Barrier coatings are used to provide an effective moisture barrier or physical barrier and a smooth base for final finishing. For example, coal tar epoxy coatings are applied for this purpose.
Provide outstanding resistance to corrosive chemicals, heat and ultra-violet light Have quick drying times Exhibit excellent dimensional stability, extreme toughness and abrasion resistance Provide strong adhesion to a wide range of substrates, including glass, metals, fibers and numerous other materials Barrier coatings may be divided into two broad categories:
Water-based coating is normally cured at ambient temperature. It is typically non-hazardous with low-flammability, facilitating transport and handling. The water base makes cleanup easier. Powder-based coating is usually cured under controlled, high temperature. It is used to produce the surface of many white appliances, such as washers, dryers, refrigerators and others. Barrier coatings are typically applied on metals and ceramics when they are unable to withstand very harsh operating conditions. Many industrial processes occur at very high temperatures under the flow of harsh, corrosive gases. Metals often can corrode, which can lead to catastrophic failure during operation. To prevent this, and to enhance their life and operating efficiencies, metals and ceramic components are coated with a different material that can withstand these demanding environments.
The property of the barrier coating material has to be matched with that of the underlying substrate. The challenge is to find a way to chemically/physically bond the topcoat to the substrate.