Principles of viscous sintering in amorphous powders: A critical review

The present work deals with the main mechanisms involved in caking of amorphous powders and its theoretical background. After a brief outline of the general basics, the review continues with summarizing available models and their analytical solutions predicting inter-particle bridge formation as the micro scale description of caking. Outputs of numerical techniques including conventional computational fluid dynamics (CFD) methods alongside with some newer methods such as lattice Boltzmann method (LBM), on capturing the inter-particle bridge interface when two particles are sticking together are also investigated. With an overview on the applications of numerical methods for describing multi-particle caking as an intermediate scale, the review continues through investigation of simulations carried out for macro scale caking. The macro scale study surveys numerical methods belonging to the discrete viewpoint - discrete element method (DEM) particularly - while continuum point of view was out of purpose. This review summarizes the basics in caking of amorphous powders along with the modeling approaches predicting viscous sintering mechanism and the use of analytical and numerical methods provided to solve such models. The review characterizes competencies and limitations of the listed methods. Prospects for future research in this area are also highlighted. The result of this study will be useful in identifying the future research directions needed in order to understand leading mechanisms in caking of amorphous powders and also to facilitate the development of more accurate and sophisticated models to predict the kinetics of this phenomenon in process industries. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.