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Powell, John
Publications (10 of 135) Show all publications
Kaplan, A. F. H., Fedina, T., Brückner, F. & Powell, J. (2023). Laser induced reduction of iron ore by silicon. Journal of Alloys and Metallurgical Systems, 4, Article ID 100039.
Open this publication in new window or tab >>Laser induced reduction of iron ore by silicon
2023 (English)In: Journal of Alloys and Metallurgical Systems, ISSN 2949-9178, Vol. 4, article id 100039Article in journal (Refereed) Published
Abstract [en]

Iron ore powder accompanied by Si-powder as a reducing agent, was melted using a high-power laser beam. During laser melting of the two different powder beds placed next to each other, silicon merged and diffused into the iron ore, forming a ternary melt phase Fe-O-Si of around 30–60–10 at%. High speed imaging of the laser melting process as well as subsequent SEM-analysis of the generated nuggets showed the formation of droplets that merge with the surrounding Si- or ore-powder and form distinct domains. Under certain circumstances, the solidifying nuggets, of the order of 0.5–5 mm in size, generated numerous small domains, up to 25 µm, of high purity iron, 90 + at%, surrounded by a matrix of the above mentioned slag. Many of these Fe-domains were created in the vicinity of regions of high Si-content.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Laser treatment, Reduction, Iron, Iron ore, Powder processing, Ore reduction, Silicon
National Category
Other Materials Engineering Metallurgy and Metallic Materials
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-102647 (URN)10.1016/j.jalmes.2023.100039 (DOI)
Funder
Swedish Energy Agency, 51021-1, P2022-00202
Note

Godkänd;2023;Nivå 0;2023-11-22 (joosat);

CC BY 4.0 License

Funder: EU ERDF Kolarctic CBC with Region Norrbotten, project I2P, (no. KO4012); LKAB

Available from: 2023-11-22 Created: 2023-11-22 Last updated: 2023-11-22Bibliographically approved
Atiyah, H., Hussein, R. D., Rashid, M. M., Powell, J. & Voisey, K. T. (2023). Thermal Degradation and Ablation Energy of Poly (Methyl Methacrylate). In: Tariq Al-Mansoori; Ali Al-Rifaie; Haider Kamil Shanbara; Furat Yasir Al-Jaberi; Othman Hameed; Alaa Al-Hussainy; Dakhil Riyadh (Ed.), 2nd Muthanna International Conference on Engineering Science and Technolog: . Paper presented at 2nd Muthanna Conference on Engineering Science and Technology 2022 (MICEST 2022), Samawah, Iraq, March 16-17, 2022. American Institute of Physics (AIP), Article ID 080002.
Open this publication in new window or tab >>Thermal Degradation and Ablation Energy of Poly (Methyl Methacrylate)
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2023 (English)In: 2nd Muthanna International Conference on Engineering Science and Technolog / [ed] Tariq Al-Mansoori; Ali Al-Rifaie; Haider Kamil Shanbara; Furat Yasir Al-Jaberi; Othman Hameed; Alaa Al-Hussainy; Dakhil Riyadh, American Institute of Physics (AIP), 2023, article id 080002Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2023
Series
AIP Conference Proceedings, ISSN 0094-243X, E-ISSN 1551-7616 ; 2806
National Category
Metallurgy and Metallic Materials
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-103385 (URN)10.1063/5.0164879 (DOI)2-s2.0-85176804280 (Scopus ID)
Conference
2nd Muthanna Conference on Engineering Science and Technology 2022 (MICEST 2022), Samawah, Iraq, March 16-17, 2022
Note

Funder: University of Nottingham;

Available from: 2023-12-22 Created: 2023-12-22 Last updated: 2023-12-22Bibliographically approved
Olsson, R., Powell, J., Frostevarg, J. & Kaplan, A. F. . (2021). Topographical evaluation of laser generated surfaces using statistical analysis of surface-normal vector distributions. In: Jan Frostevarg, Adrien Da Silva, Marie-Louise Palmblad, Lars Andersson (Ed.), IOP Conference Series: Materials Science and Engineering: . Paper presented at 18th Nordic Laser Materials Processing Conference (18th NOLAMP), Luleå, Sweden, January 18-20, 2022. Institute of Physics (IOP), 1135, Article ID 012023.
Open this publication in new window or tab >>Topographical evaluation of laser generated surfaces using statistical analysis of surface-normal vector distributions
2021 (English)In: IOP Conference Series: Materials Science and Engineering / [ed] Jan Frostevarg, Adrien Da Silva, Marie-Louise Palmblad, Lars Andersson, Institute of Physics (IOP), 2021, Vol. 1135, article id 012023Conference paper, Published paper (Refereed)
Abstract [en]

