Bench Test Evaluation of Thermal Stability and Lubricity of Anti-Wear Hydraulic Oils in an Acid Atmosphere

Abstract

A good quality anti-wear (AW) hydraulic oil must not only pass Denison HF-0 and Cincinnati Milacron P70 specifications, but also work smoothly in a modern hydraulic system, especially in those systems including servo-controlled mechanism with fine filters. Thermal oxidation stability and lubricity play important roles in developing new formulations for high performance AW hydraulic oils. To obtain more effective assessment of the properties of AW hydraulic oils in the laboratory, and to have good correlation with field trial data, a simulated aging test based on an acid catalyzed Cincinnati-Milacron thermal stability test was proposed. In addition, tests were used to study the lubricity of AW hydraulic oils. Based on the simulated aging test, the tendency of sludge formation for three AW hydraulic oils has been studied. The results correlated well with the field trial data obtained from the hydraulic system of a pickling line of a steel plant. Using the high speed reciprocating rig and scanning electron microscopy (SEM) studies, it was found that the lubricity depends on the formation of reaction films on the steel surfaces, and that the film formation depends on type and amount of ZnDDP in the formulation.

Presented at the 52th Annual Meeting in Kansas City, MO May 18–22, 1997

KEY WORDS:

• Bench Test
• Hydraulic Oil
• Scanning Electron Microscopy

Notes

Presented at the 52th Annual Meeting in Kansas City, MO May 18–22, 1997