The Effect of Composition and Temperature on the Rheological Properties of Greases Based on Calcium Soaps

The knowledge of the rheological properties of the greases based on calcium soaps is important because these properties ensure proper oiling of moving metallic parts of machines at high charges and in a large temperature range. In the present study, four greases has been prepared with different concentration of calcium soap: 5%, 10%, 15% and 20% respectively, in paraffin oil. For viscosity determination of greases, the RHEOTHEST 2 rheoviscometer with coaxial cylinders and HAAKE VT 550 rheoviscometer with cone and plate were used. After the determination of flow curve τ = f(ỳ), it was found that the greases had a non-newtonian behavior with respect to BINGHAM model, that meaning that the flow curve characterizing them had a linear form with a flowing threshold. Also, it was studied the variation of viscosity with temperature for grease with 20% calcium soap. It was found that increasing the temperature, the viscosity decreases having decreasing flow thresholds