Research On Corrosion And Inhibition Mechanism Of Typical Metals In Three Kinds Of Hydrated Salt Phase Change Heat Storage Materials

Inorganic hydrated salt phase change materials have the advantages of low phase transition temperature and high heat storage density,and are suitable for construction,agriculture and other fields.However,molten hydrated salt can cause serious corrosion of its packaging metal.In this paper,three inorganic salt phase change materials,Mg SO₄·7H₂O,Ca Cl₂·6H₂O and Ba(OH)₂·8H₂O,are selected as the research objects,and their corrosion to copper,aluminum,and stainless steel is studied.The experimental results show that copper is corroded seriously in these three hydrated salt systems,aluminum is only corroded severely in Ba(OH)₂·8H₂O system,and stainless steel is only slightly corroded in all three hydrated salt systems.Molecular dynamics simulation was carried out.When constructing the simulation structure,copper was used as the metal matrix in the three hydrated salt systems,and the Ba(OH)₂·8H₂O system constructed aluminum as the metal matrix.The adsorption and diffusion behaviors of related corrosion inhibitors relative to the metal surface in the three hydrated salt systems and the interaction between corrosion inhibitors are studied,and the corrosion inhibition rate of the corrosion inhibitors is calculated by the weight loss method.Research indicates(1)In the Mg SO₄·7H₂O system,adding 1.0%CTAB or 1.2%Na₂Cr O₄alone can exert a good corrosion inhibition effect,and the corrosion inhibition rates are 85.54%and 77.09%,respectively.After the combination of the two,due to the stable interaction between CTAB and Cr O₄^2-,a dense and stable corrosion inhibition film can be formed,so that the diffusion coefficient of SO₄^2-in Mg SO₄·7H₂O is reduced by about 6 times,and the diffusion coefficient of H₂O is also reduced.3 times of,effectively hinder the movement of corrosive particles to the metal surface.The corrosion inhibition rate of 0.6%CTAB and 0.7%Na₂Cr O₄is 92.36%,which can have a good protective effect on copper.(2)In the Ca Cl₂·6H₂O system,the corrosion inhibition rate of 1.3%BTA alone can reach75.94%,but after 1.0%Na₂Si O₃is added alone,it cannot be stably adsorbed on the metal surface,and the corrosion inhibition rate is only 10.47%.After the two are combined,due to the interaction between Si O₃^2-and BTA,Si O₃^2-can be stably adsorbed on the metal surface to fill the gaps of BTA and form a dense corrosion-inhibiting film,which reduces the diffusion coefficient of Cl^-and H₂O in the system by about 5 times.The corrosion inhibition rate of1.3%BTA and 1.0%Na₂Si O₃is 90.89%,which can effectively inhibit copper.(3)In Ba(OH)₂·8H₂O system,for copper metal,the corrosion inhibition rate of adding 1.4%C₆H₁₂O₆can reach 85.78%,and for aluminum metal,the corrosion inhibition rate of adding1.2%C₆H₁₂O₆is 84.04%.Glucose has pyran and linear structures.After adding glucose corro sion inhibitor to the system,the interaction between glucose molecules will occur,and the aldol condenses to form a more stable corrosion-inhibiting film structure,in Ba(OH)₂·8H₂O The diffusion coefficient of OH^-and H₂O is reduced by nearly 4 times,which hinders the corrosion of metals.