Determination of the feasibility of using beta radiation backscatter for the detection of surface contamination of metal panels

Abstract : The beta backscatter technique was determined to be feasible for the measurement of contaminants and surface preparation coatings. Titanium and aluminum honeycomb panels with bonded and disbonded areas were examined to identify (1) contaminants or surface preparation properties which result in disbonding and (2) surface preparation coatings which result in acceptable bonds. The poor bonding of the titanium panels was between the metal skin and the primer coating. Electron microscopy showed that the surface of the titanium skin was too smooth to favor physical bonding. Further examination showed there were no bonded areas suitable for analysis. The skins of the aluminum panels showed the bonded areas exhibited a microetchpit structure which was not present in the poorly bonded areas. It was concluded that the lack of bond of the aluminum panels was not the result of surface contamination but rather a function of the pickling parameters and perhaps the annealing of the aluminum. (Author)