Search our quarter-million Q&As

Home of the finishing HOTLINE since 1989

-----

Ductility of plated molybdenum

I am attempting to plate molybdenum wire. The wire is .018 inches in diameter. The basic plating scheme is gold over nickel. We are sintering the wire in a hydrogen atmosphere at 800 degrees C for 30 minutes. The wire is electropolished and a gold over nickel strike applied. The wire is again sintered at 800 degrees C for 30 minutes. After this, gold over nickel is plated on the wire. The problem that I am seeing is a change in the ductility of the wire. The wire can be bent through a 180 degree bend (with no breaks) prior to plating. After the plating process the wire breaks at approximately 90 degrees. Does anyone have any experience with this? Any suggestions?

Roger Smith
- San Diego, California
1999

I have not experienced this phenomenon, but suspect some type of diffusion reaction at the wire surface. I would not expect the molybdenum to be reactive with nickel, gold, or hydrogen. The molybdenum may react with some contamination in the electroplating or there may be some embrittlement reaction (nickel hydride?) in the plating layers that starts the crack.

I would recommend looking at the microstructure after sintering and doing some fractographic examination on the failed test pieces.

Good Luck.

Larry Hanke
Minneapolis, Minnesota
1999

---

1999

See ASM Metals Handbook, Volume 5: Surface Engineering, published by American Society for Metals, for information on Molybdenum, there is reference to baking operations and some relatively complicated treatments for plating onto this metal which may affect ductility.

  
Tom Pullizzi
Falls Township, Pennsylvania

Sorry! Finishing.com is temporarily Read-Only.
Please maintain your bookmarks! Although Ted Mooney is retiring, finishing.com is not!
It will have a new owner/curator very shortly!