An expansion cone useful for expanding an expandable tubular, the expansion cone includes: a base material selected from a group consisting of alloyed steel, tungsten carbide coated alloyed steel, and cemented tungsten carbide; an intermediate buffering layer; and a coating deposited on an outer surface of the intermediate buffering layer; wherein the intermediate buffering layer is deposited between an outer surface of the steel alloy base material and the coating, wherein the intermediate buffering layer is one or more selected from a group consisting of Silicon (Si), Titanium (Ti), and silicon carbide (SiC), and wherein the coating is a diamond containing coating.