Combustion Wire Thermal Spray Process Metal Spraying
Schematic Diagram of The Combustion Wire Thermal Spray Process
(also known previously as Flame Spray, Metallizing, and Metal Spray Processes)
A Complete Combustion Wire Thermal Spray (Flame Spray) Process Installation
The Combustion Wire Thermal Spray Process formerly known as
Metallizing, Flame Spray and Metal Spray Processes was
first invented in 1910 by Schoop in Switzerland
Old Type Schoop Gun
Recent Gun Spraying 13% Chromium Steel
The flame spray processis basically the spraying of molten
metal* onto a surface to provide a coating. Material in wire form is
melted in a flame (oxy-acetylene flame most common) and atomised using
compressed air to form a fine spray. When the spray contacts the
prepared surface of a substrate material, the fine molten droplets
rapidly solidify forming a coating. This flame spray process carried
out correctly is called a "cold process" (relative to the substrate
material being coated) as the substrate temperature can be kept low
during processing avoiding damage, metallurgical changes and distortion
to the substrate material.
This flame spray process has been extensively used in the past and
today for machine element work and anti-corrosion coatings.
* Ceramics and cermets can be used in rod or composite wire form.
Common materials Sprayed:
Zinc and aluminium for anti-corrosion cathodic coatings on steel
Nickel/aluminium composite wire for bond coats and self-bonding coatings
Molybdenum for bond coats
Molybdenum for hard bearing applications, excellent resistance to
adhesive wear, used on piston rings, syncromesh cones and journals.
High Chromium steel for many applications requiring hard and wear
resistant coating
Bronzes, babbitt for bearing applications
Stainless steels, nickel and monel for anti-corrosion and wear
Aluminium, nickel/aluminium for heat and oxidation resistance
Process Advantages:
Low capital investment
Simple to operate
Wire form cheaper than powder
Deposit efficiency very high
Possibly still best for applying pure molybdenum coatings for
wear resistance.
Portable system
Preheating facility built in, unlike arc spraying
Possible to use system in areas without electricity supply
Process Disadvantages:
Limited to spraying materials supplied in wire or rod form
Not capable of the low oxide, high density and high strength
coatings of plasma and HVOF
