Preparation of anorthite ceramics using SPS

• Published in: Journal of the European Ceramic Society Vol. 41; no. 8; pp. 4618 - 4624
• Main Authors: Csáki, Štefan, Lukáč, František, Húlan, Tomáš, Veverka, Jakub, Knapek, Michal
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2021
• Subjects: Anorthite; Crystallization; Kaolinite; Sintering; Kaolinite; Sintering; Anorthite; Crystallization
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2021.03.004

A mixture of kaolin (92 wt.% of kaolinite) and laboratory-grade CaCO3 was used for anorthite preparation using the spark plasma sintering (SPS) technique. The powder was heated up to the maximum temperature (850 °C–1100 °C with a step of 50 °C, heating rate 50 °C/min) using the SPS device. The as-prepared samples were compared with a reference sample produced by dry pressing and conventional firing. Rietveld refinement performed on the X-ray diffraction data revealed that before anorthite formation, gehlenite and Ca-feldspar appeared, which gradually transformed into anorthite with increasing temperature. The sample prepared by SPS at 1100 °C contained 90 wt.% of anorthite, while the anorthite content in the reference sample reached only 47 wt.%. The porosity of the samples prepared by SPS reached significantly lower values compared to that of the reference sample. Therefore, SPS can be considered as a promising technique in the preparation of anorthite ceramics at lower temperatures.