Current densities alternative

Hard anodic films, 50-100/rm thick, for resistance to abrasion and wear under conditions of slow-speed sliding, can be produced in sulphuric acid electrolytes at high current density and low temperature. Current densities range from 250 to 1 000 Am , with or without superposed alternating current in 20-100g/1 sulphuric acid at —4—I- 10°C. Under these conditions, special attention must be paid to the contact points to the article under treatment, in order to avoid local overheating. 

The most significant parameter in the relationships given above is the equilibrium exchange current density io, which can be evaluated by extra-p>olating the linear t/ vs. log / curve to tj = 0, at which log / = log io. Alternatively, /q may be evaluated from the linear Ep vs. log / curve by extrapolating the curve to the equilibrium potential. ... 

A currently popular alternative <> the ah initio method is density ftmitwnal theory, m which the energy is expressed in terms of rhe electron density rather than the w-ivi-funcron itself. The idvautogc of this approach is that it is less demanding computationally, requires less computer nine-, and m some cases—particularly for d-mctal complexes—gives bet-ter agreement with experimental values than other procedures. 

Conductivity measurements were carried out by an alternating current method using 1 kHz, and measurements were taken at a current density in the range of 2,2-270 mA-cm 2. Six samples of each formula were... 

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