A nitrided layer in combination with post oxidation to create a black oxide layer increasingly replaces chrome plating. Especially plasma nitriding is a very environmental friendly process that diffuses nitrogen into the surface to increase wear resistance, fatigue strength and corrosion resistance. With a black oxide layer it results in a smooth and sleek black surface finish, great for applications like hydraulic cylinder bars, all kinds of pistons and many more. On top of that, it has a very aesthetic look and is able to retain lubricants such as oils. In addition a nitrided layer will not peel off, unlike chrome plating.