Optical Emission Analysis Research Articles

Effect of 3D printing mode on structure and fatigue strength of 30CrMnSi steel

The desire of modern manufacturers to reduce the cost of producing goods leads to an increased search for ways to obtain the raw materials for future products more efficiently. One promising method for obtaining raw materials is electric arc surfacing (WAAM), which is discussed in this paper. The aim of the study was to investigate the effect of electric arc surfacing on the structure and fatigue strength of 30CrMnSi steel. To obtain the samples, two walls were surfaced according to the specified modes: I = 150 A, U = 25 V, Q = 600 J/mm (mode 1) and I = 110 А, U = 17 V, Q = 300 J/mm (mode 2). During the study of the walls microstructure after milling, it was found that when the metal is surfaced according to the mode 1, large accumulations of technological defects such as pores and bad welding form in the material. When the metal is treated according to the mode 2, these macroscopic defects are practically not detected. During optical emission analysis, it was observed that during the surfacing process, alloying elements are consumed and the carbon content decreases most actively. It should be noted that the burnout of elements occurs more actively when the metal is surfaced using the mode 1. This may be due to the higher energy input in this process. A predominant ferrite-sorbite structure was found in the metal surfaced using the mode 1. However, local ferritic colonies were revealed on the surface of the samples due to their height. The microstructure of the samples produced using the mode 2 is mainly composed of ferrite and pearlite. Ferrite is isolated as closed grids along the boun­daries of the austenitic grains, and traces of a Widmanstetten structure can also be seen. Perlite is present both as highly dispersed plates and partially spheroidized colonies. Despite the fact that the structure of the samples produced using the mode 1 is generally considered to be more favo­rable in terms of material properties, the fatigue strength of the samples produced according to the mode 2 exceeds that of the mode 1 by an average of 70 %. This may be due to the stronger influence of technological defects on the metal fatigue resistance than microstructural ones.

The influence of 3D printing mode on the chemical composition and structure of 30HGSA steel

The authors carried out the study of the influence of 3D printing modes on the structure and chemical composition of 30HGSA steel (chromansil) samples produced by the method of additive electric arc surfacing. To study the influence of the electric arc surfacing mode on the chemical composition of the steel under study, an optical emission analysis of the samples was carried out. The influence of the surfacing mode on the resulting structure was assessed over the entire height of the deposited walls at magnifications of ×50, ×100, ×200 and ×500. Optical emission analysis identified a change in the material chemical composition associated with the loss of chemical elements. It was found that the degree of loss of C, Cr and Si increases almost linearly and is directly proportional to the surfacing heat input (Q, J/mm). The exact influence of an increase in the surfacing heat input on the Mn content was not found, but a relationship between the degree of its loss and the voltage (U, V) during surfacing of samples was identified. Microstructural studies of all samples did not reveal a large number of systemically formed structural defects characteristic of cast and welded products (pores, shrinkage cavities, etc.), which confirms the high quality of the metal in goods produced by electric arc surfacing. Analysis of micrographs taken in different areas of the samples allowed determining that the metal microstructure does not undergo significant changes under different surfacing modes; the main tendencies in changes in the structure along the height of the sample are preserved. All samples demonstrated the formation of a highly dispersed structure, regardless of the 3D printing parameters. The most favorable metal structure, suitable for subsequent use in the production of goods using additive manufacturing, was recognized as the structure of the sample deposited using mode No.5 (I=160A, U=24V, Q=921.6J/mm). This mode can be used for further study of the problems of additive electric arc surfacing of 30HGSA steel.

Spatially resolved optical emission analysis of spokes in HiPIMS utilising Al, Cr, Cu, Ti, and W targets

Investigating spokes in high-power impulse magnetron sputtering discharge requires non-invasive diagnostic methods to characterise accurately spoke properties. A fast photodiode and a cylindrical Langmuir probe were employed to synchronise the moment of acquisition of the optical emission spectrum with the position of a passing spoke. This study provides statistical data analysis to bring insights into spoke characteristics in a non-reactive argon atmosphere, employing aluminium, chromium, copper, titanium, and tungsten targets. Utilising different target materials, the objective is to describe basic parameters such as shape, length, and propagation velocity of spokes and also analyse spoke inner parameters such as floating potential and spectral emission, under nearly identical experimental conditions. From the optical emission, the most prominent species within the spoke were determined. Additionally, the mechanism governing spoke movement was described using a phenomenological model.

Faulty machining and micro-segregation assisted fatigue failure of cylinder head stud of a diesel generator

A detailed failure analysis of cylinder head stud bolt of a four-stroke diesel generator has been presented. The study included optical emission analysis, tensile testing, hardness testing, optical microscopy, SEM, and EDX analyses. The investigation showed that the main mechanism of failure was corrosion-fatigue. Fatigue initiation was assisted by pitting corrosion induced by faulty machining, moisture, and presence of tempered martensite and non-metallic inclusions at the surface. Propagation of the fatigue crack was encouraged by localized corrosion within the tempered martensite, non-metallic inclusions, and Mn/Cr/Mo/Si micro-segregation. Both excessive C and Mn/Cr/Mo/Si micro-segregation caused the formation of mixed microstructure of tempered martensite and fresh martensite with retained austenite. The non-uniform microstructure led to non-uniform hardness distribution and caused localized deformation during cyclic loading and promoted fatigue crack propagation.

