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ABSTRACT
Particle size is a vital characterization for silicon nitride nanoparticle as its scale determines its application area. Particle size prediction for synthesis of silicon nitride nanoparticle by chemical vapor deposition (CVD) is much needed. In this study, a model is proposed for particle growth during silicon nitride nanoparticle synthesis by CVD in order to predict particle size. Comparison between modeling and experimental results validated the model. The modeling results showed that lower pressure in the condensation room would be an effective way of obtaining silicon nitride nanoparticles with smaller particle size. An expression is established to reveal the relation between the mean particle diameter of silicon nitride nanoparticle and pressure in the condensation room based on the modeling. The modeling method is capable of predicting the mean particle size of ultrafine silicon nitride powder to within 3.6% accuracy. Corresponding manufacturing thermal parameters are recommended for silicon nitride nanoparticle production with different mean particle sizes. Modeling and analysis in this article may provide theoretical guidance for production of silicon nitride nanoparticle by CVD.
© 2017 American Association for Aerosol Research
EDITOR :
Nomenclature
| Qreaction | = | energy variation of the thermochemical reaction process, W |
| Qcondensation | = | energy variation during the condensation process, W |
| Qradiation | = | energy transferred through radiation, W |
| Qconvection | = | energy transferred through convection, W |
| = | total collision frequency between the inert gas molecules and the vapor molecules, m−3 s−1 | |
| = | total frequency of collisions between the condensation nuclei and the silicon nitride molecules, m−3 s−1 | |
| = | total bonding energy of all the products, J | |
| = | total bonding energy of all the reactants, J | |
| = | energy released from each molecule when it condensates on the surface of a condensation nucleus, J | |
| = | heat absorbed by the molecule when its temperature rises by a unit of temperature, J/K | |
| = | diameter of the silicon nitride molecule, m | |
| = | nucleus diameter, m | |
| = | number density of the vapor molecules, m−3 | |
| = | number density of the inert gas molecules, m−3 | |
| = | molecule mass of the inert gas, kg | |
| = | molecule mass of the vapor, kg | |
| = | surface temperature of the condensation nucleus, K | |
| = | ambient temperature in the reaction chamber, K | |
| = | mean temperatures of the vapor molecules and condensation nuclei, K | |
| = | Temperature of the inert gas, K | |
| = | temperature increase of the argon vapor, K | |
| = | pressure in the condensation room, Pa | |
| = | probability of bonding because of collision between the condensation nuclei and the silicon nitride molecules | |
| = | surface emissivity of the condensation nucleus | |
| = | molecule number in the condensation nucleus | |
| = | molecule density inside the condensation nucleus | |
| = | Stefan–Boltzmann constant, σb = 5.67 × 10−8 W/ (m2⋅K4) | |
| = | Avogadro constant, | |
| = | Boltzmann's constant, k = 1.38 × 10−23 J/K | |
| = | collision bonding probability constant | |
| = | universal gas constant, R=8.314 J/(mol⋅K) |
Funding
This work was supported by the National Key Research and Development Program of China (grant number 2016YFB0601102).