The thermal spraying was a technology that injects the powder or melted wire on the surface of substrate by flame, arc or plasma, and the sprayed coating will be deposited on the substrate. The drawing is shown below. Thermal spraying included: flame spray, arc spray, plasma spray and HVOF (High Velocity Oxyfuel Flame) process, the sheet is shown below. The coating material could be metal, alloy, ceramic, cermet and polymer.