ABSTRACT
It is well known that rapid cooling can improve the strength
of various ceramics (Hummel and Lowery, 1951; Smoke and Koenig,
1958; Dunsmore, Fenstermacher and Hummel, 1961; Philips and
DiVita, 1964). In these references, the strengthening process
involved cooling the specimens in an air blast and it was usually
called thermal conditioning. Increases in strength up to 111% were
reported but, because the starting materials were not very strong,
the resulting strengths often remained well below the strengths of
the strongest available ceramics.
