Effect of impurity components in stainless steel dust on the coloring properties of the prepared black ceramic pigments

Stainless steel dust (SSD) can be utilized as the primary raw material for the production of Fe-Cr-Ni-Mn system black ceramic pigments because it is high in transition metal elements. However, in addition to the ingredients required for the preparation of black pigments, it also contains some impurity elements like Ca, Mg, Si and Zn, and the influence of these impurity elements on the coloring performance of the pigments is unclear. In this paper, pure chemical reagents were used as raw materials to simulate the main components of SSD for the solid-phase synthesis of black ceramic pigments doped with various impurity components (CaO, MgO, SiO2 and ZnO). The results show that the doping of MgO can improve the purity of the prepared black ceramic pigments, whereas CaO, SiO2 and ZnO can turn the pigments become reddish yellow. In the doped samples, ZnO and MgO mainly react with Fe2O3 to form ZnFe2O4 and MgFe2O4. In addition, CaO reacts with Fe2O3 to generate CaFe4O7. The reactions described above can increase the average crystallite size and distort the crystal lattice of the crystals in the pigment samples. Moreover, SiO2 exists in amorphous form among spinel grains.