Protective coating on Invar 36
Protective coating on Invar 36
(OP)
Dear sir
We are using invar 36 material for the manufacture of fiber optic couplers.It is directly exposed to the atmosphere in the final product.For our product the operating temperature range is
-40 Deg C to 90 Deg C.
Please advice me whether Invar 36 material requires any protective coating to prevent from corrosion.If required, which is the suitable one.
Awating your feedback.
Thanks & Best Reagrds
Mehaboob
We are using invar 36 material for the manufacture of fiber optic couplers.It is directly exposed to the atmosphere in the final product.For our product the operating temperature range is
-40 Deg C to 90 Deg C.
Please advice me whether Invar 36 material requires any protective coating to prevent from corrosion.If required, which is the suitable one.
Awating your feedback.
Thanks & Best Reagrds
Mehaboob





RE: Protective coating on Invar 36
RE: Protective coating on Invar 36
I would like to know whether we need any coating on kovar and stainless steel 304 material to prevent from corrosion.
These materials are used in the manufacture of fiber optic couplers and operating in the specified temperature range as -40 Deg C to 90 Deg C.
Awaiting your feedback
Thanks & Best Regards
Mehaboob
RE: Protective coating on Invar 36
For 304 SS, follow mcquire's advice in Thread367-65287.
RE: Protective coating on Invar 36
Stainless doesn't require plating but you can Ni plate to make it more robust. I've used Kovar with and without plating. I like Ni then Au flash on Kovar.
RE: Protective coating on Invar 36
The bond strength of EN (unbaked) to most steels and easy-to-plate Ni alloys should be ~60,000 psi. It is less on alloys that self-passivate readily, e.g., Al-, Cr- and Ti-alloys.
http://www.macindustrialproducts.com/mechanical.html
Electroless nickel, especially high-P, has far better corrosion resistance than electroplated nickel due to its amorphous structure. This advantage is reduced by baking. Also, high-P has a lower CTE for less mismatch with Invar and Kovar.
http://www.macindustrialproducts.com/physical.html
A gold flash over Ni is good if within budget.
RE: Protective coating on Invar 36
- Santa Clara, CA).
A fiber optic coupler will see ambient conditions. A group that approached us with a new one maintained that ambient moisture was the only concern. I assume this is worse in, say, Hawaii. Unless the corrosion is particularly harsh, I personally would probably use electrolytic Ni. Kenvlach's points are correct but a lot of companies add EN to their list of capabilities and are not reliable. I have see it flake a lot. A good litmus test is to solder a copper wire to the plating and yank on it. A simpler one is to rub and peel Scotch tape. I would be concerned about bond integrity on steel, particularly if there is no "bake on".
If you really want EN, find a house that specifically does it on steel all day long and in their sleep.
RE: Protective coating on Invar 36
Any PVD coatings that you would recommend (of comparable cost to Ni plating)?
RE: Protective coating on Invar 36