Sintering behavior of anorthite-based composite ceramics produced from natural phosphate and kaolin
Document Type
Article
Publication Date
1-1-2019
Abstract
In the present work anorthite-TCP composite ceramics was produced for the first time by the solid-state sintering process involving the mixture of local natural materials of phosphate and kaolin. Various samples were prepared by varying the kaolin content from 47 to 57 wt%. The composite ceramics were sintered in air at various temperatures ranging from 1250 °C to 1325 °C and characterized to determine the phase present, relative density, Vickers microhardness, chemical bonding of molecules and microstructural development. In general, all the samples exhibited a hybrid structure, comprising of anorthite and β-TCP as the major phases with a concomitant minor phases such as TTCP and/or gehlinite depending on the temperature and kaolin content. In addition, increasing kaolin content and sintering temperature were found to be effective in improving the densification and hardness of the sintered body. In particular, sample containing 57 wt% kaolin exhibited excellent densification at 1300 °C and 1325 °C, achieving above 97% dense bodies and highest hardness of about 6.5 ± 0.7 GPa. Microstructural investigation revealed that a dense structure was evident for these samples due mainly to enhanced particle coalescence during the liquid phase sintering, resulting in pore elimination and grain coarsening. © 2019 Elsevier Ltd and Techna Group S.r.l.
Keywords
Natural phosphate, Kaolin, TCP, Anorthite, Anorthite-TCP composite
Divisions
fac_eng
Publication Title
Ceramics International
Volume
45
Issue
16
Publisher
Elsevier