Fasano, Michaela Rose (2017-05). Thermal Cook-off Study of Pressed Nitrotriazolone (NTO) Pellets. Master's Thesis. Thesis uri icon


  • As of today, no research has been performed to study the response of Compounded High Explosive Composite (CHEC) pellet arrays to fast or slow cook off. Cook-off tests are fairly standard tests for homogeneous-fill high explosives (HE's), but, when using pressed pellet arrays as fill, the results of such cook-off tests are unknown. This research consisted of developing and designing an "indoor" cook-off test capable of testing pressed Nitrotriazolone (NTO) pellets to assess thermal stability characteristics and critical temperature. The test method designed consists of the main testing vessel--the Petersen Group strand burner IV composed of 17-4 PH stainless steel with extreme pressure and temperature capabilities--a sample bolt holder used to hold the NTO pellet, a 400-W cartridge heater, two type K thermocouples, and an aluminized heat barrier. The cartridge heater was operated using a proportional-integral-derivative (PID) temperature controller. The data from the thermocouples used to monitor pellet and surrounding air temperatures were recorded using a USB-interfaced data logger capable of taking measurements at a rate of 1 sample per second. A series of thermal cook-off tests was conducted revealing critical temperatures for the NTO pellets ranging between 175 and 203?C. For slow cook-off tests, the average critical temperature, TC, was determined to be 196?7?C. Fast cook-off tests revealed an average TC of 189?1?C. Due to these temperatures occurring over such a wide range and evidence of partially burned explosive residue material after each test, it is suggested that the pellets are undergoing premature decomposition, and thus a critical temperature for these NTO pellets cannot be determined to a high accuracy. As such, the thermal stability of NTO pellets in CHEC arrays remains to be verified. This thesis details the design and development of the "indoor" cook-off test as well as the thermal characteristics of the NTO pellets when exposed to extreme heating.

publication date

  • May 2017