抄録
Hydrogen absorption by titanium coupled with dissimilar metal such as mild steel, stainless steel and naval brass was investigated in deaerated 0.01%Na2SO4 solution at high temperature simulating the environment of shell side of brine heater in a desalting plant.
As a result, uncoupled titanium and titanium coupled with stainless steel and naval brass did not pick up hydrogen in the solution even at 150°C but it coupled with mild steel picked up hydrogen over 120°C. Corrosion rate of mild steel and hydrogen content in titanium increased with an increase of Ti/Fe area ratio. Moreover, Fe3O4 deposited on the lower part of titanium specimen and hydrogen content in titanium was much in the Fe3O4 deposited part.
Fe3O4 seems to be formed from Fe(OH)2. It was clarified that corrosion potential of titanium shifted to less noble side in a high concentration Fe(OH)2 solution. Therefore, it is considered that titanium absorbs hydrogen because hydrogen evolution reaction on titanium is accelerated by Fe(OH)2.
Subsequently, an appropriate countermeasure against hydrogen absorption was investigated and hydrogen absorption could be prevented by thermally oxidation of titanium.
