Viscosity of WC-Co compacts during sintering

This paper describes experiments performed on WC-Co compacts in order to measure the viscosities of a Newtonian constitutive law commonly used to simulate sintering. An intermittent loading method is used during two series of experiments. The first series are dedicated to determining the axial viscosity and takes place in a loading-dilatometer. The second one takes advantage of a video-extensometry device and provides results about the viscous Poisson's ratio. The axial viscosity is obtained as a function of relative density and temperature. Viscosity shows strong exponential increase with increasing density during isothermal conditions but decreases from 10 to 1 GPa .s between 1100 degreesC and 1325 degreesC during a conventional sintering cycle. Viscous Poisson's ratio shows low values at low densities and increases to 0.5 at full density. (C) 2001 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.