High Velocity Oxy-Fuel (HVOF)

HVOF****0 supersonic flame spray equipment;

 

Working principal

 

In the High Velocity Oxy-Fuel (HVOF) process, powder is introduced axially into a chamber in which a gas flame is constantly burning under high pressure. The exhaust gas exits through an expansion nozzle which produces a high velocity gas stream. The powder particles are heated in this gas stream and transferred by it with kinetic energy to the surface of the work piece, forming a dense coating with excellent bonding properties.

 

Due to the moderate transfer of heat to the powder particles and to the work piece, which remains relatively cool, there is little metallurgical change to either the sprayed material or work piece.

 

Benefits of HVOF are:

Very Dense Coatings

Excellent Bonding

Minimal Metallurgical Changes

Minimal Temperature Effects

Additional Information:

 

 

 

HVOF****0 consists of :

 

Spray gun, powder feeding machine, control system, heat-exchanger system and pipeline system. Please refer to related photos as attached .

 

Feature :

 

It’s a compact equipment with the traits of easy-operating, stable working performance, low fuel consumption and high-quality coating .

 

Process combusts oxygen and propane gas(C3H8),, easy to operate with high production, operate steady and safety , dense , low porosity coatings…The mixture gas of oxygen and fuel gas is sent to the burning area of spray gun exit under high pressure. Then the burning gas is accelerated to form a supersonic flame with the help of peripheral compressed air. The spray powder is sent into burning flame and make a functional coating.

 

How to work:

 

The HVOF is fueled by propylene/ propane gas(C3H8)  &oxygen with compressed air softening the particles that are carried by nitrogen onto the surface being sprayed. The gun features a combustion chamber that actually expands the products going through a small orifice in the gun at high velocities producing "shock diamonds" exiting the nozzle. Gas velocities have been reported exceeding Mach 1 using this process. HVOF coating are very dense and produce an extremely high tensile bond strength.  uses this process on steel mill roll bodies, piston rods, internal pump surfaces, and as a replacement to chrome plating ,steel structure , multi-functional coating ,even more can use for MDPE/HDPE and various plastic coating .

 

 

 

Some parameters of HVOF ****0 spray gun:

 

 

 

 

 

Powder feeder's parameters of HVOF ****0 spray  equipment

 

 

 

 

 

 

 

Spray gun with manual and machine fixed way of operation. Gas needed: oxygen and propane (C3H8), weight: 2kg. velocity of spray particles: ≥**0m/s. It can work a long time stably.

 

 

 

Powder feeding machine :

Used to store spray powder and send them to burning flames according to technological requirements. The feeding gas is nitrogen, which pulverizes the powder and sends the pulverized particles along with the gas to spray gun. Can regulate the feeding velocity by the localizer on the regulating control panel.

Powder feeder's parameters of HVOF ****0 spray  equipment

 

 

Here are several coatings offered and their general properties:

 

(WC) Tungsten Carbide- based coating: Excellent wear resistance (abrasion, erosion, cavitation, friction, etc.) at low temperature <**0oC and very good resistance to corrosion/oxidation. Grindable, not-machinable. Surface finish after grinding as high as 4RMS

 

(CrC) Chromium Carbide-based coating: Excellent wear resistance (abrasion, erosion, cavitation, friction, etc.) at high temperature up to **0oC  and excellent resistance to hot corrosion/oxidation. Grindable, not machinable. Surface finish after grinding as high as 4RMS.

 

(T**0, Stellite) - Co based coating: Very good resistance to wear and corrosion/oxidation. Produces a hard and dense coating, low coefficient of friction. Operating temperature up to **0oC. Machinable and grindable.

 

(SS/Fe) Iron-based coating: Good for rebuilding, good resistance to wear and corrosion. Machinable and grindable.

 

(Ni-Al; Ni- Cr,Ni-Cu) Nickel-based coating: Good for rebuilding, good resistance to wear and corrosion up to **0 C. Machinable and grindable.

 

 

PE plastic and ceramic based coating……

 

MonelK****-based coating:

 

UNS N****0    /Other common names: Alloy K**0

 

Monel K**0 is a precipitation-hardenable nickel-copper alloy that combines the excellent corrosion resistance characteristic of Monel **0 with the added advantage of greater strength and hardness. These amplified properties, strength and hardness, are obtained by adding aluminum and titanium to the nickel-copper base and by a thermal processing used to effect precipitation, typically called age hardening or aging. When in the age-hardened condition, Monel K***0 has a greater tendency toward stress-corrosion cracking in some environments than Monel **0. Alloy K***0 has approximately three times the yield strength and double the tensile strength when compared with alloy **0. Plus, it can be further strengthened by cold working prior to precipitation hardening. The strength of this nickel steel alloy is maintained to ***0° F but stays ductile and tough down to temperatures of **0° F. Its melting range is ********0° F.

 

This nickel alloy is spark resistant and non-magnetic to ***0° F. However, it is possible to develop a magnetic layer on the surface of the material during processing. Aluminum and copper may be selectively oxidized during heating, leaving a magnetic nickel rich film on the outside. Pickling or bright dipping in acid can remove this magnetic film and restore the non-magnetic properties

 

nickel alloy K***0 has a greater tendency toward stress-corrosion cracking in some environments. Monel K***0 has been found to be resistant to a sour-gas environment. The combination of very low corrosion rates in high-velocity sear water and high strength make alloy K***0 particularly suitable for shafts of centrifugal pumps in marine service. In stagnant or slow-moving sea water, fouling may occur followed by pitting but this pitting slows down after a fairly rapid initial attack.

 

What are the characteristics of Monel K**0 coatings

 

Corrosion resistance in an extensive range of marine and chemical environments. From pure water to non-oxidizing mineral acids, salts and alkalis.

Excellent resistance to high velocity sea water

Resistant to a sour-gas environment

Excellent mechanical properties from sub-zero temperatures up to about **0C

Non-magnetic alloy

In what applications is Monel K***0 coatings used?

 

Sour-gas service applications

Oil and gas production safety lifts and valves

Oil-well tools and instruments like drill collars

Oil well industry

Doctor blades and scrapers

Chains, cables, springs, valve trim, fasteners for marine service

Pump shafts and impellers in marine service

Steel industry and steel alloy hardware……

 

Various derivatives are available. For more technical information, you can communicate with us. Our team of engineers will be happy to answer to your questions