Barrier life

Case C-0411. Hydrogen through a chromium barrier by grain-boundary diffusion, with Monte Carlo over the placeholder activation energy. Rules R10, R12 to R15, R20, R21. The sliders re-run R12, R13 and R15 in the browser.

Inputs

R10 mock, R00 quality C

Barrier thickness 150 nm

Grain size mock18 nm

Service temperature 50 °C

GB activation energy Q_gb quality C83 kJ / mol

Hydrogen pressure no effect in v17 MPa

Grain size from the simulated XRD peak, R10. Replace with a TKD map (.ang or .ctf) to remove the width on the grain-boundary fraction.

Sensitivity

R20, S_T on log10 t_bt

Q_gb

1.00

D0_gb

0.04

grain size d

0.01

barrier thickness h

0.00

Breakthrough

R13, R15, 4000 draws

Deterministic t_bt, R13

3.74 a

regime B

Median of draws

3.79 a

5 to 95 %: 494.6 h to 219.25 a

P(survive 19.99 a)

0.26

design life

D_eff at service T

3.18e-23

m2 / s, R12

Breakthrough before the design life in 74 % of draws; required: thicker barrier or coarser grains for P >= 0.9.

Measure next

R21, S_T x uncertainty / cost

Rank	Quantity	Instrument	S_T	After	Format
1	Q_gb	permeation or diffusion couple	1.00	10 %	.csv t and J
2	D0_gb	permeation or diffusion couple	0.04	10 %	.csv t and J
3	grain size d	EBSD	0.01	5 %	.ang, .ctf