Douglas Fir wrote:

Paul,

Is this one of the companies you are searching for in Britain? UltraHard
Materials LTD. Their subsidiary CeZIR Ceramic Components is proposing a
ceramic  rotary engine that wouldn't need the water jacket for cooling. Easy
to say in project proposals:)

http://www.ultrahardmaterials.co.uk/links.html

Go to the  http://www.ultrahardmaterials.co.uk/CeTZPvsMetals.html
for a comparison of their ceramic product characteristics with aluminum and
cast iron.

This engine would be years away but right now it should be technically
possible to have combustion chambers ceramic coated.  It might improve the
thermal characteristics by  retaining more heat.  Time to  speak to Kyocera
again.

Doug in Japan

_____________________________________________________________________

 Mechanical Properties
                               UHM's CeTZP
                                                 Silicon Nitride
 Vickers Hardness (GPa)
                                9.1 - 13.6+
                                                  17 - 19+
 Fracture Toughness (MPa.m1/2)
                                 10 - 15.3
                                                  4.0 - 5.4
 Tensile Strength (MPa)
                                360 - 420#
                                                  400 - 580#
 Bend Strength (MPa)
                                1080 - 1260
                                                  190 - 980
 Compression Strength (MPa)
                                1045 - 1459
                                                  550 - 2000
 Young?s Modulus (GPa)
                                 190 - 200
                                                  280 - 310
 Density (g/cm3)
                                 6.1 - 6.2        3.2 - 3.5

________________________________________________________________________

One of the big advantages of silicon nitride for apex seals is its low
density. Less centrifugal force on the rotor housing at high RPM.
This material would be twice the weight but I like the fracture
toughness advantage. However... as far as I can tell.... there have been no 
incidences of fractured SiNi apex seals caused by detonation. I could be 
way wrong on this. Obviously the natural resonant frequency of SiNi apex 
seals is different (a lot higher) than the stock cast iron three piece 
apex seals. 
                                                  
Paul Lamar
 
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