Since aluminum responds to various oxidizers and has a high energy density, there are high expectations for its usefulness as a fuel. However, it is covered with an aluminum oxide film, which has a high melting point, and thus, its ignition is difficult. One method suggested to solve this problem is nickel coating; however, in contrast to the extensive amount of research conducted on the overall phenomenon of aluminum combustion, research regarding Ni-coated aluminum is still in nascent stages. This study was carried out to further elucidate the ignition mechanism; thus, millimeter-sized (∼2.38 mm) aluminum particles were used to observe the surface where ignition occurs in air. The spatial and temporal resolutions were heightened by prolonging the heating period. The aluminum particles were nickel coated using electro/electroless methods, and surface analysis by SEM, thermal analysis by TGA/DSC, and species analysis by XRD and EDS were carried out. In addition, two-wavelength pyrometry was used to measure the ignition temperature. The results show that regardless of the nickel content in the coating of the aluminum particles, the ignition temperature was approximately 2400 K, similar to the melting point of aluminum oxide. The thermodynamic and thermophysical characteristics of nickel, aluminum, aluminum oxide, and nickel (II) oxide, and the surface/cross-sectional analysis, thermal and species analysis, and high-speed cinematography of the quenched samples provided a detailed explanation of the ignition process. Through this ignition mechanism, the emitted spectrum of AlO (as an intermediate combustion material) was traced to explain the decrease in ignition delay with increase in nickel content.
|Number of pages||16|
|Journal||Combustion and Flame|
|Publication status||Published - 2018 Dec|
Bibliographical noteFunding Information:
This work was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD) ( KRF-2007-511-D00026 ) and the Defense Acquisition Program Administration and Agency for Defense Development under the Contract UD110095CD .
© 2018 The Combustion Institute
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Fuel Technology
- Energy Engineering and Power Technology
- Physics and Astronomy(all)