Treated metal surface corrosion resistance measuring - by variable frequency digital techniques using in-phase and quadrature components of electrolyte metal interface admittance

摘要

The sample, acting as an electrode (7), is subjected to a variable frequency alternating voltage (8) superimposed on the steady electro-chemical dissolution potential. The current produced is analysed using digital techniques. The output signal voltage (9) is derived from this current (4) passes to an amplifier with a gain which is preselectable from decade ranges. From the separated in-phase and quadrature components the real and imaginary parts of the admittance of the corrosive electrolyte-metal interface are measured. Following measurement at several frequencies the zero-frequency resistance is extrapolated from a graph.