Impact of Substrate Thickness and Surface Roughness on Al/Ni Multilayer Reaction Kinetics
Abstract
Reactive multilayers comprising alternating nanoscale layers of Al and Ni exhibit potential across various applications, including localized heating for welding and joining. Control over reaction properties is pivotal for emerging applications, such as chemical time delays or neutralization of biological or chemical weapons. In this research, insights are offered into the intricate interplay between substrate thickness, surface roughness, and the behavior of Al/Ni reactive multilayers, opening avenues for tailored applications in various domains. To observe this interplay, silica with various thicknesses from 0.4 to 1.6 μm is deposited on polished single-crystalline Si and rough poly-Si base substrates. Additionally, to analyze the impact of varying silica thickness along the sample length on reaction behavior, silica in steplike shape is fabricated. Subsequently, Al/Ni multilayers with 5 μm total thickness and 20 or 50 nm bilayer periodicities are deposited. Reaction velocity and temperature are monitored with a high-speed camera and pyrometer. In the results, it is indicated that silica thickness significantly affects self-propagation in multilayers. The reaction is not self-sustained for silica layers ≤ 0.4 μm, depending on bilayer periodicity and substrate roughness. The velocity increases or decreases based on the direction of reaction propagation, whether it moves upward or downward, in relation to the thickness of silica.
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Source: Preview Image: Vardo, E., Sauni Camposano, Y.H., Matthes, S., Glaser, M., Bartsch, H., Hildebrand, J., Bergmann, J.P. and Schaaf, P. (2024), Impact of Substrate Thickness and Surface Roughness on Al/Ni Multilayer Reaction Kinetics. Adv. Eng. Mater. 2302269. https://doi.org/10.1002/adem.202302269