Abstract
This is a study on the comparison of lead enamel and lead free enamel which were patented in foreign countries, and borosilicate enamel which has been newly invented by us. The problem of pre-treatment of aluminium plate is also considered. The result is as follows;
(1) By conventional method, alluminum plates are treated with solution of caustic soda and potassium chromate before snamelling, and then oxide film is made on the surface of the plates. But this film is not satisfactory concerning adherence and gloss.
In our experiment they were treated with 3-5% solution of sodium perborate, keeping A.C. at 100V, and bath temperature at 45-50°C, for 5min., and the film of γAl2O3 was formed by anodic oxidation.
(2) Lead enamel showed better results than iron enamel. The former also had higher workability.
(3) Lead-free enamel showed similar results to those of iron enamel in shock and bending test, but in corrosion test it was found to be inferior.
(4) Borosilicate enamel showed about the same or better results as iron enamel in various tests, but was not so good in corrosion resistance. In luster, adherence and fluidity, it showed good results, and also had a strong point of easily handling.
