Role of Nickel Dip in Enameling of Sheet Steel

Abstract

SUMMARYAn investigation was made of the effects of (a) the firing time and (b) the weight of nickel deposited frm the nickel-dip solution on the adherence developed by a cobalt-free and a cobalt-bearing ground-coat enamel on both enameling iron and a titsmim-bearing low-csrbon steel. At 1550°F it was found that the maximum benefit from the nickel on the measured adherence index occurred at 2-minute firing. The effect of the nickel, however, dropped markedly with longer firing times. It was also found that there was an optimum nickel deposit for maximum adherence. This optimum varied from 50 to about 120 milligrams per square foot, depending on the type of cleaning used and the type of enamel applied.It was found that the nickel dip reduced the tendency toward fishscaling. Furthermore, there appeared to be a relation between fishscaling resistance and good adherence; no spec~en with~a~erence~dex of 70 .or over showed fishscaling tendencies.Metallographic studies of the interface of coated specimens showed .that nickel dipping of the steel prior to enameling brought about a surface roughening during the firing operation. A relation ms noted between the degree of roughetig and the measured adherence index. The roughening of the steel surface was ascribed to galvanic corrosion.

Exploring the hindering mechanism of element Ti on the adherence of CoO‐bearing one‐coat enamel/steel

“…Accordingly, titanium‐bearing enamel with good chemical stability and excellent opacification effect is the ordinary practice in industry . With respect to bonding to metal, a great deal has been said and written on the subject of additional treatment of the metal surface before one‐coat enameling . However, the improvement of bonding strength is marginal in addition to that these methods have many other disadvantages such as environmental problems, increasing the cost of production and unhealthy working conditions.…”