Kermetico HVAF ID Gun to HVAF Spray Metals and Carbides onto Internal Diameters
The High Velocity Air-Fuel (HVAF) ID gun is advanced equipment for the thermal spray deposition of quality carbide and metallic alloy coatings to protect internal surfaces of industrial equipment from severe wear and corrosion.
The AK-ID gun was developed in 2012, and since that time it has demonstrated robustness in the harshest environment, spraying internal diameters as small as 3.15 inches (80mm) to a length of up to 5 feet (1,500 mm) deep. Low power (just 30 kW) prevents the ID gun and a workpiece from overheating, and the efficient design of the gun allows for the effective spraying of Hastelloy-type and tungsten carbide coatings onto internal surfaces.
Interior surfaces frequently become a critical part of plant equipment lifecycles. The proper thermal spray coating improves abrasion and corrosion resistance of internal surfaces.
When considering the coating of inner diameters (IDs), vendors start to speak of spray angles, low deposition efficiency and porous layers that require sealing. Kermetico are different.
They developed their first internal diameter high-velocity combustion gun to spray oil refinery sleeves.
Those sleeves five years on, are still in service after the HVAF coating application. Since that time, the ID guns have deposited hundreds of kilograms of tungsten carbide, metal and alloy coatings on internal diameters of various pipe spools and tubular vessels.
As seen in these representative micrographs, the coatings are extremely dense, which allows us to recommend thinner coats than other coating processes require for wear and corrosion resistant applications.
Micrographs of tungsten carbide (WC-10Co-4Cr) coatings sprayed with the AK-ID gun in 4.0” (a) and 4.5” (b) ID auger barrels.
Features
Heating efficiency: Heating of the spray particles in the combustion chamber occurs at high pressure, where heat transfer is the most efficient. The size of the chamber provides a long residence time for spray particles to heat. Thus, the energy transfer efficiency increases noticeably compared to other high-velocity spraying methods. This results in much higher spray rates with HVAF guns produced by Kermetico.
Acceleration efficiency: Kermetico HVAF guns have a large nozzle diameter that eliminates the nozzle length limitations of HVOF guns. The spray particles can be accelerated up to the gas velocity. The spray particle velocity is often purposely limited to reach the target deposit efficiency (cost) and decrease residual stresses in the coating.
Uniform coating quality: The diameter of the spray particle jet is several times smaller than the nozzle diameter. The influence of the nozzle wall on the spray particle velocity is negligible, providing even acceleration of the powder and improved consistency of the coating structure.
Applications
We have found that the Kermetico ID gun is an effective instrument for spraying tungsten carbide and Hastelloy-type coatings.
The Kermetico HVAF AK-ID system is ideal for lining inside diameters of pipes, tubes, barrels, and cylinder bores which can be effectively rotated.
The gun provides uniform non-permeable wear and corrosion resistant cermet coatings with a spray rate of 5 kg or 11 lbs. per hour, achieving a tungsten carbide coating hardness of 950 HV300 in internal diameters less than 4” and over 1,100 HV300 hardness in 4.0” (100 mm) and larger internal diameters.
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