In-situ preparation of copper azide by direct ink writing

•A new method of porous copper azide precursor construction is proposed.•The designed ink has sufficient surface area to ensure the azide reaction.•The binder doesn’t hinder formation of pores but maintains a 3D porous structure.•The 3D porous structure maintains certain strength and adhesion after drying.•Performance of copper azide can be adjusted by tuning the ink parameters. The aim of the present work is to design a copper azide precursor direct writing ink for primary explosive-on-a-chip. The mixture of water/vinyl alcohol and isopropanol/ethyl cellulose was used as binder. Cetyltrimethylammonium bromide (CTAB) used as foaming agent and dodecanol as foam stabilizer were added into the binder to produce plenty of bubbles. 40 wt% of nano-copper powder was added into the binder and the three-dimensional porous precursor ink was obtained. After 24 h of in-situ gas–solid azide reaction, the copper precursor ink was completely transformed into copper azide. An explosive device was designed to verify the detonation performance of the copper azide by direct writing, and the result showed that it can reliably initiate the CL-20 into complete detonation.