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Number of results: 118
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Abstract

Strained layer InGaAs/GaAs SCH SQW (Separate Confinement Heterostructure Single Quantum Well) lasers were

grown by Molecular Beam Epitaxy (MBE). Highly reliable CW (continuous wave) 980-nm, broad contact, pump lasers were

fabricated in stripe geometry using Schottky isolation and ridge waveguide construction. Threshold current densities of the

order of Jth ≈ 280 A/cm2 (for the resonator length L = 700 um) and differential efficiency η= 0.40 W/A (41%) from one

mirror were obtained. The record wall-plug efficiency for AR/HR coated devices was equal to 54%. Theoretical estimations

of above parameters, obtained by numerical modelling of devices were Jth ≈ 210 A/cm and η = 0.47 W/A from one mirror,

respectively. Degradation studies revealed that uncoated and AR/HR coated devices did not show any appreciable degradation

after 1500 hrs of CW operation at 35oC heat sink temperature at the constant optical power (50 mW) conditions.

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Authors and Affiliations

M. Bugajski
B. Mroziewicz
K. Regiński
J. Muszalski
K. Kosiel
M. Zbroszczyk
T. Ochalski
T. Piwoński
D. Wawer
A. Szerling
E. Kowalczyk
H. Wrzesińska
M. Górska
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Abstract

In this contribution an optical method of controlling the state of soft biological tissues in real time, exposed to laser radiation is discussed. The method is based on the assumption that the change dynamics of the amplitude of the scattered diagnostic radiation (λ = 635 nm) is compatible with the change dynamics of the tissue inner structure exposed to the Nd:YAG laser radiation (λ = 1064 nm). In this method the measurement of the tissue temperature is omitted. Exemplary results of the laboratory research on this method and an interpretation of the results are presented.

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Authors and Affiliations

A. Zając
D. Podniesiński
D. Kęcik
M. Kęcik
J. Kasprzak
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Abstract

A mode-locked Tm3+-doped fibre laser and amplifier operating at a central wavelength of 1994.3 nm is demonstrated. A thulium oscillator is passively mode-locked by a semiconductor saturable absorber mirror to generate an average power of 17 mW at a fundamental repetition rate of 81 MHz in a short linear cavity. This 2-µm laser train is amplified to an average power to 20.26 W by two double-clad thulium-doped allfibre amplifiers. The pulse energy, duration and peak power is 250 nJ, 23 ps and 9.57 kW, respectively. This represents one of the highest values of average power at ∼ 2-µm-wavelength for picosecond thulium-doped fibre lasers and amplifiers. The performance of the laser system is described in details.

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Authors and Affiliations

Paweł Grześ
Maria Michalska
ORCID: ORCID
Jacek Świderski
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Abstract

In this paper the overview of the recent study on the rare-earth activated waveguides performed in the Optoelectronic Department of IMiO is presented. We reported on the development of rare earth-doped fluorozirconate (ZBLAN) glass fibers that allow a construction of a new family of visible and ultraviolet fiber lasers pumped by upconversion. Especially the performance of holmium devices is presented. The properties of laser planar waveguides obtained by the LPE process and the growth conditions of rare earths doped YAG layers are presented. In this paper we present also the theoretical study of the nonlinear operation of planar waveguide laser, as an example the microdisk Nd:YAG structure is discussed. We derived an approximate formula which relates the small signal gain in the Nd:YAG active medium and the laser characteristics, obtained for whispering-gallery modes and radial modes, to the output power and real parameters of the laser structure

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Authors and Affiliations

W. Woliński
M. Malinowski
A. Mossakowska-Wyszyńska
R. Piramidowicz
P. Szczepański
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Abstract

Although laser scanning ideas and hardware solutions are well-known to experts in the field, there is still a large area for optimization. Especially, if long-range and high-resolution scanning is considered, the smallest defects in optical quality should be perfected. On the other hand, the simplicity, reliability, and finally the cost of the solution plays an important role, too. In this paper, a very simple but efficient method of optical correction is presented. It is dedicated to laser scanners operating from inside cylindrical glass domes. Such covers normally introduce aberrations into both the laser beam and receiving optics. If these effects are uncorrected, the laser scanner performance is degraded both in terms of angular resolution and maximum range of operation. It may not be critical for short-range scanning applications; however, if more challenging concepts are considered, this issue becomes crucial. The proposed method does not require sophisticated optical solutions based on aspheric or freeform components, which are frequently used for similar purposes in imaging-through-dome correction but is based on a simple cylindrical refractive correction plate.
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Authors and Affiliations

