Metal Coating Spray with Specialized Thermal Spray Equipment
Kermetico engineer alloy-specific high velocity thermal spray systems dedicated to spray metal coating with the best quality and cost. They also manufacture advanced coating systems for cold spraying metals: Al, Au, Ag, Cu, Sn, Ti, Zn and alloys.
The above image shows a typical micrograph of an HVAF aluminum Coating, 100x.
The Kermetico Specialised HVAF S Systems range consists of the following:
- HVAF SL – the Specialised HVAF SL System has been designed to metal spray with a low melting point temperature.
- HVAF STi – the Specialised HVAF STi System is designed for spraying of Ti alloy and titanium coatings in the air. The STi system allows repairing titanium alloy parts.
- HVAF SP – the Specialsed HVAF SP System is specifically designed for the spraying of precious metals, Gold and Silver.
As the Australian distributor for Kermetico HVAF/HVOF equipment, MSSA supply specialised Kermetico equipment for the spraying of metal for Corrosion and Wear Resistance.
Uncommon Substrates Spraying
Kermetico Makes Specialized HVAF Systems to Spray Metal Coatings and Alloyed Powder Compositions onto Uncommon Substrates such as Acme Threads, Thin Walls and Temperature Sensitive Materials.
The Kermetico HVAF process is extremely stable due to the utilization of micro-flame combustion technology enhanced with the catalytic insert.
Modular hardware design makes it possible to build specialized equipment: we adjust combustion chambers, nozzles and powder injectors to achieve optimized results.
A variety of fuel gases and the possibility of multiple additional gas injections make the process even more versatile and efficient.
Kermetico have engineered several systems optimized to spray particular powders. Here is the range of the Specialized guns’ possibilities.
| Feature | S.I. Units | U.S. Units |
| Feedstock | Powders up to 150 microns | |
| Combustion Temperature | 1,500 – 2,000oC | 2,732 – 3,632oF |
| Gun Equivalent Power | 20 – 200 kW | |
| Particle Temperature in the Jet | 900 – 1,600oC | 1,650 – 2900oF |
| Particle Velocity | 400 – 1,000+ m/sec | 1,300 – 3300+ ft./sec |
Why Does this Matter?
Once set up, the spray gun is technologically stable. That means that it will spray coatings with the required quality, spray rate and deposit efficiency with a broad range of spray parameters.
Why is That?
The gun designs are well-calculated and made of modern materials, so our spare parts experience extremely low wear. Depending on the erosive properties of the feedstock material we often get over one hundred hours of spraying from a nozzle.
SL System – Low Melting Point Spraying
The unique Kermetico Specialised HVAF SL System has been designed to metal spray with a low melting point temperature. It deposits bulk-like, non-oxidized, dense aluminum, tin, copper, zinc and alloyed metal coatings.
The twin wire arc and flame spray processes apply aluminum or copper with high spray rates along with high porosity and high oxide levels so that the coating is inexpensive while it is of poor quality.
The cold spray process sprays a coating without oxidation and with low porosity, but its low spray rate and high equipment and gas costs make this coating expensive.
The Kermetico SL HVAF system provides an option to spray low melting point materials, like zinc coating, at up to a 10kg (22 lbs.) per hour spray rate, without oxidation, and with an applied cost not substantially higher than twin wire arc spray.
Thermal Spraying a Tin Coating with the Kermetico SL High Velocity System. For more on this application, Click Here.
Process
- HVAF machine sprays metals and carbides at optimal temperature, not overheating it. That is how we are spraying bulk-like gas and liquid impermeable wear and corrosion resistant coatings.
- The HVAF SL Gun sprays metal powders, heated and accelerated by the air-fuel gas combustion products
- The mixture of compressed air and the chosen fuel gas flows into the combustion chamber through the orifices of a catalytic ceramic insert
- The initial ignition of the mixture results in the heating of the insert above the mixtures’ auto-ignition temperature, and then the hot insert continuously ignites the mixture
- When entering the gun, the compressed air cools the chamber and the nozzle assembly.
- Then part of the preheated air is mixed with the chosen fuel gas and combusted.
- The metal spray powder is injected axially into a wide combustion chamber.
- The powder exiting the chamber is propelled into the nozzle of chosen length and configuration, where it is accelerated to a velocity that may be over 1,000 m/s (3300 ft./sec.)
- When impacting a substrate, the spray powder particles form a metal coating
The above video shows the SL HVAF system’s ablility to clad 10+ mm layers of machinable aluminum, copper, and alloys.
Key Features
- Axial metal powder injection.
- Protection against feedstock oxidation.
- No metal evaporation in the coating process.
- No nozzle clogging.
- Uniform, dense, high-bond Al, Zn, Sn, Cu and copper alloys coatings.
