The invention relates to the field of aluminum
alloy decoration and protection
coating for ships, in particular relates to an environmentally-friendly
corrosion-
contamination resistant
chemical conversion agent and application thereof in a
chromium-free
chemical conversion film, and solves the problems of poor
corrosion resistance, high cost, difficulty in large-area construction and the like in the prior art. The
chemical conversion agent comprises a component A and a component B. The method for preparing a chemical conversion film comprises the following steps of: forming a first
inorganic chemical conversion film layer by the component A and forming an organic
contamination resistant closed film by the component B. The component A is a water solution prepared from a main salt, a film-forming accelerator, a
buffering agent, a surfactant and the like, and the component B is prepared from
silicate,
silane, a silica
sol,
titanate,
zirconate, waterborne resins and the like. The chemicalconversion agent does not contain
chromium ions and phosphates, and the
chromium-free chemical conversion film prepared from the chemical conversion agent has excellent
corrosion resistance and
contamination resistance, can be used for construction of large-area aluminum
alloy sections, and can be used as surface decoration and protection coatings for 5xxx and 6xxx series aluminum alloys.