patman

iTrader: (3)

Hey guys,

Ive been doing some searching and I can't find record of anyone trying nikasil as a refinishing method for housings and plates. I am an engineer at a large fabrication facility and could produce the capability to coat both housings and plates.

I have a couple questions though- First, is anyone still trying to ceramic coat housings? I know there were a couple of companies doing it in the last few years but my understanding is that neither one went anywhere.

The other thing is that in researching nikasil I found that its first iteration was initially developed by/for NSU for the RO80, which makes me wonder if it was successful in this instance and if so why it hasn't been used since then?

I also have the capability to produce aluminum plates, so getting the nikasil production figured out first would be a logical step. Just wanting to see if anyone has knowledge of any reason I am overlooking that this isn't a good idea...

Thanks
Pat

farberio

iTrader: (7)

I would imagine that the Nikasil surface isn't really tested all that much. From the sounds of things, every manufacturer went their own way when it came to surface coatings. Since Mazda is the only company that produced successful cars with a rotary, its the only one we know about it.

I have found some information on non Mazda rotaries though, there is one paragraph of information here.
http://books.google.com/books?id=Vvy...0engine&f=true

It reads
“Other Wankel builders have used various solutions, Mazda uses carbon and aluminum sealrls on a chrome-plated aluminum face, NSU uses iron-based Ferro-Tic seals against an Elnisil (silicon carbide) plating. Mercedes-Benz is experimenting with silicon nitride seals on a nickel-silicon surface. GM is going its own way. The Iron track will not be plated, but will have a light metallic coating sprayed on. The seals will be a low cost ceramic “

This is from Popular Science from the '70s, so probably should be taken with a grain of salt. Especially the part about how Wankels will completely eliminate pistons....

Another resource I am eying to purchase is here: http://books.google.com/books?id=IB2...page&q&f=false

It looks like it has some information on non-Mazda Wankels and might be another place to look if Nikasil was found to be unsuitable.

ronbros3

this may help,, ramaircraft.com they do nickel coatings, nikasil maybe

ronbros3

ramaircraft.com nickel-carbide cylinders, package

patman

iTrader: (3)

they do 13b parts? can you post a better link i could only find info on lycoming and continental cylinders?

Barry Bordes

Pat,
The best info I could find is http://www.lnengineering.com/whynickies.html

An excerpt:

Nikasil™, or it's similarly performing NSC (nickel silicon carbide composite) plating, while the best solution around, it is also the most expensive. Reynolds and Kolbenschmidt developed a process that still uses cast iron or similarly clad piston rubbing on an etched high-silicon aluminum bore. The Chevrolet Vega was among the first of the vehicles to use this new material technology. Needless to say, the Vega did not have a good reliability record and only limited 2.7 and 3.0 liter 911 models adopted Alusil™ cylinders, later replaced by Nikasil™ cylinders except on water-cooled models. Porsche's newest Boxster and 911 models use a modern version of Alusil™ called Lokasil™ while Porsche models like the GT2, GT3, and Carrera GT still utilize Nikasil™ platings in their bores.
There is quite some debate concerning the re-useability of Alusil-™ type cylinders going back to the etching/honing process done to the raw aluminum bores and re-ringing. This is not an issue with Nikasil™, as it can be readily re-honed or stripped and replated if required. An Alusil ™ cylinder can also be plated with a Nikasil™ or NSC-platings to allow reuse of these type of aluminum cylinders with conventional pistons and rings.
http://www.lnengineering.com;/whynickies.html

patman

iTrader: (3)

Thanks for the replies guys, I guess I didnt make myself very clear: I have a good understanding of Nikasil and related materials, my question is more like: Is anyone already doing this for rotaries, and if not, why not?

ronbros3

good question,, you may have to call them and ask, directly to an engineer.

im sure they can do it , but will they do it?

they have some mazda rotary aircraft flyin around, youd think one of those guys would ask.

BLUE TII

iTrader: (9)

From what I read Nikasil does not like low quality liquid gasoline contact as the sulfur reacts with it. We in the US have low quality high sulfur gas.

Check out the issues the BMW M60 and Jaguar AJ V-8s had with Nikasil damage. Jaguar engines are 1998-2000 BTW so it isn't really a long term issue even.

While you are reading about those engines' issues imagine how much more liquid gas the wear surfaces of the rotary are subjected to...

j9fd3s

iTrader: (3)

the bmw trouble starts in 93-94 with the 530/540. although the engine failure rate still stays well below the rear subframe falling out of the car rate, the trouble with the liners continues right up until they switched to iron liners in 1998.

cptpain

iTrader: (1)

As far as i know, i've never heard of Nikasil....

JHB Performance is the only place i know of that does resurfacing/recoating of the rotor housings with a more durable coating..... it may or may not be Nikasil they use since they dont want to give out that info except they call it Cermet X i believe, but its been proven on a lot of motors that the coating they use is top notch and is very resilient when apex seals get tossed around in the motor

g14novak

iTrader: (1)

http://www.docstoc.com/docs/39655335...Patent-4729729

You may want to take a look at that site. Lots of good information there.

