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Unformatted text preview: Biomaterials 2009 Fall Home Work No.4 W6.4 When -iron is subjected to an atmosphere of nitrogen gas, the concentration of nitrogen in the iron, C N (in weight percent), is a function of hydrogen pressure, p N2 (in MPa), and absolute temperature (T) according to C N = 4 . 90 10- 3 p N 2 exp - 37 . 6 kJ / mol RT Furthermore, the values of D and Q d for this diffusion system are 3.0 10 7 m 2 /s and 76,150 J/mol, respectively. Consider a thin iron membrane 1.5 mm thick that is at 300C. Compute the diffusion flux through this membrane if the nitrogen pressure on one side of the membrane is 0.10 MPa (0.99 atm), and on the other side 5.0 MPa (49.3 atm). Ans: This problems asks for us to compute the diffusion flux of hydrogen gas through a 1-mm thick plate of iron at 250 C when the pressures on the two sides are 0.15 and 7.5 MPa. Ultimately we will employ Equation (5.3) to solve this problem. However, it first becomes necessary to determine the concentration of hydrogen at each face using Equation (5.11). At the low determine the concentration of hydrogen at each face using Equation (5....
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This note was uploaded on 10/11/2009 for the course MATERIAL 839 taught by Professor Chen during the Spring '09 term at N.C. Central.
- Spring '09