FC–D61 是一種液態的含鉻酸 ,溶于水后會在鋁及其合金表面形成鉻酸(0.1-1.0克/平方米)。這一涂層具有極好的防腐蝕性能，而且能提高附著力，延長涂層的使用壽命。FC-D61既能噴淋處理，也可浸漬處理。 
FC-D61 is a kind of liquid containing chromic acid, it can form chromic acid on the surface of aluminum and its alloys after dissolving in water (0.1-1.0 g / m²). The coating has excellent corrosion resistance performance, and can improve the adhesion, extend the service life of the coating. FC-D61 can both spray processing and dip treatment.