Surfaces generated by Additive Manufacturing or laser texturing can involve the solidification of droplets of liquid, which can give rise to overhanging features on the solidified surface. Overhanging features add a layer of complexity to the surface topography and are undetectable by standard surface roughness measurement techniques such as profilometry. Such features are important because they can have a considerable effect on surface properties such as wettability. New techniques and algorithms are therefore required to analyse and quantify convoluted surfaces with overhanging (re-entrant) features. Earlier work by the authors introduced the concept of using X-ray micro-computed tomography (Micro-CT) to identify the directions of vectors normal to the surface at any point and thus indicate the presence or absence of overhanging features. This paper divides overhanging features into two types; simple and compound, and introduces new, size independent, analysis techniques which measure what proportion of each type is on the surface. Another extension of the analysis is the comparison of surface profiles taken in different directions in order to identify any surface roughness anisotropies.

Place, publisher, year, edition, pages
Institute of Physics (IOP), 2021
Series
IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-89469 (URN)10.1088/1757-899X/1135/1/012023 (DOI)000766307500023 ()
Conference
18th Nordic Laser Materials Processing Conference (18th NOLAMP), Luleå, Sweden, January 18-20, 2022
Note

Funder: EU-ERDF-InterregNord (20201279)

Available from: 2022-03-10 Created: 2022-03-10 Last updated: 2023-01-24Bibliographically approved
Fedina, T., Sundqvist, J., Powell, J. & Kaplan, A. F. . (2020). A comparative study of water and gas atomized low alloy steel powders for additive manufacturing. Additive Manufacturing, 36, Article ID 101675.
Open this publication in new window or tab >>A comparative study of water and gas atomized low alloy steel powders for additive manufacturing
2020 (English)In: Additive Manufacturing, ISSN 2214-8604, E-ISSN 2214-7810, Vol. 36, article id 101675Article in journal (Refereed) Published
Abstract [en]

This work reports a study of the differences between laser processing of water and gas atomized low alloy steel powders with a focus on powder behavior and performance in additive manufacturing. Material packing densities were measured to establish a relationship between powder packing and track formation. The results showed that the track height when using water atomized powder was 15% lower than the value achieved for the gas atomized powder. High-speed imaging was utilized to observe the material behavior and analyze the powder particle movement under laser irradiation. It was found that water atomized powder has less particle entrainment due to its tendency towards mechanical interlocking. The occurrence of powder spattering and melt pool instabilities was also studied. More frequent spatter ejection is believed to be due to the higher amount of oxygen in the water atomized powder.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Additive manufacturing, Laser powder bed fusion, Water atomized powder, Packing density, Low alloy steel, High-speed imaging
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-81523 (URN)10.1016/j.addma.2020.101675 (DOI)000600807800194 ()2-s2.0-85095580581 (Scopus ID)
Funder
Interreg Nord, 304–7463-2018
Note

Validerad;2021;Nivå 2;2021-01-04 (alebob);

Finansiär: EIT Raw Materials Knowledge and Innovation Community, Europe (17070)

Available from: 2020-11-23 Created: 2020-11-23 Last updated: 2023-09-06Bibliographically approved
Olsson, R., Powell, J., Frostevarg, J. & Kaplan, A. F. H. (2020). Normal vector distribution as a classification tool for convoluted rough surfaces with overhanging features. Paper presented at 38th International Congress on Applications of Lasers & Electro-Optics (ICALEO 2019), 7-10 October, 2019, Orlando, Florida, United States. Journal of laser applications, 32(2), Article ID 022030.
Open this publication in new window or tab >>Normal vector distribution as a classification tool for convoluted rough surfaces with overhanging features
2020 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 32, no 2, article id 022030Article in journal (Refereed) Published
Abstract [en]