Jacek Wojtanowski
1
ORCID: ORCID

  1. Institute of Optoelectronics, Military University of Technology, ul. gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland
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Abstract

An efficient operation of a Ho:YLF laser pumped by a Tm-doped fibre laser is reported. The research in a continuous-wave (CW) operation was done for two crystals of the same 0.5 at.%Ho dopant concentration and with different lengths (3×3×30 mm3 and 3×3×50 mm3). For an output coupling transmission of 20% and a crystal length of 50 mm, the maximum CWoutput power of 38.9 W for 81.4 W of incident pump power, corresponding to the slope efficiency of 52.3% and optical-to-optical conversion efficiency of 47.8% (determined with respect to the incident pump power) was achieved. The highest opti- cal-to-optical conversion efficiency of 70.2% with respect to the absorbed pump power was obtained. The influence of a heat-sink cooling water temperature on theCWlaser performance was studied. For a Q-switched operation the pulse repe- tition frequency (PRF) was changed from 2 to 10 kHz. The maximum average output power of 34.1 W at the PRF of 10 kHz was obtained for a 50 mm holmium crystal length. For 2 kHz PRF and 71.9 W of incident pump power, pulse energies of 13.7 mJ with a 21 ns FWHM pulse width corresponding to 652 kW peak power were recorded.

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Authors and Affiliations

J. Kwiatkowski
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Abstract

Self-swept erbium fiber laser emitting around 1.56 μm is reported in detail. Both sweep directions were registered: pointing toward longer and shorter wavelengths, redshift and blueshift sweeping, respectively. We describe method of determining the direction of the wavelength drift using the monochromator based optical spectrum analyzer. Possible root for this sweeping regime, i.e., the gain modulation along active fiber, is discussed with the help of a simple model calculating the overall cavity gain that can predict the direction of the laser wavelength sweeping.

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Authors and Affiliations

P. Navratil
Pavel Peterka
ORCID: ORCID
P. Vojtisek
I. Kasik
J. Aubrecht
P. Honzatko
V. Kubecek
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Abstract

This document provides a simplified solution to the problem of calculation of laser hazard distances defined in the Advisory Circular 70-1B by the U.S. Federal Aviation Administration regarding atmospheric attenuation (assuming its constant value) and measurement uncertainties. The calculation approaches and examples presented in this document do not specify the procedure that should be followed in the case of atmospheric attenuation, nor do they take into account the uncertainties associated with the measured parameters. The analysis presented in the article complements to some extent AC 70-1B and can be used by those who need such a simplified solution regarding illumination of landing or taking off aircrafts. The article presents a sample analysis for a typical laser pointer, where the necessary parameters of the laser beam along with the appropriate uncertainties were determined in accordance with the methods accredited by the Polish Centre for Accreditation while the appropriate laser hazard distances were calculated taking into account different atmospheric attenuation coefficients.
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Authors and Affiliations

Jarosław Młyńczak
1

  1. Military University of Technology, Institute of Optoelectronics, Gen. S. Kaliskiego 2, 00-908 Warszawa, Poland
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Abstract

1) Background: the modeling, characterization, transformation and propagation of high-power CW laser beams in optical (including fiberoptic) trains and in the atmosphere have become hot topics in laser science and engineering in the past few years. Single-mode output is mandatory for high-power CW laser applications in the military field. Moreover, an unstationary, dynamic operation regime is typical. Recognized devices and procedures for laser-beam diagnostics could not be directly applied because of dynamic behavior and untypical non-Gaussian profiles. 2) Methods: the Wigner transform approach was proposed to characterize dynamically variable high-power CW laser beams with significant deterministic aberrations. Wavefront-sensing measurements by means of the Shack-Hartmann method and decomposition into an orthogonal Zernike basis were applied. 3) Results: deterministic aberration as a result of unstationary thermal-optic effects depending on the averaged power of the laser output was found. Beam quality determined via the Wigner approach was changed in the same way as the measurements of the beam diameter in the far field. 4) Conclusions: such an aberration component seems to be the main factor causing degradation in beam quality and in brightness of high-power CW laser beams.

