**2.2 "Casing-friendly" material stage**

"Casing-friendly" material has a low friction factor, resulting in lower casing wear. Small friction and friction heat can be produced when this hardbanding material is in contact with the inner wall of the casing. There are two main types of "casing-friendly" materials: one is the "amorphous" hardbanding material; the other one is the "crystalline" hardbanding material. The crystalline material refers to a material in which atoms follow a certain law in the arrangement. On the other hand, the material whose internal atoms are arranged in an irregular state is called the amorphous material [12, 13].
