The structural changes produced on commercial powdered kaolin deformed by compaction and shear was investigated by X-ray diffraction (XRD), low temperature FTIR, differential thermal analysis and thermogravimetry (DTA/TG). Kaolin is composed by 40% of well orderered kaolinite, 18% of dickite and 42% of quartz. The deformation was induced through a specifically built planetary ball milling working in a controlled thermodynamic environment at room temperature and at a vacuum of 0.13 Pa (10-3 Torr). In this controlled environment the mechanical apparatus induces simultaneous compaction and shear stress to the material. Kaolin samples were milled for 1, 5, 10 and 20 hours. The deformation treatment produces a kaolinite structural order decrease, from a low-defect kaolinite to a high-defect kaolinite according to the AGFI index determined by XRD. An index to evaluate the changes produced on dickite was determined following a fitting procedure. The results indicated that dickite is apparently less affected by the deformation than kaolinite. A structural order was defined by FTIR and the results were correlated with AGFI results.
Kaolinite and dickite behaviour after deformation by compaction and shear
VALDRE', GIOVANNI
2010
Abstract
The structural changes produced on commercial powdered kaolin deformed by compaction and shear was investigated by X-ray diffraction (XRD), low temperature FTIR, differential thermal analysis and thermogravimetry (DTA/TG). Kaolin is composed by 40% of well orderered kaolinite, 18% of dickite and 42% of quartz. The deformation was induced through a specifically built planetary ball milling working in a controlled thermodynamic environment at room temperature and at a vacuum of 0.13 Pa (10-3 Torr). In this controlled environment the mechanical apparatus induces simultaneous compaction and shear stress to the material. Kaolin samples were milled for 1, 5, 10 and 20 hours. The deformation treatment produces a kaolinite structural order decrease, from a low-defect kaolinite to a high-defect kaolinite according to the AGFI index determined by XRD. An index to evaluate the changes produced on dickite was determined following a fitting procedure. The results indicated that dickite is apparently less affected by the deformation than kaolinite. A structural order was defined by FTIR and the results were correlated with AGFI results.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
