"Engineered Surfaces for Exceptional Performance"
"Engineered Surfaces for Exceptional Performance"
What is Metal Spray / Thermal Spray?

 

Metal Spray is a process used all over the world, where molten metal or softened particles are applied to a prepared surface (substrate) to enhance its properties (hardness, anti-corrosion, wear, dielectric, restoring dimensions etc.).

The process is predominantly used for anti-corrosion and rebuilding engineering dimensions and has been used in every conceivable industry including Aerospace, Automotive, Biomedical, Agriculture, Space Travel, Power Generation, Infrastructure, Mining and many more applications.

No solvents or chemicals are used.

Metal Spray is the ideal surface to receive any top-coating from painting to powder-coating.

Our Metal Spray equipment consists of Arc Spray, Flame Spray, Plasma Spray, High Velocity Air-Fuel (HVAF), High Velocity Oxygen-Fuel (HVOF) and Spray Weld Equipment. More information on each process is available by clicking on the relevant tabs.

metal-spray-originate

Dr Max Ulrich Schoop (pictured above) pioneered metal spraying in the early 1900’s when he, whilst firing pellets out of a toy cannon he had bought for his young son, discovered that molten lead and zinc would stick to almost any surface.

The metal/thermal spray/metallizing process is a coating procedure used to change the surface properties of a part by adding a layer(s) of material to increase many factors:

  • Durability
  • Hardness
  • Wear resistance
  • Increase or decrease in friction
  • Increase of corrosion protection
  • Change electrical properties
  • Replacing worn or damaged material

The materials used in this coating procedure can be:

  • Metallic
  • Ceramic
  • Cermets
  • Plastic

Substrate materials include:

  • Metals
  • Glass
  • Carbon Fibre
  • Plastics
  • Plaster
  • Polystyrene
  • Ceramics
  • Wood

How Does Metal Spray compare with Painting?

  • Materials are of consistent quality and purity, no mixing required before application.
  • Materials have an infinite shelf life if stored correctly.
  • Fewer process steps required. This allows simpler quality control and fewer opportunities for error.
  • Sprayed components require no protracted curing or drying times giving superior utilisation to floor space.
  • Sprayed Zinc, Aluminium and their Alloys give effective corrosion resistance and protection immediately.
  • Sprayed metals are more robust than paints and can withstand rougher usage.
  • Even if the sprayed layer is damaged, the sacrificial action prevents corrosion.
  • Metals can be sprayed in a wider range of climatic conditions (temperature and humidity) than paints.
  • The materials used since the early 1900’s have not changed they are still in existence today, whereas numerous paint systems have been superseded many times over.

How Does Metal Spray compare with Galvanising?

  • Low heat input during spraying eliminates the risk of component distortion.
  • There is no limit to the size of component to be treated.
  • Components can be treated on site, meaning there are no transport or waiting issues.
  • Metal spraying is used to restore corrosion protection on damaged areas of welded galvanised steel and International Standards exist covering this.
  • Coating thickness can be varied from area to area to provide extra protection in critical areas.
  • The Metal Spray process is not limited to Zinc as Aluminium, Steels, Bronzes etc. can also be applied for a variety of applications.
  • No re-work required from galvanising dross.
  • The Metal Spray coating is porous and therefore the perfect surface to accept paint (that’s if required as it is not necessary).
    • No need to pre–etch etc.
Is this new technology?

No, the Metal Spray process has been in existence since the early 1900’s and is used in numerous applications all around the world. Check out our Industry Applications for more information.

How does Metal spray / Thermal spray compare with Galvanising

The process of Metal Spraying/Thermal Spray/Spray Galvanising refers to the same process which has been in existence since the early 1900’s and is a process used worldwide.

The Metal Spray process involves the melting of a wire and projecting it onto the work piece in order to provide a coating that can be tailored to suit the environment into which the component will be located.

How does Metal Spraying compare with Galvanising?

  • Low heat input during spraying eliminates the risk of component distortion.
  • There is no limit to the size of component to be treated.
  • Components can be treated on site, meaning there are no transport or waiting issues.
  • Metal spraying is used to restore corrosion protection on damaged areas of welded galvanised steel and International Standards exist covering this.
  • Coating thickness can be varied from area to area to provide extra protection in critical areas.
  • The Metal Spray process is not limited to Zinc as Aluminium, Steels, Bronzes etc. can also be applied for a variety of applications.
  • No re-work required from galvanising dross.
  • The Metal Spray coating is porous and therefore the perfect surface to accept paint or powder coat (if required as it is not necessary).
    • No need to pre–etch etc.
Does Metal spray use solvents?

No, the process only uses a heat source through which a powder or wire is fed, melted and projected onto the substrate.

How does it compare with welding?

Metal Spraying Offers the Following Advantages:

  • Low pre-heat or no pre-heating required
  • No heat treatment is necessary after coating
  • Little heat is transferred to the substrate during coating
  • No risk of thermal distortion
  • Almost any substrate can be coated
  • There is no dilution of the coating by the substrate material
  • A wider range of coatings can be applied
  • Operator skill requirements are lower
  • Better control over deposit thickness
  • Machining allowances are reduced, thus saving material
  • Machining times will also be reduced
Do I have to paint / powder coat the coating afterwards?

