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Kaplan, Alexander F. H.ORCID iD iconorcid.org/0000-0002-3569-6795
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Publications (10 of 365) Show all publications
Brandau, B., Brueckner, F. & Kaplan, A. F. H. (2024). Absorbance determination of a powder bed by high resolution coaxial multispectral imaging in laser powder bed fusion. Optics and Laser Technology, 168, Article ID 109780.
Open this publication in new window or tab >>Absorbance determination of a powder bed by high resolution coaxial multispectral imaging in laser powder bed fusion
2024 (English)In: Optics and Laser Technology, ISSN 0030-3992, E-ISSN 1879-2545, Vol. 168, article id 109780Article in journal (Refereed) Published
Abstract [en]

This study presents an approach for in-situ monitoring of laser powder bed fusion. Using standard laser optics, coaxial high-resolution multispectral images of powder beds are acquired in a pre-objective scanning configuration. A continuous overview image of the entire 114 × 114 mm powder bed can be generated, detecting objects down to 20 µm in diameter with a maximum offset of 22–49 µm. Multispectral information is obtained by capturing images at 6 different wavelengths from 405 nm to 850 nm. This allows in-line determination of the absorbance of the powder bed with a maximum deviation of 2.5% compared to the absorbance spectra of established methods. For the qualification of this method, ray tracing simulations on powder surfaces and tests with 20 different powders have been carried out. These included different particle sizes, aged and oxidized powders.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Spectroscopic Measurement, Correction Method, Laser Powder Bed Fusion, Scanning Method, Metal Powder, Multispectral Imaging, Laser Material Processing
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-99249 (URN)10.1016/j.optlastec.2023.109780 (DOI)2-s2.0-85166468238 (Scopus ID)
Note

Validerad;2023;Nivå 2;2023-08-07 (hanlid)

Available from: 2023-08-02 Created: 2023-08-02 Last updated: 2023-11-17Bibliographically approved
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
Fedina, T., Brueckner, F., Kaplan, A. F. H. & Wilsnack, C. (2023). Laser-assisted reduction of iron ore using aluminum powder. Journal of laser applications, 35(2), Article ID 022007.
Open this publication in new window or tab >>Laser-assisted reduction of iron ore using aluminum powder
2023 (English)In: Journal of laser applications, ISSN 1042-346X, E-ISSN 1938-1387, Vol. 35, no 2, article id 022007Article in journal (Refereed) Published
Abstract [en]

This study reports on the laser-assisted reduction of iron ore waste using Al powder as areducing agent. Due to climate change and the global warming situation, it has become ofparamount importance to search for and/or develop green and sustainable processes for ironand steel production. In this regard, a new method for iron ore utilization is proposed in thiswork, investigating the possibility of iron ore waste reduction via metallothermic reaction withAl powder. Laser processing of iron ore fines was performed, focusing on the Fe2O3-Alinteraction behavior and extent of the iron ore reduction. The reaction between the materialsproceeded in a rather intense uncontrolled manner which led to a formation of Fe-rich domainsand alumina as two separate phases. In addition, a combination of Al2O3 and Fe2O3 melts aswell as transitional areas such as intermetallics were observed, suggesting the occurrence ofincomplete reduction reaction in isolated regions. The reduced iron droplets were prone toacquire a sphere-like shape and concentrated mainly near the surface of the Al2O3 melt or at theinterface with the iron oxide. Both SEM, EDS and WDS analyses were employed to analyzechemical composition, microstructure and morphological appearances of the reaction products.High-speed imaging was used to study the process phenomena and observe differences in themovement behavior of the particles. Furthermore, the measurements acquired from X-raycomputed microtomography revealed that approximately 2.4 % of iron was reduced during thelaser processing of Fe2O3-Al powder bed, most likely due to insufficient reaction time orinappropriate equivalence ratio of the two components.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2023
Keywords
iron ore, aluminum, reduction, sustainability, laser powder bed fusion, additive manufacturing
National Category
Metallurgy and Metallic Materials Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-95787 (URN)10.2351/7.0000856 (DOI)2-s2.0-85150388187 (Scopus ID)
Funder
Swedish Energy Agency, 51021-1, P2022-00202
Note

