Self-assembling monolayers as contamination protection. Evaluation of adsorbed alkylamine films from ODACON F emulsion

The main goal of this work was to test, whether the contamination on tools used during the revision in a nuclear power plant can be reduced by film-forming amines (Chapter 4). Furthermore, alkylamine application processes should be developed in laboratory scale for coating metal coupons under mild conditions and without additional technical effort. Following this, the quality of the formed films was assessed. For this purpose, optical and electrochemical measurement methods were applied, which have been already described in literature. In addition, a method was developed by means of open potential measurements for evaluation of the formed films. Due to this, a proportional relationship between the coating quality and general coating parameters such as concentration or temperature could be found by electrocatalytic investigations. In the first two chapters, background knowledge on the current use of film-forming amines in engineering, as well as the construction of a boiling water reactor and the most important radiochemical foundations in blocks B and C, in which practical investigations took place, are discussed. Furthermore, the emulsion used by Framatome GmbH, ODACON F, as well as the most common analysis methods of film-forming amines in the literature are summarized and discussed. The objectives already mentioned here at the beginning, are described and explained in detail in Chapter 3. Chapter 4 describes practically performed experiments in nuclear power plant, where various metal samples were representative coated for tools and stored for a certain time in the primary circuit of a boiling water reactor. These samples were subsequently tested for their contamination and compared with uncoated samples. The practical work in power plant was followed by examinations in the laboratory. For an easy-to-apply coating, emulsions of various dilutions in the range from 1 to 2500 ppm were produced, using a commercial emulsion (ODACON F). Additionally, coating processes in a steel-autoclave and glassware were developed and tested. Using the newly prepared emulsions, it was possible to perform coatings in glass vessels, simply and quickly by changing individual parameters. Chapter 6 contains the analyses of the resulting hydrophobic films. First, commonly used analytical methods of literature were tested. A proprietary contact-angle measuring device was built to study the hydrophobic character of coated metal surfaces. The electrochemical behavior of the films was investigated by means of impedance spectroscopy and polarization measurements. Initially, samples were analyzed which were coated in a previous step. In addition, samples were electrochemically analyzed for several hours, each with and without the addition of film-forming amines and compared afterwards. To further evaluate the film quality, a new measurement method was introduced in which the time until the potential of a metal sample in a redox buffer stabilizes, is an indication for the film quality. This measurement method is based on the time until the mixed potential stabilizes (intensive unit) and has been supplemented with a further measurement method based on electrocatalysis. The reaction kinetics or the mixed current density (extensive unit) represents a direct proportional relationship to the free metal surface, which ultimately allowed a statement to be made about the film quality.