Geopolymer-Based Nepheline Ceramics: Effect of Sintering Profile on Morphological Characteristics and Flexural Strength

• Published in: Crystals (Basel) 2022-09, Vol.12 (9), p.1313
• Main Authors: Ahmad, Romisuhani, Ibrahim, Wan Mastura Wan, Abdullah, Mohd Mustafa Al Bakri, Pakawanit, Phakkhananan, Vizureanu, Petrica, Abdullah, Arman Shah, Sandu, Andrei Victor, Ahmad Zaidi, Fakhryna Hannanee
• Format: Article
• Language: English
• Subjects: Aluminum compounds; Ceramic materials; ceramic-based geopolymer; Ceramics; Clay; Crystallization; Flexural strength; geopolymer; Geopolymers; Heating rate; High temperature; Investigations; Kaolin; Liquid sodium; Low temperature; Microscopy; Microstructure; Morphology; Nepheline; Porous materials; Sintering; Sintering (powder metallurgy); Sodium hydroxide; Sodium silicates; Surface layers; tomography; Viscosity
• ISSN: 2073-4352; 2073-4352
• DOI: 10.3390/cryst12091313

The focus of this study is the fabrication of innovative and sustainable ceramic-based geopolymer with improved low temperatures performances. Kaolin was mixed with liquid sodium silicate (Na2SiO3) and 12M of sodium hydroxide (NaOH) solution using alkali activator ratio of 0.24 and solid-to-liquid ratio of 1:1 to synthesize kaolin geopolymer. The effect of the sintering profile on the microstructure, pore evolution and flexural strength were investigated. The heating exposure aided consolidation and created a fairly uniform microstructure, resulting in a smooth surface texture. In comparison to the unheated geopolymer, 3D pore distribution showed a significant increase in the range size of ~30 µm with the appearance of isolated and intergranular pores. The flexural strength at 1200 °C with a heating rate of 5 °C/min and was increased by 146.4% to 85.4 MPa, as compared to the heating rate of 2 °C/min. The sintering process has an impact on the final microstructure formation thus improving the characteristic of geopolymer-based nepheline ceramic.