Abstract
The thermal stability of greases has become an important factor in modern mechanical engineering applications. With this in mind, experiments were conducted with a carbon black as a filler in a carrier fluid of siloxane (MS 550) in order to obtain higher operating temperatures. It was determined that the colloidal system formed depended upon solids concentration by weight. Viscosity–shear rate characteristics were observed to be highly non-Newtonian for high solid concentrations and less marked for lower concentration, resulting in poor mechanical stability. Special surface treatment of the carbon black showed an improvement. When subjected to oscillatory shearing of variable strain amplitude the system was again observed to depend upon the percentage solid concentration. The fundamental wave suggests stronger elastic properties at low strain amplitude than for similar systems tested for frequency dependence.
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