Copper Ultrasonic-electrodepositing On Zn Alloy From Non-cyanide Alkaline Baths And The Investigate Of Modificatior For HEDPA

In this paper,we mainly study HEDPA was used as the base coordination agent in non-cyanide copper plating system to improve their performance.Firstly is copper ultrasonic-electrodepositing on Zn Alloy in alkaline bath containing 1-hydroxyethylene-1,1-diphosphonic Acid.On the other hand,we come up with the AMDPA in order to modified HEDPA from the molecular structure.Zn alloy die casting is easily corroded and porous,so it is hard to obtain the strong adhesion strength between the substrate and the metal coating.In this paper,Cu coatings were prepared by ultrasonic-electrodepositing on Zn alloy in a cyanide-free deposition bath containing a base agent of 1-hydroxyethylene-1,1-diphosphonic acid(HEDPA).The effect of ultrasound on the electrochemical behavior of bath and the morphology of the coating were investigated by potential sweep and by SEM,respectively.Experimental results indicate that pre-treatments,such as electrolytic degreasing,have a remarkable influence on adhesion strength.Application of ultrasonic increases the limiting current density of cathode and enhances the throwing power of bath.Application of ultrasonic also promotes the formation of network-cross copper coating which enhances the adhesion strength between the substrate and the coating.In this paper,AMDPA was used as the base coordination agent in non-cyanide copper plating system.Aminomethylenebisphosphonate(AMDP)is prepared from diphenylamine,tritely orthoformate and diethyl phosphate by refluxing,reducing and acid hydrolysis.The plating bath was investigated by potentiometer titration,and the result showed that AMDPA is more likely to form complex species with Cu2+ than 1-hydroxyethylene-1,1-diphosphonic acid(HEDPA)in the environment of alkaline.And complex species is more stable.The result also indicated the dissociation constants of AMDPA and the stability constants.AMDPA-Cu system was compared with HEDPA-Cu by electrochemical measurements.The electrochemical performance was studied by scan with different speed indicated that with the increase of scanning speed,the cathode reduction peak constantly shifted negatively,the significant slowdown evolution.In addition,Changes the pH of the bath can change the form of coordination compounds,which led to reduction and oxidation of copper and product changes.From Cathode polarization curve on stainless steel electrode from AMDPA and HEDPA bath,we can know that the cathode polarization curves of AMDPA was shifted towards negative,cathode polarization increase,reduction potential move toward negative.Above all conducive to obtain the detailed and crystalline copper plating.In summery we can see that the system of AMDPA is much better then HEDPA on the electrochemical measurements.