Desenvolvimento de meios porosos cerâmicos por manufatura aditiva de dupla extrusão de pasta com e sem agente porogênico

Abstract

Porous media (PM) play an important role in various industrial applications, especially in the Oil & Gas industry. With an emphasis on the need to control pore hierarchy to meet specific requirements, such as regulating fluid flow to replicate the properties of sedimentary rock reservoirs, additive manufacturing (AM) emerges as a promising technique for creating such porous materials with complex geometries, with lattice structures being one of the alternatives. However, it is important to highlight the limitations in producing lattice structures with respect to hierarchical porosity, particularly as the need to reduce pore diameter increases. This study proposes the use of dual extrusion in AM with ceramic materials, such as porcelain ceramic paste, incorporating porogenic agents like starch and calcium carbonate. Preliminary tests were conducted to select the porogenic agent with the best adhesion to porcelain and processability with AM’s Material Extrusion (MEX) Direct Ink Writing (DIW) technologies. The materials used included one with only porcelain (MB – base material) and materials with different porogenic agents incorporated into porcelain (MAP – material with porogenic agent). The tests involved evaluating the shrinkage of the materials and identifying interface failures between the two extruded materials, MB, and MAP. After selecting starch as the porogenic agent for printing the PM, porous media were produced by dual extrusion. In the lack of a second extruder head, a manual application method for MAP was developed to replicate the proof of concept. The geometry of the PM consisted of a conventional lattice structure from MEX technologies with filaments deposited in a zigzag pattern, interspersed by rotating the MB raster angle by 90°. In the void regions between the MB filaments (gaps), MAP was manually deposited. To verify its application as PM, the PM were tested in a permeameter to determine the Darcian coefficient k1 and non-Darcian coefficient k2 and compared with existing literature results of siliciclastic sedimentary rock reservoirs. The PM showed a mass reduction of 13.9%, with a standard deviation of only 0.4%. The density registered an average value of 1.54 g/cm³ and a coefficient of variation of 1.56%, indicating notable consistency in the developed manufacturing process regarding the regularity of the deposited material quantity. The PM showed the presence of pores in the range of tenths of millimeters and the uniformity of material deposition. In cross-sections of the material, it was possible to clearly visualize and identify each area of the section, with the ellipses of the filament cross-sections measured. Regarding the permeability of the PM, the average values of the coefficients k1 (10.65×10-15 m2) and k2 (5.32×10) m) obtained in the tests indicate the stability of the developed process for both coefficients. These results indicate that the method can be successfully applied to the production of PM with customized strategies, going beyond a “conventional” lattice. Furthermore, it stands out for its ability to control deposition provided by material extrusion in additive manufacturing. This threedimensional control makes it possible to achieve properties, such as permeability, like those of porous materials obtained by conventional techniques and even natural rocks.Keywords: porous media; additive manufacturing; dual extrusion; lattice structures; pore forming agent; ceramic materials.