This preview shows page 1. Sign up to view the full content.
Unformatted text preview: x through the same Al 2 O 3 crystal at T=1000C. b. Calculate the temperature at which the diffusion rate of Al through an Al 2 O 3 crystal will be 10 times that of T=1000C. 6. a. Describe the mechanisms of degradation of polymeric materials. b. Why would you not store benzene in polystyrene containers? Suggest a better alternative (describe pros and cons of the suggested material). 7. Explain cathodic protection. How does it work? What are the material requirements (composition and shape) of the sacrificial anode? 8. At one instance of time, there is a constant gradient in concentration of Cu in an Al crystal: 0.19%at Cu at the surface and 0.18%at Cu at a depth of 1.2mm below the surface. The diffusion coefficient of Cu in Al at the temperature of the system is D= 4*10-14 m 2 /s. The lattice parameter of FCC Al is 4.049. What is the flux of Cu atoms, and in which direction do they flow?...
View Full Document
This note was uploaded on 08/02/2011 for the course ENMA 300 taught by Professor Alsheikhly during the Spring '11 term at University of Maryland Baltimore.
- Spring '11