No, it is not necessary to paint or powder coat the coating afterwards. However, in doing so, when correctly applied, it can enhance the life of the coating further. As the colours of Metal Sprayed coatings are limited, a paint or powder coat layer on top of the Metal Sprayed layer is often used for decorative purposes.

How does Metal spray compare with painting?

Metal Spraying Offers the Following Advantages Over Painting:

  • Materials are of consistent quality and purity, no mixing required before application.
  • Materials have an infinite shelf life if stored correctly.
  • Fewer process steps required. This allows simpler quality control and fewer opportunities for error.
  • Sprayed components require no protracted curing or drying times giving superior utilisation to floor space.
  • Sprayed Zinc, Aluminium and their Alloys give effective corrosion resistance and protection immediately.
  • Sprayed metals are more robust than paints and can withstand rougher usage.
  • Even if the sprayed layer is damaged, the sacrificial action prevents corrosion.
  • Metals can be sprayed in a wider range of climatic conditions (temperature and humidity) than paints.
  • The materials used since the early 1900’s have not changed they are still in existence today, whereas numerous paint systems have been superseded many times over.
How does Metal spray compare with electroplating?

Benefits of Metal Spraying Over Electroplating:

  • Adhesion is usually better
  • Non-metallic surfaces can be treated
  • Engineering alloys can be applied as coatings
  • Thicker deposits can be applied
  • There is no risk of Hydrogen embrittlement
  • Deposition rates are higher
  • There is no component limitation size
  • Coatings can be applied on site
  • There is no effluent disposal problem
  • Complex chemical control techniques are not required.
Can I use Metal spray on site applications also?

Yes, the Flame, Arc and HVOF processes can all be operated on site as they are available in mobile forms. For any on-site scenarios, the same standards of Health & Safety procedures need to be applied after undertaking a site risk assessment.

Do International Standards exist?

Yes, over the years the Metal Spray Industry has developed International Standards (ISO) as well as regional standards based on the International ones. The standards cover such things as:

  • Technical supply conditions for wires, rods, cords and powders
  • Approval testing procedures for sprayers
  • Acceptance Inspection of equipment
  • Protective coating procedures
  • Design of articles to be metal sprayed
  • Quality requirements for sprayed structures and more
How do I prepare the surface ready for Metal spraying?

If you are applying an anti-corrosive coating of Zinc, Aluminium or one of their alloys to a substrate, the surface would need to be clean and dry and then grit-blasted. If an engineering coating is being applied, the component should be de-greased and  pre-machined normally by turning a rough thread.

If the component has been in service and/or running in oil, pre-heating the component to between 260°C and 370°C and maintaining this temperature until oil ceases to come to the surface (or until all smoking stops) will satisfactorily clean the component.

Can I use sand to blast the component?

No, the media to be used for surface preparation should be:

  • Metallic Grit - Normally Angular Chilled Iron
  • Non-Metallic Grit – Aluminium Oxide
  • On-Site Blasting – Garnet or Copper Slag
What coating thickness can I apply?

Generally speaking there is no limit. However, from a practical point of view, excessive coating thickness is unnecessary. In some cases the coating thickness may be determined from standards that will give life expectancy until first maintenance, in other cases it can be the requirement necessary to restore a part to its original condition.

If I apply an Anti-corrosive coating what guarantees can I give my customer?

The International Standard BS EN ISO 2063 as well as AS/NZ 2312 gives recommendations of coating thickness and time until first maintenance.

In North America, the Metal Spray process is known as “Metallizing” or “Thermal Spray”, with early work being carried out by the American Welding Society (AWS) who in 1953 exposed panels coated with flame sprayed zinc and aluminium and various sealers. Very favourable results were reported after 19, 34 and 44 years of exposure at coastal and industrial sites. This work was followed up by the US Army Corps of Engineers with successful trials of Metal Spray as a more abrasion resistant coating than vinyl on dam gates, and which resulted in a comprehensive design manual (USACE, 1999) which is available on the internet.

The US Federal Highway Agency noted (FHWA 1997) that work by the AWS and US Navy showed that “properly applied metallized coatings (zinc, 85% Zinc/15% Aluminium, and Aluminium) of at least 6 mils thickness provide at least 20 years of maintenance free corrosion protection in wet, salt-rich environments and are expected to provide 30 years of protection in most bridge exposure environments”. The FHWA has sponsored several research projects coating steel bridge beams with TSM, including one of environmentally acceptable materials which found that the thermal sprayed zinc (TSZ) systems were the best performing over 40 coating systems tested (which included top coated and single coat “high-ratio” and other inorganic zinc silicates) with no undercutting at scribe marks after 6.5 years exposure, and had the lowest Life Cycle Cost.

Thermal Sprayed Aluminium (TSA) has been widely used in offshore oil and gas industry and by 1997 over 400,000 sq. metres of TSA had been applied to oil platforms in the North Sea to provide corrosion protection to flare stacks, riser pipes in the splash zone and submerged tethered legs (e.g. Conoco’s Hutton platform built in 1984). Experience indicated that TSA coatings, when properly applied and with the use of specific sealer systems, will provide a service life in excess of 30 years with zero maintenance required.

In short, the years of testing and results which have accumulated into the various standards demonstrate the coatings ability to withstand the harshest of environments and to with stand the test of time.