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Authors and Affiliations

J. Jabczyński
P. Gontar
Ł. Gorajek
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Abstract

The paper describes the research on soft X-ray lasers with an active medium created using a gas puff target irradiated

with high-intensity laser pulses. The gas puff target in a form of an elongated gas sheet is produced by pulsed injection of

gas through a slit nozzle using a high-pressure electromagnetic valve. The method of generation of soft X-ray lasers using a

laser-irradiated gas puff target has been developed at the Institute of Optoelectronics. The collaborative experiments were

performed at various laser laboratories using high-intensity laser systems to irradiate the gas puff target and pump the X-ray

laser active medium. Results of these experiments are presented and discussed. Works aimed at increasing the efficiency of

X-ray lasers using a longitudinally irradiated gas puff target are also reviewed.

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Authors and Affiliations

H. Fiedorowicz
A. Bartnik
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Abstract

This paper presents the results of a numerical analysis of nitride-based edge-emitting lasers with an InGaN/GaN active region designed for continuous wave room temperature emission of green and blue light. The main goal was to investigate whether the indium thin oxide (ITO) layer can serve as an effective optical confinement improving operation of these devices. Simulations were performed with the aid of a self-consistent thermal-electrical-optical model. Results obtained for green- and blue-emitting lasers were compared. The ITO layer in the p-type cladding was found to effectively help confine the laser mode in the active regions of the devices and to decrease the threshold current density.

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Authors and Affiliations

M. Kuc
A.K. Sokół
Ł. Piskorski
M. Dems
M. Wasiak
R.P. Sarzała
T. Czyszanowski
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Abstract

In this paper, the two-temperature thermoelasticity model is proposed to a specific problem of a thermoelastic semi-infinite solid. The bounding plane surface of the semi-infinite solid is considered to be under a non-Gaussian laser pulse. Generalized thermoelasticity analysis with dual-phase-lags is taken into account to solve the present problem. Laplace transform and its inversion techniques are applied and an analytical solution as well as its numerical outputs of the field variables are obtained. The coupled theory and other generalized theory with one relaxation time may be derived as special cases. Comparison examples have been made to show the effect of dual-phase-lags, temperature discrepancy, laser-pulse and laser intensity parameters on all felids. An additional comparison is also made with the theory of thermoelasticity at a single temperature.

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Authors and Affiliations

Ashraf M. Zenkour
Ahmed E. Abouelregal
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Abstract

Widely-tunable, fully-monolithic, mid-infrared (mid-IR) deference frequency generation source (DFG) is presented. By using a custom designed fiber-pigtailed periodically poled lithium niobate (PPLN) crystal module the idler beam was generated with an efficiency of 21%/W, yielding 2.6 mW of optical output power. The proposed all-fiber configuration radically simplified the optical frequency conversion setup, making it robust and easily configurable. The usefulness of the constructed source was verified by performing simultaneous wavelength modulation spectroscopy (WMS) laser trace gas detection of methane, near 2999 cm−1, and ethane, near 2997 cm−1, via two independently generated, tunable idler beams.

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Authors and Affiliations

K. Krzempek
G. Dudzik
A. Hudzikowski
A. Gluszek
K. Abramski
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Abstract

Advances in photonic technologies, with new processes and scopes of photonic integrated circuits, have generated a lot of interest as the field allows to obtain sensors with reduced size and cost and build systems with high interconnectivity and information density. In this work, answering the needs of photonic sensors that must be portable, more energy-efficient, and more accurate than their electrical counterparts, also with a view to the emerging field of neuromorphic photonics, a versatile device is presented. The proposed device makes use of the well-known advantages provided by optical bistability. By combining two distributed feedback-multi quantum well semiconductor laser structures, this new optical multiple inputs - digital output device offers various essential purposes (such as logic gates, wavelength detector and monitoring) with no need for specific manufacturing for each of them. Through a commercial computer-aided design tool, VPIphotonics™, the necessary characterization of proposed device is also described.
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Bibliography

