Accelerated Lifetime Testing of Porous Silicon Energetic Materials

When infused with an oxidizer, on-chip porous silicon (PS) shows tremendous potential as an energetic material. However, applications such as fuzing and propulsion require long-term material stability. The present work utilizes accelerated lifetime testing methods for PS samples with sodium perchlorate (NaClO₄) oxidizer. These devices are aged by baking at elevated temperatures in a controlled environment, and after set time intervals, electrically ignited to determine the failure points while measuring power, energy, and time to ignition through the device bridgewires. Failure points are defined as the time point when at least 50% of the devices failed to ignite. Differential scanning calorimetry (DSC) through comparison of baseline porous silicon samples with aged samples, confirms that device failure results from aging due to the baking process rather than electrical failure of the integrated initiator. Samples were heated over a temperature range of 185-300^oC, with respective failure times ranging from 0.75 hr to 16.5 hrs. An Arrhenius acceleration model is used to represent the time-to-fail data, and to predict a mean time to failure of 23 years. Aside from the predicted failure time, results provide heating limits for processing a device with on-chip PS/sodium perchlorate.