Validerad;2023;Nivå 2;2023-04-12 (hanlid);

Available from: 2023-03-02 Created: 2023-03-02 Last updated: 2023-05-08Bibliographically approved
Da Silva, A., Frostevarg, J. & Kaplan, A. F. H. (2023). Melt pool monitoring and process optimisation of directed energy deposition via coaxial thermal imaging. Journal of Manufacturing Processes, 107, 126-133
Open this publication in new window or tab >>Melt pool monitoring and process optimisation of directed energy deposition via coaxial thermal imaging
2023 (English)In: Journal of Manufacturing Processes, ISSN 1526-6125, Vol. 107, p. 126-133Article in journal (Refereed) Published
Abstract [en]

In Laser-based Directed Energy Deposition of metal powder, the use of optimised parameters allows the deposition of defect-free material, while diverging from these optimised parameters can typically result in high porosity, high dilution or different track geometry. One of the main challenges when building complex geometries is that the geometrical and thermal conditions of the deposition are constantly changing, which requires to adjust the process parameters during the production. In order to facilitate this process, sensors such as thermal cameras can be used to extract data from the process and adapt the parameters to keep the process stable despite external disturbances. In this research, different signals extracted from a coaxial thermal camera are investigated and compared for process optimisation. To investigate such possibilities, five overlapped tracks are deposited at constant laser powers in order to extract average pixel values as well as the melt pool area, length, width and orientation. The behaviour of each track deposition is modelled as a function of the laser power, and these models are used to calculate and test laser power reduction strategies based on different signals. The results show that the melt pool area is the most relevant signal to use for an efficient process control, resulting in a stable process with only ±1.6 % of signal variation from track to track.

Place, publisher, year, edition, pages
Elsevier, 2023
Keywords
Laser cladding, Laser metal deposition, Direct metal deposition, Thermal camera, Process control
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-95797 (URN)10.1016/j.jmapro.2023.10.021 (DOI)
Projects
MONACOIDiDI2P
Funder
Vinnova, 2021-02154Norrbotten County Council, 20358021, KO4012
Note

Validerad;2023;Nivå 2;2023-10-30 (hanlid);

Funder: EU-Interreg Aurora (20358021); EU-Kolarctic CBC (KO4012);

Licens full text: CC BY

Available from: 2023-03-06 Created: 2023-03-06 Last updated: 2023-10-30Bibliographically approved
Brandau, B., Da Silva, A., Wilsnack, C., Brueckner, F. & Kaplan, A. F. .. (2022). Absorbance study of powder conditions for laser additive manufacturing. Materials & design, 216, Article ID 110591.
Open this publication in new window or tab >>Absorbance study of powder conditions for laser additive manufacturing
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2022 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 216, article id 110591Article in journal (Refereed) Published
Abstract [en]

Absorbance is often used for simulations or validation of process parameters for powder-based laser materials processing. In this work, the absorbance of 39 metal powders for additive manufacturing is determined at 20 laser wavelengths. Different grain sizes and aging states for: steels, aluminum alloys, titanium alloys, Nitinol, high entropy alloy, chromium, copper, brass and iron ore were analyzed. For this purpose, the absorbance spectrum of the powders was determined via a dual-beam spectrometer in the range of λ = 330 - 1560 nm. At the laser wavelengths of λ = 450 nm, 633 nm and 650 nm, the absorbance averaged over all materials was found to increase by a factor of 2.4 up to 3.3 compared to the usual wavelength of λ = 1070 nm, with minimal variations in absorbance between materials. In the investigation of the aged or used powders, a loss of absorbance was detectable. Almost no changes from the point of view of processing aged and new AlSi10Mg powders, is expected for laser sources with λ = 450 nm. The resulting measurements provide a good basis for process parameters for a variety of laser wavelengths and materials, as well as a data set for improved absorbance simulations.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Spectroscopic measurement, Absorption spectra, Laser powder bed fusion, Metal powder, Multiple reflections, Laser absorption
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-90043 (URN)10.1016/j.matdes.2022.110591 (DOI)000793277800004 ()2-s2.0-85128304808 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-04-01 (joosat);

