| 摘要 |
<p>The surface is treated with (a) an aq. alkaline soln. contg. Zr ions with a complex forming agent and with pH >10. Treatment (a) is pref. followed by (b) a water rinse; and then (c) surface treatment with an aq. acid soln. contg. a tanning or tannic acid, esp. 0.1-50 g./l. tannin. Soln. (a) pref. has a pH of 10-14 and contains 0.01-10 g./l. of a zirconium cpd. Used to form a protective film on the Al to provide good resistance to corrosion and good adhesion of paint when the Al is used to mfr. boxes, automobiles, electrical appts., or in the construction of buildings etc. The obtd. coating can replace chromate coatings which are toxic to humans, pollute the environment and require costly disposal treatments; and can also replace anodising which requires a lot of electrical energy.</p> |
