This process provides fine active crystal centres on the surface of the metal which ultimately results into tine phosphate coating layer in phosphating stage. This process helps to attain a uniform phosphate coating.
There are two types of activation processes:
This is a cheaper process. Here bath testing and control is not required. Bath can be prepared in hard water. The process results into coarser bigger crystalline coating. Not suitable for non ferrous substrates such as Aluminium.
This process is based on titanium based compounds which are most suitable for Ferrous & non Ferrous substrate. It gives more compact, uniform fine crystalline coating having better corrosion resistance. Disadvantages are: