The effect of an ultrasonic field on elastic properties of steel during zinc plating

During chemical degreasing in hot solutions containing 100 g/ℓ of NaOH, springs made of steel U8A lose some of their elasticity. Upon superposition of an ultrasonic field, the elasticity loss increases rapidly at first but eventually the elastic properties are restored to their original level.

Ultrasound accelerates pickling in hydrochloric acid with 8–10 g/ol of inhibitor PB-8, by a factor of three to five. There is no deterioration during the first two minutes, but it becomes very pronounced when pickling is continued. In the absence of an inhibitor, the elasticity remains unimpaired only the first 20 seconds whereupon it deteriorates rapidly.

The cold galvanizing process is shortened by the application of ultrasound owing to the increased current density. There is virtually no loss of elastic properties when the zinc coat is thin. During deposition in cyanide electrolytes of a sixμthick layer and application of an ultrasonic field, the mechanical properties of the springs change relatively little and are similar to those found after zinc coating in sulphate electrolytes. In zinc coating in acidic electrolytes in an ultrasonic field, loss of elastic properties is reduced, but to a lesser extent than it is in cyanide baths.