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Determination of tungsten in Ni-W-P

April 7, 2010

Hello!

I am a university student and have tried to develop electroless Ni-W-P coating on mild steel. My bath constituents were mainly based on the available research articles from the journals. But when EDAX analysis was performed on the coating, Tungsten content (weight) was found to be zero although Nickel and Phosphorous were found to be about 93% and 7% respectively. Then I changed my bath composition and based it on another journal paper and again the tungsten content was found to be zero in EDAX. I want to know whether EDAX should be performed on the cross section of the coating rather than just on the surface(as was till now done). Or should I go for any other analysis to know the Tungsten content.
Any suggestion would be welcome. Thank you.

Suman Das
Student - Kolkata, India

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Hi, Suman. Please tell us about those research papers so that we can review them if we have them. As far as I know, tungsten is not an electroplateable material, so I would not expect it to be electrolessly plateable. However, many different materials including diamonds and Teflon (and presumably tungsten particles) can be incorporated into electroless nickel deposits by occlusion (suspending the particles in a fluidized bed so that the electroless nickel encapsulates them in the deposit). Is it possible that this is what you are referring to?

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
April 8, 2010

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April 9, 2010

Thanks Ted Sir for your response.

No I am not referring to a bath consisting of tungsten particles. Tungsten is added to the electroless bath in the form of sodium tungstate from which tungsten is supposed to be reduced and form a ternary alloy of Ni-W-P.
A couple of papers I referred to are :

1) Wear 265(2008) 735-740.

2) Journal of Alloys and Compounds 486 (2009) 468-473.

Thanks again.

Suman Das
- Kolkata, India

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April 14, 2010

Ted,
Metallic tungsten can be electro and electroless plated alloyed with other metals. Besides the mentioned scientific papers, it is well known that reputed vendors of brush plating chemicals have been offering nickel-tungsten and cobalt-tungsten solutions for long.
Could it be you were thinking of Titanium?
Regards,

Guillermo Marrufo
Monterrey, NL, Mexico

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April 15, 2010

Thanks, Guillermo. No confusion, just something I didn't know :-)

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

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Suman,

Make sure you have maintained the pH of the plating bath during deposition.

EDX analysis is not quantitative. Try conventional wet chemical analysis for analyzing the tungsten content.

T.S.N. Sankara Narayanan
- Chennai, Tamilnadu, India
(ed.note: The good doctor offers a fascinating blog, "Advancement in Science" )
April 27, 2010