Nitrocellulose Propellants Standard Stability Tests Enhancement Employing Semiconductor Sensors

Abstract

Nowadays, solid propulsion is the workhorse of a wide range of applications, from gun ammunition to missiles; and Nitrocellulose, NC, is still widely used in propellant compositions. However, its long-time storage represents a serious risk due to NC natural autocatalytic degradation process, that may lead to severe accidents. Some National Surveillance Programs continue using the so-called Stability Tests to monitor Nitrocellulose condition and storage risks; nevertheless, most users consider these tests technologically outdated and difficult to achieve a precise interpretation. This manuscript deals with this NC stability challenge, developing an innovative technology but maintaining Stability Tests phenomenological behaviour, in order to quantify naturally emitted nitrogen oxides, NOx, from Nitrocellulose vapours, as the main indicator for propellants degradation degree. However, accurate NOx quantification is usually strongly interfered by other naturally emitted vapours from gunpowder components, both in Stability Tests and in the technological proposal. Consequently, this document not only describes the technology and main development milestone, but individual components are also studied to reach a proper essay validation, employing Metal Oxide sensors, MOx. Additionally, signal deconvolution is presented to sharpen the NOx determination from interferences with two real samples (NC gunpowder), which are natural and artificially aged, determining performance of sensors and comparing conclusions with those from classical tests. Finally, presented results have shown insignificant interference of other chemicals present in the gunpowder over NOx quantification. According to these conclusions, this technology can be considered a technological improvement on NC Stability Tests.