The invention relates to a spray powder with a superferritic iron-based compound for the thermal coating of a substrate, wherein the spray powder includes, apart from impurities, a chemical list from the list of chemical elements consisting of C, Mn, Cr, Mo, Ni, Nb, P, S, Si, Fe, Al, O, and Zr. In accordance with the invention, the spray powder has the following chemical composition: C at a maximum up to 0.7% by weight, Mn at a maximum up to 0.7% by weight; Ni at a maximum up to 0.5% by weight, Nb at a maximum up to 1.2% by weight, Pat a maximum up to 0.1% by weight, S at a maximum up to 0.1% by weight, Si at a maximum up to 0.2% by weight, Cr in the range from 20% to 40% by weight, Mo in the range 2.0% to 6% by weight, and a ceramic component Al2O3/ZrO2 up to a maximum of 50% by weight, with the remainder being Fe, and otherwise a total of a maximum of 0.4% by weight of further chemical components being contained as impurities. The invention furthermore relates to a substrate, in particular to a brake disk, having a superferritic thermal spray layer.