3D printing of solution processed ceramics

• Main Author: Lee, Yan Yi
• Other Authors: Nripan Mathews
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering
• Online Access: https://hdl.handle.net/10356/176091
• Institution: Nanyang Technological University

The traditional ceramics-making process involves mixing, molding, and sintering of the green body produced to obtain a densified and high mechanical strength ceramics. However, cracking during both forming and sintering stages is a common issue leading to product failure. Chemically bonded phosphate ceramic (CBPC) is an advanced ceramics alternative that relies on chemical bonding by acid-base reaction to obtain its mechanical properties, eliminating the need for high-temperature sintering. Although the properties of CBPC will be different from traditional ceramics as it is not as dense and strong, it has its unique properties which include being fireproof, resistant to corrosion, and a form of nuclear-shielding protectant. Additive manufacturing has been integrated into the ceramics production industry. It offers a more environmentally friendly and cost-effective alternative to traditional ceramics manufacturing with greater freedom in the design of products. The integration of CBPC into additive manufacturing is possible using Direct Ink Writing (DIW) which makes use of the extrusion base method of viscous slurry which the CBPC mixture can be before hardening. However, no extensive research on CBPC being used in additive manufacturing has been done. This research study will therefore revolve around exploring the feasibility of pairing DIW with CBPC, optimising the printing process, and analysing and characterising the feedstock and printed samples. This project is a continuation of a previous project where an optimum printing CBPC slurry is produced: Wollastonite-CBPC with the addition of boric acid. During the experiment, different shapes and patterns were trialed for printing. Viscosity is an important factor in the success of DIW printing where optimum printing viscosity was achieved by varying the slurry temperature. The low temperature goes against the exothermic reaction of the CBPC hardening process, slowing it down. The extrusion process was controlled by the pressure which is proportional to the viscosity of the slurry. The optimal printing slurry pressure should coincide with the viscosity to extrude smoothly without a burst or drip phenomenon at the tip which will affect the dimension printed. Knowing the parameters to control printing allows the control of the resolution of print and the success in printing layered 3D objects. From the characterisation results it can be concluded that the CBPC printed sample has a relatively low hardness as compared to traditional ceramics. This coincides with the low density measured. Having low density would imply good insulation and heat storage capacity due to high porosity. Therefore, an effective thermal barrier and a lighter option of ceramics.