摘要 |
Conversion coatings containing elpasolite and/or cryolite can be formed on aluminum substrates by contacting the substrates with an aqueous liquid composition containing adequate free fluoride ion activity and concentrations of dissolved sodium and potassium, if a potassium content in the coating is desired as is usual. The aqueous liquids preferably also contain phosphate and polyhydroxy organic compounds and may contain surfactants if a cleaning effect is desired. |