Cylinder coating 2

[divergent]

I am in the process of integrating a small 2-stroke rc engine (5hp) into a UAV. The cylinder head has a Nikasil coating. The manufacturer has stated that I should expect to see approx. a 200hr life out of the coating but I'm suspicious as I have seen a significant amount of wear after only 20 hrs of run time. Granted, I am running the engine on a dyno where I am no doubt putting the engine through higher stresses then it will see in regular use.

Does anyone have any experience with this coating and what sort of practical life to expect?

Thanks.

 

[bazeleur]

Azmio,
I hate to come across like a dodo, but I wasn't able to find anything on either Kolbenschmidt's site or Gehring's site. All I did find was a paper outlining the design and manufacture of the Cayenne's V8 cyl block, as well as briefly going over the ALUSIL process (nothing new to me) I seem to recall reading somewhere that the three-step process starts by honing with 220-grit stones, followed by honing with 400-grit stones, and finish honing with 600-grit stones, but I'm rather sketchy on the details, and I'm not sure I'm convinced either... So I'm hoping you can fill in the blanks for me, because we'll be doing this from scratch (meaning the machine shop has absolutely no experience with this... Just for the record, this is for a mercedes M117/119 block. As always, thank you for your time.

 

[swall]

I'm not an expert on cylinder boring, but thought I'd throw in my two cents worth, since polishing of metallographic specimens often results in harder particles standing out in relief of a softer matrix (which is usually something you do not want in metallographic samples, btw). If a material with a soft matrix and hard particles is polished with a resilent polisher, the soft matrix will be removed leaving the particles. So, if some sort of buff with polishing or lapping compound were to be used as the final step in bore prep, it could accomplish the desired effect of leaving the silicon particles standing proud of the soft matrix.Preliminary honing steps with 400 and 600 would be beneficial in removing smeared aluminum from the bore, which would tend to cover over the silicon particles.

 

[Azmio]

Bazeleur

Here is the website, go over the PDF files and you will get some ideas on the Alusil material

http://www.kolbenschmidt.de/index.php?lang=3&fid=312

Gehring's website is in german but you can pick up some info from it

http://www.gehring.de/

The 3 step honing are basically divided into: -
1) Pre honing to improve the cylinder shape
2) Basic honing to remove the destroyed Silicone layer
3) Finish honing to recess the Al matrix

The honing tools are unique with the combination of diamond, SiC and corundum. The bonding of the material to the honing tool is also unique.

I dont mean to discourage you from performing this but there are lots of knowhow involve in the manufacturing process that only KS and the honing specialists would be able to tell you