Why Can Enamel Be Used As Water Heater Liner?
Water heaters of high-end brands or high-end lines of some brands no longer use stainless steel inner tanks, but enamel inner tanks. Why? Mainly because of the water erosion resistance of enamel.
The water erosion resistance of enamel is very strong. Cold water has almost no corrosive effect on enamel. Only hot water or water vapor can slightly corrode the enamel layer. However, when the water contains dissolved substances, especially when it contains carbonic acid or carbonic acid When compounds such as salt are used, the porcelain layer is slightly corroded.
The stability of enamel enamel to water depends on the relative content of SiO2, and alkali metal oxides K2O, Na2O, etc. The increase of SiO2 content will improve the water corrosion resistance; the order of influence of alkali metal oxides on water corrosion resistance is Li+<Na+<K+. When the content of K2O and Na2O is greater than 18%, the hydrolysis of enamel is enhanced, and its water corrosion resistance is weakened.
When replacing part of SiO2 with alkali metal oxides or other divalent metal oxides, the influence of enamel on the chemical stability of water is smaller than that of alkali metal oxides. Among the divalent oxides, BaO and PbO have the strongest effect on reducing the chemical stability of enamel to water, followed by MgO and CaO, but if PbO is used to replace part of the alkali metal oxide as flux, it is beneficial to the chemical stability of water Improved stability.
The water and acid resistance of borosilicate and aluminosilicate enamels is very good.
The ability of enamel to resist water vapor is almost equal to the ability to resist water corrosion.
The chemical stability of enamel mainly depends on the reasonable proportion of all components, not simply on the content of alkali metal oxides. For example, in enamel containing ZnO, BaO, PbO and SiO2, if BaO or ZnO is used to replace PbO in an equal amount, the chemical stability of water resistance will increase, and if B2O3, Na2O and MgO are used instead of PbO, it will decrease.