Convoluted rough surfaces involving overhanging features can be a natural consequence of laser additive manufacturing and other spray techniques or can be generated deliberately by laser surface texturing, e.g., to aid osseointegration. Overhanging features add an extra level of complexity to the topography of a rough surface and can have a substantial effect on wettability, etc. However, features of this type are invisible to traditional surface roughness measurement techniques. This work presents a computer-based surface analysis method that gives useful information about the presence and nature of overhanging features on rough technical surfaces. The technique uses micro-computer tomography to generate a typical cross section of the surface under investigation. The angles of the vectors normal to the surface can then be analyzed to reveal the presence of overhanging features, which can also be indicated by the standard deviation of the normal vector distribution. Titanium surfaces generated by six different techniques were compared. The characteristics of these surfaces varied strongly, as did the shapes of the overhangs involved. These variations are reflected by different statistical distributions of the normal vectors.

Place, publisher, year, edition, pages
Laser Institute of America, 2020
Keywords
laser, surface structuring, implants, surface topography, classification, micro-CT, SEM
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-74143 (URN)10.2351/7.0000067 (DOI)000531740200003 ()2-s2.0-85111996671 (Scopus ID)
Conference
38th International Congress on Applications of Lasers & Electro-Optics (ICALEO 2019), 7-10 October, 2019, Orlando, Florida, United States
Note

Godkänd;2020;Nivå 0;2020-07-01 (alebob);Konferensartikel i tidskrift

Available from: 2019-06-03 Created: 2019-06-03 Last updated: 2022-06-30Bibliographically approved
Olsson, R., Powell, J., Palmquist, A., Brånemark, R., Frostevarg, J. & Kaplan, A. (2019). Formation of osseointegrating (bone integrating) surfaces on titanium by laser irradiation. Journal of laser applications, 31(2), Article ID 022508.
Open this publication in new window or tab >>Formation of osseointegrating (bone integrating) surfaces on titanium by laser irradiation
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2019 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 31, no 2, article id 022508Article in journal (Refereed) Published
Abstract [en]

Pulsed lasers can be used to modify the surface of medical implants in order to accelerate bone growth (osseointegration). A surface covered in attached droplets with diameters between 1 and 20 μm is a beneficial surface for rapid osseointegration. This paper presents the results of an experimental program in which a broad range of laser parameters and different atmospheres were used to create different surface textures on titanium substrates, including the desired "attached droplet" topology. The resulting surfaces were analyzed by scanning electron microscopy and micro-computer tomography. The paper explains how different types of surfaces are created by the laser-material interaction under different conditions and focus characteristics. It is shown that optimization of the laser parameters results in a robust process, which produces a surface that is fundamentally different from those created by nonlaser methods.

Place, publisher, year, edition, pages
Laser Institute of America, 2019
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-73825 (URN)10.2351/1.5096075 (DOI)000484435200078 ()2-s2.0-85064218607 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-05-03 (johcin)

Available from: 2019-05-03 Created: 2019-05-03 Last updated: 2019-10-01Bibliographically approved
Pocorni, J., Powell, J., Frostevarg, J. & Kaplan, A. F. H. (2018). Dynamic laser piercing of thick section metals. Optics and lasers in engineering, 100, 82-89
Open this publication in new window or tab >>Dynamic laser piercing of thick section metals
2018 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 100, p. 82-89Article in journal (Refereed) Published
Abstract [en]

Before a contour can be laser cut the laser first needs to pierce the material. The time taken to achieve piercing should be minimised to optimise productivity. One important aspect of laser piercing is the reliability of the process because industrial laser cutting machines are programmed for the minimum reliable pierce time. In this work piercing experiments were carried out in 15 mm thick stainless steel sheets comparing a stationary laser and a laser which moves along a circular trajectory with varying processing speeds. Results show that circular piercing can decrease the pierce duration by almost half compared to stationary piercing. High speed imaging (HSI) was employed during the piercing process to understand melt behaviour inside the pierce hole. HSI videos show that circular rotation of the laser beam forces melt to eject in opposite direction of the beam movement, while in stationary piercing the melt ejects less efficiently in random directions out of the hole.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Laser cutting, laser piercing, reliability, efficiency, fibre laser, high speed imaging
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-63492 (URN)10.1016/j.optlaseng.2017.07.012 (DOI)000414108700010 ()2-s2.0-85026484330 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-08-15 (andbra)

