title: Time resolved quantitative imaging of charring in materials at temperatures above 1000 K.
abstract: A device is presented allowing for in situ investigation of chemically changing materials by means of X-ray imaging. A representative cork ablator sample, additionally instrumented with thermocouples, is encapsulated in an evacuated cell heating a sample surface with a heat flux of 230 kW/m(2). The images show the sample surface and the in-depth progression of the char front dividing the char layer from the virgin material. Correlating the images to thermocouple data allows for the deduction of a reaction temperature. For the representative cork ablator investigated at the present conditions, the progression rate of the pyrolysis layer is determined to 0.0285 mm/s and pyrolysis temperature is 770 or 737 K, depending on the pre-existing conditions. It is found that the novel device is ideally suited for volume process imaging.
authors.affiliation: Institute of Structures and Design, German Aerospace Center (DLR), D-70569 Stuttgart, Germany.
authors.forename: Hannah
authors.initials: H
authors.lastname: Böhrk
authors.affiliation: Institute of Structures and Design, German Aerospace Center (DLR), D-70569 Stuttgart, Germany.
authors.forename: Raouf
authors.initials: R
authors.lastname: Jemmali