Rheological properties of high-temperature lubricating greases

Reports results from an investigation of the rheological properties of high-temperature greases of the carbon black, silica gel, and phthalocyanine types, in which conventional test procedures were applied to model systems. Uses the petroleum oil MS-20 and the polymethylchlorophenylsiloxane fluid KhS-2-1VV as dispersion media. Investigates the variation of rheological properties of the plastic systems in the stage preceding steady-state flow. Finds that greases distinguished by a high degree of heat-hardening (phthalocyanine greases) cannot be used to lubricate components in which a limited starting torque is available, nor in sliding-contact bearings, owing to the difficulty of access of the grease to the working zone of the component. Recommends phthalocyanine greases, which are mechanically stable but harden when heated, for high-speed bearings operating at high loads and large shearing forces. Suggests that carbon black greases should be used in low-speed rolling-contact and sliding-contact bearings. Points out that of the nonsoap greases investigated, the greases based on the organic-modified silica gel AM-2 are outstanding.