Available from: 2017-05-23 Created: 2017-05-23 Last updated: 2023-09-04Bibliographically approved
Atiyah, H., Powell, J., Petring, D., Stoyanov, S. & Voisey, T. (2018). Fiber laser cutting: The use of carbon-filled acrylic as a qualitative and quantitative analysis tool. Journal of laser applications, 30, Article ID 032009.
Open this publication in new window or tab >>Fiber laser cutting: The use of carbon-filled acrylic as a qualitative and quantitative analysis tool
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2018 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 30, article id 032009Article in journal (Refereed) Published
Abstract [en]

The use of carbon-filled black acrylic (CFBA) as a quantitative and qualitative analytical tool for fiber laser cutting is investigated. In the qualitative work, CFBA targets placed below the laser cutting zone when cutting stainless steel showed a distinctive “leaf” shaped evaporation crater which can provide information about the nature of the reflections taking place in the cut zone. Quantitative measurements have revealed a specific evaporation energy of 3.4 J/mm3 for CFBA. However, this figure is only applicable when considering intense beams when the CFBA target is stationary with respect to the laser beam.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2018
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-70243 (URN)10.2351/1.5045349 (DOI)000443892000012 ()2-s2.0-85051221820 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-08-07 (andbra)

Available from: 2018-08-07 Created: 2018-08-07 Last updated: 2020-08-26Bibliographically approved
Haglund, P., Frostevarg, J., Powell, J., Eriksson, I. & Kaplan, A. (2018). Holographic measurement of distortion during laser melting: Additive distortion from overlapping pulses. Optics and Laser Technology, 100, 1-6
Open this publication in new window or tab >>Holographic measurement of distortion during laser melting: Additive distortion from overlapping pulses
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2018 (English)In: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 100, p. 1-6Article in journal (Refereed) Published
Abstract [en]

Laser - material interactions such as welding, heat treatment and thermal bending generate thermal gradients which give rise to thermal stresses and strains which often result in a permanent distortion of the heated object. This paper investigates the thermal distortion response which results from pulsed laser surface melting of a stainless steel sheet. Pulsed holography has been used to accurately monitor, in real time, the out-of-plane distortion of stainless steel samples melted on one face by with both single and multiple laser pulses. It has been shown that surface melting by additional laser pulses increases the out of plane distortion of the sample without significantly increasing the melt depth. The distortion differences between the primary pulse and subsequent pulses has also been analysed for fully and partially overlapping laser pulses.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-66009 (URN)10.1016/j.optlastec.2017.09.053 (DOI)000417669700001 ()2-s2.0-85030758159 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-10 -09 (andbra)

Available from: 2017-10-09 Created: 2017-10-09 Last updated: 2017-12-28Bibliographically approved
Pocorni, J., Powell, J., Frostevarg, J. & Kaplan, A. F. .. (2018). The geometry of the cutting front created by Fibre and CO2 lasers when profiling stainless steel under standard commercial conditions. Optics and Laser Technology, 103, 318-326
Open this publication in new window or tab >>The geometry of the cutting front created by Fibre and CO2 lasers when profiling stainless steel under standard commercial conditions
2018 (English)In: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 103, p. 318-326Article in journal (Refereed) Published
Abstract [en]

Cutting fronts created by CO2 and fibre lasers in stainless steel at thicknesses between 2 mm and 10 mm have been ‘frozen’ and their geometry has been measured. Standard commercial cutting parameters were used to generate the cuts for both types of laser. The resulting three-dimensional cutting front shapes have been curve fitted as polynomials and semicircles. Various features of the cutting front geometry are discussed including the lack of correlation of the cut front inclination with either the relevant Brewster angle or the inclination of the striations on the cut edge.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-67687 (URN)10.1016/j.optlastec.2018.01.055 (DOI)000427339000041 ()2-s2.0-85041470309 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-02-19 (andbra)

Available from: 2018-02-19 Created: 2018-02-19 Last updated: 2022-10-25Bibliographically approved
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