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Cylinder plating process

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Ya know, I'm probably stepping on sacred ground, but the question is killing me.

I am familiar with generic plating processes (chrome plating, anodizing, etc.)

and I have some experience with the process. I worked for a company that made M-16 barrels for the military and have firsthand experience with hard chrome (industrial) plating the bore/chamber of said barrels.

What I can't find anywhere are details of the plating process for cylinders. I know that Nikasil is a trade name owned by Mahle (the German piston manufacturer) and the process deposits Nickel with Silicon Carbide particles imbeded within on the aluminum surface. There are other processes where Nickel Silicon Carbide plating is deposited that aren't protected by the 'Nikasil' trade name or process but I'll be damned if I can find any information anyhere.

The best I can come up with is that a Nickel bearing solution with Silicon Carbide particle suspended is used. Other than that, I run out of details. I know that Nickel plating can be done with two methods; lectroplating and electroless. The later, obviously doesn't use an electric current but rather a catalytic reaction.

I know there are only a handfull of busineses that offer this service and I'm sure that all of the are tight lipped about how they perform this process, but it can't be THAT big of a secret. It's been widely used industrial process for nearly 50 years.

Any enlightment would be greatly appreciated.

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I work as an engineer at an industrial plating facility, one of the only ones in the US to offer more than a handful of coatings in one facility. We do not do Nikasil unfortunately, but from what I have seen I believe you are on the right track. I have heard that Nikasil is electro-deposited, but we offer a couple proprietary electroless nickel based coatings that seem to be along the same idea as nikasil. Unfortunately I cannot offer too many details about the plating, but there are a few electroless nickel based coatings out there that offer good wear resistance as well as a low coefficient of friction.

On a side note, I have often wondered how another plating would work in a cylinder, but haven't had the guts to try it in anything. I'd imagine hard chrome would work alright. I may have to try some things out on a cheap lawnmower engine or something :bonk:

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Didn't Kawasaki or Suzuki use hard chrome in cylinders? The coating is too thin and tends to flake. Nikasil is outperforms hard chrome in every way. Some large industrial engines ventured into hard chrome liners but eventually settled on laser hardened iron liners with chrome faced rings.

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interesting.

how will the piston rings react to hard crome plating?

Aluminum and iron piston skirts work fine on hard chrome cylinders but you have to use iron rings. Chrome faced, stainless steel, and moly faced rings will damage chrome plated cylinders.

I think, what the world figured what with chrome liners, is that you're trading liner wear at the expense of ring wear. Well the liners have a lot more material to give up than the rings. So it was decided liner wear was more tolerable than ring wear and the chrome plated liner has since disappeared.

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Didn't Kawasaki or Suzuki use hard chrome in cylinders? The coating is too thin and tends to flake. Nikasil is outperforms hard chrome in every way. Some large industrial engines ventured into hard chrome liners but eventually settled on laser hardened iron liners with chrome faced rings.

Yamaha tried chrome over aluminum as others have and the problem with chrome is its lack of porosity. It doesn't hold lubricating oil very well. Nickel is very tough and wears well. No one has found a reliable method for making chrome stick to aluminum under the harsh environments of an engine.

Kawasaki used a process called Electrofusion for many years and it worked ok but didn't wear very well. It was more like vacuum depositing than plating. It involved placing wires of different material (iron, nickel, molybdenum, etc.) through the bore, placing the whole assembly in a vacuum chamber and vaporizing the wires with an electric current.

Suzuki uses a proprietary process called SCEM. It's similar to Nikisil.

Cylinders with chrome bores can not use chrome plated rings.

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I work as an engineer at an industrial plating facility, one of the only ones in the US to offer more than a handful of coatings in one facility. We do not do Nikasil unfortunately, but from what I have seen I believe you are on the right track. I have heard that Nikasil is electro-deposited, but we offer a couple proprietary electroless nickel based coatings that seem to be along the same idea as nikasil. Unfortunately I cannot offer too many details about the plating, but there are a few electroless nickel based coatings out there that offer good wear resistance as well as a low coefficient of friction.

