铝粒表面微凸起对凝聚产生的影响

Influence of microconvexities of aluminium particle surface on agglomeration

关键词:  含铝推进剂  凝聚  铝粉  表面微凸起  金属燃烧

Key words:  Aluminized propellant  Agglomeration  Powdered aluminium  Surface microconvexities  Metal combustion

摘要:

为进一步研究非球形铝粒表面微凸起对含铝推进剂凝聚燃烧的影响,用Young Laplace公式和化学势的微分式,推出非球形铝粉凝聚起始温度下降公式。发现铝粒表面微小凸起的平均半径越小,则铝粉凝聚起始温度就越低,其影响不容忽视。用电化学微电池理论,阐明了铝粉与NaOH溶液的反应机理。铝粒与NaOH溶液构成局部腐蚀电池,金属铝在阳极上失去三个电子,发生氧化反应。由于非球形铝粒组织和物理状态的均匀性比球形铝粒的差,表面的微电池数目比球形铝粒的多,因此有较大的反应速率。

Abstract:

Formula for describing the starting point of agglomerating depression of unspheroidal aluminium powder is given by Young-Laplace equation and differentiation of chemical potential. The smaller average radius of microconvexities of aluminium particle surface is, the lower agglomerating starting point. It is elucidated that the influence of microconvexities on agglomeration can not be neglected. Reaction mechanism between metal Al and NaOH solution is revealed by electrochemical microcell theorem. Local corrosion microcells are composed of aluminium particles and NaOH solution. The metal Al loses three electrons at the anode of microcell, so the process at the anode is an oxidation reaction. Because the structure and physical state in unspheroidal aluminium particles are less uniform than in spheroidal one, the number of microcells of unspheroidal aluminium particle surface is larger than of spheroidal one, and NaOH solution reacts more with unspheroidal aluminium powder than with spheroidal one.