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Cold Compaction and Solid‐State Sintering of WC‐Co‐Based Structures: Experiments and Modeling
Author(s) -
Favrot Nathalie,
Besson Jacques,
Colin Christophe,
Delannay Francis
Publication year - 1999
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1999.tb01889.x
Subject(s) - sintering , compaction , materials science , creep , constitutive equation , die (integrated circuit) , composite material , pressing , metallurgy , finite element method , thermodynamics , nanotechnology , physics
Cold compaction (200‐1900 MPa) and sintering (1250°‐1350°C) of cermets based on WC‐Co were experimentally studied using die compaction, cold isostatic pressing, sintering, and creep tests. Two different‐sized WC powders were used. The cobalt content varied over a range of 10‐30 wt%. Cold‐compaction behavior has been described by using a Cam‐Clay model. Die‐wall friction was measured by using green powder compacts that had different aspect ratios. Friction coefficients were 0.28‐0.85, depending on the WC particle size and cobalt content. Simple constitutive equations have been used to model the high‐temperature behavior (sintering and creep). The constitutive equations were implemented in a finite‐element program to model the compaction, ejection, and sintering of bilayer structures that had different cobalt contents. The model can represent the effect of die‐wall friction on the average density, as well as deformation inside the green compact. Density gradients were generated; they were revealed during sintering, because the compact does not deform homogeneously. Simulation also can be used to evaluate deformations that are induced by sintering.