"Nitride coated valves" 4

[ivymike]

I've heard some talk of people getting "nitride coated valves" in their hi-perf engines, and I was wondering a few things.

* What's the coating made of? Silicon Nitride? Titanium Nitride?
* How is it applied?
* What are the intended benefits? Reduced wear? Reduced friction?
* Where is the coating applied on the valves?

Thanks in advance.
Isaac

 

[cycle]

Ivymike,You might try looking at,

http://www.dbfilms.com

or

http://www.i-byte.com

for your answer. I do know the valves I use in some of the engines I build are titanium nitride coated.It increases surface hardness (wear resistance)and better lubricity.. The entire valve is coated (gold in color).. I have had very good luck with these,zero failures,and great longevity. About all I can tell you... Craig

 

[hpfreak]

Nitride is a process to harden the outer layer of steel. The benefiut in this case is to increase wear resistance at the valve seat.

 

[NickB]

It's the same type of coating as used on some lots of machine shop cutting tools to lengthen tool life. They work extremely well in those situations, often lasting 5-10 times longer than an uncoated tool.

It would also increase wear resistance at the valve stem.

 

[ivymike]

hpfreak, I'm familiar with "nitriding" to increase hardness. Nitriding, of course, is not a coating applied to the outside of a part. It's this "nitride coating" that I was not sure about.

I think the others have sufficiently identified this coating, although there exist at least 3 different "nitride" coatings that I'm aware of for drill bits and other tools.

Thanks to everyone for the info.

 

[riktoo]

Valve coatings,
Nitriding works fine for resistance as it hardens the valve. The seats get pounded by a harder valve so there is a possibility that seat wear is increased . Watch that closely.
For durability there is another solution and that is a heat resistant ceramic coating on the face only, the part that is exposed to the combustion.This keeps the valve much cooler and is great for the exhaust valve which operates at higher temp.
Check the coatings industry . Search "Jet-Hot Coatings "which uses a plasma arc deposition technique among others.

 

[Adley]

Just to clear up some confusion, nitriding is a thermal diffusion process in which atomic nitrogen is absorbed by the material creating a case depth and a nitride layer. TiN, TiCN, TiAlN are all titanium based coatings, often applied in a vacuum and plasma assisted.

 

[SWB]

TiN is used on Titanium valves so that the stems will not gall the guides. Some manufactures use this process while others use a ceramic coating. You can not run Titanium valves without some kind of coating or the stems will gall very quickly. Titanium is also very notch sensitive, so that will lead quickly to cracks, which equal failure.

Sean

 

[patprimmer]

Shaun and Adley are spot on by my opinion Regards
pat