The coating/plating analysis
In order to prevent the problem of corrosion, wear, or fatigue fracture appeared in the process of storage and using of the steel material. all kinds of surface coating treatment has been widely used.Including the surface has been infiltrate with zinc, Al, Cr, V, Nb, B, etc. Coating technology include hot dip, electroplating, electroless plating and heat treatment, etc. Paint/coating not only can decorate the appearance of the parts and repair the defects of parts surface , but also can give special performance to the parts surface, including making the surface hardness , wear resistance, corrosion resistance, electrical conductivity and high temperature oxidation resistance to be higher. Involved products include home appliances, automobile, doors and Windows, metal fasteners and electronic products, etc.
The tested items
detecting the thickness of the coating,
Coating thickness is the vertical distance from the surface to the interface boundary layer of.as the situation of only having compound layer and the straight interface ,the determination of deep layer is simple. And in the permeation of diffusion layer, layer thickness should include compound layer and diffusion layer. the determinated methods of coating thickness include Coulomb's law method, metallographic method, eddy current method and X-ray fluorescence method.
Coating porosity test
In the process of permeation and Immersion , the elements of permeation spread in-diffusion, and iron elements spread out-diffusion, and the diffuse velocity of them is different, so in the compound layer, especially where it is near the surface will inevitably produce pore (or loose) .and .the quantity, size and distribution will directly affect the weldability of steel and service performance.
Coating crack test
In the process of management , it could let a brittle compound layer crack as the phase transformation stress,the crack also directly affect the service performance, therefore we should test the characteristics of the crack, that’s to say,we should test the crack length, number and distribution state.
In addition, the metal laboratory also can provide the coating composition analysis, surface stain analysis, surface hardness and adhesion strength analysis.
Plating thickness - coulomb's law method
Plating thickness - metallographic method
Plating thickness - electron microscope method
JB/T 7503-1994，ASTM B748-1990(2006)
Plating thickness - X ray method
The quality of the galvanized layer
GB/T 1839-2008，ISO 1460:1992(E)
Coating composition analysis
( spectroscopy )
Adhesion strength - methods of thermal shock / bending / thermal shock
SJ 20130-1992，ASTM B571，ISO 2819
Adhesion strength - hot and cold cycle , chromium coating crack , chromiumplating porosity