Preparation And Performance Of Organic-inorganic Hybrid Protective Coatings On Bronze

Bronze relics with high historical, artistic and scientific value are one of thesymbolizations of ancient civilization of human being. Due to their long buried time,changes of the storage condition after excavation etc., it is a great challenge for us totake measures to prevent the ancient bronze relics from corrosion.In order to develop a new protective material for the bronze relics, theγ-glycidoxypropyltrimethoxysilane (GPTS)/methyltrimethoxysilane (MTMS) hybridcoatings on the bronze substrates were prepared by a sol-gel method. The sol-gelGPTS/MTMS hybrid coatings were modified by the corrosion inhibitor benzotriazole(BTA) and other assistant agents. The protective properties of the coatings werestudied by Salt Spray Test and electrochemical impedance spectroscopy (EIS). Inorder to evaluate the reversibility of these protective materials, we have investigatedthe composition of the possible chemicals and the processing parameters for removingthe organic-inorganic coatings on the bronze substrates.The results showed that the corrosion resistance of organic-inorganic coating isrelated to the roughness of Bronze substrate. The efficiency of their corrosionresistance is enhanced by the increase of surface roughness and the protective abilitiesof the BTA-modified coatings could be enhanced remarkably. Removing resultspresented herein indicate that a dilute zincate solution, of the type commonly used asa pretreatment for electroless and electroplated nickel deposition on bronze,effectively removed the organic-inorganic coating at room temperature. This coatingremoval technique leaves a thin zincate layer on the bronze surface, slowingdissolution of the metal in the basic solution, hence, maintaining the integrity of thebronze substrate. The residual zincate layer may be easily removed using dilutephosphoric acid. This coating material was also applied for protection of the bronzerelics excavated from Jinsha site near Chengdu and proved to be effective for thebronze relic protection.This article provides a foundation for developing the GPTS-base organicallymodified silicate hybrid protective coatings, and all the results of this research will beimportant for the anti-corrosion application of the bronze relics and other copperproducts.