Catalytic Combustion Chamber Coatings

[Flamefront]

Has anyone had experience with coating the interior surfaces of a IC engine's combustion chamber with a catalytic material to promote "end gas" combustion?

I know that piston coatings for friction reduction and wear have been used for decades, with some success. I have seen some references to catalytic coatings in old Combustion Engineering journals, but they are all in analog form and not in my best engineering libraries.

Any comments to add to the idea??

Flamefront
(Automotive)

 

[kenvlach]

A 'catalytic material to promote "end gas" combustion' would promote pre-ignition.
Possibly useful in a direct injection engine, but catalysts need surface area, thus some porous volume (with maybe a dead zone). I'm not really into automotive, but it doesn't seem like a good idea in terms of combustion or materials.

 

[Fabrico]

That and surface temperature would likely be such a problem, you would probably have better luck coming up with yet another additive instead.

 

[Flamefront]

Thanks for the input -

I was considering that only the exhuast valve and piston head would be of concern from a pre-ignition standpoint if they were coated with a catalytic surface. Since they would run at around 650ºC (of course, depending on hundreds of variables, i.e. throttle setting, load, etc..). The cooler combustion chamber walls are more like 400ºC, which is still enough to be a concern, but the concept is to tune the activity level of the coating to match the worst conditions and take what you can get elsewhere.

I certainly think that for the ring lands and rings, crevice volume would be well-served by a catalytic coating...

 

[ivymike]

650degC sounds pretty hot for a piston... what did you base that figure on?

Good steel pistons can run up to about 550degC max before they run into serious material degradation problems (cheaper steels <500degC), and the aluminums are generally constrained to 350degC-400degC before they get really weak...

 

[turbocohen]

Active metals in the chamber is a been there done that. The surfaces run too cool to be effective. In fact, it would be preferable if the surfaced were deactivated and free of carbides to inhibit deposit formation.