EFFECT OF COMPOSITION ON PROPERTIES OF TITANIUM ENAMELS*

The development of a superopaque, acid-resistant titanium enamel is described. Different components of the batch were varied systematically and the properties, such as reflectance, color, flow, gloss, and acid resistance, were determined. Variations in composition, reflectance curves, and spectrophotometer curves are given for all of the enamels investigated. The stability of this type of enamel during firing and smelting was also studied. Spectrophotometric analyses of this type of enamel show a characteristic low reflectance in the short-wave length region of the visible spectrum, differing in this respect from superopaque antimony and zirconia enamels. Additions of as much as 0.5% Fe₂O₃ and 0.2% V₂O₅ to the titanium enamel did not cause any appreciable variations in color. Although some differences in the spectrophotometer curves were noted over the field of enamels investigated, the only major change in color occurred when minute amounts of Cr₂O₃ were present. X-ray diffraction patterns of enamels show that rutile crystals in most cases, or sometimes anatase, are the crystals causing opacity.