The Scientific Bulletin of VALAHIA University MATERIALS and MECHANICS –Vol. 16, No. 14 DOI 10.1515/bsmm-2018-0006 COMPACTION BEHAVIOUR MODELLING OF METAL-CERAMIC POWDER MIXTURES. A REVIEW Ileana Nicoleta POPESCU 1 , Ruxandra VIDU 2,* 1 Valahia University of Targoviste, Faculty of Materials Engineering and Mechanics, Str. Aleea Sinaia, No. 13, Targoviste, Romania 2 California Solar Energy Collaborative, University of California, Davis, 1, Shields Ave, Davis, USA E-mail: pinicoleta24@yahoo.com, *rvidu@ucdavis.edu Abstract. Powder mixtures compaction behavior can be quantitatively expressed by densification equations that describe the relationship between densities – applied pressure during the compaction stages, using correction factors. The modelling of one phase (metal/ceramic) powders or two-phase metal-ceramic powder composites was studied by many researchers, using the most commonly compression equations (Balshin, Heckel, Cooper and Eaton, Kawakita and Lüdde) or relative new ones (Panelli - Ambrózio Filho, Castagnet-Falcão- Leal Neto, Ge Rong-de, Parilák and Dudrová, Gerdemann and Jablonski. Also, for a better understanding of the consolidation process by compressing powder blends and for better prediction of compaction behavior, it's necessary the modeling and simulation of the powder pressing process by computer numerical simulation. In this paper are presented the effect of ceramic particles additions in metallic matrix on the compressibility of composites made by P/M route, taking into account (a) the some of above mentioned powder compression equations and also (b) the compaction behavior modeling through finite element method (FEM) and discrete element modeling (DEM) or combined finite/ discrete element (FE/DE) method. Keywords: Powder compression equations, Numerical simulation,Compaction Modeling, Metal-Ceramic Powders, Composites 1 INTRODUCTION Powder compaction equations are essentially mathematical descriptions of the compaction process that express the theoretical and experimental relationships between strength - density, density – applied pressure of the consolidated material, their pressing conditions and the different properties of the powders (chemical composition, shape, average size and granulometric distribution, apparent / tap density, porosity, specific surface, compressibility and fluidity) using correction factors [1-17]. The interest in powder compaction equations was initially motivated by a practical problem—the need to be able to predict the compaction pressures to achieve a certain density, in order to provide the optimum required properties to the green compact and implicit to the final product. Nowadays, numerous researchers try to find and /or validate a ‘simple but adequate’ mathematical description of experimentally observed compaction curves and to determine and explain quantitatively the predominant mechanisms of powders’ densification, such as the compaction stages [4-23]. Over time, a number of empirical equations have been proposed to characterize compression behaviours and densification mechanisms of one phase: metal (iron, steel, electrolytic Cu, spherical Al, nickel, Mo, Ti, W, atomized Pb and Sn, Ni–Fe-based alloy etc.) powders, ceramic (graphite, Al 2 O 3 , spherical glass, WC, TiC, NbC etc.) powders or two-phase metal-ceramic powders: Al and Cu alloys with ceramic (Al 2 O 3 , SiC, TiO 2 ) powders, Steel+NbC, Fe-Cu-(SiC-diamnante), TiH 2 -SS316L (nano) composite powders [1-23]. 2 COMPACTION BEHAVIOUR MODELLING 2.1. Powder Compression Equations The most common models of powder compaction were developed by Shapiro – Kolthoff and Konopicky (1947-1948) [15, 17], Balshin (1949) [5,15, 19] , Heckel (1961) [5,15,19] Cooper-Eaton (1962). [3,6,12,15,17], Kawakita and Lüdde (1971) [5,15,19]. Later, Ge Rong-de [5,8,10,17] (1991), Panelli and Ambrossinni - Filho (1998) [4,5,7,17], Parilák and Dudrová (2004) [11,14,18], Castagnet & Leal Neto 2008 [8] Gerdemann and Jablonski (2011) [9] have contributed to the old equations (for instance evaluate the validity and applicability of them to the new powder mixture, at wide range of pressure, composition of mixture, average sizes, etc.) or developed new ones. In Table 1 are shown the compression equations that describe the compaction behaviours and densification mechanisms of one phase (metal or ceramic) powders or two-phase metal-ceramic powder composites of all above mentioned researchers. In most used mathematical equations (Shapiro–Kolthoff and Konopicky, Bal'shin, Heckel) and also in the new equations of Ge Rong-de, Panelli and Ambrossinni- Filho, Parilák and Dudrová, Castagnet & Leal Neto or Gerdemann and Jablonski, the Ai (i = 1-3, 6-9) parameter is used to demonstrate the plastic deformation capacity of the powders or powder mixture and corresponds to the inclination angle of the compressibility curve (the higher Ai, the greater the deformation). 28