Porcelain enamel has been around for 4000 years and shows no signs of disappearing any time soon. Although alternative materials like stainless steel, plastics and paints continue to gain market share and have completely taken over some markets, such as dishwashers, the cooking and laundry appliance markets remain strong, and total frit production remains about the same. However, some manufacturers believe a huge revolution in materials technology is needed to ensure the continued success of the industry. Both suppliers and manufacturers are doing their share to help ensure that this revolution takes place.
Porcelain enamel coatings are made from a frit based on low melting temperature (2000 to 2500°F) borosilicate glasses. After the glass raw materials are melted (generally in recuperative furnaces) at rates ranging from 5 to 50 tons per day, rapid quenching is used to shatter the resultant glass into small particles. Further particle size reduction is achieved by grinding. The coating is applied using wet suspension or dry electrostatic powder processes, and is then heated to about 1500°F to produce chemical bonding with the metal substrate.
Pre-milled frits now allow enamelers to custom blend their own enamel formulations without using costly milling equipment. The enameler can blend the exact amount required for the job, eliminating waste. Blends can be made almost “just in time,” eliminating the need for a large wet enamel inventory.
Many frit manufacturers have switched from air/gas to oxygen/gas combustion systems to lower their emissions, and this trend is expected to continue. Smelters have become more automated, and larger capacities are being used as product volumes increase through the increased standardization of frits.
For instance, unique appearance characteristics are under development, including metallic lusters to simulate copper metal or stainless steel appearances. Refinements in frit products are also being made to achieve “easy to clean” oven coatings, as well as infrared reflectivity for faster cooking. In addition, hybrid coatings are being investigated to take advantage of properties provided by both porcelain enamel and organic coatings.
This article comes from ceramicindustry edit released