zinchromate 161 and 161 spl
blue chromate conversion processes
these are blue passivating formulations specially developed tproduce a clear bluish bright chrome like chromate conversion coating on zinc plated components. By simple immersion 161 or 161 spl provide a very attractive uniform blue colour coating which protects zinc from finger staining, discoloration and corrosion. They are characterized by low concentration, low cost, no leaching deep is required and very simple in preparation and operation.Zinchromate 161 is a low cost passivating salt and used considerably in all applications.While zinchromate 161 spl is a specially formulated passivating salt for getting highly bluish
bright chrome like chromate conversion coating .
Solution composition and operation :
zinchromate 161 or 161 spl gm/lit. 4.0
nitric acid (54 %) gm/lit. 12.0-15.0
temperature room
ph 0.5-1.2
time second 5-30
preparation :
dissolve the required quantity of zinchromate 161 or 161 spl in clean water and add with care the required amount of concentrated nitric acid (54 %) with stirring. Add water to make up the final volume.
Equipment:
for this solution pvc or polythene containers or pvc lined m.S tank can be used.
Process sequence:
1. Bright zinc plate (6-8 microns thick )
2. Swill thoroughly in cold water (twice)
3. Bright blue passivisation in zinchromate 161 or 161 spl.
4. Water swill
5. Water swill and dry
maintenance of the solution
if the solution is worked continously,an occasional addition of conc. Nitric acid 2 ml/lit. And 0.5 gm/lit of zinchromate 161 or161 spl. Will be beneficial. However when bath solution spent, it can be discarded and a fresh solution can be prepared. Roughly 1000 to 1250 sq.Ft.Of zinc plated components are passivated by 1 kg of zinchromate 161 or 161 spl.