HVOF Services (High Velocity Oxygen Fuel thermal spray)

The HVOF process is a high velocity, low temperature coating process. HVOF is a thermal spray system utilizing the combustion of gases, such as Hydrogen or a liquid fuel such as kerosene. The process creates a very high velocity which is used to propel the particles at near supersonic speeds before impact onto the substrate. One of the basic rules of spraying is that high combustion pressure = high gas velocity, high particle velocity and resulting high coating quality.

The success of HVOF coatings in the aircraft industry paved the way to the industrial markets including textile, steel, plastic, paper/pulp, chemical and power generation. The HVOF applications are nearly endless.

How does it work

HVOF (High Velocity Oxy-Fuel) is a process that utilizes supersonic acceleration of coating material to several times the speed of sound. The tremendous impact energy fuses the coating particles to the part surface to form an extremely strong coating. Both, kinetic and thermal energies are combined in a very effective fashion.

Fuel and oxygen are fed into the spray gun where they're ignited in the internal combustion chamber providing the energy source for this unique coating system. The desired material in powder form is injected into the stream from a controlled feeder, where it gets heated and accelerated as it's exiting the nozzle. The material stream reaches velocities of several times the speed of sound as it impacts the work surface to form a solid homogenous coating. Shock diamonds in the spray stream can be observed in front of the spray gun nozzle.

HVOF advantage

HVOF coatings use a unique system that has even faster material particle velocities, resulting in what is called "Impact Fusion". The particles are practically forge welded onto the surface and onto each other to form the coating. Higher particle velocities and Impact Fusion result in denser, better bonded coatings. Compressive stresses within the coating ensure very high adhesion (even at thicker coatings). Conventional or HVOF coatings have higher residual stresses which are in tension. This condition can cause cracking. This condition results in better coating integrity, enhanced corrosion properties and improved thermal fatigue properties.

TSS HVOF process provides carbide & metal coatings unsurpassed quality and wear life. The HVOF gun is essentially a liquid fuelled rocket running at high pressure. It imparts extremely high velocity molten coating particles. This velocity is much higher than other application methods. Higher Velocity means higher quality coatings in terms of bond, wear and corrosion.

Typical HVOF surface applications / industry

Compared to other processes

HVOF wear resistant coatings typically out-perform the wear life of hard chrome plating, hardening, anodizing and other hard facing techniques most of the time by a great deal.

Carbide coatings contain higher carbide percentage than other methods, which makes them more wear resistant at lower thickness.

TSS s.r.l is unique in its ability to work with its customers and provide them with a custom engineered solution for their specific surface engineering requirements. 

Due to our vast 30 years experience in the field of thermal spray coatings as well as the capabilities of our laboratory facilities, engineering department, and machining facilities, TSS s.r.l is highly capable of assisting you in any phase of thermal spray coatings.

High Definition HVOF video (58Mb)