- High metal spray rate:6 kg/hour (13 lbs./hour) for aluminum coatings.
- 10 kg/hour (22 lbs./hour) for copper, bronze, brass, tin and zinc coatings.
- Blast & spray operation capable.
- Air cooling (no need for water chiller, mobile friendly).
- Allows deposition of copper and its alloys (including brass, bronze and even some special grades of Cu-In-Ga) in “warm-spray” and “hot-spray” modes.
Click on the following link for more information on the HVAF SL Low Melting Point Spray System.
STi System for Spraying Titanium
The Kermetico STi was developed as an answer to an industry request for a uniform non-oxidized Titanium coating with a thickness of 50 to 250 microns. (0.002”-0.010”).
This Titanium-focused system sprays non-oxidized dense Ti and Ti alloy coatings.
This system is designed for spraying of Ti alloy and titanium coatings in the air. The STi system allows repairing titanium alloy parts.
Titanium is not an easy material to spray. It reacts with oxygen and nitrogen at relatively low temperatures. That is why most of the developers were trying to deposit it with a vacuum or an inert gas atmosphere. These approaches make the coating extremely expensive.
Kermetico have chosen a different approach, creating an inert atmosphere inside the high velocity thermal spray gun.
Kermetico HVAF STi System Spraying a Titanium Coating
A keen observer will notice in the picture that the Titanium jet is several times narrower than the nozzle and starts oxidizing around 150 mm (6”) from the nozzle.
Key Features
- High-velocity thermal spray titanium coatings in the air in an inert gas shroud.
- Low level of oxidation, silver-like coating appearance.
- Dense coating.
- For corrosion resistant coatings and material build-up.
Sprayed Ti Alloy and Titanium Coatings Properties
- The two most useful properties of titanium are corrosion resistance and the highest strength-to-density ratio of any metallic element.
- In its unalloyed condition, titanium is as strong as some steels but less dense.
- Like aluminum and magnesium, titanium metal and its alloys oxidize immediately upon exposure to air.
- Titanium readily reacts with oxygen at 1,200°C | 2,190°F in the air, and at 610°C ] 1,130°F in pure oxygen, forming titanium dioxide.
- It is slow to react with water and air at ambient temperatures because it forms a passive oxide coating that protects the bulk metal from further oxidation.
- When it first forms, this protective layer is only 1–2 nm thick but continues to grow slowly; reaching a thickness of 25 nm in four years.
- Atmospheric passivation gives titanium excellent resistance to corrosion, almost equivalent to platinum, capable of withstanding attack by dilute sulfuric and hydrochloric acids, chloride solutions and most organic acids. However, titanium coating is corroded by concentrated acids.
Titanium Spray Coating Applications
Due to high resistance to corrosion by sea water, titanium and its alloys are used to make:
- Propeller shafts.
- Rigging.
- Heat exchangers in desalination plants.
- Heater-chillers for salt water reservoirs and aquariums.
- Aerospace parts.
- Housings and components of ocean-deployed surveillance and monitoring devices for science and the military.
Click on the following link for more information on the HVAF STi System for Spraying Titanium.
SP System for Gold and Silver Spraying
It is critical to have a stable and predictable technological process working with precious metals.
The Kermetico SP High Velocity Air Fuel (HVAF) gun heats silver or gold powder just below their melting points which prevents material evaporation.
Then it delivers hot powder to the solid metal substrate at supersonic speed and deposits it densely.
With this system, you will not lose your precious metals due to evaporation. Most of it will be deposited as a high-quality coating; the remainder will go into your filtration system.
The HVAF SP System is specifically designed for the spraying of precious metals, Gold and Silver.
A Silver Coating Deposited by the Kermetico HVAF-SP System
This HVAF system is well suited for a precious metal coating process due to its low combustion temperature, high technological efficiency and process stability. The temperature of propane combustion in air – 1,980 °C (3,600 °F) is enough to preheat precious metal particles in the jet below their melting point as the dwell time is too short to melt them. Additionally, we protect axially injected particles from overheating in the combustion chamber with inert gas. We avoid metal deposition on the combustion chamber and nozzle walls by computational flow modeling and maximize deposition efficiency by engineering it into the trouble-free technology. And we supply spare parts that will not wear out for hundreds of hours, providing consistent plating quality and precious metal deposition efficiency. As a result, you will get a high-bond, 100% dense metal silver or gold coating with minimized (and predictable) material loss.
Key Features
- Axial powder injection.
- Protection against feedstock oxidation.
- No precious metal evaporation in the coating process.
- Deposition of uniform, dense, high-bond gold and silver coatings 50-500 microns (0.002” – 0.020”) thick.
Click on the following link for more information on the HVAF SP System for Gold and Silver.
For more information on this equipment, call us on 07 3823 1004, or email us using our contact form.