In-situ constructing nano ternary Ni-P-Cu alloy shell on the micro-aluminum surface: Enhancing its ignition and combustion performances

To improve the combustion efficiency of widely used micro-aluminum (μAl) particle, enhancing its ignition and combustion performances is a critical issue via breaking through the intrinsic Al₂O₃ layer covering the Al-core. This study proposed a facile in-situ ‘one-pot’ electroless plating method to functionalize the surface of μAl particles with ternary-shelled nickel-phosphorus-copper alloy coating and furthermore investigated the thermochemical and ignition/combustion behaviors of energetic core–shell composites (defined as Al@Ni-P-Cu). The microstructure characterization results of Al@Ni-P-Cu demonstrated that a spherically distributed triple-shell Ni-P-Cu alloy with the thickness of 129 nm was tightly coated on μAl particle surface. Through TG-DSC analysis, the Al@Ni-P-Cu composites exhibited improved heat release (7597.7 J/g) and decreased initial oxidation temperature (814.3 °C) in comparison to that of μAl particle with 949.2 J/g and 960.1 °C, respectively. The Al@Ni-P-Cu exhibited extremely shorter laser ignition delay time of 36.3 ms under 1 MPa O₂ atmosphere, reducing by 86.86% compared with that of raw μAl particles (276.3 ms); and its maximum flame temperature could reach up to 1588.93 °C, increasing by 243.36 °C compared with that of μAl (1345.57 °C). The drastic improving performances were attributed to the synergistic effects of surface/interfaces reactions along with heat release in the core–shell structure, resulting in enhanced mass and heat transfer to facilitate the combustion of internal Al-core.