A sheet of steel 4.7 mm thick has nitrogen atmospheres on both sides at 1200°C a

Question

A sheet of steel 4.7 mm thick has nitrogen atmospheres on both sides at 1200°C and is permitted to achieve a steady-state diffusion condition. The diffusion coefficient for nitrogen in steel at this temperature is 5.2 × 10-11 m2/s, and the diffusion flux is found to be 1.5 × 10-7 kg/m2-s. Also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 5.1 kg/m3. How far into the sheet from this high-pressure side will the concentration be 2.9 kg/m3? Assume a linear concentration profile.

Explanation / Answer

J = -D(dc/dx)

J = 1.5 × 10-7
D = 5.2 × 10-11
dc = 5.1 - 2.9

1.5 × 10-7 = -5.2 × 10-11*(2.2/dx)

Using simple algebra, I got 136.33 mm

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.