On a side note, I have often wondered how another plating would work in a cylinder, but haven't had the guts to try it in anything. I'd imagine hard chrome would work alright. I may have to try some things out on a cheap lawnmower engine or something :bonk:

So, is there any type of reference material or other source of information that explain the process of composite plating in detail?

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So, is there any type of reference material or other source of information that explain the process of composite plating in detail?

It's funny how tight lipped the metal finishing industry is about certain processes and how open they are about others. I'm sure there are references for certain processes and the basics behind most processes, but you will most likely never find details on trademarked processes. The company I work for has created its own collaboration of reference material just for training employees, but obviously I cannot offer any of that. Finishing.com is one of the best sources for information on plating there is, I would suggest checking there first.

As you have already found with the links you posted, most plating won't stick to bare aluminum, you must use a combination of underplatings, most commonly zincate or cyanide copper. Sometimes these are used in combination with a nickel strike to get the final nickel layer to plate.

As for electroless nickel vs. electroplating, the advantage of electroless is that it builds at uniform thickness all over. With electroplating you will have areas of high current density (especially near corners) where the plating will be thicker. To try to get a uniform thickness with electroplating you have to use an elaborate system of anodes, shields, and robbers to try to "steal" the plating away from the high current density areas and throw more into the low current density areas.

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The website for where I work has a little information on different plating processes if you browse around. I'm not sure how helpful it will be. http://anoplate.com/index.html

Now this has got me thinking. We do offer a codeposited silicon carbide electroless nickel for industrial applications. I never really thought too much about it, but now I'm wondering how close to Nikasil this is.

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This is great info! I'm glad there is some others interested in this subject.

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Yamaha tried chrome over aluminum as others have and the problem with chrome is its lack of porosity. It doesn't hold lubricating oil very well. Nickel is very tough and wears well. No one has found a reliable method for making chrome stick to aluminum under the harsh environments of an engine..

I once had (and this is going to date me) a Bridgestone racer with a chrome plated bore. On inspection, it had little "pits" in the chrome surface to help the lubrication process. The pits were obviously less deep than the chrome thickness, rectangular in shape and, Im guessing here, maybe 20 thou. high and 40 thou. wide. After about 60 to 70 hrs. of racing use, half at a full-out race pace, it needed rings but the bore showed slight wear and measured basically at as-new specs. I'd say whatever they did....WORKED.

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Don't quote me on this (<-read I'm guessing) but, I believe that the "Nikasil" coating process is done in a vacuum. It's called something like plasma deposition. The material erodes off of the "anode" (which would be the "Nikasil" or equivalent) and passes through the space to the "cathode" (i.e. the cylinder wall). :smirk:

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Some of the high end chainsaws stayed with chrome, with their cheaper models using nicasil. There were a few years where chrome was thought to be better. Guess that may have changed now. The biggest thing as someone mentioned is the ring material has to slightly harder or softer than the bore. Some manufacture cut this pretty close and also are known for their Loooong break in time, newer BMW boxers for example. But they last a long time once seated. Moto Guzzi was the 1st one I can remember using nicasil.

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As far as I was aware, Nikasil is an electroplating process where the part is submerged in a solution containing dissolved nickel ions (I've seen a picture of it it's green in color) and an extremely fine powdered silicon carbide. I'm not sure how the silicon carbide gets deposited because I don't think it is conductive. I think it randomly gets trapped on the surface of the nickel and then gets covered by the nickel as the plating builds.

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Yamaha tried chrome over aluminum as others have and the problem with chrome is its lack of porosity. It doesn't hold lubricating oil very well. Nickel is very tough and wears well. No one has found a reliable method for making chrome stick to aluminum under the harsh environments of an engine.

yeah, i remember my 74 yz250 had the "chrome bore". went 3 seasons and 2 pistons before i had to replace it.

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