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Authors and Affiliations

Antonio M. Alaíz-Gudín
1
ORCID: ORCID
Ana P. González-Marcos
1
ORCID: ORCID

  1. Photonic Technology and Bioengineering Department, Universidad Politécnica de Madrid (UPM), Madrid, 28040 Spain
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Abstract

A new approach to passive electromagnetic modelling of coupled–cavity quantum cascade lasers is presented in this paper. One of challenges in the rigorous analysis of such eigenvalue problem is its large size as compared to wavelength and a high quality factor, which prompts for substantial computational efforts. For those reasons, it is proposed in this paper to consider such a coupled-cavity Fabry-Perot resonant structure with partially transparent mirrors as a two-port network, which can be considered as a deterministic problem. Thanks to such a novel approach, passive analysis of an electrically long laser can be split into a cascade of relatively short sections having low quality factor, thus, substantially speeding up rigorous electromagnetic analysis of the whole quantum cascade laser. The proposed method allows to determine unequivocally resonant frequencies of the structure and the corresponding spectrum of a threshold gain. Eventually, the proposed method is used to elaborate basic synthesis rules of coupled–cavity quantum cascade lasers.

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Authors and Affiliations

M. Krysicki
B. Salski
P. Kopyt
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Abstract

We demonstrate MW-level, single resonance optical parametric oscillator, based on KTP Type-II crystal with noncritical phase-matching. The OPO is pumped by electro-optically Q-switched Nd:YAG slab laser providing 55 mJ of pulse energy. At the output, we achieved 28 mJ of signal pulse energy at 1.57 μm with 51% conversion efficiency, corresponding to 1.4 MW of peak power.

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Authors and Affiliations

M. Kaskow
L. Gorajek
W. Zendzian
J. Jabczynski
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Abstract

Accurate understanding of the three-dimensional (3D) morphology of a complex goaf and its relative displacement in space is a precondition to further analyzing the stability of the cavity. In this study, to make an accurate stability analysis of the goaf, laser detection and numerical simulation are used to study the interior space form of goaf and the change characteristics of stress and displacement in goaf. The results of the study show that the BLSS-PE mining 3D laser system as a field detection tool can detect the morphology of the cavity more comprehensively and improve the accuracy of the detection data to a certain extent. Combined with the numerical simulation software analysis, it can be seen that the maximum principal stress in the 818-2# goaf increases after excavation. In addition, the maximum value appears in the top and bottom plates of the goaf, and the minimum stress remains nearly unchanged. The tensile stress appears in the upper and lower plates but is lower than the surrounding rock. The maximum horizontal and vertical displacements of the 818-2# goaf are small. The plastic zone appears in the surrounding rock of the goaf as the mining work progresses, but the area is small. It is concluded that the goaf is relatively stable overall. The research results may provide a strong reference for ground pressure management in mines and comprehensive control of goaves.
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Authors and Affiliations

Gangyou Sun
1
ORCID: ORCID
Yuandi Xia
2
ORCID: ORCID
Qinrong Kang
2
ORCID: ORCID
Weizhong Zhang
2
ORCID: ORCID
Qingzhen Hu
2
ORCID: ORCID
Wei Yuan
2
ORCID: ORCID

  1. The Fourth Research and Design Engineering Corporat ion, China
  2. School of Resources and Safety Engineering, Wuhan Institute of Technology, China
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Abstract

The above-threshold operation of a Fabry-Perot laser with a nonlinear PT (parity time) mirror is investigated. For the first time, the analysis accounts for gain saturation of an active medium as well as gain and loss saturation effects in the PT mirror. The obtained laser output intensity characteristics have been demonstrated as a function of various PT mirror parameters such as: the ratio of the PT structure period to laser operating wavelength, number of PT mirror primitive cells, and gain and loss saturation intensities of the PT mirror gain and loss layers. Two functional configurations of the laser have been considered: laser operating as a discrete device, and as a component of an integrated circuit. It has been shown that, in general, the laser operation depends on the PT mirror orientation with respect to the active medium of the laser. Moreover, when the laser radiation is outcoupled through the PT mirror to the free space, bistable operation is possible, when losses of the mirror’s loss layer saturate faster than gain of the gain layer. Furthermore, for a given saturation intensity of the mirror loss layers, the increase of the saturation intensity of the mirror gain layers causes increasing output intensity, i.e., the PT mirror additionally amplifies the laser output signal.
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Bibliography

