký tlak nasycených par. Vzhledem k těmto fyzikálním vlastnostem, jsou tyto kapaliny používány pro zařízení ve vesmíru a jako maziva ve vakuových podmínkách. V této studii byla provedena nenewtonská termální analýza elastohydrodynamicky mazaného kontaktu s tekutinami PFPE .

Using three kinds of commercial perfluoropolyether (PFPE) fluids, the authors carried out high pressure density test at the pressure up to 1.2 GPa. Tangent bulk modulus and secant bulk modulus of the PFPE fluids were calculated by using the test results. Relationships of these moduli with pressure and temperature were examined. High pressure viscosity of each PFPE fluid was measured and the pressure viscosity coefficients of the PFPE fluids were obtained. In addition, the maximum traction coefficient and the limiting shear stress of each fluid were evaluated from the traction test employing a ball-on-disk testing machine. As a result, it was found that the maximum traction coefficient and the limiting shear stress are closely related to the tangent bulk modulus and the secant bulk modulus, respectively. The significant relationship of the maximum traction coefficient with the molecular packing parameter represented by the product of the pressure viscosity coefficient and the mean Hertzian pressure was also confirmed.

numerické řešení, tření

point contact numerical solution, phase diagram

2014

09.05.2014

Helsinky University of Technology

Helsinky

0780-2285

32

2

29–37

9