以低壓扁平焰-噴霧熱分解程序製備高分散性奈米粉體

Preparation of Highly-Dispersed Nanoparticle via Low Pressure Flat Flame-Spray Pyrolysis Process

朱志偉(Chih-Wei Chu)

指導教授 ： 張幼珍

元智大學/工程學院/化學工程與材料科學學系/碩士(2003年)

摘要

無資料

關鍵字

奈米粉體

並列摘要

This study mainly combines low pressure flat flame and spray pyrolysis, to establish a complete low pressure flat flame-spray pyrolysis process system. Each part of system is examined and computational fluid dynamics package FLUENT is applied to assist in the investigation of flow behaviors and temperature distribution around the reactor system.
In simulations, the model system is a low pressure flat flame reactor referring to a real reactor system. We establish a 2D coordinate model system with geometric figure and mesh. With simulations, fuel gas flow rate, chamber pressure and boundary condition are controlled to assist in the investigation of the burned situation, flame structure and temperature distribution.
In experiments, we introduce low pressure flat flame and spray pyrolysis systems, to explain their theorems and functions. Different situations of combustion can be controlled by different ratio of flow rate, e.g., an excess of methane or oxygen, and complete combustion. Through the observation of flame combustion and temperature distribution, the effect of precursor flow on powder synthetic properties is examined.
It shows that combustion of an excess of methane results in higher temperature around 1600-1800 K, and the highest temperature occurred in 6 mm above the burner fane, c.a., 1755 K. The bright blue-color flame shows structure of flat and disc, and thickness is around 8.9 mm with diameter around 55.1 mm. The powder of zirconic oxide collected was examined by SEM, and the size distribution is between nano- and micro- scale, c.a., 50-100 nm. The powder structure is sphere and well-dispersed. Besides, the powder of pyrex glass was examined by SEM, and the size distribution is about submicro-scale. The powder structure is uniform sphere and well-dispersed, and significantly narrow size distribution is also found. In addition, N4 plus and Coulter Multisizer Ⅱ show particle size around 750 nm.
The zirconic oxide sol (15 nm)-prepared powder was examined by SEM. It shows particle size distribution around 100-300 nm and well-dispersed particle. We supposed that the agglomeration of zirconic oxide sol resulted from high temperature flame drying. The other zirconic oxide sol (65 nm)-prepared powder was also examined by SEM. It shows particle size distribution around 50-70 nm and well dispersed particle. Particle size is similar to sol particle. However, particle size around 100 nm is also found. We supposed that the larger particle size resulted from agglomeration.

並列關鍵字

Nanoparticle

參考文獻

1. Baek S.W., Do Young Byun, Ju Hyeong Cho, “Microexplosion of aluminum slurry droplets,” International Journal of Heat and Mass Transfer, 42, 4475-4486(1999).

2. Becker, M.F., Brock, J.R., Cai, Hong, Henneke, D.E., Keto, J.W., Lee, Jaemyoung, Nichols, W.T., “Metal nanoparticles generated by laser ablation,” Nanostructured Materials, 10, 853-863(1998).

3. Bickmore, C.R., Kurt F. Waldner, Rita Baranwal, Tom Hinklin, David R. Treadwell and Richard M. Laine, “Ultrafine Titania by Flame Spray Pyrolysis of a Titanatrane Complex,” Journal of the European Ceramic Society, 18, 287-297(1998).

5. Ekerdt, J.G., W. Thomas Leach, Jian-hong Zhu, “Thermal desorption effects in chemical vapor deposition of silicon nanoparticles,” Journal of Crystal Growth, 243, 30 -40(2002)

6. Flagan, R.C., H.V. Nguyen, “Particles formation and growth in single-stage aerosol reactors,” Langmuir, 7, 1807-1814(1991).