JEC COMPOSITES MAGAZINE - Issue #134 - May/June 2020 - 28

MANUFACTURlNG surface treatment

The violet light at the end of the tunnel

Sam Rogers,
Marketing Content Writer
Ushio Europe B.V.

xcimer vacuum-ultraviolet (VUV)
lamp technology and its comprehensive
collection of applications still appears
to be relatively unknown among composite
industry leaders. However, a surge in popularity for this versatile technology is spreading
enthusiasm from innovators across the worlds
of industry and science.
Ushio Europe has been refining its VUV lamps
for over 25 years and is the leading producer
of excimer light emitters. As the development
of thinner advanced materials has introduced
stronger and lighter products to end users,
the race is on to find solutions that enhance
the quality of these materials economically.

USHIO UV Excimer

Ushio Europe is perfecting a stress-free alternative to traditional composite treatment methods for automotive and
aerospace applications based on excimer UV technology.

Excimer has finally burst onto the scene,
providing simultaneous surface activation,
disinfection, matting, UV curing, and a fairly
new concept called Photobonding™.
Excimer eliminates UV safety
protocols with human-safe light
Ushio's ExciJet modules have been developed
to concentrate light wavelengths between 170
nm and 310 nm on the chosen substrates.
Within this wavelength range, ultraviolet
radiation is unable to penetrate the top layer
of the skin and, in fact, deactivates any bacteria
that may be present on the surface.
UV light has the deserved reputation of being
hazardous to humans. However, this only
takes place at wavelengths deeper than 354
nm. At 354 nm, UV light gains enough intensity that it is able to penetrate the epidermal
layer of the skin and cause molecular changes
in the layers beneath.
Yet one question remains on the minds of
prudent industrialists: why leave behind triedand-tested surface modification treatments
such as corona and plasma discharge? Ushio
Europe explains why their ExciJet series of
lamps can cure the quality assurance headaches of manufacturers across the world.
Surface treatments can cause
permanent damage to materials
Corona and plasma treatments are both electrical discharge methods, so the object being
treated receives a rather violent molecular impact to its surface. Electrical discharge occurs
when fluid particles in the air surrounding a
conductor are ionised to form a plasma, which

jec composites magazine / N°134 May - June 2020

in the case of corona and plasma surface
treatment is created by applying a high voltage
between two electrodes.
Within the resulting plasma, atoms and
molecules, such as oxygen, become excited
and are accelerated at the surface of the
substrate. As this impact takes place, the
matter violently sputters the substrate surface.
Sputtering is a significant energy transfer that
leads to chemical reactions, but also results in
the integration of excited molecules into the
molecular structure of the treated material.
These accelerated molecules carry a lot of
weight and their impact on the surface results
in a significant heat load.
No discharge? No damage!
Excimer's utilisation of VUV light to treat the
surface means there is no direct discharge
reaction or damage to the substrates. The
photons emitted from the excimer lamp
maintain a relatively low energy compared
to the accelerated particles in other treatment
methods. This softer approach means the
substrate surface does not become rough, a
far cry from the damage caused by corona
and plasma treatments.
Viewing a discharge-treated surface under an
electron microscope will reveal a moon-like
surface with large scattered holes resulting
from the elevated levels of molecular bombardment. When viewing the same material
type after excimer treatment, the surface
remains smooth, benefiting from a higher
level of homogeneity, thereby promoting
enhanced adhesive qualities. Ultimately,
the lower heat load from the "cold" light of

JEC COMPOSITES MAGAZINE - Issue #134 - May/June 2020

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