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Inspection methods for electroplated products

2020-5-15


Electroplating technology is widely used in manufacturing industries, such as furniture, building materials, handicrafts, accessories, hardware and electrical appliances, etc. will have electroplated parts. Electroplating is the process of depositing metal or alloy on the surface of parts by means of electrolysis to form a uniform, dense, well-combined metal layer. The simple understanding is that it is a physical or chemical change or combination.
 
So how do we inspect the electroplated products? We introduce from the following aspects.

 
 

A. Appearance

Visual inspection, line of sight 500mm, visual acuity above 1.0 (including after correction), the light is natural light or bright fluorescent lamp.

B. Thickness measurement

Steel substrate: electro-galvanized, magnetic thickness gauge to test the total thickness. Chrome plating, magnetic thickness gauge for total thickness, and Coulomb thickness gauge for chromium thickness.

Hot-dip galvanized sheet: test the thickness of the galvanized layer with the weight difference before and after the sample is faded out:
Dezincification solution: 1.6g antimony trichloride, 250ml distilled water, 250ml analytically pure hydrochloric acid. Sample: area 40-60cm2, measure the weight of the sample before dezincification. Put the sample into the solution. After the violent reaction stops, take out the sample and weigh it. The difference between the front and back weight is the weight of the galvanized layer.

Calculation formula: g = (weight before zinc removal-weight after zinc removal) / sample area (g / m²)

Aluminum / zinc-aluminum alloy substrate: The electrolytic thickness gauge measures the total thickness and the thickness of the chromium layer.

Plastic substrate: copper-nickel-chromium plating, the thickness of each coating layer is measured with a Coulomb thickness gauge.

C. Corrosion resistance

According to GB / T10125 "Salt Spray Test for Artificial Atmosphere Corrosion Test", galvanized parts are tested by neutral salt spray test (NSS), and chrome-plated parts are tested by copper accelerated acid salt spray test (CASS).

D. Bond strength

Steel electro-galvanized: Use a blade or grid to mark 25 squares with an area of ​​1mm2 on the surface.

Chrome plating of metal parts: Use steel files or grinding wheels to grind the edges of the plated parts. The grinding direction is from the base metal to the coating. When grinding, pay attention to the direction of the applied force. The stress map separates the cover layer from the substrate.

Chrome plating of plastic parts: According to GB / T12610 "Thermal Cycle Test of Electroplated Coatings on Plastics", the test conditions are: one at -20 ± 2 ° C, 20 ± 5 ° C, 75 ± 2 ° C, and 20 ± 5 ° C for 1 hour each Cycle, requires 4 cycles.

E. Adhesion of passive film

For the electro-galvanized passivation film, use rubber or white cotton cloth to wipe the coating film back and forth evenly for 2-3 seconds, about 10 times, each time about 50mm long.
 
 
 

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