Tape casting and 3D printing of glass slurries

• Grant number: 19/16747-4
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): September 01, 2019
• Effective date (End): August 31, 2020
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal researcher: Eduardo Bellini Ferreira
• Grantee: Letícia Cursini
• Home Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass, AP.CEPID

Abstract

Tape casting has been widely used in the electronics industry in multi-layer capacitors, Micro-Electro-Mechanical Systems (MEMs) and Solid Oxide Fuel Cells (SOFC). This forming technique essentially consists of the deposition of a slip or suspension of ceramic particles on a polymer film. After evaporation of the organic fraction and sintering, dense or porous ceramic films or thin tapes of thicknesses between 10 ¼m and 1 mm are obtained. We designed and manufactured a tape-casting machine characterized by the simplicity of operation and low cost, for the production of homogeneous and precise tapes, which allows R&D and tests for production scale-up. The highlights of this equipment are the suspension tank on a flat table; the special blade, a traction system of the collector film, and a flat table with drying chamber. The Low-Temperature Cofired Ceramics (LTCC) process allows the combination of different materials, making it easier to integrate different basic electrical functions. An advantage of using LTCC technology is the possibility of incorporating passive components and metal electrodes into interconnected substrates. Glass-ceramic systems produced from the sintering of vitreous powders with simultaneous crystallization, mainly from the surface, can be used in LTCC process. With controlled crystallization, the formed phases will determine the final dielectric and thermomechanical properties. The densification depends directly on the particle size and packing, and high-temperature viscosity and crystallization kinetics. The kinetics of viscous flow sintering and surface crystallization must be controlled to promote complete densification of the material. Rapid surface crystallization prevents viscous flow and therefore densification. We plan to develop glass-ceramic materials based on diopside (CaO.MgO.2SiO2) to produce tape-cast substrates for LTCC technology. Diopside has low dielectric constant (K <10), the relatively low coefficient of thermal expansion and sinters at low temperatures (<900°C).The microstructure of crystallized diopside, such as phase composition, crystallite size, and intergranular and intra-granular porosities directly affect the dielectric, mechanical and thermal properties, and can be controlled to maximize their performance. Fine 3D-printing was also recently showed for high-purity quartz glass with the respective chemical and physical properties. The resolution achieved the few-micrometer range. The structures may have dimensions in the range of a few centimeters. Small, complex structures were produced, and very small analytical systems could be made out of miniaturized glass tubes for biological and medical technologies. A variety of optical areas, from eyeglasses meeting special requirements to lenses in laptop cameras, may advantage from this technology.With a focus on the above manufacturing processes, the researcher will explore the possibilities of these techniques.