Evaluation of porcelain enamels of directional signs used in the UAE

Blue coloured enamel coatings on 3003 aluminium alloy panels have been produced. The enamels used to produce the coatings were of similar compositions except for titanium dioxide, colouring and other metal oxides. The first enamel composition was a standard one as recommended by the supplier and contains 7% of the expensive opacifier titanium dioxide. This recommended composition has been modified to form the second enamel. Higher amounts of the less expensive colouring and other metal oxides were added on the expense of titanium dioxide which was reduced to 1%. Different firing temperatures and enamel slip fineness were used to produce the modified enamel coatings. Scanning electron microscopy, accelerated weathering, spalling and dry erosion tests have been used to evaluate different enamel coatings. Results have shown that the modified enamel composition has produced coatings of comparable quality as compared to coatings produced using the supplier recommended composition. Firing the modified enamel below 500 °C results in enamel coatings of inferior quality, whereas firing at temperatures above 525 °C produces coatings of good performance. Coatings produced using small fineness have resulted in enamel coatings having pores of relatively smaller sizes.