Electrical pulse formation during high temperature reaction between Ni and Al

Abstract

Articles you may be interested inThe role of microstructure refinement on the impact ignition and combustion behavior of mechanically activated Ni/Al reactive composites A new experimental setup for the time resolved x-ray diffraction study of self-propagating high-temperature synthesis Rev. Sci. Instrum. 73, 422 (2002);An electric voltage pulse ͑duration of about 2 ms͒ with an amplitude of up to 0.6 V was generated during the reaction between nickel and aluminum powders by a high temperature moving reaction front. The electrical signal formed during the initial stages of the combustion was annihilated before the moving front attained its maximum temperature. The voltage amplitude and combustion temperature depended on the particle size of the reactants as well as the Al to Ni ratio in the reactant mixture, and their largest values were attained for a mixture containing 27-31.5 wt % Al. The combustion temperature increased when smaller Al particles were used. The electric signals annihilated either due to the growth of the initially formed product layer and/or as a result of the formation of a molten Al matrix as the reaction propagated. Oscillatory signals formed during unstable combustion in which the reaction front was perturbed. Unipolar and nonoscillating signals formed when the combustion front was planar. We conjecture that the electric field was generated by the different diffusion rates of charge carriers through a reaction generated thin exterior intermediate products shell of Al 3 Ni/ Al 3 Ni 2 .

Historical perspective and contribution of US researchers into the field of self-propagating high-temperature synthesis (SHS)/combustion synthesis (CS): Personal reflections

“…Another interesting activity conducted by this group is focused on spontaneous magnetization generated by solid state combustion [222][223][224][225][226][227][228]. Using a highly sensitive high-T c superconducting quantum interference device (SQUID), they were able to conduct the first measurement of the very low intensity (order of nT) transient magnetic field formed by a combustion front motion.…”

EMF measurements across the front of combustion wave during layer by layer surface laser sintering of exothermal powder compositions

“…In all the experiments a small, short temperature drop occurred before the electric signal formed [12,13] . The initial increase in the heat release rate following ignition was not sufficient to compensate for the termination of the external heating by the match and led to the transient temperature drop.…”

“…Several experimental studies revealed that the high-temperature front propagation during the combustion synthesis of Record [ materials generated an electrical voltage and a residual magnetic field of up to 1.5 V and 10 µT, respectively [7][8][9][10][11][12][13][14][15][16] . At present time mechanism was no established, which explains the generation of the temporal electric fields and spontaneous magnetization during the combustion of either ferromagnetic or nonferromagnetic materials.…”

Study of the Charge Generation in the Synthesis of Nanosized Complex Oxides in the Combustion Reactions of Organo-Inorganic Precursors

“…Как было показано ранее, возникновение разности потенциалов в прекурсорах или генерирование электрических зарядов при получении наноразмерных оксидных, сложнооксидных и др. материалов в реакциях самораспространяющегося высокотемпературного синтеза (СВС) [1][2][3][4][5][6][7] и горения органо-неорганических композиций [8][9][10][11][12] происходит из-за различной подвижности носителей зарядов разного знака при движении фронта горения либо вследствие уноса в газовую среду заряженных частиц газообразных продуктов горения. В первом случае отмечена разность потенциалов величиной, составляющей доли вольта [1][2][3][4][5][6][7][13][14][15][16].…”

“…материалов в реакциях самораспространяющегося высокотемпературного синтеза (СВС) [1][2][3][4][5][6][7] и горения органо-неорганических композиций [8][9][10][11][12] происходит из-за различной подвижности носителей зарядов разного знака при движении фронта горения либо вследствие уноса в газовую среду заряженных частиц газообразных продуктов горения. В первом случае отмечена разность потенциалов величиной, составляющей доли вольта [1][2][3][4][5][6][7][13][14][15][16]. При горении органо-неорганических прекурсоров, например, полимерносолевых (нитратсодержащих) композиций, разность потенциалов между прекурсором или твердофазными продуктами синтеза и землей, начиная от долей вольта, может достигать сотен вольт, что соответствует зарядам высокой плотности [8][9][10][11][12].…”