Chromium-free and phosphorus-free conversion liquid as well as preparation method and application thereof

The invention discloses a chromium-free and phosphorus-free conversion solution as well as a preparation method and application thereof. The chromium-free and phosphorus-free conversion liquid provided by the invention is prepared from the following raw materials: molybdate, permanganate, metavanadate and a film-forming additive. According to the chromium-free and phosphorus-free conversion liquid provided by the invention, through the synergistic effect of the preparation raw materials, on one hand, the use of a high-toxicity chromium-containing compound and a heavy-pollution phosphorus-containing compound can be avoided, and on the other hand, the chromium-free and phosphorus-free conversion liquid can be used under a near-neutral condition to form a good conversion film; the economical efficiency, the environmental protection property and the operation safety of the chromium-free and phosphorus-free conversion liquid are integrally improved. The invention also provides a preparation method and application