Ignore the title...

patman

iTrader: (3)

That patent describes the mazda coating that uses a chromium-molybdenum coating rather than pure chromium. What I am talking about is a Nickel-silicon coating that is often used in piston engines....

g14novak

iTrader: (1)

I guess its not on that page. I remember reading something in a old article. The Nikasil coating was originally tried in the testing phase of the single rotor Sachs engine but found that their was a vast appearance of pitting and chatter due to the softness of the material once heated up. Their was also some issues with the longevity of the engine because of how fast the Nikasil got worn.

This was the reason they switched to the Cr-Mo mixture. The heat resistance of the Mo combined with the wear and corrosion resistance of the Cr is almost a unbeatable combo. The friction Coef just topped it all off. That was the main reason the surface isn't 100% Chromium.

It was in a old article that was scanned from the 70's-80's so it could all be bs. But the facts sound pretty straight to me.

Mercedes did use Nikasil apex seals in their C111 3 and 4 rotor but I don't know if they worked well or not. Not a lot is known about the car.

Hope this info helped.

ronbros3

odd nobodys tried it, comon guys somebody step up and give it a try.

application technique has changed a lot in past few yrs

g14novak

iTrader: (1)

Maybe a mixture of Nikasil and something to help with the corrosion of the gas + something to help with the wear. At that point, you'll have some sort of frankenmetal that might not even be cost effective compared to a brand new housing. I don't see why people don't just try and replicate mazdas Cr-Mo coating, just change the mixture ratios so you don't get sued.

For what it costs, the only real reason someone would want to re-coat a housing is if their is other mods to the housing that they don't want to do over again. Or the part isn't able to be replaced through mazda like 13a or early 12a or even 10a housings.

Like for example 73 12a housings. To get one of those in good condition, the price is crazy.

ScrapFC

iTrader: (5)

I wonder if there was a problem with the specific allow/process BMW was using? Suzuki has been using Nikasil in their GSX-Rs since the mid-90's with no apparent ill effects.
I find the search for modern coatings with rotary compatibility to be very exciting. Esp as stocks of older housings and plates dry up.

BLUE TII

iTrader: (9)

Dog engaged transmissions, basket clutches, individual throttle bodies, shower injectors and engine removal for basic maintenance never really translated into production cars either because of driveability/durability/cost reasons.

I expect this might be the case with nikasil, no one will complain when their sport bike doesn't make it to 150,000 miles without losing compression but this is unacceptable in a car.

In fact, a google search of Nikasil brings up a whole lot of companies advertising recoating motorcycle cylinders and warnings about Jaguars and BMWs...

BLUE TII

iTrader: (9)

Like everything else rotary Nikasil would probably be perfect in a racing application and a liability in a streetcar.

j9fd3s

iTrader: (3)

[QUOTE=g14novak;10026932

Like for example 73 12a housings. To get one of those in good condition, the price is crazy.[/QUOTE]

those things are like sand in the desert! they are ALL good. carbon apex seals are very easy on the chrome. ive got enough to build like 3 engines. by contrast the iron seal housings, peel and flake, its not until the FC they fixed that

the BMW motors ive heard about all failed really quickly, the ones that didn't fail um didn't fail.

having looked at a couple of BMW's like we look at the mazda's, its certainly likely BMW used a cheap grade of nikasil, or applied it to the wrong alloy or something. these are the people who use a nylon lined ball joint in the lower control arms BECAUSE it wears out, after all

g14novak

iTrader: (1)

Either your lucky or my old mechanic in FL is crazy. He use to pay like 300-400 a housing for them. Were both talking about the same ones right? with the 3 exhaust holes instead of a single exhaust port?

RotaryEvolution

iTrader: (30)

nickelsil has been brought up before if you do some searching.

no one that i know of has been able to bond anything to the chromoly plating that i have seen and have good results with it, i doubt that will change anytime soon either. chromoly doesn't hold other materials very well.

and the early 12A housings were all good EXCEPT you can't run steel seals on them, take a look at how thin the chrome plating is on them, it's super thin and would scrape off in less than 1k miles with the 3mm 12A steel seals. i'm sure people think they are smart for using them but unfortunately they were never meant to be used with the later model seals. now if we could get some 6mm ceramic seals instead of carbon made, then mazda would have been geniuses! a bulletproof rotary that would have lasted longer than anything else on the road. of which im sure they did eventually try ceramics but opted away from it because it cost a few bucks more to produce the seals and the cars were already making it to and beyond warranty limit.

j9fd3s

iTrader: (3)

3 holes is non US spec. the 3 hole rotor housings came on the NON emissions cars, so they had the small exhaust port and almost a header stock

the US got a normal exhaust port and a thermal reactor.

the parts catalogs are all online now, so you can look if you like.

patman

iTrader: (3)

Please post a link, i looked around pretty good and didnt find much.

The process I would use would start by removing the factory plating and bond the new surface directly to the insert.

Ive been researching this some more, still seems feasible, been meaning to call and try to find a knowledgeable engineer at one of the plating companies but havent had time lately. I'll keep y'all up to date if i find anything useful.

j9fd3s

iTrader: (3)

the wost thing that would happen is you end up with just the iron plating like a lapped or pre nitride housing.