Study of the evolution of transport properties induced by additive processing sand mold using X-ray computed tomography

Abstract

Accurate characterization of the mass transport properties of additively processed sand molds is essential in order to achieve reproducibility of the produced castings and control of gas defects in foundry industries. The present work highlights the potential use of X-ray microcomputed tomography (µ-CT) to characterize the evolution of permeability and some major microstructural features of such additively processed sand molds. The evolution of mass transport properties of sand mold samples under specific processing conditions met in additive manufacturing and its influence on the porosity, the permeability, the tortuosity, and the pore and throat size distributions were characterized from 3D images provided by X-Ray µ-CT. The obtained results showed that the mass transport properties of additively processed sand molds can be closely predicted by using non-destructive in situ methods, such that improvements to the casting can be made to create more optimized 3D printed structures for foundry applications.

Assessment of the effect of 3D printed sand mold thickness on solidification process of AlSi13 casting alloy

“…The aim of this study is to print sand molds that should be rigid enough to resist during casting and sufficiently permeable to facilitate the gases released. For these reasons and based on the laboratory's knowledge of the 3DSP process [5][6][7][31][32][33][34], the printing parameters listed in Table 2 are chosen. A special attention was given to the X resolution (X r , i.e., binder content) and the recoater speed (R s ).…”

“…A special attention was given to the X resolution (X r , i.e., binder content) and the recoater speed (R s ). The X resolution has a direct influence on the mechanical strength of the printed sand specimens [6,[32][33][34][35]. The decrease of the binder content leads to a considerable decrease in strength.…”

On the Relation between the Gas-Permeability and the Pore Characteristics of Furan Sand

“…However, in the case of foundry cores and molds, it also depends on the compaction methods and forces. Mitra et al [ 16 ] studied the mass transport properties of 3d-printed sand cores using X-ray micro-computed tomography and correlated the permeability results using a non-destructive method. They measured the permeability in Darcy units and obtained permeability numbers of the range 4.43 × 10 −11 –9.18 × 10 −11 for samples with porosity ranging from 49–53%.…”

“…The authors deduced the permeability of coal samples using the MIP data for different ranks of coal. Although MIP has been used extensively over the years for the characterization of pore networks in porous bodies, some authors [ 16 ] have been skeptical about the usage of this method on foundry sands. They mention that foundry sand is an unconsolidated material, and therefore they cite the potential danger of destructing the integrity of the sample and causing void collapse.…”

A New Approach to Calculate the Velocity of Interdendritic Fluid Flow during Solidification Using Etched Surface Height of Actual Metal Ingot

“…For example, because the velocity magnitude can probably be calculated by Darcy's Law if the permeability is obtained, many researchers are interested in the experimental measurement of permeability and mathematical models of how permeability varies with fraction solid, columnar or equiaxed structures, different processing, etc. [8][9][10][11][12][13][14]. However, because the structures are somewhat conceptual and the pressure gradients are assumed or approximate, the calculated velocities always deviate from the real.…”