Kermetico HVAF Benefits

Kermetico HVAF system sprays tungsten carbide HVOF coatings 

  • 5-7 times faster spray rate than Diamond Jet or JP5000 HVOF systems
  • 20-30?tter deposition efficiency than standard HVOF
  • 30% more stable parameters than HVOF system.


  HVAF Combo HVOF + HVAF costs one-half the operating cost per hour of the Diamond Jet or JP5000

HVAF HVOF Process Benefits

WC/Co/Cr Coating Feature Typical HVOF Gun Economy setup

Gun Balanced setup

Gun Ultra-quality setup Coating Porosity, %
Deposit efficiency, % 40-55%               60-70 48-58 36-42 <0.8
Hardness, HV300 1050-1250 HV300 1050-1250 1350-1450 1500-1700 <0.8
Apparent metallographic porosity <0> <0> <0> <0> <0.5
Bond strength (@0.040” thickness), PSI More than +12,000 PSI <0.3
Range of as-sprayed roughness, µm  3.5-4.5 micron Ra 1.0-3.2 micron Ra
Maximum coating thickness, mm  0.300- 0.500 mm 12.7 mm 3 mm 1.5 mm

HVAF – High Velocity Air Fuel process description

HVAF Process Inputs

  • Compressed Air
  • Fuel (propane, propylene, natural gas, etc.)

Carbide or Metal Powder is fed into a Kermetico HVAF thermal spray system. The gun burns the compressed air and fuel gas generating a high-velocity jet of gases. The powder is heated and accelerated in the gun.  The powder impacts a workpiece (substrate) to form a coating.

Kermetico HVAF systems produce coatings of high quality and efficiency is a result of

  1. Low combustion temperature of the air-fuel mixture
  2. Axial injection of the feed stock through the long combustion chamber.  In this long combustion chamber the controlled gas velocity provides sufficient time for the powder particles correct heating.

Powder acceleration occurs in the large diameter nozzle. The large diameter of the nozzle assures that the nozzle walls do not contact powder.  No contact reduces the nozzle wear dramatically.  That means that Kermetico can design a nozzle that is if needed for powder acceleration to over 1,200 meters per second.

HVAF Coatings are better quality than HVOF:

Low temperature
HVAF air-fuel combustion temperature is typically 1000°C lower than in HVOF oxygen-fuel combustion. This lower HVAF temperature is ideal for the gradual heating of the powder to or slightly above the metals’ melting temperature.

Low oxygen

The oxygen content in the HVAF combustion gas mixture is 80% lower compared to any HVOF process.

Ductile Coatings

Low Oxygen and lower temperatures prevent the oxidation of metals and the decomposition of carbides and their dissolution into the metal binder. HVAF process retains the original ductility of the powder feedstock material in the final coating.  The ductility is kept even when the hardness of the tungsten carbide coating exceeds 1700 HV300.

The HVAF process and HVAF coatings are better quality compared to HVOF coatings. The HVAF process is cooler than HVOF by 1,000 C .  The air fuel combustion produces much less oxides than high temperature oxygen fuel HVOF.  

Process Requirements
The HVAF process runs on a fuel gas such as Propane, LPG, or Natural gas (supplied at 140 psi), and compressed air (supplied by a 400 CFM air compressor at 125 psi). There are no additional requirements for water cooling.