Zinc plating test methods can be divided into non-destructive, destructive and special tests according to different needs
Author: Anna
Zinc plating test methods can be divided into non-destructive, destructive and special tests according to different needs, as follows:
I. Non-destructive testing methods
Magnetic Thickness Measurement
Measurement of zinc layer thickness using magnetic field changes, applicable to ferromagnetic substrates (e.g. steel), the accuracy of which is affected by the surface roughness of the substrate.
Eddy current thickness measurement
Measurement of zinc thickness on non-magnetic metal substrates (e.g. aluminium, copper) based on the eddy current effect, non-destructive and fast.
X-ray fluorescence (XRF) method
Analyses the composition and thickness of the zinc layer by X-ray excitation fluorescence, suitable for complex shaped workpieces.
II. Destructive testing methods
Microscope method (cross-section method)
Intercepting the sample and directly observing the cross-section of the plating layer through a microscope can accurately measure the thickness and uniformity, but it is necessary to destroy the sample.
Weighing method
After removing the zinc layer by chemical or physical methods, weigh the sample and calculate the average thickness according to the weight difference, suitable for laboratory analysis.
III.Other specialised tests
Adhesion test
Scribing method: A grid is scribed and then peeled off using adhesive tape to observe the zinc layer peeling off;
Drawing method: testing the bonding strength of the zinc layer to the substrate by tensile force.
Corrosion resistance test
Salt spray test: simulates a marine or industrial environment to assess the corrosion resistance of the zinc layer (e.g. neutral salt spray NSS, acetate spray ASS);
Copper sulphate spot-drop test: observe the discolouration time by spot-dropping the corrosive solution to quickly determine the corrosion resistance.
Electrochemical test
Analyse the electrochemical behaviour and corrosion rate of the zinc layer through polarisation curves, electrochemical impedance spectroscopy (EIS), etc.
Mechanical Property Tests
Including tensile, bending and impact tests to assess the mechanical properties of galvanised materials.
Chemical composition analysis
Detect the composition of the coating and the plating solution (e.g. zinc ions, free NaCN concentration) using energy spectrometry (EDS) or chemical titration.
IV. Environmental and Functional Tests
High and low temperature cycling test: verify the stability of the plating layer under temperature change;
UV aging test: simulate sunlight irradiation to evaluate the weather resistance of the plating layer;
Abrasion resistance test: Measure the hardness and anti-abrasion ability of the plating layer by rubbing instrument.
The above methods need to be selected in conjunction with specific application scenarios and standards (e.g. ISO 1461, ASTM B633) to ensure comprehensive and reliable test results.