Quantifying Spin‐Charge Conversion Mechanisms for THz Emission in Magnetic Multilayers

AbstractUltrafast control of both electric and spin currents triggered by femtosecond laser pulse has attracted much attention due to future applications for broadband THz emitter as well as high‐speed spintronic devices. Optically generated spin current is converted to charge current via multiple spin‐charge conversion mechanisms, generating THz wave emission in magnetic multilayers. However, to date, quantitative and comparative investigation of THz emission originating from spin‐charge conversion mechanisms has not yet been fully explored. Here, direct and straightforward nondestructive probing to measure THz emission is provided at original Co/Pt and Co/Ta interfaces embedded in Pt/Co/Ta multilayers with polarization analysis of both optical pump and THz emission. These results allow a fundamental understanding of various spin‐charge conversion phenomena, which is a key basis for future spintronic THz source development.

Electrostatic discharge induced degradation of optical-electrical properties and defect evolution of GaAs-based oxide-confined VCSELs.

GaAs-based oxide-confined vertical-cavity surface-emitting lasers (VCSELs) exhibit relatively low resistance against reliability-related damage. In order to gain a deeper understanding of the degradation and failure mechanism in oxide-confined VCSELs caused by electrostatic discharge (ESD)-induced defect proliferation, we investigated the effects of ESD stress on the degradation of optical-electrical characteristics and the evolution of defects in VCSELs under human body model test condition. The degradation threshold values for forward and reverse ESD pulse amplitudes were estimated to be 200 V and -50 V, respectively. Notably, VCSELs demonstrated greater sensitivity to reverse bias ESD compared to forward bias ESD. Analysis of optical emission and microstructure provided evidence that the device failure is attributed to an increase in ESD current density, leading to the multiplication of dark line defects (DLDs) originating from the edge of the device's oxide aperture. The formation of defects occurred suddenly in discrete events within small regions, rather than progressing gradually and uniformly. These defects propagated and led to damage across the entire active region. We believe that our results would be meaningful for improving the reliability of VCSEL in the future.

The Galactic supernova remnant CTB 1: optical and X-ray emission analysis

ABSTRACT We present the kinematic results for the supernova remnant (SNR) CTB 1, obtained with the PUMA equipment of the 2.1-m telescope at San Pedro Mártir National Astronomical Observatory, Baja California, Mexico. The observations were made on the H α line using a Fabry–Perot interferometer. The kinematics derived from the Fabry–Perot velocity cubes allowed us to estimate a kinematic distance for this SNR. We estimate that CTB1 is about 3.8 kpc from the sun, corresponding to a linear diameter of 19 pc, with an expansion velocity of $286 \rm ~ km ~s^{-1}$. Additionally, we analyse the diffuse X-ray emission from CTB 1 using data from the XMM–Newton observatory. From the best fits to the spectrum of southwest and northeast regions, we obtained a hot plasma temperature $\sim 0.1-0.3 ~\rm keV$ with an overabundance in O and Ne and a lower abundance in Fe, which could be caused by a SNR with a stellar progenitor between 10 to $70 \, \rm {\rm M}_{\odot }$. The initial energy of the supernova explosion is estimated between (0.6–1.0) × 1050 erg for soft X-ray emission. The X-ray emission also presents a non-thermal component of low surface brightness in the hard X-ray band. Images in radio and X-ray emission allow us to classify CTB 1 as mixed-morphology supernova type. The evolution models show that the cloudy ISM model is the only one that reproduces the mixed morphology type observed in the SNR CTB 1.

Diagnostics of laser-induced plasma on carbon-based polymer material using atomic and molecular emission spectra

Time-integrated optical emission analysis of laser-induced plasma on Teflon is presented. Plasma was induced under atmospheric pressure air using transversely excited atmospheric CO2 laser pulses. Teflon is a C-based polymer that is, among other things, interesting as a substrate for laser-induced breakdown spectroscopy analysis of liquid samples. This study aimed to determine the optimal experimental conditions for obtaining neutral and ionized C spectral lines and C2 and CN molecular band emission suitable for spectrochemical purposes. Evaluation of plasma parameters was done using several spectroscopic techniques. Stark profiles of appropriate C ionic lines were used to determine electron number density. The ratio of the integral intensity of ionic-to-atomic C spectral lines was used to determine the ionization temperature. A spectral emission of C2 Swan and CN violet bands system was used to determine the temperature of the colder, peripheral parts of plasma. We critically analyzed the use of molecular emission bands as a tool for plasma diagnostics and suggested methods for possible improvements.

