How
Does Thermal Spray Work?
Coating
materials are fed into a “gun” where they are heated
to a molten or semi-molten state by electric or combustion energy.
High-pressure
gas/air atomizes and propels the heated particles to a substrate
that has been cleaned and prepped by abrasive grit blast. The
heated particles impact the surface and flatten, which bonds
them to the substrate where they build to create a dense, tightly-bound
coating.
The
Benefits of Thermal Spray Coatings
Feature
- Low
porosity
- Wide
variety of materials
- Good
adherence to substrate
|
Benefit
- Low
permeability
- Excellent
corrosion or wear resistance
- Reliable,
long-lasting protection
|
While
welded overlays have been used for many years, improvements in
Thermal Spray equipment and process controls offer bond strengths
and thickness potentials that rival welding. Added benefits of
thermal spray are the relative smooth and consistent surface
finish “as sprayed” allowing for a quicker and more
efficient machine grinding to final size. Additionally, there
is no heat affected zone (HAZ) associated with thermal spray.
Because of the limited temperature exposure of thermal spray
(<300°F), substrate strength and temper characteristics
are not altered.
Ellison
Surface Technologies’ High Velocity Oxygen Fueled (HVOF)
coating method uses tightly controlled processing to apply an
array of coatings, such as tungsten or chromium carbide, in place
of hard chrome.
Some
of the HVOF benefits are:
- Reduced
oxide content
- Reduced
solutioning of carbides
- Neutral
or compressive stress
- Smother
as-sprayed surface
- True
coating uniformity
- Tensile
band strength >10,000 psi.
Thermal Spray Coatings adhere to a wide variety of substrates.
Their low permeability provides long-lasting protection against
corrosion and wear. Thermal spray coating methods include HVOF, Plasma, Flame Spray and Electric Arc.

Flame Spray – a low cost, mature
coating technology |

Plasma Spray – combines gases and
electrical power to achieve high temperature
capabilities with a broad base of materials,
including ceramics
|

Electric Arc – a high capacity, medium
cost technology good for a wide range of
materials possibilities |

HVOF – state-of-the-art, high velocity
process of dense, well-bonded surface
treatments | |