 Funder: EIT Raw Materials, European SAMOA project (18079)

Available from: 2022-04-01 Created: 2022-04-01 Last updated: 2023-09-04Bibliographically approved
Hauser, T., Reisch, R. T., Kamps, T., Kaplan, A. F. .. & Volpp, J. (2022). Acoustic emissions in directed energy deposition processes. The International Journal of Advanced Manufacturing Technology, 119(5-6), 3517-3532
Open this publication in new window or tab >>Acoustic emissions in directed energy deposition processes
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2022 (English)In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 119, no 5-6, p. 3517-3532Article in journal (Refereed) Published
Abstract [en]

Acoustic emissions in directed energy deposition processes such as wire arc additive manufacturing and directed energy deposition with laser beam/metal are investigated within this work, as many insights about the process can be gained from this. In both processes, experienced operators can hear whether a process is running stable or not. Therefore, different experiments for stable and unstable processes with common process anomalies were carried out, and the acoustic emissions as well as process camera images were captured. Thereby, it was found that stable processes show a consistent mean intensity in the acoustic emissions for both processes. For wire arc additive manufacturing, it was found that by the Mel spectrum, a specific spectrum adapted to human hearing, the occurrence of different process anomalies can be detected. The main acoustic source in wire arc additive manufacturing is the plasma expansion of the arc. The acoustic emissions and the occurring process anomalies are mainly correlating with the size of the arc because that is essentially the ionized volume leading to the air pressure which causes the acoustic emissions. For directed energy deposition with laser beam/metal, it was found that by the Mel spectrum, the occurrence of an unstable process can also be detected. The main acoustic emissions are created by the interaction between the powder and the laser beam because the powder particles create an air pressure through the expansion of the particles from the solid state to the liquid state when these particles are melted. These findings can be used to achieve an in situ quality assurance by an in-process analysis of the acoustic emissions.

Place, publisher, year, edition, pages
Springer, 2022
Keywords
Wire arc additive manufacturing, Laser metal deposition, WAAM, LMD, In situ monitoring, Airborne acoustic emissions
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-88283 (URN)10.1007/s00170-021-08598-8 (DOI)000740196700001 ()2-s2.0-85122527372 (Scopus ID)
Funder
Swedish Research Council, 2020–04250
Note

Validerad;2022;Nivå 2;2022-03-10 (hanlid);

Funder: BayVFP (IUK-1905–0013); EIT RawMaterials (18079);

Artikeln har tidigare förekommit som manuskript i avhandling

Available from: 2021-12-10 Created: 2021-12-10 Last updated: 2022-07-04Bibliographically approved
Brandau, B., Mai, T., Brueckner, F. & Kaplan, A. F. H. (2022). Angular dependence of coaxial and quasi-coaxial monitoring systems for process radiation analysis in laser materials processing. Optics and lasers in engineering, 155, Article ID 107050.
Open this publication in new window or tab >>Angular dependence of coaxial and quasi-coaxial monitoring systems for process radiation analysis in laser materials processing
2022 (English)In: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 155, article id 107050Article in journal (Refereed) Published
Abstract [en]

Process monitoring is becoming increasingly important in laser-based manufacturing and is of particular importance in the field of additive manufacturing [e.g. Laser Powder Bed Fusion (LPBF)]. Process monitoring enables a reduction of production costs and a lower time-to-market. Furthermore, the data can be used to create a digital twin of the workpiece. There are already many established processing head-integrated monitoring systems for such applications as the multispectral analysis of process radiation. However, the monitoring of complex signals in systems with F-Theta scanner lenses is very challenging and requires specially adapted optics or measuring sensors.

