A process for activating a metal surface for conversion coating

摘要

The invention is a process for applying a phosphate coating to a metal substrate in which the metal substrate is contacted with an aqueous activating bath before the phosphate coating is applied. The improved process is obtained by applying ultrasonic vibration energy to the aqueous activating bath. The ultrasonic energy can be applied to the aqueous activating bath when the aqueous activating bath is in contact with the metal substrate or when the metal substrate is not in contact with the aqueous activating bath.