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From: "George Lendich" <lendich@optusnet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-3120921@logan.com>
Subject: Re: [FlyRotary] Re: New rotary engine-mazda points on design
Date: Wed, 10 Sep 2008 07:42:34 +1000
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> George Lendich wrote:
>>>> Dale,
>>>> What is it, what does it consist of?
>>>> George ( down under)
>>>
>>>
>>> Aluminized Titanium Nitride
>>>
>>> Titanium Nitride is the gold-tone stuff you see on a lot of the
>>> "better" drill bits, of late.
>>>
>>> Dale R.
>> Dale,
>> Very good but the substrate aluminum has to have high density, which is 
>> insufficient in most castings. Hence the steel liner.
>> George (down under)
>
>
> That may be; but there is no particular reason, as yet, to believe
> that they are doing it that way.  They could make the end-walls
> twice as thick, and they would still be less than two-thirds the
> weight of the steel end housings.
>
> The technology for applying a hard, anti-scuff coating such as
> AlTiN/TiAlN is actually less problematic than trying to make
> a steel liner stay attached.
>
> Dale R.
Dale,
I agree entirely, a flat steel liner is problematic. I also agree the 
coating you suggest is excellent, probably fantastic.

However you have to understand that no matter how good the surface treatment 
if the substrate is insufficient the surface will fail as the substrate 
moves or compresses - no matter how thick the aluminum is, it will still 
move or compress. This has been the underlying problem with aluminium end 
housings. A flat steel liner would have to be 5mm thick to avoid moving/ 
drumming under these side loads.

I gave up trying to make aluminum housings with a steel wear plate, when I 
came to the realization that there was little weight advantage.

The det gun coatings penetrate deep into the aluminum surface and at the 
same time compress the surrounding aluminum, making it much  denser. Another 
way is a composite aluminum, I suggested steel grains in the aluminum 
matrix, but this poses other problems - another suggestion might be ceramic 
grains/ powder mix with the aluminum prior to injection molding. Mixed 
components have to be compatible or it poses a whole host of problems. 
Mistral may have found such a composite as there latest endeavour is a much 
denser material. But remember denser may mean heavier as well.

You have to remember that these engine manufacturers such as Mistral, 
Powersport tried every process known to man, within budgetary restraints and 
within their own expertise AND THEY ALL FAILED, except the det gun process 
thus far.
George (down under)