dc.description.abstract | An experimental reactor system has been optimized throughout a series of
experiments for making titanium tubes from an electrically heated titanium
coil filament by a chemical vapour deposition method, based on the original
van Arkel-de Boer -process. The titanium is thermally decomposed on the
filament from vapourized titanium tetraiodide in a method not seen in similar
experiments. The small-scale reactor is built for this purpose, and the associated
systems and methods are developed to maintain the optimal conditions
for a continuous metal deposition. A filament current control system is made
of an Arduino micro-controller, utilizing a photo-resistor to measure thermal
radiation from the filament, working for maintaining a constant filament temperature.
Five experiments are conducted with the small-scale reactor and
presented in this thesis, where different procedures, materials, duration and
amount of starting material is tested. By the use of copper electrodes, it was
quickly found that the metal could easily be contaminated from other metal
sources. The most important precautions necessary to achieve a good deposition
of high purity is to keep air out of the system, and a purpose-built
glove box is made to fulfill this. In the first two experiments, titanium was
deposited on a platinum wire and tungsten wire, respectively. In the three
following experiments, a titanium coil filament was used, whereas experiment
5 was considered the most successful, by the purity of the deposited titanium
and the growth on the coil filament, forming a solid tube.
Index Terms: Chemical vapour deposition, thermal decomposition, titanium, titanium
tetraiodide | nb_NO |