Change of Oxidation Mechanisms by Laser Chemical Machined Rim Zone Modifications of 42CrMo4 Steel

Schupp, Alexander; Pütz, René Daniel; Beyss, Oliver; Beste, Lucas-Hermann; Radel, Tim; Zander, Daniela

doi:10.3390/ma14143910

Cited by 4 publications

(3 citation statements)

References 41 publications

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“…Figure 7 reports the HR XP spectra concerning the Ti 2p line ( Figure 7 a) and the O 1s line ( Figure 7 b) of the studied samples. First of all, as normally occurs with doped samples, i.e., when the amount of the doping element is low with respect to the parent matrix, the Fe 2p lines (insets of Figure 7 a) were weak in intensity and extremely noisy, finally hampering any kind of curve-fitting procedure, since in order to study Fe 2+ /Fe 3+ oxidation states, reference should be made to satellite peaks, which are notoriously weaker than the corresponding lines [ 63 ].…”

Section: Resultsmentioning

confidence: 99%

Photocatalytic Degradation of Crystal Violet Dye under Visible Light by Fe-Doped TiO2 Prepared by Reverse-Micelle Sol–Gel Method

et al. 2023

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A reverse-micelle sol–gel method was chosen for the preparation of Fe-doped TiO2 samples that were employed in the photodegradation of the crystal violet dye under visible light irradiation in a batch reactor. The dopant amount was varied to assess the optimal photocatalyst composition towards the target dye degradation. The photocatalysts were characterized through a multi-technique approach, envisaging XRPD and QPA as obtained by Rietveld refinement, FE-SEM analysis, DR UV−vis spectroscopy, N2 adsorption/desorption isotherms measurement at −196 °C, ζ-potential measurement, and XPS analysis. The physical-chemical characterization showed that the adopted synthesis method allows obtaining NPs with uniform shape and size and promotes the introduction of Fe into the titania matrix, finally affecting the relative amounts of the three occurring polymorphs of TiO2 (anatase, rutile and brookite). By increasing the Fe content, the band gap energy decreases from 3.13 eV (with undoped TiO2) to 2.65 eV (with both 2.5 and 3.5 wt.% nominal Fe contents). At higher Fe content, surface Fe oxo-hydroxide species occur, as shown by DR UV-vis and XP spectroscopies. All the Fe-doped TiO2 photocatalysts were active in the degradation and mineralization of the target dye, showing a TOC removal higher than the undoped sample. The photoactivity under visible light was ascribed both to the band-gap reduction (as confirmed by phenol photodegradation) and to dye sensitization of the photocatalyst surface (as confirmed by photocatalytic tests carried out using different visible-emission spectra LEDs). The main reactive species involved in the dye degradation were determined to be positive holes.

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Section: Resultsmentioning

confidence: 99%

Photocatalytic Degradation of Crystal Violet Dye under Visible Light by Fe-Doped TiO2 Prepared by Reverse-Micelle Sol–Gel Method

et al. 2023

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“…Finally, a transfer of the modeling technique to laserchemical machining (LCM, e.g. Reference 57) is aspired, which requires to adapt the evolution equation of the dissolution level from an electrically to a thermally based formulation 58…”

Section: Discussionmentioning

confidence: 99%

A novel numerical strategy for modeling the moving boundary value problem of electrochemical machining

Velden

Ritzert

Reese

et al. 2023

Numerical Meth Engineering

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This work presents a new numerical approach to efficiently model the cathode's moving surface in the moving boundary value problem of electrochemical machining. Until recently, the process simulation with finite elements had the drawback of remeshing required by the changing surface geometries. This disadvantage was overcome by an innovative model formulation for the anodic dissolution that utilizes effective material parameters as well as the dissolution level as an internal variable and, thereby, does not require remeshing. Now, we suggest a new numerical method to model arbitrarily shaped and moving cathodes. Two methodologies are investigated to describe the time varying position of the cathode and compared in terms of implementational effort and numerical efficiency. In the first approach, we change the electric conductivity of elements within the cathode and, in a second approach, we apply Dirichlet boundary conditions on the nodes of corresponding elements. For both methods, elements on the cathode's surface are treated with effective material parameters. This procedure allows for the efficient simulation of industrially relevant, complex geometries without mesh adaptation. The model's performance is validated by means of analytical, numerical and experimental results from the literature. The short computation times make the approach interesting for industrial applications.

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“…Finally, a transfer of the modeling technique to laserchemical machining (LCM, e.g. Schupp et al [2021]) is aspired, which requires to adapt the evolution equation of the dissolution level from an electrically to a thermally based formulation (Klocke et al [2016]).…”

Section: Discussionmentioning

confidence: 99%

Modeling moving boundary value problems in electrochemical machining

Velden¹,

Ritzert²,

Reese³

et al. 2022

Preprint

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This work presents a new approach to efficiently model the cathode in the moving boundary value problem of electrochemical machining. Until recently, the process simulation with finite elements had the drawback of remeshing required by the changing surface geometries. This disadvantage was overcome by a novel model formulation for the anodic dissolution that utilizes effective material parameters as well as the dissolution level as an internal variable and, thereby, does not require remeshing. Now, we extend this concept to model arbitrarily shaped and moving cathodes. Two methodologies are investigated to describe the time varying position of the cathode. In the first approach, we change the electric conductivity of elements within the cathode and, in a second approach, we apply Dirichlet boundary conditions on the nodes of corresponding elements. For both methods, elements on the cathode's surface are treated with effective material parameters. This procedure allows for the efficient simulation of industrially relevant, complex geometries without mesh adaptation. The model's performance is validated by means of analytical, numerical and experimental results from the literature. The short computation times make the approach interesting for industrial applications.

show abstract

Change of Oxidation Mechanisms by Laser Chemical Machined Rim Zone Modifications of 42CrMo4 Steel

Cited by 4 publications

References 41 publications

Photocatalytic Degradation of Crystal Violet Dye under Visible Light by Fe-Doped TiO2 Prepared by Reverse-Micelle Sol–Gel Method

Photocatalytic Degradation of Crystal Violet Dye under Visible Light by Fe-Doped TiO2 Prepared by Reverse-Micelle Sol–Gel Method

A novel numerical strategy for modeling the moving boundary value problem of electrochemical machining

Modeling moving boundary value problems in electrochemical machining

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