Metal or thermal spraying is a technology which protects or extends the life of a wide variety of products in the most hostile environments and in situations where coatings are vital for safety and performance.

In essence, metal spraying involves the melting of a raw material in wire or powder form, before propelling the atomised material towards the workpiece at high velocity to create a coating.

Different coating materials offer different types of protection. For instance, Aluminium/5% Magnesium or Monel(30% Nickel) coatings are ideal for the marine environment and preventing sea-water corrosion, while Molybdenum and molybdenum composites perform vital functions in automotive applications such as cylinder liners and synchromesh gears.

Arc Spray, Flame Spray, Plasma Spray and HVOF are all variations on the basic principles of metal spraying but offering different results and forms of operation.

The metallising process was invented in 1910 when Dr Schoop from Switzerland experimented with spraying heated metal powder. Since that time, a very sophisticated world market has emerged where over 400,000kg of metal powders are consumed every year.

Thermal spray applications have now penetrated all types of industries. World-wide, the aerospace industry is probably the largest user of thermal sprayed coatings accounting for approx 65% of all powder.

The Rolls Royce engines which power the Boeing 747 have over 2,000 parts. Of these, approximately one third are thermal spray coated. Common uses are thermal barrier coatings such as yttria-stabilised zirconia on combustion chambers, exhaust ducts and nozzle guide vanes and abradable materials such as aluminium polyester, aluminium graphite and nickel graphite on clearance control coatings to increase engine effciency.

Because there's no room for experimentation in the aerospace industry, thermal spray coatings are only utilised after intensive trials to optimise parameters for each specific material and function. While this cautious approach is essential in aviation, other industry sectors have been more innovative and open to using newer processes such as HVOF, HVAF and PURECOAT™ at their development.

Today, thermal spray is used in many engineering applications ranging from salvage or reclamation through to the provision of wear and corrosion resistant coatings. Further applications are found in the electrical, electronic, marine and transport industries.