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Pine Beach, NJ
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Hard Chrome Plating Peels Off of Inconel
Q. Hi I'm trying to plate Inconel 718 with hard chrome but facing several issues including peel off, no adhesion, adhesion only on certain parts.
Can someone help provide a right way to plate inconel?
- India
October 14, 2024
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Q. I am trying chrome plating (FED QQ-C-320 ) on Inconel investment castings to a thickness of 0.2-0.3 mm. The plating is to be done in a through cylindrical hole of about 6 inches long and an internal diameter about 4 inches. However, I am faced with poor adhesion problem. When removed from chrome tank at mid time, the chrome plated layer appear to be OK. However, after re-immersing into chrome tank and plated to required thickness, the plated layer start showing some localized non-adhesion problem. It peels of chips off (between chrome layer and base metal)when lightly knocked at the pump up spot. Some porosity also appears. Before chrome plate, we bake the parts in oven, degrease, sand blast and rinse thoroughly with hot DI water. We have chrome plated similarly on stainless steel parts without problem.
Is there a difference between chrome plating of Inconel and Stainless steel material (such as chrome solution, temperature, current, plating jig or anode used etc ) ?
Any advice would be much appreciated.
Tan Pang Choon / PC Tan- Singapore
2002
Q. Dear friends,
I am still facing with the same adhesion problem when chrome plating the Inconel 718 casting. There was suggestion that we should try Wood's Nickel Strike before dipping parts into the chrome bath will help. Could anyone help to provide more details on what exactly is "Woods Nickel Strike", please?
Thank you,
Tan Pang Choon / PC Tan [returning]- Singapore
A. Mr Tan Pang,
If you read thread 12398, there have I described the pretreatment step for Inconel alloy.
Sincerely,
Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden
A. A Woods Strike, also called a Nickel Chloride Strike is 2 pounds per gallon Nickel Chloride plus 2 quarts per gallon Hydrochloric Acid, room temp, 50 amps per square foot, 3 to 5 minutes, fast transfer to rinse and on to chrome tank. Use Rolled Depolarized anodes and take the anodes out when not in use.
To plate chrome on chrome when you take the part out "mid-cycle" you must reverse current treat for two minutes before resuming cathodic plating.
Robert H Probert
Robert H Probert Technical Services
Garner, North Carolina
|
Q. Thanks for the info, friends. Dear Anders, I visited letter 12398. You indicated that it is important that parts must have the same temperature as the chrome solution have. What steps do I need to take to ensure this? Dear Robert, Is the Woods nickel strike to be done with anode or cathode and what is the proper material ? What is "Rolled Depolarized anodes ? Is it used in chrome bath or Woods nickel strike bath ? What is the material and how to depolarize? Thanks again for the your clarification. Regards, PC Tan- Singapore A. We hard chrome plate Inconel successfully by using a nitric/HF predip of 3 parts HF to 1 part nitric to activate. after a through rinse go directly into the bath hot ( apply current to the part as you put the part into the bath. All we give it is a good wet hone prior to the HF/nitric dip. we plate Inconel almost everyday with great success.. Good Luck, David Ackley- Peoria, Arizona, USA |
Q. David,
You mention a Nitric/HF pre-dip for hard chrome plating of Inconel. Is this diluted with water or used as a concentrated solution from the Nitric and HF acids? Is it used anodically or as a dip? How long should the parts be left in the Nitric/HF dip?
Frank Meegan & Associates. - Ratoath, Co. Meath, Ireland.
September 9, 2008
A. PC,
Let part hang in the chrome solution until the part has the same temperature as the chrome solution 2-5 minutes before you increases the current.
Regards,
Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden
A. There are many good suggestions here for improving adhesion. Activation and/or a nickel strike will work, but be aware that you may drag in undesired anions into your chrome bath. You are probably seeing delamination at thicker chrome deposits due to increased tensile stresses. If your customers spec allows, there are ways to decrease stress in the deposit, like the addition of Indium sulphate. Before you make any changes on your line, research first, make sure you understand fully what people are suggesting.
Steve Delaney- Ontario, Canada
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