PROCESS FOR OBTAINING A HARD LAYER OF ELECTRICALLY INSULATING ALUMINIUM OXIDE ON A SUPPORT OF AL995 OR ALUMINIUM ALLOY

摘要

The invention relates to a process for obtaining a hard layer of aluminium oxide, in galvanostatic condition, in an electrolitic solution containing a polyprotic acid. The electric characteristic voltage-current is applied on a sample, beginning with 20 V, in successive voltage steps up to 55 V, at a current density of 25...50mA/cm2, so that the voltage have a value of 90...100% of the critical voltage.