High-Heat-Flux Thermogravimetric Analysis With Radiography

A process and a laboratory setup to implement the process (see figure) have been devised to enable the acquisition of time-resolved data on the thermal decomposition of a specimen of a solid material exposed to a heat flux comparable to the heat flux in a typical rocket engine. The process is called "RTR-TGA" because it includes a combination of real-time radiography (RTR) and thermogravimetric analysis (TGA). In the process, one specimen surface (e.g., representing a surface exposed to flames in a rocket engine) is heated by a continuous-wave CO2-laser beam while the interior temperature of the specimen is measured and the specimen is observed by an x-ray apparatus that produces video images that can be recorded. The major advantage of this process over older processes for observing thermal decomposition of material specimens is that the environment to which the specimen is exposed approximates more closely the heating environment in a full-scale rocket engine.