Evaluation Of Dynamic Viscosity Research Articles

Evaluation of Dynamic Viscosity in the 10 MHz Range Using a General-Purpose Quartz Crystal Microbalance

This study examined the validity of viscosity measurements in the frequency region of 10 MHz using a commercially available quartz crystal microbalance (QCM). Ethylene glycol aqueous solutions were used as model samples. From the changes in the resonant frequency and dissipation parameter before and after the introduction of the sample liquid, we determined dynamic viscosity through Johannsmann's equation and compared it with literature data for zero shear viscosity. As a result, the viscosity estimated by QCM was systematically higher. Based on the analysis of the electrical equivalent circuit of the resonator, we considered that such deviation is due to the energy loss inside the quartz resonator and the non-ideal nature of the interface in contact with the sample liquid. To avoid such non-idealities, we proposed a method of applying a calibration equation to the viscosity value obtained from the Johannsmann equation. This makes it possible to easily measure viscosity in the 10 MHz regions with an accuracy of ± 3 % error.

Evaluation of dynamic viscosity and rheological properties of ceramic materials during liquid phase sintering by numerical‐experimental procedure

AbstractThe effective shear and bulk viscosity, as well as dynamic viscosity, describe the rheological properties of the ceramic body during the liquid phase sintering process. The rheological parameters depend on the physical and thermo‐mechanical characteristics of the material such as relative density, temperature, grain size, diffusion coefficient, and activation energy. In this paper, the numerical‐experimental method has been developed to study both viscous and rheological behavior of hard porcelain ceramic body during liquid phase sintering. The other aim is to acquire a complete understanding of the response of an incompressible viscose material during sintering such as stress‐strain relations, sintering, and hydrostatic stress. Densification results confirmed that the bulk viscosity was well‐defined with relative density. The stress analysis proved that the sintering stress is more than the hydrostatic stress during the entire sintering time so, the sintering process occurs completely. Deflection results showed that the shear viscosity was a fair estimation of real ones. Dilatometry, SEM, XRD investigations as well as bulk viscosity simulation results confirmed that the “mullitisation plateau” was presented as a very little extraordinary expansion at the final sintering stage.