Wear- and corrosion-resistant surfaces are needed to protect critical components in various industries. The High Velocity Oxygen Fuel (HVOF) process supplies this protection by producing very dense, hard coatings with fine microstructures.
The spray flame hits the substrate in the HVOF spraying process
High Velocity Oxygen Fuel (HVOF) spraying uses oxygen and fuel to form a combustible mixture. Liquid-fuel HVOF (HVOF-LF) generally uses liquid kerosene as the fuel. Gas-fuel HVOF (HVOF-GF) employs fuel gases such as propylene, propane, hydrogen, or natural gas (methane).
The fuel is thoroughly mixed with oxygen within the gun and the mixture, combusted and then ejected through a nozzle at supersonic velocities. The feedstock material, in powdered form, is fed through the gun, generally using nitrogen as a carrier gas. The ignited gases surround and uniformly heat the powder material as it exits the gun and is propelled onto the workpiece surface.
As a result of the high kinetic energy transferred to the powder particles the feedstock powder material generally does not need to be fully melted. The resulting coating has a very predictable chemistry that is homogeneous and has a fine granular structure.
Illustration of a spray gun for HVOF spraying with gas fuel
Illustration of a spray gun for HVOF spraying with liquid fuel
By utilizing a high-velocity stream of gas, along with a powdered coating material, the HVOF spraying process creates a dense, tightly adherent coating layer on surfaces, i.e. HVOF coatings. HVOF coatings have exceptional mechanical properties, such as high hardness, wear resistance, and corrosion resistance. Industries ranging from aerospace to automotive utilize HVOF coatings to protect critical components subjected to harsh environments.
Notably, the versatility of HVOF coating extends to various coating materials, including metallic powders such as tungsten carbide and chromium carbide, ceramic powders like alumina and zirconia, carbide powders offering exceptional hardness, and even thermal barrier coatings (TBCs) for high-temperature applications. These materials are selected based on the specific application requirements, ensuring tailored properties and optimal performance for diverse engineering components.
Faced with a unique challenge with its MX-30 e-SKYACTIV R-EV project: the car maker aimed to optimize the rotary unit of this model by transitioning from cast iron to aluminum, seeking to reduce weight by 15 kg while maintaining durability and performance. Oerlikon‘s advanced thermal spray solution using HVOF technology played a pivotal role in Mazda‘s transformation.
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