| 摘要 |
<p>An improved process for activating metal surfaces prior to a phosphating treatment whereby relatively thin, dense, fine-sized and uniform crystalline adherent phosphate coatings are produced providing superior corrosion protection and paint adherence when coated substrates are subjected to cyclical temperature and ambient environments typifying normal service conditions. To prepare the aqueous activating solution, a dry activating composition is prepared which is adapted to be dispersed in water at a controlled concentration and which comprises a mixture of about 60 to about 90% by weight of a particulated dried reaction product of a titanium-containing compound and sodium phosphate compound containing at least about 0.005% by weight titanium with the balance comprising tetrasodium pyrophosphate. The dry activating composition is dispersed in the aqueous solution to provide a total concentration of from about 0.1 to about 10 g/l. In accordance with the process aspects of the present invention, the aqueous dispersion containing the activating composition is applied to cleaned metal surfaces such as steel, zinc and aluminum before the following zinc phosphating step whereby improved phosphating coatings are produced. 19</p> |
