Sol-Gel Manufacturing Process
Do Sol-Gel Coatings Require Special Equipment for Application?
Applying sol-gel coatings doesn't require any special equipment, but as with any other coating, there is a step by step process that should be followed to achieve maximum performance and quality.
The Sol-Gel Coating Process
The sol-gel coating process includes 4 steps as follows:
The individual sol-gel coating components must first be mixed thoroughly. This process helps to ensure that fillers do not settle and that a more consistent and reliable coating can be created. Then, once components have been mixed, all components can be combined and mixed together for a set amount of time.
The mixed components are then filtered. Filtering is a required step in the application process to eliminate imperfections and help ensure a smooth and homogeneous coating.
- Surface Preparation:
To guarantee adequate adhesion of the sol-gel coating the proper surface preparation steps must be taken. First, objects must be properly cleaned and degreased to ensure the surface is completely free of any kind of oil. Any grease or oil can corrupt the blasting material and prevent proper adhesion of the sol-gel coating.
Grit blasting is often used to help roughen the surface to be coated and provide something for the sol-gel coating to adhere to. However, it is important to avoid over-smoothing the surface with grit blasting or leaving the surface too rough. In either instance the adhesion of the sol-gel coating could be negatively affected and lead to performance issues down the road.
In most cases, aluminum and stainless steel are the most common substrates used with sol-gel coatings, however active research is in progress to enable the use of sol-gel coatings on carbon steel and cast iron.
After the surface is properly prepared, the surfaces to be coated need to be heated. Then, the coating is applied in a one or two coat system with conventional spray equipment.
The parts to be coated not only need to be preheated, but they need to keep a temperature of about 120 to 160° F throughout the application process. Otherwise, the sprayed coating could sag and lead to defects in the overall finish.
A critical last step is to cure the parts in conveyor or batch ovens.