Chromating of aluminium substrates for magnetic storage plates - via acid soln. sprayed onto the plates to ensure that adherent chromate passivation with good corrosion resistance is obtd.

摘要

The substrates are kept in a horizontal position while they are conveyed through a spraying chamber, in which the substrates rest via changing point contact on a support. Vertical streams of an acid soln. are sprayed for a specified time downwards and upwards from nozzles onto the substrates to form the chromate. The substrates are then washed with water and dried via warm air. During the spraying of the acid soln., the nozzles are pref. subjected to swivel or yawing motions. The finely machined surface of the Al is passivated by a chromate layer prior to the deposition of a magnetisable layer, to obtain good corrosion resistance, and good adhesion of the magnetisable layer. The process improves the quality of the passivation.