The surface of the steel is mainly composed of FeO, Fe3O4 and Fe2O3. Fe2O3 is red, Fe3O4 is black, and FeO is blue. Since the proportion of various oxidized components in the iron varies with the oxidation process, the color is different. When the ratio of Fe2O3 is large, it is red, and when FeO is more, it is blue-gray. Kn95 Mask,Kn95 Respirator Mask,Kn95 Nonwoven Mask,Nonwoven Earloop Kn95 Mask Chongqing Yilun Sanzi new packaging Co., Ltd , https://www.yilunmask.com
