Comparison of Warpage, Cross‐Bend, Torsion, and Expansiometer Ring Tests on Titania Enamels

Abstract

The fit of titania enamels as determined by warpage and the expansiometer ring tests is compared to torsion and cross‐bend failures. Tests were selected on the basis of normal use and acceptance by the industry. Titania enamels used for the tests cover a wide range of warpage values from low to high compression in the enamel. The major part of the work was conducted with the normal system of ground coat and cover coat. However, some comparative results are given for enamels applied directly on a titanium‐bearing steel. The data obtained are shown graphically.It was found that warpage values and expansiometer ring values vary directly with the weight of application, and expansiometer ring values and warpage values are proportional. Cross‐bend values vary inversely with weight of application, and higher warpage enamels have higher cross‐bend values. Cross‐bend values are lower when enamel is applied directly than when the cover coat‐ground coat system is used; they are not affected by adherence variations. Torsion values in either system vary inversely with thickness. Torsion values do not vary according to warpage, ring value, or cross bend.