Traditional gas and powder inerting techniques widely used in metal processing fail to fit the fire prevention demands of additive manufacturing nano-aluminum dust, which features nanoscale particle size, high activity and accumulated layered distribution.
In a study published in the KeAi journal Defense Technology , a team of researchers evaluated the rationality of eight traditional inert powders to suppress accumulated nano-aluminum dust layers generated by additive manufacturing, revealing severe hidden fire risks of conventional inerting methods and offering theoretical guidance for dust explosion prevention in 3D printing metal processing.
“We tested ignition sensitivity and flame spread characteristics of nano-aluminum dust mixed with three categories of inertants, and clarified distinct combustion-promoting mechanisms at low-to-medium mass fractions,” shares corresponding author Professor Zhenmin Luo. “We divided the eight inertants into three categories: high-decomposition, melting and physical endothermic inert powders, each with totally different influences on dust combustion.”
The team found that although all inertants could raise the ignition threshold of nano-aluminum dust, complete inertization demanded mass fractions above 80% or even 90%, which was impractical for on-site industrial use. “Worse still, most inertants intensify combustion within common low-to-medium dosage ranges,” adds Luo.
A series of lab tests covering minimum ignition energy and hot surface ignition temperature were then carried out to characterize ignition risk, while a horizontal ceramic mold device recorded flame spread velocity to quantify combustion intensity.
“Decomposition-type powders release large amounts of gas under heating, breaking the fragile oxide crust on dust layers and triggering violent gas-phase combustion and flying burning particles,” reveals Luo. “Nano-titanium dioxide triggers exothermic displacement reactions with aluminum, and low-melting inertants cannot form effective liquid sealing layers due to the rapid melting of nano-aluminum powder.”
Notably, only nano-alumina purely relies on physical heat absorption without combustion promotion.
The team’s experimental results demonstrated traditional inerting schemes are even counterproductive for accumulated nano-aluminum dust from 3D printing. "Our findings show the complex interaction mechanisms between inert powders and nano-aluminum dust layers, and provide critical experimental evidence and theoretical basis for developing targeted explosion prevention technologies for additive manufacturing metal dust,” Luo says.
###
Contact the author:
Zhenmin Luo, School of Safety Science & Engineering, Xi'an University of Science and Technology, Xi'an, 710054, China.
The publisher KeAi was established by Elsevier and China Science Publishing & Media Ltd to unfold quality research globally. In 2013, our focus shifted to open access publishing. We now proudly publish more than 200 world-class, open access, English language journals, spanning all scientific disciplines. Many of these are titles we publish in partnership with prestigious societies and academic institutions, such as the National Natural Science Foundation of China (NSFC).
Defence Technology
Experimental study
Not applicable
Study on the rationality of applying traditional inerting methods to nano-aluminum powder in additive manufacturing processes
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.