ABSTRACT

Lithium bromide absorption machines work under high LiBr concentrations and temperature, which favour the corrosion of the constituents materials of the absoprtion machines and favour the hydrogen evolution reaction as a consequence of the cathodic reaction associated with the corrosion phenomenon, resulting in the reduction of the efficiency.
The main objectives of the thesis “Study of the influence of anodic and cathodic polarization under the electrochemical behavior of nickel, chromium and stainless steels in LiBr” are study the corrosion behavior f nickel, chromium, an austenitic stainless steel (nickel base alloy) and a duplex stainless steel in heavy brine LiBr solution of 992 g/l at temperatures between 25 and 75 ºC and to study the hydrogen evolution reaction (HER) of those materials in such conditions. On the other hand the influence of the hydrogen evolution reaction is studied on the electrochemical behavior of the materials in LiBr. Different electrochemical techniques, as open circuit potential measurements, polarization curves or electrochemical impedance spectroscopy, are used. This study will give one information to select suitable materials for the design of LiBr absorption machines.
The simultaneous acquisition of real-time images corresponding to the electrode surfaces and of the electrochemical data allows one to relate the electrochemical phenomenon to the corrosion morphology of the material. 
On the basis of the obtained results it is concluded that all the studied materials present good corrosion behavior, being spontaneously passive in 992 g/l LiBr solution and that they present high overpotentials for the HER. The nickel base alloy presents the best electrochemical behavior and it recovers passivity after the hydrogen generation on its surface; therefore is the most suitable among all the studied materials for its use in LiBr absoprtion machines.