Unformatted text preview: limit(a) will cause the material to fail. Since the critical crack length of ceramics is much lower than metals, the amount of porosity must be kept very low to none as to not cause the material to fail. From the equation E = E (1-1.9P+.9P 2 ) it can be seen that the modulus of a ceramic drops as a function of amount porosity. Due to the ductility of metals, the porosity doesn’t have this type of effect on the modulus. 2. Alumina(Al 2 O 3 ) ceramic has a density of 3.97 g/cm 3 . Sketch below two stress-strain curves; one for the completely dense and one for alumina which has a level of porosity that reduces the density to 2.5 g/cm 3 . Clearly label which curve corresponds to which ceramic. Fully Dense Less Dense(2.5 g/cm 3 ) Stress Strain...
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- Spring '08
- Aluminium, 2.5 g, Electrical conductivity