Smal l diameter tubes
A precise
approach to
intricate tube
coating
Hardide Coatings, a specialist in
advanced surface coating technology,
has developed a new surface
engineering technology that can be
applied to complex geometries and
internal surfaces.
Advanced tungsten carbide-based
coatings can be used to protect both
internal and external surfaces of small
diameter, high-precision tubes from
wear, erosion and acidic corrosion to
increase critical component lifetime.
Using low temperature chemical vapour
deposition (CVD), the coatings can be
applied to a wide range of metallic
substrates. CVD coatings are crystallised
from the gas phase atom-by-atom,
producing a conformal coating that
can coat internal and external surfaces
and complex shapes. CVD takes place
in a vacuum chamber reactor at a
temperature of approximately 500°C.
The coatings are a metallic tungsten
matrix with dispersed nano-particles of
tungsten carbide typically between one
and ten nanometres in size. Dispersed
tungsten carbide nano-particles give
the material enhanced hardness that
can be controlled and tailored to give
a typical range of hardness of between
1,100 and 1,600Hv and, with some
types of Hardide coating, up to 3,500Hv.
Abrasion resistance is claimed to be up
to 12 times better than hard chrome or
500 times better than Inconel.
Nano-structured materials are known
to possess toughness, and crack
and impact resistant features. For
example, Hardide-T has proven this
by withstanding 3,000 microstrain
deformation without any damage; this
deformation will crack or chip most
other thick hard coatings.
A number of Hardide coating variants
are offered to solve problems such
as severe wear, corrosion or galling.
Applications range from metering,
control and shut-off valves, centrifugal,
rotary and axial pump components,
to the internal surfaces of very small
diameter nozzles and tubes as well as
bends, liners, elbow joints and flanges.
The coatings can also be used in severe
conditions such as in fracking and
oil drilling tools including mud driven
hydraulic parts.
Other successful applications include
ejector pumps and combustion tubes
for bio-fuel applications. In these
applications, the coatings are able to
withstand extremely abrasive, erosive
and corrosive operating environments,
such as sour well applications with H
2
S
and acidic fluids.
In the past, hard chromium electroplating
has been used successfully in many
applications, but this process is being
severely restricted or phased out under
REACH and OSHA environmental
and health and safety regulations, as
carcinogenic hexavalent chromium salts
are used in its production.
The patented coatings reduce
operational costs by saving downtime,
increasing productivity and improving
performance. With wear and corrosion
resistance combined with toughness
and ductility, Hardide technology is an
effective option for small diameter high-
precision tubes.
Hardide Coatings
– UK
Hardide coats internal surfaces
Hardide coating reactor being loaded
112
Tube Products International March 2014
