| 摘要 |
A method for treating a metal surface involves contacting the metal surface with an aqueous silicate solution, contacting the silicate-coated metal surface with an aqueous organo-functional silane solution, and then contacting the silane-coated metal surface with a chrome-free pretreatment. Preferably, the bath containing the aqueous silicate solution also includes a cleaning agent for cleaning the metal surface. Alternatively, the metal surface may be cleaned in a separate step before the metal surface is contacted with the aqueous silicate solution and, optionally, the metal surface is rinsed with water after the metal surface is cleaned and before the metal surface is contacted with the aqueous silicate solution. The silicate-coated metal surface may be rinsed with water before it is contacted with an aqueous organo-functional silane solution. In addition, the silane-coated metal surface may be rinsed with water before it is contacted with a chrome-free pretreatment. As an alternative or in addition to these rinsing steps, excess solution may be removed from the silicate-coated or silane-coated metal surface prior to the subsequent steps. Preferably, the aqueous silicate solution includes water and either sodium silicate or potassium silicate, and the aqueous organo-functional silane solution comprises an aminopropyl silane and water.
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