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Authors and Affiliations

Agnieszka Mossakowska-Wyszyńska
1
ORCID: ORCID
Piotr Witoński
1
ORCID: ORCID
Paweł Szczepański
1 2
ORCID: ORCID

  1. Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warsaw, Poland
  2. National Institute of Telecommunications, ul. Szachowa 1, 04-894 Warsaw, Poland
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Abstract

The paper concerns the accuracy of determining particle size distributions of the fine-grained materials by means of laser diffraction method. Selection of measuring method for determination of materials granulation depends on various properties of the sample, but mainly on the range of particle size in the sample. It must be taken into consideration that each of the measurement methods inherently generate different information about particle size distribution. The applied measurement method generates the main impact on the results of research because it uses various material properties, like: geometric properties, density or type of the surface (porosity).

Influence of density and particle shape on the results of measurements by laser diffraction was studied in the paper. This method becomes a standard for measuring particle size of mineral powders. Analysis of raw materials particle size distribution was performed using a laser particle-meter Analysette 22. Investigations included measurements of particle size of raw materials characterized by various densities (coal, porphyry, barite) and the shape of the particles (copper shale ore, fly ash from coal combustion). The density of raw materials was determined by helium pycnometer, while the particle shape was expressed by coefficient which was calculated on the basis of particles geometric parameters. Geometry of the grains was measured using an optical microscope with a digital record of images by means of image analysis method. The accuracy of laser granulometric analyzes was expressed by variation coefficient of narrow particle fractions contents. Results of analyzes confirmed that the laser granulometric analysis provides accurate information about the finestparticle size distribution. No significant effect of the material density on the accuracy of granulometric analysis was observed. Effect of particle shape of the tested materials caused more stable values of the variation coefficient for particles of more spherical shape what is related to the applied method of laser measurement. The accuracy of laser granulometric analyzes varies dependably on the measured particle size range of particles. The most accurate analyzed materials are these ones being the part of narrow particle fractions.

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Authors and Affiliations

Damian Krawczykowski
Aldona Krawczykowska
Kazimierz Trybalski
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Abstract

Number of trace compounds (called biomarkers), which occur in human breath, provide an information about individual feature of the body, as well as on the state of its health. In this paper we present the results of experiments about detection of certain biomarkers using laser absorption spectroscopy methods of high sensitivity. For NO, OCS, C2H6, NH3, CH4, CO and CO(CH3)2 an analysis of the absorption spectra was performed. The influence of interferents contained in exhaled air was considered. Optimal wavelengths of the detection were found and the solutions of the sensors, as well as the obtained results were presented. For majority of the compounds mentioned above the detection limits applicable for medicine were achieved. The experiments showed that the selected optoelectronic techniques can be applied for screening devices providing early diseases detection.

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Authors and Affiliations

T. Stacewicz
Z. Bielecki
J. Wojtas
P. Magryta
J. Mikolajczyk
D. Szabra
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Abstract

Laser-generated surface patterns provide the means for local mechanical interlocking between the joined materials, tunes the wettability of surfaces that come in contact, and generally are the main factor for bonding strength enhancement, especially between dissimilar materials. This paper presents the influence of different patterning overlays generated with a pulsed laser on the surface of stainless-steel sheets. For all experiments, an overlapping degree of 90% has been chosen between three different patterns, while the engraving speed, pulse frequency and number of passes have varied. The textured surfaces’ morphology was assessed through optical microscopy, and the roughness of the surfaces was correlated with the corresponding experimental parameters. The results have indicated promising insights for joining stainless steel to plastic materials, which is otherwise difficult to assess through usual welding techniques.
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Authors and Affiliations

