Why does copper - clad steel ground bar become black?

Qingdao LeiKeShi power technology co., LTD., over the years committed to the production of copper clad steel grounding rods, accessories, affordable, copper plating processing services, for the national region supplies plating of copper, copper clad steel grounding rods, grounding round steel, copper clad steel, flat steel, copper clad steel wire, copper grounding flat wire products, such as small make up today to share with you why copper clad steel grounding rods for changing mowing? 

Copper clad steel grounding rod, after a period of time will be found that the color of the surface turned black, it should be said that all copper clad steel products will appear this situation. Because copper clad steel grounding rod or copper stranded wire and other products exposed to the air for a long time will react with oxygen molecules in the air, that is, oxidation, met with rain or air humidity will accelerate the oxidation reaction, so that the surface becomes black. This is normal because it is the oxidation that makes it resistant to corrosion. Or there is another situation that when purchasing copper-clad steel ground rod or copper-clad steel strand and other products, there will be a certain color difference in the same batch of products. This is because it is not a batch of electroplated products, so it is normal to have a small color difference.