In this paper a potential arrangement for spectroscopy-based process monitoring in pre-objective scanning is presented. The process radiation was monitored using a coaxial and a quasi-coaxial observation system. The measurements were carried out on both a solid and a powder coated sample of 2.4668 (Inconel 718) to show the potential use of these systems in laser-based additive manufacturing. In order to obtain comprehensive data about the process signal, the process zone was analyzed at different angles of incidence (AOI) of the laser using a high-speed camera (HSI) and a spectrometer. The connection between the HSI and the spectral measurements is discussed. The ionization of the material and the formation of a plasma was observed and found to lose intensity as the angle of incidence increases. A model of the system that demonstrates the intensity of the emitted radiation of the plasma was created. It enables the measured values to be corrected. The corrected measurement data can be used to detect impurities or a non-ideal energy input across the entire processing field, which is a move towards robust process monitoring.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Laser scanner, Process control, Laser powder bed fusion, Laser welding, Spectroscopic measurements, Monitoring techniques
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-90062 (URN)10.1016/j.optlaseng.2022.107050 (DOI)000819874000003 ()2-s2.0-85127174513 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-04-04 (hanlid)

Available from: 2022-04-04 Created: 2022-04-04 Last updated: 2022-07-15Bibliographically approved
Naesstroem, H., Brückner, F. & Kaplan, A. F. H. (2022). Blown powder directed energy deposition on various substrate conditions. Journal of Manufacturing Processes, 73, 660-667
Open this publication in new window or tab >>Blown powder directed energy deposition on various substrate conditions
2022 (English)In: Journal of Manufacturing Processes, ISSN 1526-6125, Vol. 73, p. 660-667Article in journal (Refereed) Published
Abstract [en]

Blown powder directed energy deposition of SS316L powder is carried out on various substrate surface conditions of SS304 such as cleaned, sand blasted, milled, oily, cold galvanised and painted to study their influence on the process. High-speed imaging is used for process observation and the deposited tracks are analysed qualitatively and quantitatively using surface images, cross sectional macrographs and x-ray images. Frames from high-speed imaging reveal the removal of additional material from the substrate surface such as paint and oil. The stages involved in their removal: peeling and evaporation are presented. EDS analysis showed that no additional elements other than powder and substrate material are found in the track volume. The quantitative results for all specimens show that the surface conditions had minor influences on track width, track height, wetting angle, dilution and deposited cross sectional area. Defects such as porosity, inclusions and cracking were not observed related to the surface conditions. These findings could significantly reduce processing time by skipping the cleaning step before directed energy deposition such as laser cladding or repair in industrial applications.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Laser cladding, Laser metal deposition, Surface conditions, Contaminated surfaces, High-speed imaging
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-83612 (URN)10.1016/j.jmapro.2021.11.048 (DOI)000740842200001 ()2-s2.0-85120158320 (Scopus ID)
Note

Validerad;2021;Nivå 2;2021-12-02 (johcin)

Available from: 2021-04-13 Created: 2021-04-13 Last updated: 2023-09-13Bibliographically approved
Fedina, T., Belelli, F., Lupi, G., Brandau, B., Casati, R., Berneth, R., . . . Kaplan, A. F. .. (2022). Influence of AlSi10Mg powder aging on the material degradation and its processing in laser powder bed fusion. Powder Technology, 412, Article ID 118024.
Open this publication in new window or tab >>Influence of AlSi10Mg powder aging on the material degradation and its processing in laser powder bed fusion
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2022 (English)In: Powder Technology, ISSN 0032-5910, E-ISSN 1873-328X, Vol. 412, article id 118024Article in journal (Refereed) Published
Abstract [en]

