PhaCTIV - Phase Change Thermally Initiated Venting System The Phase Change Thermally Initiated Venting System (PhaCTIV) consists of the following: 1) A structual plate (external) - low melt alloy - structual plate - thermal barrier (internal). 2) Structural plates are joined together with low-melt alloy having an operating range of 230°C to greater than 480°C, depending on requirements. 3) Thermal barrier materials (TBC) on the internal surface. The PhaCTIV is installed into sections of the motor case with the thermal barrier layer toward the interior. The thermal barrier preserves the integrity of the low-melt alloy during the firing of the motor. However an external fire will melt the alloy resulting in the structural plates falling away from the case venting the rocket motor resulting in thrust termination. This system has the following features: No pyrotechnics No energetics No sensors to activate the system No electronics No power required No maintenance The proposed thermal barrier system (TBS) also acts as an adhesive enhancement system for the propellant material. A version of the system was demonstrated in a test firing for an Armys rocket case with a diameter of 225 mm. Both laboratory and commercial applications demonstrate that the TBC effectively insulates the low-melt alloy. This TBS is a version of the same system used in flight and land-based gas turbine engines with operating combustion temperatures in excess of 1150°F for thousands of hours. Utilizing the joining and metallurgical properties of the low-melt alloy with the structural plate system will provide strength equal to the bulk of the case. Tests are required to demonstrate that the bond strength of the plates to the low-melt alloy are stable over the anticipated temperature range of the motor during firing.
Keywords: Thrust Termination, Venting, Insensitive Munitions, Sensors, Phase Change
