Viscosity of WC-Co compacts during sintering

This paper describes experiments performed on WC-Co compacts in order to me asure the viscosities of a Newtonian constitutive law commonly used to simu late sintering. An intermittent loading method is used during two series of experiments. The first series are dedicated to determining the axial visco sity and takes place in a loading-dilatometer. The second one takes advanta ge of a video-extensometry device and provides results about the viscous Po isson's ratio. The axial viscosity is obtained as a function of relative de nsity and temperature. Viscosity shows strong exponential increase with inc reasing 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 incre ases to 0.5 at full density. (C) 2001 Acta Materialia Inc. Published by Els evier Science Ltd. All rights reserved.