ABSTRACT
The corrosion of ceramics (i.e., weight gain/loss) is proportional to the porosity; the more porous the sample, the more corrosion that is exhibited. This is in reality related to the surface area exposed to corrosion. The fact that one material may yield a better corrosion resistance than another does not necessarily make it the better material, if the two materials have different porosities. This is very important, for example, when comparing different sintering aids for silicon nitride and their effects upon oxidation. The more oxidationresistant material may not be due to the chemical species of the sintering aid used, but in actuality may be due to the fact that one particular sintering aid yields a denser sintered ceramic. One must remember that it is not the total porosity that is important, but the surface area of the total porosity, thus making the pore size distribution an important parameter to determine.
