Which is more environmentally friendly, phosphating, vitrification or silane?

Phosphating and ceramization are both acidic liquids.

It is forbidden to discharge phosphorus-containing wastewater by phosphating. The main components of ceramic liquid are fluorozirconate, silane coupling agent and other phosphorus-free raw materials. Cermet can partially replace phosphating solution, but it is also an acidic liquid, and it still needs to produce acidic cleaning wastewater. Silane is an alkaline liquid, which is more environmentally friendly than phosphating and ceramization. However, the most fatal problem of silane is that the pretreatment degreasing cleaning water must be clean, otherwise there will be no adhesion. Because the silane film is transparent, the naked eye can't tell whether it is qualified or not. Because of this problem, the production of many factories is very unstable and the rework rate is extremely high. So few people can control it and really use it. Recently, our company adopted 3 oil-free phosphating solution YFFe60 1SN, which is a Liuhe undrained phosphating solution. The whole process of metal pretreatment, degreasing+surface adjustment+phosphating+passivation is completed in one tank, and there is no water or drainage in the whole process, and it does not contain hydrochloric acid, sulfuric acid and nitric acid, which greatly reduces the pollution to the environment and is a new trend of treating environmental protection chemicals before painting in the future.