E.R. Moldovan
1
ORCID: ORCID
C. Concheso Doria
2
ORCID: ORCID
J.L. Ocaña Moreno
3
ORCID: ORCID
L.S. Baltes
1
ORCID: ORCID
E.M. Stanciu
1
ORCID: ORCID
C. Croitoru
1
ORCID: ORCID
A. Pascu
1
ORCID: ORCID
M.H. Tierean
1
ORCID: ORCID

  1. Transilvania University of Brasov, Brasov, Romania
  2. BSH Electrodomésticos España S.A., Zaragoza, Spain
  3. Universidad Politecnica de Madrid, Madrid, Spain
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Abstract

This paper presents a new stand for studying the linear shrinkage kinetics of foundry alloys. The stand is equipped with a laser displacement sensor. Thanks to this arrangement, the measurement is of a contactless nature. This solution allows for the elimination of errors which occur in measurements made using intermediary elements (steel rods). The supposition of the expansion (shrinkage) of the sample and the expansion of the heated rod lead to the distortion of the image of the actual dimensional changes of the studied sample. A series of studies of foundry alloys conducted using the new stand allowed a new image of shrinkage kinetics to be obtained, in particular regarding cast iron. The authors introduce in the study methodology a real-time measurement of two linked quantities; shrinkage (the displacement of the free end of the sample) and temperature in the surface layer of the sample casting. This generates not only a classic image of shrinkage (S) understood as S = f (t), but also the view S = f (T). The latter correlation, developed based on results obtained using the contactless method, provide a new, so far poorly known image of the course of shrinkage in foundry alloys, especially cast iron with graphite in the structure. The study made use of hypo- and hypereutectic cast iron in order to generate an image of the differences which occur in the kinetics of shrinkage (as well as in pre-shrinkage expansion - expansion occurs during solidification).

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Authors and Affiliations

J. Zych
ORCID: ORCID
T. Snopkiewicz
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Abstract

The article presents research on solid particle erosive wear resistance of ductile cast iron after laser surface melting. This surface treatment technology enables improvement of wear resistance of ductile cast iron surface. For the test ductile cast iron EN GJS-350-22 surface was processed by high power diode laser HPDL Rofin Sinar DL020. For the research single pass and multi pass laser melted surface layers were made. The macrostructure and microstructure of multi pass surface layers were analysed. The Vickers microhardness tests were proceeded for single pass and multi pass surface layers. The solid particle erosive test according to standard ASTM G76 – 04 with 30°, 60° and 90° impact angle was made for each multi pass surface layer. As a reference material in erosive test, base material EN GJS-350-22 was used. After the erosive test, worn surfaces observations were carried out on the Scanning Electron Microscope. Laser surface melting process of tested ductile cast iron resulted in maximum 3.7 times hardness increase caused by microstructure change. This caused the increase of erosive resistance in comparison to the base material.

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Authors and Affiliations

A. Kotarska
D. Janicki
J. Górka
ORCID: ORCID
T. Poloczek
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Abstract

Laser cladding is a method that can be applied to repair the crack and break on the mold and die surfaces, as well as generate new attributes on the surface to improve toughness, hardness, and corrosion resistance. It is used to extend the life of the mold. It also has the advantages of superior bonding strength and precision coating on a local area compared with the conventional thermal spraying technology. In this study, we investigated the effect of cladding on low carbon alloy steel using 18%Cr-2.5%Ni-Fe powder (Rockit404), which showed high hardness on the die surface. The process conditions were performed in an argon atmosphere using a diode laser source specialized for 900-1070 nm, and the output conditions were 5, 6, and 10 kW, respectively. After the cladding was completed, the surface coating layer’s shape, the hardness according to the cross-section’s thickness, and the microstructure were analyzed.
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Authors and Affiliations

Cheol-Woo Kim
1
ORCID: ORCID
Hyo-Sang Yoo
1
ORCID: ORCID
Jae-Yeol Jeon
1
Kyun-Taek Cho
1
Se-Weon Choi
1
ORCID: ORCID

  1. Smart Mobility Materials and Components R&D Group, Korea Institute of Industrial Technology, 1110-9 Ory ong-dong, Buk-gu, Gwan gju, Republic of Korea

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