SOL QUIZ #5

# SOL QUIZ #5 - 2 How does the flexural strength obtained...

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Cr 2 O 3 wt% Cr 2 O 3 Al 2 O 3 T (°C) T (°C) 2275 °C 2045°C L L + SS SS Name: MSE 230- REC 5&6 QUIZ # 5 Crystal structures : Calculate the minimum cation to anion radius ratio for a coordination number of 8. Hint: Use the CsCl crystal structure and assume that anions and cations are just touching along the cube diagonals and that anions are just touching along the cube edges. (8 pts) (1) (2) 2 2 3 2 Cs Cl Cl r r a r a + - - + = = Taking the ratio (1) (2) 1 3 Cs Cl r r + - + = Thus 0.732 Cs Cl r r + - = Phase diagrams : Sketch and label the Al 2 O 3 -Cr 2 O 3 phase diagram knowing that Al 2 O 3 and Cr 2 O 3 form a complete solid solution. (8 pts) Tm (Al 2 O 3 ) =2045°C Tm (Cr 2 O 3 ) =2275°C Mechanical properties : How is the Young’s Modulus E affected by porosity? (4 pts) An increase in Porosity leads a decrease of E. E = E 0 (1-1.9P + 0.9P
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Unformatted text preview: 2 ) How does the flexural strength obtained through a 3-point bend test compare to the flexural strength obtained through a 4-point bend test? Explain why. (6 pts) The flexural strength obtained through a 3-point bend test is higher than the flexural strength from a 4-point bend test. There is a larger area under the load in the 4-point bend test. The probability to have a flaw is higher. The sample can break under a smaller load. Processing: Portland cement is obtained through reaction of water with CaO-SiO2 TRUE or FALSE and is then heated to high temperature to form a dense solid . (2 pts) Glasses are deformed by viscous flow, not but plastic deformation. (2 pts) TRUE or FALSE...
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