Low-Cost, Modular Modification to a Desktop 3D Printer for General Purpose Gel/Paste Extrusion & Direct Ink Writing

We propose a design for a simple paste extruder modification that can be used for the selective deposition and patterning of gels and pastes, using a desktop 3D printer as the primary platform. This technology has found use with a variety of materials in seemingly disparate fields, including the printing of ceramics, food and biological materials, each with a variety of material-specific solutions to enhance printability. However, we focus on a syringe-pump driven system that is simple, low-cost, modular, easily assembled and highly modifiable with a low barrier of entry in order to maximise the generalisability and range of printable materials.

Modeling and Numerical Study of Ceramic Paste Extrusion

The extrusion processes of ceramic pastes, including 3D printing, are used for the production of high-value products. Ceramic paste extrusion is a complex process which depends on the paste rheological properties, die and extruder geometries, and operational parameters. Modeling and quantitative analysis of paste molding are important to design proper extrusion process for the production of high-value extrudates of desired strength, shape, and morphology. In this paper, the mathematical model of ram extrusion of ceramic materials is established, and the paste continuity and momentum equations for non-Newtonian fluid based on the modified Herschel-Bulkley viscous model were solved numerically. The effects of die geometry and paste feed rate on the distributions of paste velocity and pressure in the extruder and die were investigated numerically. As a result, the steeper radial profile of longitudinal velocity and higher value of longitudinal velocity were obtained in the narrow die. The pressure significantly increases in the die at a high feed rate, and the pressure profile is almost flat in the barrel. The rate of increase of the maximum pressure decreases with an increase of paste feed rate. The pressure steeply increases in the die of small diameter. The maximum pressure linearly increases with the ratio of die length to diameter.

A review on additive manufacturing of ceramic materials based on extrusion processes of clay pastes

This paper aims to present a state of the art of additive manufacturing (AM) of ceramic materials based on extrusion processes of clay pastes, reviewing the definitions and classifications of the AM field under current international standards. A general overview on the AM category ‘material extrusion’ is provided and the class ‘paste deposition modeling’ is proposed for those techniques based on the extrusion of pastes that are solidified by solvent vaporization, with the aim of distinguishing it from the class ‘fused deposition modeling’, which is applied to extruded polymers through temperature plasticization. Based on the survey of background information on 3D printing technology by ceramic paste extrusion, a classification and historization of the innovations in the development of this technology are proposed.

Three-dimensional Printing of Supercapacitors based on Different Electrodes

A fused deposition modeling (FDM) printing machine and a paste extrusion system were integrated, and supercapacitor samples were fabricated using a combination of two three-dimensional (3D) printing techniques. The FDM provided a simple method for creating a frame of electric double layer capacitor (EDLC) samples. The paste extrusion system offered the possibility of depositing different materials to complete the functions of the EDLC samples. A combination of these two 3D printing methods offered one continuous manufacturing process with a high accuracy of manufacturing. Different materials were used to build current collectors and electrodes. Silver and carbon conductive paints were used as current collector materials. Different electrode materials based on activated carbon (AC), carbon conductive paint, and their combination were prepared as three different slurries and deposited to form the electrodes of EDLC samples. The results showed that silver conductive paint was a suitable material for constructing current collectors, and carbon conductive paint mixed with AC was highly effective for use as an electrode material for supercapacitors.

Fabrication of Three-Dimensional Piezoelectric Ceramics Using the Dispenser System

We fabricated lead-free (K,Na,Li)NbO3 (KNLN) and BaTiO3 (BT) piezoelectric ceramics using a dispenser system. After dissolving polyvinyl butyral in ethanol, a paste for extrusion was fabricated by mixing KNLN or BT ceramic powders. After several times of paste extrusion with a dispenser system, degreasing was performed at 650°C. The KNLN moldings were sintered, at 1,100–1,170°C, and sintering of BT moldings were performed by two-step sintering at 1,320°C and 1,150°C. From the x-ray diffraction pattern, the fabricated KNLN ceramics had a perovskite structure. The density of the KNLN and BT moldings fabricated by the dispenser system was 3.94 and 5.42 g/cm3, respectively. In addition, the BT moldings had the dielectric constant εr = 1.95 × 103. The Curie temperature of the BT moldings was confirmed at about 125°C, as with the BT piezoelectric ceramics fabricated by uniaxial pressure molding. The BT moldings had the piezoelectric constant d33 = 60 pC/N. The fabrication methods studied in this work provided the potential to fabricate simple three-dimensional piezoelectric ceramic devices for applications in acoustic wave sensors.