Why most of the engines now seen are not ture ABC rather ABN or I have heard some third terminology that reduced the production cost even more. I don't like this ... any comments...

Chrome plating is a nasty process and has been greatly regulated in many countries because of the human and environmental risk of waste material. I suspect that fact when coupled with economic factors of the reduced supply and requisite increasing prices are forcing the engine makers to move to nickel (itself a fairly nasty process, but not as bad as chrome) and other processes.

Most of my engines are ringed, so I don't sweat it. I only have an OS 61FX ABN engine left that I fly regularly. The miniscule loss of power of a ringed engine over an ABC/ABN equivalent is not worth it to me, plus I like to run all synthetic fuel.

I'm wondering why the glow guys haven't moved to Nikasil like the small gas engines have. Perhaps it's only compatible with steel liners and ringed pistons versus the ABC/ABN interference cylinder design...anyone know?

Either an electr-plating or wet chemical deposition process is used to put chrome or nickel on a sleeve. Nikosil sounds like an alloy (nickel/silicon/moly) that would require cladding or perhaps the entire sleeve is cast of this alloy. Some of the best engines are now ABN. OS, Webra, Thunder Tiger, and YS. I have OS, Webra, and one TT and have always used all synthetic fuel they all have hundreds of flights on them. I also fly Enya, Rossi, and Super Tigre and they are good engines but none have lasted longer than my OS 46FX or Webra 50 Speed.

Nikasil is a plating process (nickel silicon oxide) used in motorcycle racing engines among other things (it's starting to show up in chainsaw engines, line trimmers, etc. as well). As for it's applicability in glow engines, I have no idea...I'm a mechanical engineer, but my plating experience is very limited...

Pretty well of the snowmobile engines are Nikasil plated also. When Kawasaki went from a sleeve to Nikasil they peeled for the first couple of years till they perfected the plating method.

I believe BMW also uses Nikasil in some of its automotive engines.

While it is true that nickel plating is not as hard as chrome, if the process is done right and the engine designed well, they should both perform just fine. However, for me personally, if all else are equal (which of course they never are) I would still prefer true chrome plating to others.

Everybody is familiar with chrome plating for cosmetic purposes on cars and motorcycles. However, chrome plating is widely used in industrial applications where wear and errosion resistance is essential, among other reasons. It is not going to be legislated out of existence by the Green Nazis any time soon.

As much as I hate to think about it, I do also suspect that the production cost differential between ABN and ABC does figure into an RC engine manufacturer's decision to go with one or the other.

The reason cars do not use nikosil due to the high sulphur content in the fuel used. The suphur pits and corrodes the coating. It is only useful if you use very high octane petrol (100 and above).

The effect of nitro fuel is not known to me.
I belive it is not used due to cost, the plating is nickel based but it also uses less than 10% SILICON CARBIDE.

Here's a quote from the Laser engines website:

Is this the same as Nikasil, or is it something better?

Matthew

Yes, it is commonly refered to as Nikasil for Nickle Silicon.

There is also another system -- diamond coating. Revolution Engines has tested their 52 cc gas engine with diamond coated cyl bores -- amazingly, it is cheaper than Nickel plating. I'm not sure if it is in regular production yet.

Don't get excited about ABN -- the nickel plating on the liner is much harder & tougher than the aluminum piston (which is the actual wear component). You should be more concerned about which manufacturer is using ABN -- they are not all equal. The good ones are bullet-proof (every bit as good as ABC), but there is at least one with a recent track record of not getting it quite right. This has nothing at all to do with nickel & everything to do with cutting cost corners.

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Ah come on, Britbat. I wasn't paying attention and it got by me. Who is it? <G>

Diamond coating is fantastic but has the limitation that an ABC type (ABD?) can't be done as yet. The base material has to be heated far above the point where either brass or aluminium melt so it's only done on steel. However, it's quite possible to have a ringed piston running in a diamond coated steel sleeve. It's still in the development stage but is being tested on car crankshafts and transmission gear teeth (with very good results I might add ).

For ABC type model engines, I think the next thing will be the ceramic liners like Norvel use (and the replacement piston/liners that have been developed here in Australia for various engines). Actually the Norvel set up is near ideal in that there's no seperate liner because the cylinder is one complete unit somewhat like the old steel fin OS Max engines and several others. This means there's no barrier to heat transfer from the cylinder wall to the cooling fins.

Errr...and Ed, those Aussie replacement ceramic liners are available for that brand that escaped your attention

Norvel use a form of hard anodizing on their bores which creates a layer of sapphire (aluminum oxide), a type of ceramic which is an extremely hard and wear-resistant substance. Even better, hard anodizing is slightly porus in nature, thus it retains a small amount of oil that helps with lubrication.

One of the problems with hard-anodizing is that it becomes increasingly difficult to get a thick layer of oxide built up because the oxide itself is an insulator. In effect, the anodizing current (and therefore the rate of anodizing) decreases rapidly as the oxide builds up.

Plasma-sprayed ceramics achieve the same result, albeit usually imparting a thicker layer of the oxide more quickly by virtue of being sprayed on in a superheated stream of plasma (10,000 deg C) rather than being built up slowly in an electrochemical reaction. In theory, you can deposit almost any thickness of oxide through this spray deposition process.

Norvel obviously think that the level of deposition offered by anodizing is adequate for their engines, larger engines however probably need the kind of layers that only plasma spray deposition can provide.

If you use a ceramic-coated bore it becomes more important to have a softer piston material in order to allow for some degree of "running in" to occur. Unlike steel, or even chrome, ceramic won't show any appreciable wear for a long time so the use of a hard piston/ring material will mean very long break-in times. It's probably for this reason that Norvel nickel-plate their pistons -- nickel being a somewhat softer material than chrome. The nickel has a very low coefficient of friction (much lower than aluminum) yet is soft enough (unlike chrome) to allow sufficient wear for a good fit.