Method for self-repairing of damage to inorganic protective layer on metal surface

Abstract

Disclosed is a method for self-repairing of damage to an inorganic protective layer on a metal surface. The method includes: placing a metal with the inorganic protective layer having a damaged surface in a chloride ion solution, and performing self-repairing, wherein the metal with the inorganic protective layer comprises a metal substrate and a layered double hydroxide protective layer intercalated by acid anions covering a surface of the metal substrate; and the acid anions are selected from the group consisting of phosphate anions and molybdate anions.

1 . A method for self-repairing of damage to an inorganic protective layer on a metal surface, comprising:
 placing a metal with the inorganic protective layer having a damaged surface in a chloride ion solution, and performing self-repairing,   wherein the metal with the inorganic protective layer comprises a metal substrate and a layered double hydroxide protective layer intercalated by acid anions covering a surface of the metal substrate; and   the acid anions are selected from the group consisting of phosphate anions and molybdate anions.   
     
     
         2 . The method of  claim 1 , wherein the metal substrate comprises one selected from the group consisting of steel material, zinc material, magnesium material, aluminum material, and copper material. 
     
     
         3 . The method of  claim 1 , wherein the layered double hydroxide protective layer intercalated by acid anions has a thickness of less than or equal to 50 micrometers. 
     
     
         4 . The method of  claim 1 , wherein the metal with the inorganic protective layer is prepared by a process comprising the following steps:
 mixing a first divalent metal salt, aluminium nitrate and water to obtain a mixed solution;   taking the mixed solution as a deposition solution, constructing a three-electrode system with a metal substrate as a working electrode, and performing electrodeposition with the three-electrode system to obtain a post-deposition metal substrate;   mixing a second divalent metal salt, aluminium nitrate, an acid anion source and water to obtain a mixture, and adding ammonia water to the mixture to adjust a pH value thereof to 9-12 to obtain a hydrothermal reaction solution; and   placing the post-deposition metal substrate in the hydrothermal reaction solution, and performing hydrothermal reaction to obtain the metal with the inorganic protective layer,   wherein the first divalent metal salt and the second divalent metal salt are each independently selected from the group consisting of zinc nitrate and magnesium nitrate; and   the acid anion source comprises one selected from the group consisting of a dihydrogen phosphate or a molybdate.   
     
     
         5 . The method of  claim 1 , wherein the chloride ion solution comprises a sodium chloride solution; and the sodium chloride solution has a concentration of 3.5 wt %. 
     
     
         6 . The method of  claim 1 , wherein the self-repairing is performed at room temperature. 
     
     
         7 . The method of  claim 2 , wherein the metal with the inorganic protective layer is prepared by a process comprising the following steps:
 mixing a first divalent metal salt, aluminium nitrate and water to obtain a mixed solution;   taking the mixed solution as a deposition solution, constructing a three-electrode system with a metal substrate as a working electrode, and performing electrodeposition with the three-electrode system to obtain a post-deposition metal substrate;   mixing a second divalent metal salt, aluminium nitrate, an acid anion source and water to obtain a mixture, and adding ammonia water to the mixture to adjust a pH value thereof to 9-12 to obtain a hydrothermal reaction solution; and   placing the post-deposition metal substrate in the hydrothermal reaction solution, and performing hydrothermal reaction to obtain the metal with the inorganic protective layer,   wherein the first divalent metal salt and the second divalent metal salt are each independently selected from the group consisting of zinc nitrate and magnesium nitrate; and   the acid anion source comprises one selected from the group consisting of a dihydrogen phosphate or a molybdate.   
     
     
         8 . The method of  claim 3 , wherein the metal with the inorganic protective layer is prepared by a process comprising the following steps:
 mixing a first divalent metal salt, aluminium nitrate and water to obtain a mixed solution;   taking the mixed solution as a deposition solution, constructing a three-electrode system with a metal substrate as a working electrode, and performing electrodeposition with the three-electrode system to obtain a post-deposition metal substrate;   mixing a second divalent metal salt, aluminium nitrate, an acid anion source and water to obtain a mixture, and adding ammonia water to the mixture to adjust a pH value thereof to 9-12 to obtain a hydrothermal reaction solution; and   placing the post-deposition metal substrate in the hydrothermal reaction solution, and performing hydrothermal reaction to obtain the metal with the inorganic protective layer,   wherein the first divalent metal salt and the second divalent metal salt are each independently selected from the group consisting of zinc nitrate and magnesium nitrate; and   the acid anion source comprises one selected from the group consisting of a dihydrogen phosphate or a molybdate.