Papers by Éanna McCarthy
Laser Micro- and Nano-Scale Processing, 2021
Journal of Manufacturing and Materials Processing
In this report, a novel non-contact, non-invasive methodology for near and quasi real-time measur... more In this report, a novel non-contact, non-invasive methodology for near and quasi real-time measurement of the structuring of metal surfaces using pulsed laser ablation is described. This methodology is based on the use of a multi-messenger data approach using data from Optical Emission Spectroscopy (OES) and Radio Emission Spectroscopy (RES) in parallel. In this research, radio frequency (RF) emission (in the range of 100–400 MHz) and optical emission (200–900 nm) were investigated and acquired in real-time. The RES and OES data were post-processed and visualized using heat maps, and, because of the large data sets acquired particularly using in RES, Principal Component Analysis (PCA) statistics were used for data analysis. A comparison between in-process RES-OES data and post-process 3D images of the different ablated holes generated by a picosecond laser with different powers (1.39 W, 1.018 W, and 0.625 W) on aluminum (Al) and copper (Cu) was performed. The real-time time-series d...
Key Engineering Materials
Silver nano-colloids have been generated via Laser Ablation Synthesis in Solution (LASiS) system.... more Silver nano-colloids have been generated via Laser Ablation Synthesis in Solution (LASiS) system. Nanoparticle formation with particle size below 50 nm in DI water was confirmed using UV-VIS spectroscopy, Dynamic Light Scattering (DLS) technique, and transmission electron microscopy (TEM). Supercapacitor structure, having dimension 11 mm x 10 mm, was successfully Aerosol Jet printed on an untreated polymer substrate using as produced LASiS silver nano-colloid.
Chemical Engineering Journal
Materials
Every year, the EU emits 13.4 Mt of CO2 solely from plastic production, with 99% of all plastics ... more Every year, the EU emits 13.4 Mt of CO2 solely from plastic production, with 99% of all plastics being produced from fossil fuel sources, while those that are produced from renewable sources use food products as feedstocks. In 2019, 29 Mt of plastic waste was collected in Europe. It is estimated that 32% was recycled, 43% was incinerated and 25% was sent to landfill. It has been estimated that life-sciences (biology, medicine, etc.) alone create plastic waste of approximately 5.5 Mt/yr, the majority being disposed of by incineration. The vast majority of this plastic waste is made from fossil fuel sources, though there is a growing interest in the possible use of bioplastics as a viable alternative for single-use lab consumables, such as petri dishes, pipette tips, etc. However, to-date only limited bioplastic replacement examples exist. In this review, common polymers used for labware are discussed, along with examining the possibility of replacing these materials with bioplastics,...
Nano-Structures & Nano-Objects, 2022
ESAFORM 2021, 2021
Metal nanoparticles have unique chemical, physical, electrical, and optical properties that make ... more Metal nanoparticles have unique chemical, physical, electrical, and optical properties that make them attractive for a wide range of applications in sensing, anti-fouling surfaces, medicine, and conductive inks. Pulsed Laser Ablation in Liquid (PLAL) is a green method of nanoparticle colloid production, capable of producing ligand-free nanoparticles in solution without the need for hazardous, environmentally unfriendly chemicals. Control of the process parameters can give control over the resulting colloid properties such as particle size distribution. In this work, silver (Ag) nanoparticles (NPs) with average particle size from 2.04 to 19.3 nm and copper (Cu) NPs with average particle size from 40 to 85.9 nm were produced by PLAL) technique.
Surface and Coatings Technology, 2022
Photovoltaics (PVs), the generation of electricity by the direct conversion of sunlight using sol... more Photovoltaics (PVs), the generation of electricity by the direct conversion of sunlight using solar cells, is considered to be one of the most promising energy choices for a sustainable future. However, its main limitations such as low efficiency and high cost need to be addressed for its broad practical application. Enhancing light-trapping is a key method to improve solar cell efficiency. Studies show that the light-trapping photon management strategy based on photonic crystals is successful in the improvement of efficiency and cost reduction. This chapter therefore consider the light-trapping in PCs and briefly discusses the ray-optic and wave-optic theory of light trapping and absorption enhancements in 2D and 3D photonic crystal (PC) structures.
This study is investigating the effect of the laser surface melting of 316L stainless steel cylin... more This study is investigating the effect of the laser surface melting of 316L stainless steel cylindrical samples on the surface residual stresses and the corrosion resistance. A high speed CO 2 laser beam with power range of 300-500 W was used in pulse mode to initiate the surface melting in an argon and argon-nitrogen atmosphere. The produced samples were cross sectioned and the elastic modulus and nano-hardness test were carried out showing no alteration between the modified and the bulk material. A noticeable degradation in the corrosion resistance was found due to the formation of the chromium carbide and chromium nitride which act as electrolytic cells in addition to the disruption of the free chromium content at the melted zone.
Materials, 2020
Laser-Powder Bed Fusion (L-PBF) of metallic parts is a highly multivariate process. An understand... more Laser-Powder Bed Fusion (L-PBF) of metallic parts is a highly multivariate process. An understanding of powder feedstock properties is critical to ensure part quality. In this paper, a detailed examination of two commercial stainless steel 316L powders produced using the gas atomization process is presented. In particular, the effects of the powder properties (particle size and shape) on the powder rheology were examined. The results presented suggest that the powder properties strongly influence the powder rheology and are important factors in the selection of suitable powder for use in an additive manufacturing (AM) process. Both of the powders exhibited a strong correlation between the particle size and shape parameters and the powder rheology. Optical microscope images of melt pools of parts printed using the powders in an L-PBF machine are presented, which demonstrated further the significance of the powder morphology parameters on resulting part microstructures.
Additive Manufacturing, 2021
Surface and Coatings Technology, 2020
Optics and Lasers in Engineering, 2018
Applied Surface Science, 2019
Key Engineering Materials, 2019
The manufacture of metal parts requires post processing in most cases. These processes include he... more The manufacture of metal parts requires post processing in most cases. These processes include heat treatment for releasing of the residual stresses resulting on the metal surface due to the excessive mechanical forces applies to cut the metal during machining, i.e. milling, turning and drilling. Another example would be the polishing of parts using different techniques. In predominant, polishing is used enhance the part’s roughness to improve the friction coefficient, to give the parts a better view and most important is to adjust the final dimensional accuracy in the microns and sub-microns scale. Traditional polishing methods include the mechanical polishing by using abrasive media or grinding machines, chemical polishing which has the benefit of reaching the inaccessible features although this method requires longer processing time in addition to the impact on environment. Sometimes the thermal deburring method is also applied for the chamfer of sharp edges and corners. In the r...
Materials, 2019
One of the established limitations of metal additive manufacturing (AM) methods, such as selectiv... more One of the established limitations of metal additive manufacturing (AM) methods, such as selective laser melting (SLM), is the resulting rough surface finish. Laser polishing is one method that can be used to achieve an improved surface finish on AM printed parts. This study is focused on the laser surface polishing of AM parts using CO2 laser beam irradiation. Despite the fact that several researchers have investigated the traditional abrasive polishing method, there is still a lack of information reporting on the laser surface polishing of metal parts. In this study, AM 316L stainless steel cylindrical samples were polished using CO2 laser beam irradiation in continuous wave (CW) working mode. Two design of experiment models were developed for the optimization of the input processing parameters by statistical analysis of their effect on the resulting roughness. The processing parameters investigated were the laser beam power, the rotational speed of the sample, the number of laser...
Journal of Materials Processing Technology, 2018
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Papers by Éanna McCarthy