Parameters for Inherently Homogeneous Sintering Processes

Thermodynamic criteria are introduced to calculate the driving force for the formation of heterogeneous metastable states during sintering. As already shown for one special case of liquid phase sintering, these metastable states significantly affect the reliability of sintered ceramics. Inherently safe sintering processes are proposed, providing a homogeneous evolution of microstructure. A desintering parameter is defined which can be used for a quantitative evaluation of different sintering processes in terms of their tendency for formation of heterogeneity. The desintering parameter has been calculated using sintering simulations in 3D representative volume elements. For that, a deterministic model has been developed. It considers interface energy minimization and grain growth for random arrangements of particles. Computational effort could be significantly reduced by periodic continuation of the microstructure at the sides of the RVE. Basic parameters controlling inherently homogeneous sintering are presented. Surface diffusion is positive at large dihedral angles. Unexpectedly, grain growth can be advantageous as well, provided that it acts continuously during the entire sintering cycle.

[1]  Yue Chen,et al.  ER81 Expression in Breast Cancers and Hyperplasia , 2011, Pathology research international.

[2]  Veena Tikare,et al.  Numerical simulation of microstructural evolution during sintering at the mesoscale in a 3D powder compact , 2010 .

[3]  I. Aksay,et al.  Thermodynamics of densification of powder compact , 2009 .

[4]  F. Raether,et al.  Investigation of sintering mechanisms of alumina using kinetic field and master sintering diagrams , 2009 .

[5]  F. Delannay,et al.  On the control of the liquid-phase distribution in multi-material assemblies processed by liquid-phase sintering , 2008 .

[6]  H. Exner,et al.  A Critical Assessment of Porosity Coarsening during Solid State Sintering , 2006 .

[7]  F. Raether,et al.  Simulation of the Thermoelastic Properties of Sintered Ceramics , 2006 .

[8]  F. Wakai.  Modeling and Simulation of Elementary Processes in Ideal Sintering , 2006 .

[9]  F. Delannay.  Modelling of the influence of dihedral angle, volume fractions, particle size and coordination on the driving forces for sintering of dual phase systems , 2005 .

[10]  Suk‐Joong L. Kang,et al.  Enhanced Densification of Liquid‐Phase‐Sintered WC–Co by Use of Coarse WC Powder: Experimental Support for the Pore‐Filling Theory , 2005 .

[11]  G. Messing,et al.  Constrained Densification of Alumina/Zirconia Hybrid Laminates, II: Viscoelastic Stress Computation , 2005 .

[12]  L. C. Jonghe,et al.  Microstructure Refinement of Sintered Alumina by a Two‐Step Sintering Technique , 2005 .

[13]  D. Bellet,et al.  Bulk observation of metal powder sintering by X-ray synchrotron microtomography , 2004 .

[14]  F. Lange,et al.  The Effect of Inclusions on Densification; III, The Desintering Phenomenon , 1992 .

[15]  B. Kellett,et al.  Thermodynamics of densification. II: Grain growth in porous compacts and relation to densification , 1989 .

[16]  B. Kellett,et al.  Thermodynamics of Densification: I, Sintering of Simple Particle Arrays, Equilibrium Configurations, Pore Stability, and Shrinkage , 1989 .

[17]  F. Lange,et al.  Powder Processing Science and Technology for Increased Reliability , 1989 .

[18]  H. Exner.  Neck shape and limiting GBDSD ratios in solid state sintering , 1987 .

[19]  Frederick F. Lange,et al.  Processing‐Related Fracture Origins: II, Agglomerate Motion and Cracklike Internal Surfaces Caused by Differential Sintering , 1983 .

[20]  Robert L. Coble,et al.  Initial Sintering of Alumina and Hematite , 1958 .

[21]  Tobias Malte Müller,et al.  3D modelling of ceramic composites and simulation of their electrical, thermal and elastic properties , 2014 .

[22]  K. Maca,et al.  Two-Step Sintering of oxide ceramics with various crystal structures , 2010 .

[23]  F. Raether,et al.  Improving strength by controlling segregation in liquid phase sintered aluminium nitride ceramics , 2007 .

[24]  Kenneth A. Brakke,et al.  The Surface Evolver , 1992, Exp. Math..

[25]  J. A. Pask.  Thermodynamic and Geometric Factors in Sintering , 1990 .

[26]  C. Handwerker,et al.  Sintering of Ceramics , 1989 .