This study investigates the impact of powder aging on the degradation of AlSi10Mg powder during processing in laser powder bed fusion. Powder aging as result of handling, continuous storage and recycling is a fundamental concern for aluminum alloys as it introduces oxygen to the feedstock material. In this work, the analysis of the powder properties, affected by laser exposure and the aging procedure, showed a change of chemical and morphological characteristics of the powders in virgin and aged conditions. The oxygen content in the powders appeared to have a significant effect on the powders' surface appearance and light absorbance, gradually deteriorating the processability of the powders with the increase of oxygen level. Optical microscopy and X-ray computed tomography were used to analyze the porosity distribution in the printed part samples, identifying the origin, size and location of the pores. A direct relationship between the pore occurrence in final parts and the oxygen content in the powders was observed, revealing a higher degree of porosity in the aged powder sample (6.5%) in comparison with the virgin state (3.16%). The evolution of mechanical properties in the part samples after laser processing and powder aging was also studied, demonstrating a rapid decrease of ultimate tensile strength and elongation from virgin condition to aged.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Additive manufacturing, Aging, Aluminum, Laser powder bed fusion, Powder absorbance, Powder condition
National Category
Manufacturing, Surface and Joining Technology Materials Chemistry
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-93764 (URN)10.1016/j.powtec.2022.118024 (DOI)2-s2.0-85140083469 (Scopus ID)
Note

Validerad;2022;Nivå 2;2022-10-31 (hanlid);

Funder: EIT Raw Materials (18079 SAMOA)

Available from: 2022-10-31 Created: 2022-10-31 Last updated: 2023-03-02Bibliographically approved
Da Silva, A., Belelli, F., Lupi, G., Bruzzo, F., Brandau, B., Maier, L., . . . Kaplan, A. (2022). Influence of aluminium powder aging on Directed Energy deposition. Materials & design, 218, Article ID 110677.
Open this publication in new window or tab >>Influence of aluminium powder aging on Directed Energy deposition
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2022 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 218, article id 110677Article in journal (Refereed) Published
Abstract [en]

The use of aluminium alloys for Additive Manufacturing is of high interest for advanced geometries and lightweight applications. In Directed Energy Deposition, a powder stock is processed with a laser beam, which offers a high process flexibility. However, aging of the powder feedstock during storage or after recycling remains fundamentally challenging for aluminium alloys because of their sensitivity to oxida-tion and porosity. In order to investigate these effects, AlSi10Mg powder batches were aged in different conditions and processed by Directed Energy Deposition. The results showed that powder aging does not significantly change the particle size or morphology, but it introduces more oxygen and hydrogen in the powder. The oxidation of the particles reduces the laser beam absorbance of the powder and increases wetting of the melt pool, which affects the track geometry. A 3.5 to 4.2 times higher porosity was observed in the material deposited from aged powder, which are most likely hydrogen pores causedby the increased hydrogen content in the aged powder. The tensile properties of the parts built with aged powder showed 19.0% lower yield strength, 14.2% lower ultimate strength and 99.2% higher elongation, which are most likely the results of the coarser microstructure and increased porosity.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Direct Metal Deposition, Laser Metal Deposition, Laser Powder Bed Fusion, Oxidation, Porosity
National Category
Manufacturing, Surface and Joining Technology
Research subject
Manufacturing Systems Engineering
Identifiers
urn:nbn:se:ltu:diva-90849 (URN)10.1016/j.matdes.2022.110677 (DOI)000800225800004 ()2-s2.0-85129120353 (Scopus ID)
Projects
SAMOA (no. 18079)
Note

Validerad;2022;Nivå 2;2022-06-02 (sofila);

Funder: EIT Raw Materials.

Available from: 2022-06-01 Created: 2022-06-01 Last updated: 2023-09-04Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-3569-6795

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