Diffusible hydrogen determination

American Welding Society, Standard Methods for Determination of Diffusible Hydrogen Content , ANSI/AWS, A4.3-93, AWS, Miami, FL, (1993). 

Smith 11, R.D., Benson, D.K., Maroef, I., Olson, D.L. and Wildeman, T.R., The Determination of Hydrogen Distribution in High Strength Steel Weldments Part 2 Opto-Electronic Diffusible Hydrogen Sensor , AWS, Welding Research Supplement, (1997), pp. 122-126. 

Figure P6.4 shows the logarithmic dependence of the adsorption of chloride ions, log(T - r/r, on time, /(min). The adsorbing metal is aluminum, the concentration of chloride ions in solution is 1(T3 mol dm-3 at pH 12, and the potential in the hydrogen scale is -0.9 V. On the assumption that the adsorption is diffusion controlled, determine the standard free energy of adsorption of chloride ions on the surface concerned. 

The requirements for the base plates for the testpiece assemblies, for the consumables under test and for the welding fixtures are exactly the same as for the determination of diffusible hydrogen. Welding is also carried out using the same procedure, with storage of samples at dry ice or liquid nitrogen temperature until required for analysis. 

Part 3 1988, Primary method for the determination of diffusible hydrogen in ferritic steel weld metal. 

If the hydrogen diffusion alone determines the curve, then j j,, and... 

By assuming that the pressure loss of one of the reactants, say hydrogen, determines the concentration over-voltage and that the pressure drop between the bulk and the TPB region is linear, a simple expression for the concentration over-voltage can be derived as follows. If the system is at steady state, then the absolute rate of diffusion of the gas for a unit of geometric area must be equal to the current. Therefore... 

The Barnacle Electrode Technique for Determination of Diffusible Hydrogen Concentration... 

Up to the present the principal interest in heteroaromatic tautomeric systems has been the determination of the position of equilibrium, although methods for studying fast proton-transfer reactions (e.g., fluorescence spectroscopy and proton resonance ) are now becoming available, and more interest is being shown in reactions of this type (see, e.g., references 21 and 22 and the references therein). Thus, the reactions of the imidazolium cation and imidazole with hydroxyl and hydrogen ions, respectively, have recently been demonstrated to be diffusion controlled. ... 

---