Thermally stable color pigments with nanofiber coating

A method of increasing the thermal stability of iron oxide pigments comprising:

• placing iron oxide pigment in a coating material precursor solution, wherein the coating material precursor solution is a precursor of one or more of aluminum oxide and silicon oxide;
• treating the iron oxide pigment and the coating material precursor solution with ultrasound at a temperature of less than 100° C. to promote nanoparticle formation on the iron oxide pigment;
• and
• growing a coating from the coating material precursor solution to grow nanoparticles of one or more of the aluminum oxide and the silicon oxide on a surface of the iron oxide pigment such that the resulting iron oxide pigment is thermally stable to a temperature of at least 230° C.;
• wherein the ultrasound treatment occurs at a frequency where the ultrasound wavelength is approximately an integral multiple of a rod length of the iron oxide pigment with one of the treatment frequencies being between approximately 40 and 55 kHz;
• wherein the rod length is 714.3±137.5 nm.