Using Microcalorimetry to Establish Kinetics and Determine the Accelerated Aging Factor for Surveillance Testing of the MK 14 MOD 0 Explosive Lead for the Sidewinder Missile

摘要

In FY 04 NSWC Crane was tasked by the AIM-9M Sidewinder Joint Surveillance Program to project serviceability of the MK 14 MOD 0 Explosive Lead to 25 years using Heat Flow Microcalorimetry (HFM). The MK 14 Explosive Lead is a secondary explosive which is attached to the output end of the MK 13 MOD 2 Safety-Arming Device and is used to initiate the acceptor charge in the WDU-17/B Warhead of the Sidewinder Missile. The MK 14 Lead contains 820 milligrams of RDX composition CH-6. The microcalorimetry test facility at Crane was used to obtain the accelerated aging factor. Using the accelerated aging factor, the test samples were aged to 25 years and then performance tested. During FY 02 surveillance tests, thicker closure discs and discolored enamel were found. The FY 04 evaluation also assessed the affect of these anomalies on performance. The objective of HFM analysis is to determine extremely slow aging degradation, shelf life and long-term stability and compatibility of explosives under various environmental stimuli. HFM analysis was used to estimate the aging affect of temperature on the MK 14 Leads. Using this analysis, aging affects due to temperature can be accelerated. The analysis consisted of placing the MK 14 leads in a stainless steel sample holder and into a heat flow calorimeter. Heat flow output was measured at 60°C, 70°Cand 80°C using three MK 14 Leads at a time in order to obtain measurable heat flow output. Two different lots were evaluated and produced comparable heat flow results. Using the Arrhenius plots, the temperature affect on the rate of degradation was tabulated. Based on a storage temperature of 25°C, the output function units were then aged to 25 years by conditioning them at a higher temperature (70°C) for a shorter duration (36.35 days). Explosive output function was conducted on the units after they were aged to 25 years and depth of dent and firing time were measured. The output function results indicated that all MK 14 MOD 0 Explosive Leads are currently serviceable and are projected to remain serviceable for 25 years at normal storage temperature.