Nikasil® nickel-silicon plating process supplier or applicator

A. Nikisil® is a proprietary product of Mahle. If you desire information you should contact Mahle.

A. Although Nikisil® is a trademark of Mahle Corporation, our company has engaged in nickel silicon-carbide plating and diamond honing in the United States since the mid 1960s. We are presently one of the largest such companies in the world. We have found that by far the greatest demand for nickel silicon-carbide has been for aluminum cylinder bores, and the market still appears to be growing. We have no method of "brush plating" this coating.

A. My company has been offering a Nickel/Silicon Carbide coating service on aluminum cylinders for many years both here in Alabama and at our original facility in England, and have a throughput of several thousand cylinders each year. Like them too, we are not aware of any brush plating technique that offers good results and a quick survey of our associated companies around the world yields the same response, but I suspect that one could be developed given sufficient demand.

A. My electroless nickel reference indicates that Elnisil is a galvanically deposited dispersion coating of carbide, presumably carbide in nickel. Brush plating of this process may be less problematic than Kanisil or Nikasil, although the abrasion resistance is less for Elnisil.

See Metzger, W. et al. galvanotechnik 61 (1970) 12, 998

A. Kumar R. You need a special plant for Nickel + SiC carbide plating. Normally that coating is applied on cylinders and liners made of aluminum alloys, so you need a pretreatment plant for this material and then a tank for nickel plating. You need special tank with agitation for keeping Silicon carbide powder dispersed in the liquid.

A. Hi, Ozgur

I think you will find that Alusil is an outdated predecessor of today's nickel-silicon electroplating. Threads 551, and 2858 address similar topics. scholar.google.com is a free search engine for literature searches and it will find abstracts for what you seek. Good luck.

Regards,

A. OZGUR: Alusil is a ipereutectic Al-Si alloy, that is, a massive aluminum casting with primary silicon crystals in an Al matrix.
Nikasil is trade name of Mahle for a coating of Nickel with codeposited SiC particles (mean dimension 3 micron) applied on cylinder liner. None of this material is used for pistons (but for cylinders).

A. The first thing to be aware of is that the Nikasil layer will probably be very thin, and so you should be prepared for that when considering any machining operation.

Typically, engine manufacturers using Nikasil and similar processes 20 years ago would have deposited a finish-machined thickness of about 0.10 mm (0.004"). More recently, we have noted that cylinders from several Japanese manufacturers have thinner coatings, sometimes as thin as 0.05 mm (0.002"), almost certainly as a result of improvements in the plating technology enabling a reduction in materials and processing times.

In normal use, it should be unnecessary to hone Nikasil-type engine cylinders since the wear resistance and oil retention derives almost as much from the presence of the silicon carbide particles in the nickel matrix as from the original underlying honed surface finish. In Bill S's situation, it appears that there are marks on the bore which will need to be removed to avoid damaging new components during a re-build, and so honing will almost certainly be required. It is important that this be carried out using diamond honing tools of an appropriate grade, since the original surface finish can easily be "polished" by using conventional honing stones, and that may lead to a lack of adequate lubrication during the initial running of the engine.

One of the big performance advantages of Nikasil-type bore over traditional cast iron sleeves (other than a major weight saving) is the ability to operate an engine with smaller piston to bore clearances since the piston and the cylinder will tend to expand a similar amount when heated. For that reason, it will be important for Bill S to accurately measure the bores after honing, then select pistons which will give him a clearance which satisfies the engine manufacturers specifications. Most normal piston ring materials work well with Nikasil-type bores, but chrome faced rings (at least the compression rings) are by far the most commonly supplied by engine manufacturers. Close attention should be paid to the ring-end gap to ensure compliance with manufacturers specs.

Sorry the reply is so long, but I hope it answers Bill S's and some other questions at the same time.

I would like to thank Mr. Geoff Slater of Auburn, AL for the rapid and informative response to my engine rebuilding questions. In his response, Geooff apologized for making a long reply. Apology accepted, however no apology was necessary. Geoff provided a great bit of information in a very concise manner. Not only did I gain the confidence to rebuild the engine, but I was also provided with useful practical and factual information. Believe me, there are quite a few people claiming to be knowledgeable about engine coating and plating that make it up as they go.

One last item, Geoff. The subject engine has been reassembled and runs like a fine watch. The Italian motorcycle which this engine powers is a 1986 Moto Morini 350K2. This model was one of the last manufactured by Morini before they went out of business. The engine is a V-twin having 70 degree cylinder offset and Heron heads (flat head, combustion chambers in piston).

Thank you.

Pretty impressed with the help you gave the guy on his Nikasil question. You're a wealth of usable information on the subject. This is what the Internet is supposed to be about, real help with real info by real knowledgeable people in their respective field.

A. There seem to be alternatives to Nikasil for the wear resistance improvement of aluminum cylinder bores. I've found companies that specialize in the ceramic coating of engine components; even worn out ones. Their claims seem to imply tremendous advantages. Check out their sites and see what you think. There are also coatings for "lubricity" using graphite and Molybdenum disulfide that are deposited on cylinders and pistons to reduce friction & galling. These are very high temperature coatings which ceramics seem ideally suited to and various process for deposition seem to be well worked out and not expensive. They have been used in racing vehicles for many years. It's a real eye opener what ceramics can do for an engine.

Good luck.

A. Hi all,
Nikasil coating is now common on the bore of most Japanese engines. They are inclined to run without liners (saving weight) and the bore is coated with Nikasil which is a very hard surface finish. Pistons normally run with chrome plated rings (also a hard surface) and because of this there is a requirement to run the two parts "hard" to bed in to each other. Normal running in will not allow the parts to bed in to each other and will cause piston blowby. This will allow excess pressure into the crankcase causing oil to be pushed out from the engine. If a Nikasil engine seizes, usually the piston melts onto the Niksil surface and the bore can be reclaimed by honing the deposited piston metal off the bore.

Guys an gals hope this helps and greetings from Ireland (The Capital Of the World) :)

Fast Fergie.

A. Right, to answer Steve Turnip
No, don't hone it, it's too thin. if you remove the coating the bore will be oversize and not seal and you will be running on an aluminum base and it will last a very short time (seconds probably). If you leave the bore scored then you will get blow by, low compression, burnt piston/bore as the combustion gases rush by. Won't last long! Sorry but re plate is the only real answer.

Q. Now here is a question for you platers can anyone machine and replate the epitroidal housing used in the norton rotary engines? It seems that some engineering processes become impossible.