GALVANIZING STEEL HARDWARE

Description

The main task of yellow galvanic galvanizing of steel hardware (bolts, nuts, screws, fasteners ) - protection against corrosion and increased service life. The thickness of the coating, depending on the requirements, can range from 6 to 50 micrometers. Applying a layer less than 6 microns is impractical, because the protective characteristics of zinc will be unacceptably low. Thicknesses greater than 15 microns increase the risk of exceeding tolerances. For example, after coating the threaded part of a bolt with a thick zinc coating of 40 microns, the thread diameter  will increase in size by 0.08 mm and the standard nut may not fit onto the bolt. In the bell, coatings of 6-12 microns are usually applied, a larger layer is applied on pendants. The thickness of rainbow chromate film is 0.25-0.5 microns and does not affect the diameter of the product. The content of hexavalent chromium in it ranges from 80 to 220 mg/m². The durability of yellow zinc in 5% salt spray is 200-300 hours. The corrosion rate of non-passivated zinc depends on pH:

Galvanizing can be carried out using different technologies. Shiny coatings are more hard and less flexible than semi-shiny ones. The type of passivation has virtually no effect on microhardness. The electrical resistivity is slightly higher than that of metallurgical zinc due to the inclusion of carbon and sulfur from the electrolyte in the coating composition (up to 1%). It should be remembered that the contact resistance of zinc may vary depending on the passivation method. Rainbow film is of medium resistance, relatively colorless, olive or phosphate. In a bell or drum, galvanizing is more efficient, but the parts hit each other, which can lead to clogging of the thread.

You can order rainbow galvanizing of steel according to GOST 9.305-84 by phone and email indicated in the section "CONTACTS".