Thermal spraying produces high performance surfaces with a mechanical bond. There is no risk of distortion or metallurgical changes to the component. HP HVOF thermal spraying systems are available from LaserBond .
The High Pressure High Velocity Oxy-Fuel (HP HVOF) process sprays the molten droplets of coating material at high velocities, resulting in surfaces of the highest possible quality and performance.
HP HVOF coatings are dense, well bonded, and free of the oxides and tensile stresses found in coatings provided by other thermal spray processes. Consequently, they perform better in service. HP HVOF wear resistant surfaces provide more wear resistance than chrome plating, through-hardening and other hard facing techniques. They are more environmentally friendly and superior performing alternatives to chrome.
Surfaces combining resistance to corrosion and wear are also applied by HP HVOF.
HP HVOF materials include Tungsten Carbide, Chrome Carbide, Nickel alloys such as Inconel, Cobalt alloys such as Stellite, and various carbon and stainless steels.
The electric-arc spray uses a simple, low power arc drawn between two electrically charged wires. Arc spray equipment resembles GMAW (MIG) welding equipment, in the power source and wire feeding units. Common arc spray units are capable of spraying iron and copper alloys at rates up to 18kg/hr using only 12kW (42 MJ) of electricity.
Electric-arc spraying produces the fast coating rates of any technology. Electric-arc spray devices are thermally efficient and, as there is no flame or plasma, only little heat is transferred to the part being coated. This process is most suited to applications requiring large build-ups, where coating quality (density and oxide content) is not as important as coating cost and rate of deposition.
Plasma-arc spraying is a versatile process, spraying all materials that are considered sprayable. In plasma spray devices, an arc is formed in between two electrodes in a plasma forming gas, which usually consists of either argon/hydrogen or argon/helium. As the plasma gas is heated by the arc, it expands and is accelerated through a shaped nozzle, creating velocities up to MACH 2.
Temperatures in the arc zone approach 36,000°F (20,000°K). Temperatures in the plasma jet are still 18,000°F (10,000°K) several centimetres form the exit of the nozzle.
For economical dimensional restoration, Arc Wire and Combustion metal spraying systems are used. Typical materials include stainless and carbon steels, nickel alloys, bronzes, aluminium and copper.