Chromium is a kind of silver-white metal with a slight blue color. Modern scientific research has found that its relative atomic mass is 51.99, density is 6.98~7.21g/cm3, melting point is 1875~1920℃, standard electrode potential is Yushi /C, -0.74V, old “/ C, “-0.41V and P very E +/Cr dip-1.33V. Chromium metal passivates easily in air, forming a very thin passivated film on the surface, thus showing the properties of precious metals.
Chromium plating layer has a very high hardness, according to the composition of bath and process conditions, its hardness can vary in a wide range of 400~1200HV. Chrome-plated layer has good heat resistance. When heated below 500℃, its gloss and hardness have no obvious change. When the temperature is greater than 500℃, it begins to oxidize and change color, and when the temperature is greater than 700℃, the hardness begins to decrease. Chromium plating has low friction coefficient, especially dry friction coefficient, which is the lowest among all metals. So chromium plating has good wear resistance.
Chromium plating has good chemical stability and does not react in alkali, sulfide, nitric acid and most organic acids, but is soluble in hydrochloric acid (such as hydrochloric acid) and hot sulfuric acid.
In the visible light range, chromium has a reflection ability of about 65%, between silver (88%) and nickel (55%), and is superior to silver and nickel because chrome does not change color and retains its reflection ability for long periods of time when used.
Post time: Sep-08-2021