- Author
-
Brewer, W. D.
|
Kassel, P. C., Jr.
- Title
- Evaluation of a Flash X-Ray Technique for Recession Measurements in Ablative Materials.
- Coporate
- Langley Research Center, Hampton, VA
- Report
-
NASA TN D-5669
February 1970
22 p.
- Keywords
-
ablative materials
|
data analysis
|
char
- Identifiers
- recession measurements
- Abstract
- A flash x-ray technique has been developed that permits the determination of the surface and interface recessions of ablative materials during testing in arc-jet facilities. Use is made of a system with which several radiographs of a specimen can be made during a single test. The flash x-ray system and measurement techniques are discussed. Surface and interface recessions are obtained for three charring ablators tested in an arc-jet facility. The data obtained with the x-ray system are compared with results obtained by direct measurement on sectioned specimens after testing and with analytical predictions. The agreement among the results is good. Thus the x-ray technique can be used effectively to obtain reliable recession measurements. For the phenolic-nylon materials tested, the char density increases significantly toward the front surface. An epoxy-base material tested shows no char density gradient. Also, there appears to be a reduction in density of the charring materials before any visible change takes place.