METHOD OF DETERMINING PROTECTIVE CAPACITY OF CHROMATED ZINC COATING ON STEEL Russian patent published in 2009 - IPC G01N17/02 

FIELD: physics; measurement.

SUBSTANCE: invention pertains to testing materials and can be used for evaluating longevity of chromated zinc coating on steel in industrial atmospheres of operation regions. The method is realised by exposing the coated sample under investigation to acid mist in a chamber for 12 hours at (40±1)°C. The acid mist is created by dispersing a 0.06 %.vol. HCl solution and feeding sulphur dioxide gas with concentration 2.5 mg/m³ into the chamber. The sample is exposed to an air current with speed 2.7 m/s and UV radiation for 5 minutes after spraying the solution. The sample is then kept in the chamber for 12 hours. Mass loss of the sample is determined for the time before white volumetric products of zinc corrosion and the first corrosion centre in the steel appear. On a graph of mass loss (g/m²) versus time (days), lines are drawn in a defined way, the point of intersection of which allows for determination of the protective capacity of the chromate film on zinc coating. The protective capacity of chromated zinc coating on steel, taking into account its region of operation, is calculated using a given formula.

EFFECT: increased accuracy of measurement.

2 dwg, 1 tbl