Avcioglu, Celal
(Istanbul Technical University, Department of Metallurgical and Materials Engineering, Faculty of Chemical and Metallurgical Engineering, PML Laboratories)
,
Ozkal, Burak
(Istanbul Technical University, Department of Metallurgical and Materials Engineering, Faculty of Chemical and Metallurgical Engineering, PML Laboratories)
In this study, TiO2-polyvinyl alcohol (PVA) composite granules were prepared via spray drying technique. To investigate the effects of solid content and binder/powder ratio in the slurry on the granulation behavior of TiO2 powders, the feed compositions were designed to vary over a wide range. The m...
In this study, TiO2-polyvinyl alcohol (PVA) composite granules were prepared via spray drying technique. To investigate the effects of solid content and binder/powder ratio in the slurry on the granulation behavior of TiO2 powders, the feed compositions were designed to vary over a wide range. The morphology, actual densities, and average granule size and size distribution of the TiO2-PVA composite granules were characterized by using scanning electron microscopy technique, a gas pycnometer, and an image analyzing program (Image-J), respectively. The results indicate that solid content and the amount of PVA in the feedstock slurry are the dominant factors determining the granule morphology, size, and size distribution of TiO2-PVA composite. Moreover, it was observed that increasing the solid content and the amount of PVA in the slurry improved the granulation process and reduced the granule defects. For the preparation of spherical TiO2-PVA composite granules with the minimum amount of non-granulated powders, the optimized composition of the feedstock slurry was found to be 35 wt.% solid and 3 wt.% PVA.
In this study, TiO2-polyvinyl alcohol (PVA) composite granules were prepared via spray drying technique. To investigate the effects of solid content and binder/powder ratio in the slurry on the granulation behavior of TiO2 powders, the feed compositions were designed to vary over a wide range. The morphology, actual densities, and average granule size and size distribution of the TiO2-PVA composite granules were characterized by using scanning electron microscopy technique, a gas pycnometer, and an image analyzing program (Image-J), respectively. The results indicate that solid content and the amount of PVA in the feedstock slurry are the dominant factors determining the granule morphology, size, and size distribution of TiO2-PVA composite. Moreover, it was observed that increasing the solid content and the amount of PVA in the slurry improved the granulation process and reduced the granule defects. For the preparation of spherical TiO2-PVA composite granules with the minimum amount of non-granulated powders, the optimized composition of the feedstock slurry was found to be 35 wt.% solid and 3 wt.% PVA.
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제안 방법
These fine powders can be granulated by different methodologies to eliminate the negative effects mentioned above. In order to optimize the granulation behavior of TiO2 ceramic powders during spray drying, the effects of solid content and the binder/powder ratio in the slurry, solid/liquid ratio, and the amount of additive (polyvinyl alcohol; PVA) on the granulation behavior of TiO2 ceramic powders were investigated in this study.
Their morphology was investigated by scanning electron microscopy (SEM; Jeol-JSM-T330). Particle size and size distribution measurements were carried out by using a Microtrac Nano-flexTM in-situ particle size analyzer. Phase analysis was carried out using the Xray diffraction method (Bruker D8 Advance X-ray diffractometer) with CuKα radiation (λ = 1.
Phase analysis was carried out using the Xray diffraction method (Bruker D8 Advance X-ray diffractometer) with CuKα radiation (λ = 1.540 Å) from 10° to 80° at a scanning speed of 1°/min.
To investigate the effects of solid content and the binder/ powder ratio in the feedstock slurry on the granulation behavior of TiO2 , the feed compositions were designed with respect to the solid/liquid ratio (30 wt.%, 35 wt.%, and 40 wt.% solid) and the amount of the additive PVA (2 wt.%, 2.5 wt.%, 3 wt.%, and 3.5 wt.% PVA). All the compositions and sample codes are listed in Table 1.
대상 데이터
In this study, analytical grade TiO2 (99% purity, Alfa AesarTM) powder and liquid PVA (Optapix PAF35/Zschimmer&Schwarz) were used.
Before the BET analysis, the humidity of the commercial powder was removed under vacuum at 200°C for 2 h. Nitrogen (N2) gas was used as an adsorber. The equivalent particle size (DBET) was calculated from the BET surface area results by assuming that all the particles exhibit the same spherical shape and size.
이론/모형
The specific surface areas of the powders were determined based on the Brunauer–Emmett–Teller (BET) theory with the help of a BET Quanthachrome ™ Autosorb device.
성능/효과
%, the number of broken granules and non-granulated powders decreased. Additionally, the granule morphology became more spherical, the average granule size increased, and the size distribution widened. However, cracking defects developed upon further increasing the PVA amount to 3.
후속연구
It should be noted that, to tailor the granule morphology, size, and size distribution, further studies are necessary to design feedstock slurries with optimum solid/liquid ratio and binder amount for obtaining powders with different physical properties. In this study, the best combination of these factors was found to be 35 wt.
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