Abstract
Mill agents for Al-frit are added to control the flowing, suspention and viscosity of slip, and protect its surface before fusion has taken place, and also alleviate the reaction between slip and metal.
In the present experiment, to borosilicate system frit (SL 10), added were the mill agent, such as bentonite, sodium metasilicate, ammonium molybdate, sodium aluminate, ammonium carbonate, boric anbydride+sodium metasilicate, etc.
In each case the test was made as to the extent of flowing, suspention and viscosity of slip.
The result may be summarized as follows:
(1) The limit of mill addition of sodium aluminate and ammonium carbonate for effective prevention of slip from flowing was 0.3-0.4%.
Sodium metasilicate, when added up to 0.5%, showed good effect for flowing-prevention, suspention and viscosity of slip, but the finish of enamel surface was not good.
0.5% ammonium molybdate pretty well promoted the adhesion to metal. Up to 0.5% bentonite content had good effect in suspention and viscosity of slip.
(2) With boric anhydride and sodium metasilicate (1:1) up to 0.7%, a very good result was obtained in flowing prevention, viscosity and suspention of slip.
With 0.5% bentonite added to the boric anhydride and sodium metasilicate (1:1) bath, the result was much better than the previous one.
