The Ideal sandpaper for difficult metals for example iron or steel is aluminum oxide, although the top sandpaper for softer metals for example aluminum or brass is silicon carbide. Silicon carbide is a really tricky, synthetically produced crystalline compound of silicon and carbon. Its chemical formula is SiC. It is https://www.quora.com/profile/Trevor-Flatcher-2/Silicon-Carbide-in-wind-power-equipment-applications-Silicon-Carbide-in-Wind-Power-Equipment-Applications-Silicon-Carb