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topic 59952

Materials to coat invar?

A discussion started in 1997 but continuing through 2019


Q. Hi,

I am looking for a material to coat Invar. I have a small SiN ball that slides on an Invar flat plate and I would like to minimize the friction coefficient between the two surfaces. I do not want though to increase Invar's low coefficient of thermal expansion, thicken up more than .0003" Invar's surface and I would like to have a minimum 75 Rockwell Number.

Thank you in advance,

Kostas Zafiriou


A. Have you looked into coating the surface with CVD Diamond? Diamond has a coefficient of friction near to Teflon, but is one of the hardest materials available. There is a new CVD coating process now being employed utilizing laser enhancement which greatly improves the deposition rates of the process. Rates of 1 micron/second have been quoted with this process. It also allows the use of only carbon dioxide as the precursor for the carbon film. There may need to be post deposition polishing required to improve the surface smoothness and cut down on the friction. I also believe the process can be conducted at much lower temperatures than has previously been required, I am not sure whether this would upset the CTE of the Invar. One additional note, the process is performed at atmospheric pressure.

Ken Provancha


A. My feeling is that you can use Diamond like carbon. These layer should have a good adhesion to invar.

Jean-Pierre Reyal

Black coatings for Invar


Q. I am looking for information - technical, suppliers, etc. - on a reliable and robust black finish/coating of Invar

Mike A [last name deleted for privacy by Editor]
- Richardson, Texas, USA


A. Are you allowed to plate something over it, like nickel, and then blacken the nickel? We used to put nickel, then black nickel, then oil rub on magnets for mechanical gyros. That was pretty reliable, for the application. Robust and reliable in what atmosphere, condition, place?

tom & pooky toms signature
Tom Pullizzi
Falls Township, Pennsylvania

Black oxide coating on Invar


Q. Is it possible to obtain a black oxide coating on Invar (63% Iron 36% Nickel)?

Thanks and best regards,

P. Cirese
- Firenze, Italia

Coating on Invar bolts to prevent spalling


Q. I am seeking a coating to be used on Invar bolts, which will be used to secure sections of a large mandrel together for autoclave curing of composite material. The coating is needed to prevent spalling of the Invar threads which occur when unscrewing the nut from the bolt after curing. The nut will be stainless or carbon steel, as its CFE is not a factor in mold operation. Is Low-friction Chromium useful in this regard? Please suggest alternative coatings that might be suitable.

Thank you,

Ed May
composite part molding - Sedro-Woolley, Washington, USA

Coating Super Invar


Q. I am using Super Invar in a design that will allow a optical lens to travel vert. and hor. in there house. But I an not sure if there is a coating that can be placed on the surfaces to ensure that they will slide easily in the vert and hor planes. I am think something like a teflon coating but teflon in itself would not be a good choice. Can someone help?

Kenneth Stebbins
R&D; laser company - Bedford , Massachusetts


A. Very little info. What's the environment, temp, forces, expected life? Why would Teflon itself not be a good choice?

Guillermo Marrufo
Monterrey, NL, Mexico

Need nickel electroless coating on INVAR


Q. I'm looking for a procedure to deposit electroless Nickel on small pieces of INVAR for aerospace mechanisms. I need also qualified suppliers. Any help on this topics is welcomed.

Elena F [last name deleted for privacy by Editor]
Wear of Materials - San Martin, Buenos Aires Province, Argentina
^- Sorry, this RFQ is outdated
     View Current RFQs

November 4, 2009

Q. Dear colleagues,

I'd would like to know which finishings are compatible and appropriate for a part made from INVAR. I'd need low emissivity for the outer surface and high emissivity for the inner surface (? and black chromium?).

Thank you very much for your time.

Javier Moreno Raso
Design engineer - MADRID, SPAIN

Black chrome plating of Invar 36 material is not uniform

July 21, 2015

Q. I have some issues about black chrome treatment for Invar 36 material. After treatment the surface is not uniform. Anyone can help me, give me some information? Thanks.

59952pdf  59952-1athumb  59952-1bthumb  59952-1cthumb
(click thumbnails for higher rez photos)

Stefan Teo
product designer - Singapore

July 22, 2015

A. Hi Stefan,
Applying a slight tinge of oil will make the product look better. Does the presence of oil have any effect on the product?

SK Cheah
- Penang Malaysia

November 6, 2019

A. You might try bead blasting before plating.

Julian Holmes
Engineering - Wales UK

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