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A 0.001 in. BCC iron foil is used to separate a high hydrogen content gas from a low hydrogen content gas at
(b) the flux of hydrogen through the foil.
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Chapter 5 Solutions
The Science and Engineering of Materials (MindTap Course List)
- You want to carburize a steel drill bit in the presence of methane. The drill bit initially has a uniform carbon concentration of 0.25 wt% and is to be treated at 950 oC (1750 oF). If the concentration of carbon at the surface is suddenly brought to and maintained at 1.20 wt%, how long will it take to achieve a carbon content of 0.80 wt% at a position 0.5mm below the surface? (The diffusion coefficient for carbon in iron at this temperature is 1.6 x 10-11 m2/s.)arrow_forwardAn FCC iron–carbon alloy initially containing 0.25 wt% C is exposed to an oxygen-rich and carbon-free atmosphere at 1400 K. Under these circumstances the carbon diffuses from the alloy and reacts at the surface with the oxygen in the atmosphere; that is, the carbon concentration at the surface position is maintained essentially at 0 wt% C. (This process of carbon depletion is termed decarburization.) At what position (x, in mm) will the carbon concentration 0.10 wt% after a 8-h treatment? The value of D at 1400 K is 6.9 x10-11 m2/s. Round your answer to 2 decimal place.arrow_forwardAn iron-carbon alloy initially containing 0.268 wt% C is exposed to an oxygen-rich and virtually carbon-free atmosphere at 1040°C. Under these circumstances the carbon diffuses from the alloy and reacts at the surface with the oxygen in the atmosphere; that is, the carbon concentration at the surface position is maintained essentially at 0.0 wt% C. At what position will the carbon concentration be 0.201 wt% after a 7 h treatment? The value of D at 1040°C is 2.5 × 10-¹1 m²/s. erf(z) erf(z) 0.55 0.5633 1.3 0.025 0.0282 0.60 0.6039 1.4 0.9523 0.0564 0.65 0.6420 1.5 Z 0.00 0.05 0.15 0.0000 0.10 0.1125 0.70 0.6778 0.20 Z 0.1680 0.75 0.7112 1.7 0.2227 0.80 0.7421 1.8 0.45 0.4755 1.1 0.50 0.5205 Z 1.6 1.2 0.9103 erf(z) 0.9340 2.8 0.9661 0.25 0.2763 0.85 0.7707 1.9 0.9928 0.30 0.3286 0.90 0.7970 2.0 0.9953 0.35 0.3794 0.95 0.8209 2.2 0.40 0.4284 1.0 0.8427 2.4 0.9763 0.9838 0.9891 0.9981 0.8802 2.6 0.9998 0.9993 0.9999arrow_forward
- An iron-carbon alloy initially containing 0.240 wt% C is exposed to an oxygen-rich and virtually carbon-free atmosphere at 1100°C. Under these circumstances the carbon diffuses from the alloy and reacts at the surface with the oxygen in the atmosphere; that is, the carbon concentration at the surface position is maintained essentially at 0.0 wt% C. At what position will the carbon concentration be 0.180 wt% after a 7 h treatment? The value of D at 1100°C is 3.7 × 10-11 m2/s.arrow_forward6. Exhaust gas from an automobile contains air and 105 mole fractions of CO in air at 25 degC and 1.2 atm. Express this concentration as a mass concentration (kg/m³).arrow_forwardExhaust gas from an automobile contains air and 10-4 mole fractions of NO in air at 25 degC and 1.2 atm. Express this concentration as a mass concentration (kg/m3). Remember that the MW of NO is 30 g/molarrow_forward
- Diffusion of carbon into BCC iron for 12 hours at a temperature of 500 °C results in a carbon concentration of 0.2 wt% at a depth 2 mm from the surface. How long would it take to get a concentration of 0.2 wt% at a depth 3 mm from the surface at 500 °C?arrow_forwardProblem 3 An FCC iron-carbon alloy initially containing 0.35 wt% C is exposed to an oxygen-rich and virtually carbon- free atmosphere at 1400 K (1127 °C). Under these circumstances the carbon diffuses from the alloy and reacts at the surface with the oxygen in the atmosphere; that is, the carbon concentration at the surface position is maintained essentially at 0 wt% C. (This process of carbon depletion is termed decarburization.) At what position will the carbon concentration be 0.15 wt% after a 10-h treatment? The value of D at 1400 K is 6.9 x 10¹¹ m²/s.arrow_forwardYou wish to carburize 0.2 wt% C steel ball bearings. The balls have a diameter of 2.5 mm. You anneal them at 930 °C in an atmosphere which fixes the surface carbon concentration at 1 wt% C. (a) How long will it take to raise the average C concentration to 0.6 wt% ? (b) What is the concentration at the centre of each ball at this time?arrow_forward
- An FCC iron–carbon alloy initially containing 0.35wt% C is exposed to an oxygen-rich and virtually carbon-free atmosphere at 1450K (1177 degree C). Underthese circumstances the carbon diffuses from the alloy and reacts at thesurface with the oxygen in the atmosphere; that is, the carbon concentration atthe surface position is maintained essentially at 0 wt% C. (This process ofcarbon depletion is termed decarburization.) At what position will thecarbon concentration be 0.15 wt% after a 15-h treatment? The value of D at1400 K is 6.9 x 10^(-11)m^2/s.arrow_forwardThe figure below shows five different steady-state concentration profiles from five separate tests, which had the same gas across identical membranes at the same temperature. Rank the diffusion flux of the five concentration profiles from lowest to highest. Using bullet points explain your answer. C(x)' (a) (b) (c) (d) (e) Membrane Thicknessarrow_forwardNitrogen from a gaseous phase is to be diffused into pure iron at 700°C. If the surface concentration is maintained at 0.14 wt% N, what will be the concentration (in weight percent) 2.3 mm from the surface after 6.5 h? The diffusion coefficient for nitrogen in iron at 700°C is 1.4 x 10-10 m²/s. Z 0.00 0.025 0.0282 0.60 0.05 0.0564 0.30 erf(z) 0.0000 0.55 0.35 Z erf(z) 0.40 0.45 0.50 0.65 0.10 0.1125 0.70 0.6778 1.6 0.5633 1.3 0.6039 0.4755 1.1 Z 0.15 0.1680 0.75 0.7112 0.20 0.2227 0.80 0.7421 1.8 0.25 0.2763 0.85 0.7707 1.9 0.9928 0.3286 0.90 0.7970 0.5205 1.2 0.6420 1.5 1.4 0.3794 0.95 0.8209 2.2 0.4284 1.0 1.7 0.9103 2.0 erf(z) 0.9340 0.9523 0.9661 2.8 0.9763 0.9838 0.9891 0.9953 0.8427 2.4 0.9993 0.9981 0.8802 2.6 0.9998 0.9999arrow_forward
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