A discrete model for long-time sintering

TL;DR

This paper introduces a discrete model for long-term sintering of polydisperse cylinders, incorporating empirical contact laws, plasticity, cohesion, and temperature effects, revealing insights into material reorganization and force distributions.

Contribution

It presents a novel discrete model for long-time sintering that accounts for inhomogeneity, plasticity, cohesion, and temperature dependence, providing microscopic and macroscopic insights.

Findings

Density increases continuously during sintering.

Coordination number may decrease despite densification.

Attractive contacts dominate during cool-down, forming strong bonds.

Abstract

A discrete model for the sintering of polydisperse, inhomogeneous arrays of cylinders is presented with empirical contact force-laws, taking into account plastic deformations, cohesion, temperature dependence (melting), and long-time effects. Samples are prepared under constant isotropic load, and are sintered for different sintering times. Increasing both external load and sintering time eads to a stronger, stiffer sample after cooling down. The material behavior is interpreted from both microscopic and macroscopic points of view. Among the interesting results is the observation, that the coordination number, even though it has the tendency to increase, sometimes slightly decreases, whereas the density continuously increases during sintering -- this is interpreted as an indicator of reorganization effects in the packing. Another result of this study is the finding, that strongly attractive contacts occur during cool-down of the sample and leave a sintered block of material with almost equally strong attractive and repulsive contact forces.