AISI 4340 membrane

Case Study 8.1—Evaluation of the Atomic Hydrogen Permeation Transients Through an AISI 4340 Membrane... 

IPZ analysis of the experimentally measured steady state hydrogen permeation rates through AISI 4340 steel are used to estimate hydrogen kinetic diffusion constants and hydrogen diffusivity within the ahoy. Atomic hydrogen permeation transients through an AISI 4340 membrane for different appHed potentials were studied in an electrolyte... 

Fig. 8.5 The atomic hydrogen permeation transition through an AiSi 4340 membrane as a function of time for different appiied cathodic potentiais in an eiectroiyte containing 0.5 M HCi04 and 0.25 M NaCi04 (pH 0.3) and the membrane thickness=0.3 mm [3]. Reproduced by the permission of The Eiectrochemicai Society.

All parts in contact with the process water, except gaskets and membrane of valves, must be AISI 316L stainless steel (distillator, tubing, heat exchangers, sensors, valves, fittings, tank, pump, and all instrumentation). 

Fig. 8.18 Hydrogen permeation transients through an AISI 4340 steel membraneat = 0.6 Vvs. SCE in the absence and presence of underpotential deposited lead. Cp, 2. =2x 10 M, membrane thickness=0.45 mm [3]. Reproduced by the permission of The Electrochemical Society.

Fig. E8.1 Plot of as a function of the hydrogen permeation current through an AISI 4340 steel membrane of 0.01 cm thick.

Chen SC, Tu GC, Hung CCY, Huang CA, Rei MH (2008) Preparation of palladium membrane by electroplating on AISI 316L porous stainless steel supports and its use for methanol steam reformer. J Membr Sci 314 5-14... 

Figure 14. Permeation transients for a AISI 410 stainless steel membrane (L = 0.5 mm) in acidified NaCl at 23 The steel was discharged after each transient, which is numbered according to its position in the sequence. — Theory - - - Range of uncertainty in fit to experimental data, which are shown as points. (After Ref. 62. Reprinted with permission from Acta MetalLy Copyright 1989, Pergamon Press pic.)...

Study of AISI 410 stainless steel, the membrane was spontaneously charged in acidified NaCl. The transients (///oo as a function of T = Dt/L ) were shown to be independent of membrane thickness, indicating that hydrogen permeation was controlled by diffusion but not whether a constant concentration or a constant flux best represented the input boundary condition. 

An SEM image of the surface and a section of a Pd membrane deposited on a macroporous AISI 316L support is shown in Fig. 3.5. Single crystals of palladium have agglomerated to form clusters of a few microns in size, obtaining the characteristic cauliflower type structure (Fig. 3.5a) the palladium layer uniformly covers the surface and is well anchored to the support the thickness is about 25 pm (Fig. 3.5b). 

Corporation is currently developing Pd-alloy membranes on AISI 310SC steel coated with a multi-graded ZrOj barrier for use up to 550°C and 20 bar. Pd-Au membranes, with thickness varying in the 3-9 pm range and alloy composition in the range 0-30% have been synthesized. Membranes... 

By using the two step procedure described above, Sintef (Norway) has produced Pd-23%Ag membranes, 2-5 pm thick, on a tubular macropo-rous AISI 316 L support 1/2 inch outer diameter (OD), supplied by Pall Corporation (Peters et al, 2009b). Sealing was obtained by clamping the film to the dense stainless steel tube ends (Klette and Bredesen, 2008). In this way membranes with a length of up to 50 cm were prepared and tested. 

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