INHIBITION OF CORROSION OF ALUMINUM AND OTHER METALS IN SODA ASH SOLUTIONS
Some previously reported curves showing the rate of attack on commercial [Formula: see text] aluminum by [Formula: see text] (by weight) aqueous solutions of various salt–soda-ash mixtures were confirmed. The inhibitive action of various commercial silicates, sodium fluosilicate, and certain other salts in dilute soda ash solutions was determined with aluminum, duralumin, copper, tin plate, and galvanized iron. Of all the salts tested, sodium fluosilicate was found to be the most efficient inhibitor of attack on aluminum. At inhibition in 0.5% aqueous solutions of the sodium-silicate–soda-ash mixtures at 60 °C. the ratio SiO2:Na2CO3 and the ratio of silica to surface area of aluminum metal were both roughly constant with all the sodium silicates studied. With sodium fluosilicate, these same ratios are maintained when calculated on the basis of SiF4. Increasing the temperature of solution above about 80 °C. appears to increase these inhibition ratios, but the ratios hold at higher concentrations of the aqueous solution of the soda-ash–salt mixture than the 0.5% studied in detail.