Fabrication Of Ceramic Parts Research Articles

DLP 3D printing of high strength semi-translucent zirconia ceramics with relatively low-loaded UV-curable formulations

DLP 3D printing is one of the additive manufacturing techniques, which allows the fabrication of ceramic parts with a complex shape, precisely controlled internal architecture and fine surface finishing. The method is based on the layer-by-layer solidification of a photosensitive ceramic suspension via UV-light projection followed by debinding of organic components and sintering and generally requires a high solid content of the ceramic filler to achieve good sintered densification. The present article aims to explore the possibility of fabricating high strength, fully dense and semi-translucent zirconia parts with relatively low-loaded UV-curable systems using a low-cost desktop DLP printer designed for printing polymers. For the slurry preparation, tetragonal zirconia powders from three different suppliers were evaluated. It was shown that with 35 vol% of zirconia content slurries, it was possible to fabricate zirconia semi-translucent ceramics with a density of 99.6%. No cracks or pores larger than 1 μm were observed on the sintered parts. According to ball-on-3-ball mechanical tests performed on the 13 × 1 mm discs an average flexural strength of the printed zirconia ceramics was 1566 MPa and a maximum of 1964 MPa could be achieved.

Reinforcement effect in printing precision and sintering performance for liquid crystal display stereolithography additive manufacturing of alumina ceramics

Liquid crystal display (LCD) stereolithography additive manufacturing has been introduced into the fabrication of ceramic parts, which offers an innovative, complex structure, low production cost and short cycle time. However, the use of this method is still limited due to the poor printing accuracy resulting from the light scattering effect of ceramic slurry and the collapse of heteromorphic components sintering at low temperatures. To overcome this situation, in this study, titania (TiO2) is designed as a dual-function key additive to improve the dimensional accuracy and sintering performance of Al2O3 ceramics 3D printing molds because of its unique light absorption and sintering properties. The shrinkage in three dimensions, open porosity, bulk density, flexural strength, and compressive strength are determined for the sintered ceramic. The experiment results show that the size of the printed cube gradually decreases and approaches the origin with the TiO2 content increasing. Furthermore, the densification of ceramics sintering at 1200 °C is enhanced, which is advantageous to the preservation of the complex structure. This study also covers the process for manufacturing Al2O3 ceramic parts with complex construction and good dimensional stability, which is applied in various applications.

Reorientation of Suspended Ceramic Particles in Robocasted Green Filaments during Drying.

This work considers the fabrication of ceramic parts with the help of an additive manufacturing process, robocasting, in which a paste with suspended particles is robotically extruded. Within the final part, the material properties depend on the orientation of the particles. A prediction of the particle orientation is challenging as the part usually undergoes multiple processing steps with varying contributions to the orientation. As the main contribution to the final particle orientation arises from the extrusion process, many corresponding prediction models have been suggested. Robocasting involves, however, further processing steps that are less studied as they have a smaller influence on the orientation. One of the processing steps is drying by natural convection, which follows directly after the extrusion process. A quantification of the reorientation that occurs during drying is mostly unknown and usually neglected in the models. Therefore, we studied the amount of reorientation of suspended particles in robocasted green filaments during drying in detail. For our study, we applied the discrete element method, as it meets various requirements: The exact particle geometry can be resolved precisely; particle–particle interactions can be described; the paste composition is reproduced exactly; the initial particle orientation can be set in accordance with the prediction from the analytical models for the extrusion part; macroscopic force laws exist to represent capillary forces due to the remaining fluid phase that remains during drying. From our study, we concluded that the magnitude of particle reorientation during drying is small compared to the orientation occurring during the extrusion process itself. Consequently, reorientation during drying might further be neglected within analytical orientation prediction models.

Polymer 3D-Printing for Fabrication of Ceramic Parts with Complex Shape

In this work, using polymer 3D printing, we obtained ceramic parts of complex shape with the topology of a triple periodic minimal surface (TPMS), of the “Schwarz primitive” type. The technology of manufacturing ceramic products from a diamond-silicon carbide composite ("Ideal") with the geometry of TPMS by pressing is described. The properties of 3D ceramics are similar to those of a monolithic material.

Effect of the Colloidal Content in Slip Based on Quartz Glass

The formation of very fine SiO2 particles during milling of quartz glass in the fabrication of ceramic parts was investigated. A method for determining the quantitative content of very fine silica in slip based on quartz glass was developed and tested. The concentration of very fine SiO2 particles in different batches of slip was determined. The influence of the content of the colloidal component in slurry on the sintering of ceramic material was evaluated.

Rapid prototyping machine based on ceramic laser fusion

This paper proposes an automatic machine using a new process, ceramic laser fusion, for rapid fabrication of ceramic parts. The machine comprises three parts: a laser scanning system, a green layer paving system, and a control system. In order to control the working procedure of layer paving and scanning process, a process computer is connected to an X–Y table, a PLC and a path/laser controller. An even green layer of 0.15 mm thickness could be paved accurately using ceramic slurry by a layer paving device. After drying by an infrared heater, the green layer could be fused to form a ceramic layer by a CO2 laser and then a 3-D ceramic workpiece could be fabricated layer by layer automatically. The time spent on fabricating a 25×25×0.15 mm ceramic specimen was 3 min. The SEM micrograph of the melted ceramic layers shows that ceramic green layers can be fused together.

SFF of Ceramic Parts: Literature Overview and Direct Experiments

ABSTRACTThe great development of Solid Freeform Fabrication (SFF) techniques from their introduction into the market, more than 20 years ago, has fueled their diffusion in the mechanical sector to the point that they are today an indispensable component of the process of designing, engineering and producing a mechanical parts.At the same time, these techniques found application in different and even distant sectors, like biomedicine or architecture. This lead to the necessity of developing SFF processes suitable for materials different from those they were at the beginning thought for. Such techniques, taken from the original ones or entirely developed ex-novo, allowed for a surprising differentiation of the applications.The fabrication of ceramic parts by SFF techniques is a relatively new field which is widening the role of such materials in sectors not traditionally covered.The present paper reports a state of the art of the techniques that appear more effective for the production of ceramic goods, with representative or even functional properties.Further, some results of 3D Printing experiments of alumina parts will be presented.