Study on the rationality of applying traditional inerting methods to nano-aluminum powder in additive manufacturing processes

Compared to the traditional metal processing industry, additive manufacturing (3D printing), due to its unique process, generates metallic dust by-products characterized by high yield, high metal purity, extremely fine particle size (down to the nanoscale), and a tendency to exist in an accumulated form. Whether traditional inert powders are suitable for this new metal process remains unknown. This study selected eight common inertants to systematically investigate their effects on the ignition sensitivity and flame propagation characteristics of nano-aluminum (nAl) dust layers. The results indicate that while all eight inert powders can reduce the ignition sensitivity of nAl dust, the content required to achieve complete inertization is excessively high. However, in terms of flame propagation, decomposition-type inert powders significantly enhance the gas-phase combustion of the nano-aluminum dust layer across most concentration ranges. nmTiO 2 also exhibits a combustion-promoting effect due to its displacement reaction with aluminum. Owing to the rapid melting of nAl dust at high temperatures, melting-type inert powders are also ineffective in providing efficient inerting through liquid sealing. This study reveals the complex mechanisms by which different types of inert powders influence the combustion behavior of nano-aluminum dust layers, providing important experimental evidence and theoretical guidance for dust explosion prevention safety in novel metal processes such as additive manufacturing.