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J Hazard Mater. 2019 Jun 5;371:53-61. doi: 10.1016/j.jhazmat.2019.02.045. Epub 2019 Feb 23.

The rapid H2 release from AlH3 dehydrogenation forming porous layer in AlH3/hydroxyl-terminated polybutadiene (HTPB) fuels during combustion.

Author information

1
School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu, 210094, China.
2
Department of Forensic Science and Technology, Jiangsu Police Institute, Nanjing, Jiangsu, 210031, China.
3
School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu, 210094, China. Electronic address: wzhang@njust.edu.cn.
4
Space Propulsion Laboratory (SPLab), Department of Aerospace Science and Technology, Politecnico di Milano, Milan, I-20156, Italy.
5
School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu, 210094, China. Electronic address: rqshen@njust.edu.cn.

Abstract

Although the motivation of AlH3 enhancing combustion were recognized in many research, the promotion mechanism have been rarely explored. Herein, a previously unreported porous layer mechanism when combustion were determined in HTPB/AlH3 fuels by SEM, thermo-analysis and a new simplified calculation method, owing to rapidly released gas phase H2 from AlH3 dehydrogenation exposing in melting layer. 5/10% 40-80 μm and 10% 80-200 μm AlH3-HTPB formulas show the regression rate increase by, 25.7%, 29.0% and 43.0% at Gox = 350 kg/m2·s, while by 57.2%, 42.0% and 44.2% enhancement at Gox = 150 kg/m2·s. The low AlH3 content (≤ 10%) promotes the regression rate obviously, while excess AlH3 content (≥ 20%) promotes slightly as a result of comprehensive factors combined by energy release, a certain porous layer mechanism, aggregated Al2O3 attached on the burning surface and the blocking effect of the gaseous released H2. A new model predicting the overlapping process of AlH3 dehydrogenation and Al oxidation in air atmosphere was developed by superimposing AlH3 dehydrogenation simulation and corresponding separated Al oxidation simulation. A 1.5th Avrami-Erofeev (A-E) simulation was proposed for Al passivation weight gain between 420 and 520 K with an activation energy of 124.92 kJ/mol and the pre-exponential of 10^12.35.

KEYWORDS:

AlH(3) dehydrogenation; Avrami-Erofeev mechanism; HTPB; Porous layer

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