Problem 1 A sheet of BCC iron 1 mm thick was exposed to a carburizing gas atmosphere on one side and a decarburizing atmosphere on the other side at 725°C. After having reached steady state, the iron was quickly cooled to room temperature. The carbon concentrations at the two surfaces of the sheet were determined to be 0.012 and 0.0075 wt%. Compute the diffusion coefficient if the diffusion flux is 1.4 x 108 kg/m2-s. Hint: Use Equation 4.9(Text Book) to convert the concentrations from weight percent to kilograms of carbon per cubic meter of iron.

Problem 1 A sheet of BCC iron 1 mm thick was exposed to a carburizing gas atmosphere on one side and a decarburizing atmosphere on the other side at 725°C. After having reached steady state, the iron was quickly cooled to room temperature. The carbon concentrations at the two surfaces of the sheet were determined to be 0.012 and 0.0075 wt%. Compute the diffusion coefficient if the diffusion flux is 1.4 x 108 kg/m2-s. Hint: Use Equation 4.9(Text Book) to convert the concentrations from weight percent to kilograms of carbon per cubic meter of iron.

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

See similar textbooks

Similar questions

Which statements about case hardening are correct? The process makes it possible to harden local areas of the component. The process promotes a fine-grain structure due to relatively low heating temperatures. Case hardening is particularly useful for austenitic steels Case hardening is well suited for small workpieces. During case hardening, the workpiece is specifically enriched with carbon and nitrogen. After in-diffusion, the workpiece is tempered with the carburized gas medium:
Problem 1. A sheet of BCC iron 1 mm thick was exposed to a carburizing gas atmosphere on one side and a decarburizing atmosphere on the other side at 725°C. After having reached steady state, the iron was quickly cooled to room temperature. The carbon concentrations at the two surfaces of the sheet were determined to be 0.012 and 0.0075 wt%, respectively. Compute the diffusion coefficient if the diffusion flux is 1.4 × 10 -³ kg/m²-s.
6. (20%) Pure zinc is to be diffused into the copper by dipping copper into molten zinc at 450°C. Calculate how long would take to obtain 10wt% zinc at a depth of 0.5 mm beneath the copper surface. Is this commercially feasible? What practical problems might arise if we raise the temperature to 1000°C ? Use Table below for error function values as needed. At 450°C, the diffusion coefficient D = 6.3 10-17 m²/s.
Problem 4 The preexponential and activation energy for the diffusion of iron in cobalt are 1.1 x 105 m²/s and 253,300 J/mol, respectively. At what temperature will the diffusion coefficient have a value of 2.1 × 10-¹4 m²/s?
DISCUSSION THEORY OF DISFFUSION AND THROUGLY EXPLAIN FIVE DIFFUSION QUANTITIES.ALSO EXPLAIN THE DIFFUSION AND HEAT TRANSFER. PLEASE GIVE 2-3 PAGE DETAILED ESSAY.
(c) Consider an alloy that is undergoing carburizing process, initially has a uniform carbon concentration of 0.27 wt% and is to be treated at 950oC (1750oF). If the concentration of carbon at the surface is suddenly brought to and maintained at 1.32 wt%, how long will it take to achieve a carbon content of 0.85% at a position 0.7 mm below the surface? The diffusion coefficient for carbon in iron at this temperature is 1.6 x 10-11 m2/s; assume that the steel piece is semi-finite.
For a steel alloy it has been determined that a carburizing heat treatment of 11.4h duration will raise the carbon concentration to 0.410 wt% at a point 2.10 mm from the surface. Estimate the time necessary to achieve the same concentration at a 4.60 mm position for an identical steel and at the same carburizing temperature. i
For a steel alloy it has been determined that a carburizing heat treatment of 18 h duration at 885°C will raise the carbon concentration to 0.46 wt% at a point 2.0 mm from the surface. Estimate the time necessary to achieve the same concentration at a 8.4 mm position for an identical steel and at a carburizing temperature of 1120°C. Assume that Do is 2.5 x 10-4 m2/s and Qa is 104 kJ/mol.
For a steel alloy it has been determined that a carburizing heat treatment of 16 h duration at 731°C will raise the carbon concentration to 0.40 wt% at a point 3.9 mm from the surface. Estimate the time necessary to achieve the same concentration at a 7.9 mm position for an identical steel and at a carburizing temperature of 1060°C. Assume that Do is 1.9 x 105 m²/s and Quis 108 kJ/mol, 3.89 -land Madin h
In precipitation hardening, after being quenched into solution, overcooling is done and then either artificial aging is done at 180-250°C or natural aging is done at room temperature, both of which occur through diffusion, where temperature and time parameters are dominant. While 180°C and 250°C provide sufficient temperature for diffusion, is it not interesting that diffusion occurs at room temperature? This is because of the thermal energy of atoms causing them to move, which may facilitate diffusion at room temperature.
Problem 2 Consider the gas carburizing of a gear 1020 steel at 927°C. Calculate the time (in minute) necessary to increase the carbon content to 0.40 wt% at 0.5 mm below the surface. Assume that the carbon content at the surface 0.9 wt% and that the steel has a nominal carbon content of 0.2 wt%. Given: Diffusivity of C in Fe at 9270C is 1.28 x 10-11 m²s-1, activation energy is 148 kJmol-1, gas constant is 8.31 Jmol-1K-1, if erf (Z) = 0.7143, Z = 0.755. %3D
Mechanical Engineering At approximately what temperature (in Kelvin) would a specimen of an alloy have to be carburized for 1.3 h to produce the same diffusion result as at 760°C for 14 h? Assume that values for Do and Qdare 3.6 x 10-6 m²/s and 163 kJ/mol, respectively.