Fig. 1 shows the evolution of total porosity (solid lines) and
open porosity (dashed lines) of test pieces made from the STD
composition and from the composition containing 0.2 wt% SiC
(average diameter 9.3m). Porosity varied with temperature for the STD composition according to the microstructural evolution
described in the introduction. The STD composition reached a
minimum open porosity value at 1200 ◦C, and began to expand
at temperatures above 1210 ◦C, when all retained porosity was
closed.