TWI Frequently asked questions
Sealers are used to fill the pores of thermal spray coatings. They are used to prevent or retard corrosion, to prevent fluid or pressure leakage or to maintain the dielectric constant of ceramic coatings. Liquid sealers penetrate bycapillary action into interconnected porosity, and then solidify. Sealers are either organic or inorganic. There are a number of organic sealers such as epoxy, silicone or phenol resins. Glass forming inorganic sealers, such as SiO 2 or other oxides, can be used to seal ceramic coatings.
A sealer layer is applied on the top of the coating by brushing, dipping, air spraying or vacuum impregnation. During vacuum impregnation, the coated component is immersed in the sealer and a vacuum is drawn and held for fewminutes. The component is then removed and the excess sealant at the surface removed by wiping. After being applied, sealers need to be cured for some days at room temperature or a few hours at higher temperature.
Copyright by TWI Ltd 2000
