Fabrication of lightweight and ultrahigh strength close-cell ceramic foams through sacrificial template method

• Main Author: Tan, Alice Shi Yi
• Other Authors: Gan Chee Lip
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Materials::Ceramic materials
• Online Access: https://hdl.handle.net/10356/156798
• Institution: Nanyang Technological University

The effects of porosity in ceramic composites, including zirconia and alumina-reinforced material, on its properties was examined in this study. Using the sacrificial template approach, the content of phenolic microballoon was adjusted to make dense and porous Alumina toughened zirconia (ATZ) ceramic. ATZ ceramics of 0, 30, 50, 70, 80, and 90 vol% porosities were produced and sintered for 2 hours at 1510°C. Archimedes principle, scanning electron microscopy, and X-ray diffraction were used to analyse the density and microstructure of the sintered alumina-zirconia ceramics. The flexural modulus, flexural strength, and dielectric characteristics were also characterized. According to the findings, when the porosity of the ceramic increases, its relative density decreases. After sintering, the microstructure revealed Al2O3 platelets ranging from 4 - 26 μm well scattered in the ZrO2 matrix, which had an average grain size of 0.57 μm. Tetragonal and monoclinic ZrO2 and α-Al2O3 were the crystalline phases found in the composites. The increase in porosity of the ATZ ceramic results in a significant drop in the sintered ceramics' flexural modulus (201 GPa to 0.16 GPa) and flexural strength (679 MPa to 0.86 MPa). The acquired results were confirmed and fitted with the Ashby-Gibson model. Because the Al2O3 reinforcement serves as a toughening agent in the ZrO2 matrix owing to crack deflection and changes in microstructural morphologies, ATZ ceramic has greater mechanical capabilities than standard zirconia ceramics. At 1000Hz, dense ATZ ceramic can have a relative dielectric constant of up to 34.