Summary for ion-plating on brass Discussion
Decorative ion-plating on brass is peeling, and the question asks whether bright nickel underplating stress is the cause or whether another factor is responsible. Kiran Shimpi reports that after conventional bright nickel plating and then TiN plus gold ion plating, the coating peels off after a few days. The answer suggests the first thing to check is cleaning before ion plating, since inadequate surface preparation can lead to adhesion failure. It also points to possible ion-plating process issues: insufficient sputter cleaning before deposition, deposition temperature that is too low, or not enough ion bombardment during plating. The reply does not confirm nickel stress as the root cause, but instead emphasizes adhesion and process conditions as likely suspects. In short, the discussion focuses on improving pre-cleaning and ion-plating parameters before assuming the nickel layer is at fault.
Q. I am interested in decorative ion-plating on brass items. Before ion-plating we do water electroplating of bright Nickel [conventional nickel electroplating] but after ion-plating (TiN+gold), we get coating peel-off of TiN and Au; it’s noticed after a few days. I think this may be due to stress formation during the Nickel plating?
How we can do Nickel plating without formation of stress? Or is there any other reason?
Kiran Shimpi
– Umargam, Gujrat, India
2001
ACRONYMS:
TiN = titanium nitride
Au = gold
A. If the TiN/Au coating is peeling off, you may not be cleaning the parts adequately before the ion plating step. There also may be problems with your ion plating process — not enough sputter cleaning before deposition, too low of a deposition temperature, or not enough ion bombardment during the plating step.
Jim Treglio – scwineryreview.com
PVD Consultant & Wine Lover
San Diego, California
2001
February 2014
A. Hi. Jim knows far more than me about ion plating, so I can’t reinforce his opinion beyond saying that, while excessive stress in the nickel plating could be a cause of the nickel peeling off, had you been encountering that, it is unlikely to be the cause of the ion plating peeling off. So focus your efforts on the ion plating step rather than the nickel plating step.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
Multiple threads merged: please forgive chronology errors and repetition 🙂
Q. Peeling off of TiN & Au is noticed mostly on the edges of the items. Remaining area has good adhesion of the coating. What should be the root cause?
Kiran C. Shimpi
– Umargam, Gujarat, India
A. Are you plating TiN directly over brass or do you have some undercoating? I have found that Ni and Cr plating over brass provides a good undercoat for TiN.
Nagalakshmi Thogulava
– India
Q. Yes. We do nickel plating first on brass items, then do TiN and gold coating by PVD process.
Kiran C. Shimpi [returning]
– Umargam, Gujarat, India
A. Please check your Ni plating for porosity / passivation after plating which might be causing this peel-off. Also, higher Zinc concentration in your brass material may create this problem, as it would leach out at low vacuum.
Nagalakshmi Thogulava [returning]
– India