Paul Lamar wrote:

The trouble with Wankel wear coatings is there is no way to inspect
them for quality control. Some that look good may or may not come
off. You can't tell unless you destructively test each article
over every square inch of the wear surface.

In other words there is no way of controlling the quality.

Russell Kent castigated Paul:

I bet this is interesting "news" to Mazda, seeing as how they have
been nitriding the side housings and chroming the rotor housing for
years without apparent problem controlling quality...

Paul, your emotional reaction to Mark Burns' letter (perhaps deserved)
is interfering with your ability to make rational statements.

Paul Lamar replied:

Passionate yes....emotional no.

First you missed a very important point Russell.

"Mazda has built over two million engines with excellent results."

Once you make a few hundred thousand engines and they are in
service for ten years you tend to get confidence in what you
are doing.

OK, so you admit that it is possible to control the quality. :-)  I'll
agree that method (build 100,000's) is not going to happen for Rotamax.

The subtle point I was trying to make was that if you're going to
chastise Mark Burns (or anyone else) for making unsupported claims, or
wishful thinking claims based on vaporous science, then you'd do well to
*avoid* making them yourself in the process.  Unless I've completely
misunderstood, this newsletter is all about the *engineering* of these
engines in an aircraft installation.  Demonstrating a reliable surface
wear coating/bonding is an engineering problem. Stating that "there is
no way of controlling the quality" is an engineering falsehood.  It's
not impossible, merely difficult.

Second; nitriding is not a coating. It is a hardening process where
a chemical is actually ingested into the surface of the metal at
high temps.

Hey, I work at TI, remember?  I know about eutectic bonding.  Every
chipmaker in the world uses it to bond 99.99% Au wires to Al, Al-Cu,
Al-Cu-Ni, Cu-Ni-Sn, ...  We use a combination of heat, pressure, and
ultrasonic vibration to produce really otherworldly alloys of Au, Al,
Cu, Ni, Sn, W, Ti, Si, Ge, ...  Getting Fe, Cr, N, and Al to bond is a
piece of cake by comparison.  'Course, I can only make it in 0.25mm
patches... :-)


Russell Kent


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