Alex Madsen wrote:
     >
     > Ceramics have great material properties but...
     >
     > Ceramics are VERY temperamental. They often behave in unpredictable
     > ways.  They are difficult to manufacture (no machining). The biggest
     > problem is that the deviation of ceramics fracture stress is very large.
     > 2 identically manufacture pieces can break at significantly different
     > stress. All this makes complicated ceramics exceedingly expensive to
     > design and manufacture.
     >
     > It would be impractical to make a ceramic engine.
     >
     > Alex Madsen
     > JR ME
     > Rose-Hulman

Alex, Not totally true. Since ceramics are a sinstered product a great deal depends on tooling. When properly pressed and fired the LOCATION of failure might
change but the stress at which it occurs is quite predictable. Silicon Nitride is much tougher, but of course even harder to machine. I believe a ceramic
rotor housing could be made but at a tremendous cost. All ceramic adibiatic (no cooling system) piston engines have already been built. One of the more
promising possibilities is one of the ceramic metal hybrids. Honda even built a bike with the cylinder liners made from the stuff. (The RC 45 750cc V-4). The
weirdest part about making ceramic parts is the nearly 1/3 volumetric change after the part is fired. (They get much smaller) With modern cnc tooling it
could, (and has) been done. The rotary would be tough to tool and the final shape diamond ground. Doable, but you would spend the money better on doing cermet
sideplates or better coatings for aluminum.
Bill Jepson

 
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