The role of chemical activation on the combustion and phase formation laws in the Ni-Al-promoter system

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• 作者：A.M. Baghdasaryan^a ; ^b ; M.A. Hobosyan^a ; H.L. Khachatryan^b ; ^haykh@ysu.am ; O.M. Niazyan^a ; S.L. Kharatyan^a ; ^b ; L.H. Sloyan^b ; Y.G. Grigoryan^a
• 关键词：SHS ; Chemical activation ; Thermal analysis ; NiAl intermetallic compound ; Reaction mechanism
• 刊名：Chemical Engineering Journal
• 出版年：2012
• 期刊代码：16_13858947
• 类别：ce
• 出版时间：15 April, 2012
• 卷：188
• 期：Complete
• 页码：210-215
• 文件大小：918 K

摘要

In this work we first time investigate the reaction mechanism and possibility of synthesizing NiAl intermetallic compound under the activated combustion mode. A halogen containing organic polymer, namely, polytetrafluoroethylene - PTFE is used as promoter. It is shown that the single-phase target product is obtained when amount of the promoter is 0.1%. Differential thermal (DTA), thermogravimetric (TG) and XRD analyses testify that reaction proceeds stepwise. It is shown that in first stage decomposition products of PTFE remove the oxide film from Al particles; then follows reaction between Ni and pure Al. This reaction undergoes two different modes. First the solid-state reaction takes place, then Al melts and reaction continues between solid Ni and molten Al. It is established that the increase in the promoter amount higher than 1%shifts kinetic activation mode to thermal-kinetic mode. The latter leads to misbalance of green mixture and formation of undesired by-products. The optimal conditions of chemically activated synthesis for NiAl intermetallic are established.