Effect of particle size of tabular talc powders on crystal orientation and sintering of cordierite ceramics

Abstract

Cordierite ceramics were prepared from several types of kaolin powders and talc powders having various median particle size with nanometer-sized alumina sol. Powder mixtures were uniaxially pressed, followed by cold isostatic pressing to make thin compacts. Crystal orientation of talc particle and resultant cordierite were evaluated using the X-ray diffraction profile measured on the uniaxially pressed surface of calcined compacts and sintered compacts, respectively. Coarser talc powders above 3¯m aligned their c-axis in vertical to the uniaxially pressed surface of the calcined compact during uniaxially pressing, owing to highly anisotropic tabular shape. The crystal orientation of resultant cordierite increased with an increase in the crystal orientation of talc powders on the pressed surface. This result indicated that the c-axis of cordierite crystal preferably oriented vertically to the c-axis of talc particle oriented. Using the combination of kaolin powders below 5¯m and talc powders having median particle size between 3 and 5¯m, densely sintered cordierite, having a relative density of 95% and high crystal orientation of approximately 85% [I 110 /(I 110 +I 002)], could be obtained.

Electrical, Microstructural and Physical Characteristics of Talc-based Cordierite Ceramics

“…However, the finest PSD is represented in BT3, BT4 and BT5 samples (90wt.% of the PSD is below 20.20, 23.20 and 26.80μm, respectively). For solid-state sintering, the fine particle grain size enhances the densification and the development of higher liquid phases at low sintering temperatures [50][51][52]. Therefore, BT3, BT4 and BT5 samples would be densified and had higher liquid phase at lower temperatures compared to other samples.…”

Electrical, Microstructural and Physical characteristics of talc-based cordierite ceramics

“…However, the nest PSD is represented in BT3, BT4 and BT5 samples (90wt.% of the PSD is below 20.20, 23.20 and 26.80μm, respectively). For solid-state sintering, the ne particle grain size enhances the densi cation and the development of higher liquid phases at low sintering temperatures [50][51][52]. Therefore, BT3, BT4 and BT5 samples would be densi ed and had higher liquid phase at lower temperatures compared to other samples.…”

Properties of 3D Printable Poly(lactic acid)/Poly(butylene adipate-co-terephthalate) Blends and Nano Talc Composites

“…On the other hand, the coefficient of volume expansion of the composites decreased when increasing the nano talc content as depicted in Figure 5(d). It was due to superior thermal resistance of the nano talc that prevented the expansion of the composites during the elevated temperature [42,43]. It has been reported that the addition of mineral fillers in 3D printing filaments decreased the coefficient of volume expansion, which contribute for improving printability, reducing warpage, shrinkage, and printing defects in the 3D printing process [3].…”