Hard coating on valve
12-01-2014, 06:23 AM,
#1
Hard coating on valve
We have dome valves hard chrome plated, but due to lesser thickness this coating gets eroded in less than a year period. Now thinking of applying arc spray coating as alternative with more thickness. at the moment hvof we can not think of. which wire should we spray for this application? shall we use bond also? what thickness of coating to produce? we think 95mxc type wire can be sprayed?

Application parameters are :-

1) Operating Temp.Max.250 deg c
2) Yes, Buffing may require
3) Due to friction after 12/18 month hard chrome layer eases out material get rusted.

Please comment.


Thanks
Reply
12-02-2014, 09:18 PM,
#2
RE: Hard coating on valve
HVOF is always going to be your best option against HCP but I have heard of ARC Spray 95mxc or equivalent being used in applications such as hydraulic cylinders and valve components. At the end of the day HVOF wasn't always around so what was used before then.....

Im sure 95mxc is good up to around 900° so it would suffice for your operating temperature. You would just need to grind and lap the surface to make it suitable for valve use.

I would definitely recommend a bond coat. Depending on your limitations on dimensions try for around 0.010 - 0.020" Bond Coat and 0.030" (finished) 95mxc. You can go much thicker than that but thicker isn't necessarily better. Before you finish machine the 95 MXC stick a good sealer on it such as dichtol

Dont know if that helps any?

Cheers

Kev
Reply
12-03-2014, 07:50 AM, (This post was last modified: 12-03-2014, 07:52 AM by Boris Eizner.)
#3
RE: Hard coating on valve
(12-01-2014, 06:23 AM)DanielOliveira Wrote: We have dome valves hard chrome plated, but due to lesser thickness this coating gets eroded in less than a year period. Now thinking of applying arc spray coating as alternative with more thickness. at the moment hvof we can not think of. which wire should we spray for this application? shall we use bond also? what thickness of coating to produce? we think 95mxc type wire can be sprayed?

Application parameters are :-

1) Operating Temp.Max.250 deg c
2) Yes, Buffing may require
3) Due to friction after 12/18 month hard chrome layer eases out material get rusted.

Please comment.



Thanks

Dear Sir
Pls look this clip from Singapore
https://www.youtube.com/watch?v=puQ39ayQY9Q
This problem is solved by HVOF Termika-3


Attached Files Thumbnail(s)
   
Reply
02-19-2015, 03:18 AM,
#4
RE: Hard coating on valve
Easy solution. Electroless nickel, baked on and polished to mirror finish. Chrome will also work, but all chrome shops do things a little different. Most of the time the thicker the chrome, the easier it is to chip (same for thermal/metal sprays).

With electroless nickel, baked on, it's harder then chrome plating and will outlast chrome 2 or 3 times longer.

My name is Boris Volkov and I am one of the owners of Axis Machine in Baltimore MD. If this is a part you do a lot of, I can do one at company cost to prove my method will out last chrome (and for future business).

Email me at AxisBallScrew@gmail.com We're a full service machine shop with OD, ID grinding, precision honing with chrome, nickel, PVD, nitride coatings done under one roof. We are located in Baltimore Maryland U.S.A. I can't imagine shipping on a part that size would be very expensive, but if you shoot me an email I can give yo some more info and get you a price if you give me some sizes.
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