Cirrus Plasma System – The effect of surface treatments on interfacial bonding

Researchers from the School of Engineering at the University of Edinburgh have recently published an article which included surface treatments on interfacial bonding using  the Henniker Cirrus Atmospheric Plasma System.

The results displayed a significant improvement in the alloys surface wettability and hydrophilic properties.

The work and results are summarised below.
(cited from the Materials and Design publication. [1])

Henniker's Cirrus and Nimbus Atmospheric Plasma Treatment Equipment Range

Novel thermoplastic fibre-metal laminates manufactured by vacuum resin infusion: The effect of surface treatments on interfacial bonding.



In the paper, Resin-infused thermoplastic fibre-metal laminates (TP-FML) have been manufactured and the bond strength between the metal and composite was tested. The wettability, topography and chemical composition of the treated Al alloy sheets were studied by employing contact-angle goniometry, coherence scanning interferometry, profilometry and X-ray photoelectron spectroscopy.


Prior to surface treatments, the Al alloy sheets were acetone-wiped with lint-free tissues to degrease the surface and afterwards they were subjected to four different surface treatments; alkaline etching, acid treatment, electrochemical etching and an atmospheric plasma treatment using a Henniker Cirrus system.


Surface wettability:

One pass of the atmospheric plasma nozzle at 1mm/s decreased the contact angle from 82 ± 1° to 32 ± 2.5°. This also increased the surface energy from 34.3mJ/m2 to 63.5mJ/m2. The atmospheric plasma treatment showed the most improved contact angle and surface energy measurements out of all four treatments used, with the next best being the acid etching decreasing contact angle to 37 ± 3°  and increasing surface energy 61.05mJ/m2.

“The plasma treated Al alloy surface exhibited a significant improvement in the surface wettability due to increased surface polarity. The oxidation of the surface and the removal of the carbonaceous components made the Al surface more hydrophilic.”  [2]

Chemical Composition:

The X-ray photoelectron spectroscopy (XPS) method was adopted to determine the chemical composition on the surface of the treated Al alloy samples. The atomic fraction of carbon on the surface of the degreased-only Al alloy sample was ~72%, which was reduced to 48% after atmospheric plasma treatment.

Keywords; Fibre-metal laminates, Thermoplastic matrix, Surface treatments, Interface bonding, Mechanical properties

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