Abstract
In this study, to solve problems on a conventional rotary viscometer, that is, the slip phenomenon of suspension along the cylinder walls, edge effects, and control methods of viscometer, an improved coaxial rotary viscometer was designed and produced, and two simple calculation methods of rheological properties of suspension were developed when the gap between cylinders was wide. The features of this improved viscometer are as follows: 1) The mechanism of transmitting torque was seperated from the mechanism of measuring the rate of shear; 2) A triple cylinder type rotary viscometer was used to minimized the edge effects; and 3) The viscometer was operated at the condition of either constant apparent deformation rate or constant shear stress.
As the simple calculation methods of rheological properties, differential and integral methods are proposed. The former is available when the angular velocity distribution in the radial direction of clay suspension is known over the distance between center and outer cylinders, the latter is available to obtain the relationship between deformation rate and shear stress from the angular velocities near them. Experimental results of clay suspensions with this viscometer differ from the results with conventional viscometers due to the consideration of the slip phenomenon.
