MEASUREMENT METHOD OF THICKNESS OF NON-FERROMAGNETIC ELECTRICALLY CONDUCTING COATING OF STEEL Russian patent published in 2014 - IPC G01N27/90 

FIELD: measurement equipment.

SUBSTANCE: invention relates to non-destructive testing by eddy current testing method. The method consists in the fact that electromagnetic field is excited by a meter in an item by harmonic signal u₁(ωt); signal u₂(ωt) is received, which is proportional to the electromagnetic field of eddy currents, which is induced in the item; phase shift Δφ of signal u₂(ωt) is assessed relative to u₁(ωt), as per which the coating thickness is determined. At manufacture of the meter, the latter is calibrated; for that purpose, phase shifts Δφ are measured on measuring specimens with known coating thickness T_c and a certain type of a steel base; calibration characteristic Δφ₁(T_c) is saved. Prior to measurements, an instrument is calibrated; for that purpose, apparent thickness of the coating of the item with no coating is measured on the other steel base. Calibration characteristic Δφ₂(T_c) is calculated for items on such a base and used at measurements. A measurement complex consists of an eddy-current converter containing an armature with excitation windings, a phase detector, a balancing circuit, a tested item and a computer made in the form of a microcontroller.

EFFECT: higher accuracy.

2 dwg