Fabrication of SiC ceramic foams with light weight and ultrahigh strength by a direct foaming method

• Main Author: Wee, Christian Luke Chye Hin
• 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/10356/156783
• Institution: Nanyang Technological University

The unique cellular microstructure of porous ceramics has made them favourable for a wide variety of applications in various industries. One such method of making these porous ceramics is by producing stabilised wet foam via direct foaming method. In this project, silicon carbide (SiC) particles were dispersed in an epoxy resin to form a slurry or suspension, and subsequently frothed by using a cationic and anionic surfactant, Dodecyl Trimethyl Ammonium Chloride (DTAC) and Sodium Dodecyl Sulphate (SDS), respectively. The consolidated foam was cast and allowed to cure before debinding the organic binders, followed by sintering to form the final porous ceramic. The effects of the types of surfactants and their concentration on the foam rheological behaviour, pore size, porosity, density, and projected strength of the ceramic foams has been systematically studied. SDS assisted direct foaming method can produce ceramic foams with a wide range of porosity and pore sizes, varying in 76 – 88% and 90 – 165 µm, respectively. Comparatively, the DTAC assisted foaming method has less variation in the porosity and pore size, changing between 64 – 68 % and 55 – 80 µm, respectively. With DTAC as the surfactant being used at a concentration of 0.72 wt.% to the weight of SiC dry powder, the sintered sample has porosities up to 67% with an average pore size of ~56 µm and a predicted compressive strength of 32.5 MPa, which brings a good balance of strength and interconnectivity of pores. This brings great potential to enhance the capabilities of porous SiC ceramics for various engineering applications in harsh environments.