experiments that would help you answer this postulate and explain how the results would distinguish between the two mechanisms. 14.A nickel membrane separates two gas phase at 1000C :a CO/CO2 gas and a H2H20,each with the same oxygen activity (reducing to NiO formation). Analyze as well as possible the steady-state transport of carbon through the membrane assuming: (a)the rate is limited by the diffusion of carbon in nickel, (b)the rate is limited by interfacial reactions at the surfaces, (c)the rate control involves both diffusion in the metal and interfacial reactaions The diffusion of hydrogen through the metal is very fast.Propose a specific rate-limiting step for hydrogen transport. What experiments would you propose to measure the carbon and hydrogen permeation rates? 15.A continuous 10m thick layer of gold his electroplated on a nickel electrical contact which is to be operated in a poor vacuum at 50-150C.Calculations using high temperature volume diffusion data indicate that the nickel will not penetrate the gold layer for at least a century.The "customer"has come back saying that some surface oxide is messing up the electrical properties of the contact after a few months. (a)Give some possible explanations of what might be happening. (b)Tell how you can setup a program to prove what's causing the degradation. (c)Suggest a fix for the product manager. 16.In the oxidation of high temperature aluminum containing alloys,it is felt that the rate controlling transport process through the protective alumina film may be grain boundary transport not lattice diffusion.Discuss how you would go about establishing when and if this is true" a)with diffusion data and equations you might find in the literature. b)any experiment you wish to suggest 17 The concentration of carbon in the case of a carburized steel is given by the expression C-C=1-erf( C。-C 2√D1 Where CO=surface concentration(gms/cm')of carbon and Ci=carbon content of steel. a)Derive an expression for the flux of carbon into the steel at surface(x=0) b)Derive an expression for the amount of carbon which has diffuse into the steel per unit of surface area after time t.experiments that would help you answer this postulate and explain how the results would distinguish between the two mechanisms. 14. A nickel membrane separates two gas phase at 1000℃ :a CO/CO2 gas and a H2H2O, each with the same oxygen activity (reducing to NiO formation). Analyze as well as possible the steady-state transport of carbon through the membrane assuming: (a) the rate is limited by the diffusion of carbon in nickel, (b) the rate is limited by interfacial reactions at the surfaces, (c) the rate control involves both diffusion in the metal and interfacial reactaions The diffusion of hydrogen through the metal is very fast. Propose a specific rate-limiting step for hydrogen transport. What experiments would you propose to measure the carbon and hydrogen permeation rates? 15. A continuous 10m thick layer of gold his electroplated on a nickel electrical contact which is to be operated in a poor vacuum at 50-150℃. Calculations using high temperature volume diffusion data indicate that the nickel will not penetrate the gold layer for at least a century. The “customer” has come back saying that some surface oxide is messing up the electrical properties of the contact after a few months. (a) Give some possible explanations of what might be happening. (b) Tell how you can setup a program to prove what’s causing the degradation. (c) Suggest a fix for the product manager. 16. In the oxidation of high temperature aluminum containing alloys, it is felt that the rate controlling transport process through the protective alumina film may be grain boundary transport not lattice diffusion. Discuss how you would go about establishing when and if this is true” a) with diffusion data and equations you might find in the literature. b) any experiment you wish to suggest 17 The concentration of carbon in the case of a carburized steel is given by the expression 0 1 (2 i i C C ) x erf C C Dt − = − − Where C0=surface concentration (gms/cm3 ) of carbon and Ci= carbon content of steel. a) Derive an expression for the flux of carbon into the steel at surface (x=0) b) Derive an expression for the amount of carbon which has diffuse into the steel per unit of surface area after time t