Electrochemical hydrogen plant for deformation study of metals and alloys
Background. The embedded hydrogen atoms cause an expansion of the crystal lattice of metal. Therefore, any concentration inhomogeneity of hydrogen, regardless of its cause, entails internal hydrogen stresses in solids. The macroscopic manifestation of the action of hydrogen stress is the deformation of metal samples during the hydrogen penetration. This should be considered when using the materials in contact with hydrogen.Materials and/or methods. Steel is the main construction material, which is often subjected to saturation with hydrogen in its use (nuclear power and technology, petrochemical production, etc.). Steel readily absorbs hydrogen at high temperatures. However, at low temperatures, steel can be saturated with hydrogen by electrolytic method even at the relatively low cathode current densities of 0.01-1 A/cm2, which is equivalent to saturation of metal from the gas phase at pressures of hundreds or thousands of atmospheres. The paper describes the designed and manufactured electrochemical hydrogen plant for a systematic experimental study at room temperature of the deformation of metal plates of stainless steel, nickel and other metals and alloys, induced by hydrogen. A nickel plate with a thickness of 0.2 mm and a length of 50 mm was used for the first experiments. The 4-percent solution of sulfuric acid was used as an electrolyte. The current density was 0.05 A/cm2. One side of the sample was protected by varnish coating from the electrochemical effects that allowed for one-sided saturation with hydrogen.Results. In the process of electrolytic saturation, the nickel plate has undergone a natural bend. The deflection has reached its maximum value of 0.55 mm in 74 min (time of saturation). 6 min after the saturation had stopped the plate began to straighten up, that was connected with redistribution of hydrogen and reduction of the stress state of the plate.Conclusion. The obtained results show that the developed device allows the systematic studying of the deformation of metal plates in different modes of hydrogen saturation by the electrolytic method.