Lubricant properties in thin lubricating films

Conference · Sun Feb 01 00:00:00 EST 1976 · Am. Chem. Soc., Div. Pet. Chem., Prepr.; (United States)

OSTI ID:5747394

Sanborn, D M; Winer, W O

The lubrication of highly loaded machine elements (gears, cams, etc.) frequently result in lubricant films less than 3 ..mu..m thick. These thin lubricant films are subjected to pressures up to 3 GN/m/sup 2/, shear stresses to 0.2 GN/m/sup 2/ and shear rates in excess of 10/sup 6/ s/sup -1/. Lubrication under these conditions is referred to as elastohydrodynamics lubrication (EHD). These conditions result in mechanical energy dissipation rates in the lubricant of up to 0.2 TW/kg which causes both high temperature and irreversible molecular degradation. Temperatures of the lubricant film have been measured by an infrared technique (I) and have been found to be as high as 300/sup 0/C. This paper describes a technique for obtaining a lubricant sample from a highly loaded sliding elastohydrodynamic contact which simulates machine elements such as cams and gears. The samples are analyzed for irreversible changes in rheological properties by measuring the viscosity and in some cases measuring the molecular weight distribution. The objective was to subject a variety of fluids to conditions found in elastohydrodynamic lubrication and to determine the extent of the molecular degradation. The fluids were subjected to peak pressures of 1 GN/m/sup 2/ and shear rates of 10/sup 6/ to 10/sup 7/ s/sup -1/ in an elastohydrodynamic simulator. Samples of the fluid were collected for low shear rate viscosity measurements. In those cases where data was available the viscosity average molecular weight of the sheared sample was also determined. In a few cases the molecular weight distributions of the sheared and unsheared samples were obtained and compared. Thin film elastohydrodynamic contacts cause extensive molecular degradation in lubricants with constituents having molecular weights above 10/sup 4/. Materials with molecular weights below 600 appear to undergo no significant molecular changes in the EHD contacts.

• Research Organization: Georgia Inst. of Tech., Atlanta, GA
• OSTI ID: 5747394
• Report Number(s): CONF-760458-P1
• Journal Information: Am. Chem. Soc., Div. Pet. Chem., Prepr.; (United States), Vol. 21:1; Conference: National meeting of the American Chemical Society, New York, NY, USA, 4 Apr 1976
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
BENCH-SCALE EXPERIMENTS
COMPARATIVE EVALUATIONS
INTERNAL COMBUSTION ENGINES
LUBRICATING OILS
ADDITIVES
DECOMPOSITION
TESTING
THERMAL DEGRADATION
EXPERIMENTAL DATA
GEARS
LUBRICATION
MOLECULAR WEIGHT
RHEOLOGY
THIN FILMS
VISCOSITY
CHEMICAL REACTIONS
DATA
ENGINES
FILMS
HEAT ENGINES
INFORMATION
LUBRICANTS
MACHINE PARTS
NUMERICAL DATA
OILS
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
PETROLEUM PRODUCTS
420500* - Engineering- Materials Testing