Synthesis of porous magnetite Fe₃O₄ and its application in thermal control coatings as new black pigment

In the present work, firstly, porous magnetite Fe₃O₄ was synthesized using mesoporous silica molecular sieve (SBA-15) as a template. Finally, the infiltrated ferrous precursor into silica mesopores was subjected to an infiltration process, in order to obtain the porous Fe₃O₄. The structural, morphological, and porosity characteristics and optical property of as-synthesized material were investigated by X-ray diffraction, field emission scanning electron microscopy, N₂ adsorption, and diffuse reflectance spectroscopy. Evaluation of the obtained results indicated that the porous Fe₃O₄ has well-defined morphology and higher light absorption in the UV/Vis region than not only the common Fe₃O₄ and the other inorganic black pigments, but also common carbon black. Investigation of the prepared coating with this pigment indicated the higher absorption (0.98) and lower reflectance (~2%) than commercial black thermal control coatings (TCC) with inorganic pigments. This pigment presents the best selection for black TCC with inorganic pigment and stable in the space environment. The as-prepared porous magnetite Fe₃O₄ also has high surface area (~24.78 m²/g) and excellent magnetic properties (M_s = 70 emu/g) at room temperature.