Browsing Mechanical Engineering by Authors
High speed CO2 laser surface modification of iron/cobalt co-doped boroaluminosilicate glassHodgson, Simon D.; Waugh, David G.; Gillett, Alice R.; Lawrence, Jonathan; University of Chester (IOP Publishing, 2016-06-10)A preliminary study into the impact of high speed laser processing on the surface of iron and cobalt co-doped glass substrates using a 60 W continuous wave (cw) CO2 laser. Two types of processing, termed fill-processing and line-processing, were trialled. In fill-processed samples the surface roughness of the glass was found to increase linearly with laser power from an Sa value of 20.8 nm–2.1 μm at a processing power of 54 W. With line processing, a more exponential-like increase was observed with a roughness of 4 μm at 54 W. The change in surface properties of the glass, such as gloss and wettability, have also been measured. The contact angle of water was found to increase after laser processing by up to 64°. The surface gloss was varied between 45 and 100 gloss units (GUs).
Rapid, Chemical-Free Generation of Optically Scattering Structures in Poly(ethylene terephthalate) Using a CO2 Laser for Lightweight and Flexible Photovoltaic ApplicationsAcademic Editor: Yan, Yanfa; Hodgson, Simon D.; Gillett, Alice R. (Hindawi, 2018-12-16)Highly light scattering structures have been generated in a poly(ethylene terephthalate) (PET) film using a CO2 laser. The haze, and in some cases the transparency, of the PET films have been improved by varying the processing parameters of the laser (namely, scanning velocity, laser output power, and spacing between processed tracks). When compared with the unprocessed PET, the haze has improved from an average value of 3.26% to a peak of 55.42%, which equates to an absolute improvement of 52.16% or a 17-fold increase. In addition to the optical properties, the surfaces have been characterised using optical microscopy and mapped with an optical profilometer. Key surface parameters that equate to the amount and structure of surface roughness and features have been analysed. The CO2 laser generates microstructures at high speed, without affecting the bulk properties of the material, and is inherently a chemical-free process making it particularly applicable for use in industry, fitting well with the high-throughput, roll to roll processes associated with the production of flexible organic photovoltaic devices.
Surface treatments to modulate bioadhesion: A critical reviewWaugh, David G.; Toccaceli, Christina; Gillett, Alice R.; Ng, Chi-Ho; Hodgson, Simon D.; Lawrence, Jonathan; University of Chester (Scrivener Publishing, 2016-03-01)On account of the recent increase in importance of biological and microbiological adhesion in industries such as healthcare and food manufacturing many researchers are now turning to the study of materials, wettability and adhesion to develop the technology within these industries further. This is highly significant as the stem cell industry alone, for example, is currently worth £3.5 million in the United Kingdom (UK) alone. This paper reviews the current state-of-the-art techniques used for surface treatment with regards to modulating biological adhesion including laser surface treatment, plasma treatment, micro/nano printing and lithography, specifically highlighting areas of interest for further consideration by the scientific community. What is more, this review discusses the advantages and disadvantages of the current techniques enabling the assessment of the most attractive means for modulating biological adhesion, taking in to account cost effectiveness, complexity of equipment and capabilities for processing and analysis.