In industries titanium is hardened through diffusion of carbon. The co...
Explanation: J=-D(∂C/∂x)
∂C/∂x= Δc/Δx=(0.25-0.68)/(0.003-0.001)=-215kg/m4
1.27*10-19kg/m2.s= -D*(-215kg/m4)
D=5.91*10-12m2/s.
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In industries titanium is hardened through diffusion of carbon. The co...
Given Data:
Concentration at 1mm, c1 = 0.25 kg/m³
Concentration at 3mm, c2 = 0.68 kg/m³
Rate of carbon entering surface, J = 1.27 × 10⁻⁹ kg/m²s
To find: Diffusion coefficient of carbon, D
Formula: Fick's second law of diffusion
∂c/∂t = D(∂²c/∂x²)
Where,
c = Concentration of carbon
t = Time
x = Distance
D = Diffusion coefficient
CALCULATION:
Let's consider the concentration gradient, ∆c = c2 - c1 = 0.68 - 0.25 = 0.43 kg/m³
Let's consider the distance, ∆x = 3mm - 1mm = 2mm = 0.002m
Let's consider the time, ∆t = 1s
From Fick's second law of diffusion,
J = -D(∆c/∆x)
Substituting the given values,
1.27 × 10⁻⁹ = -D(0.43/0.002)
D = -1.27 × 10⁻⁹ / (0.43/0.002)
D = 5.91 × 10⁻¹² m²/s
Therefore, the diffusion coefficient of carbon is 5.91 × 10⁻¹² m²/s.
ANSWER: Option (A) 5.91 × 10⁻¹²