Structural study of mullite based ceramics derived from a mica-rich kaolin waste

• Published in: Ceramics international Vol. 43; no. 4; pp. 3919 - 3922
• Main Authors: Alves, Hugo P.A., Junior, Rubens A., Campos, Liszandra F.A., Dutra, Ricardo P.S., Grilo, João P.F., Loureiro, Francisco J.A., Macedo, Daniel A.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2017
• Subjects: A. Powders: solid state reaction; A. Sintering; D. Mullite; Kaolin waste; Kaolin waste; D. Mullite; A. Powders: solid state reaction; A. Sintering
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2016.12.035

Mullite-based ceramics have been synthesized by reactive sintering of a mixture containing kaolin and a mica-rich kaolin waste. Samples fired in the temperature range from 1300 to 1500°C were characterized by X-ray diffraction (XRD). The quantitative phase analysis and unit cell parameters of the mullite were determined by Rietveld refinement analysis of the XRD data. Mullite-based ceramics with 1.2wt% quartz, 56.3wt% glass (amorphous phase), 2.64g/cm3 of apparent density, and 35±1.2MPa of flexural strength were obtained after firing at 1500°C. A liquid phase sintering mechanism activated by a total mica content of 13.3wt% allowed to increase the mullite content to 47.6wt% (2.3wt% quartz and 50.1wt% glass phase) and improve the flexural strength (70±3.9MPa) after firing at 1400°C. •Use of kaolin waste to prepare almost pure mullite ceramics.•Rietveld refinement analysis of kaolin waste processed ceramics.•Effect of the glass phase content on properties of fired ceramics.