Supernova remnant W51C: optical and X-ray emission analysis

ABSTRACT We present observations of the optical and X-ray emission from the Galactic supernova remnant W51C. From [S ii] Fabry–Pérot interferometry and H α and [S ii] images we detect filaments that are part of the optical counterpart of the supernova remnant. We obtain the kinematic distance to W51C, showing that it is one of the shortest distances reported in the literature. We also estimate other physical properties such as the velocity of the shock induced in the cloudlets emitted at optical wavelengths and the electron density of those cloudlets. From XMM–Newton observatory archival data, we obtain images of the diffuse X-ray emission of this supernova remnant. The spectrum of the X-ray emission is explored to estimate X-ray parameters such as luminosity and temperature of the hot plasma in the supernova remnant. We fit a thermal model with a plasma temperature of 1.4 keV for an X-ray thermal luminosity of 2.0 × 1036 erg s−1. With the parameters described above we test the model proposed by White & Long to explain the mixed morphology observed in W51C. We obtain an initial energy of the supernova explosion of 8.4 × 1050 erg and an age of 13 000 yr. The derived initial energy is typical of supernova remnants, but in disagreement with respect to older estimations that found higher values and suggested that W51C was the result of the explosion of two supernovae.

Study of gold ore processing by flotation methods

The article deals with the studies of gold-bearing ore benefication by flotation methods. The object of the study is a low-sulfide gold-quartz type of ores with the following petrographic composition: quartz – 90 %, quartz-chlorite schists – 10 %. The ore from this deposit consists of the weathering crust rocks including iron-mica rocks with veins and spots of granoblastic quartz. The purpose of the research is to develop an optimal flotation regime for obtaining sulfide gold-bearing concentrate. The influence of ore size, reagent mode, flotation redistribution structure, and flotation time on operations was recorded during the experiment. The paper presents the results of studying the chemical composition of the ore by the method of silicate and optical emission analysis. The flotation process used butyl potassium xanthate as a collector and a combination of pine essential oils as a foaming agent. The Hancock concentration efficiency criterion was determined based on a series of experiments. The following technological indicators of ore processing were identified: gravity concentrate with the gold grade of 1165 g/t with the yield of 0.3 % and the recovery of 73.74 %; flotation concentrate (after purification II) with the gold grade of 68.9 g/t with the yield of 1.52 % and a recovery of 22.05 %. Its silver content was 15.9 g/t. The total gold recovery was 95.79 %, with the yield of 1.82 % and the gold grade of 249.9 g/t. The gold grade in the flotation tailings was 0.19 g/t.

Investigation of the process of reactive ion-beam sputtering of gallium arsenide using optical emission spectroscopy

The aim of this work was to study the process of reactive ion-beam sputtering of gallium arsenide using optical emission analysis of plasma in the target region to determine the optimal conditions for the formation of intrinsic GaAs oxides. The ion source was a plasmatron based on an anode layer accelerator (UAS), which generated a stream of accelerated argon and oxygen ions with an energy of 400–1200 eV. The target was made from tellurium doped gallium arsenide. Intense GaI lines (2874.2 Å, 2943.6 Å, 4033.0 Å and 4172.1 Å), atomic argon ArI, argon ions, and also FeI lines were detected in the spectrum upon sputtering of GaAs by Ar+ ions. The appearance of iron lines can be explained by the sputtering of the pole tips of the magnetic system of the ion source. An increase in the accelerating voltage from 1 to 3 kV leads to an increase in the intensity of the peaks of atomic gallium GaI (4172.1 Å) by 2.38 times, the GaI line (4033.0 Å) by 3.25 times, the GaI line (2943.6 Å) 3.4 times, GaI lines (2874.2 Å) 5 times. It was found that an increase in the partial pressure of oxygen leads to a sharp decrease in the peaks of GaI (4033.0 Å) and GaI (4172.1 Å) due to the chemical interaction of gallium and oxygen. Sputtering in pure oxygen reduces the intensity of these peaks by 8 and 5 times, respectively. The intensities of the peaks of atomic gallium GaI (2874.2 Å) and GaI (2943.6 Å) decreased in 2 and 1.78 times, respectively. In the presence of a positive potential on the target, the intensity of all lines of atomic gallium monotonically decreases with increasing potential. In the emission spectrum, lines of atomic oxygen OI (7774.2 Å) and molecular positive ions O+2 (6418.7 Å, 6026.4 Å, 5631.9 Å and 5295.7 Å) were detected. In the presence of a positive potential on the target, a monotonic decrease in the intensity of the above oxygen lines was observed. This indicates an intensification of chemical interaction of oxygen with target elements and, accordingly, a decrease in the free active oxygen particles.

Multi-element optical emission and mass-spectrometry analysis of high-purity cadmium with vacuum preconcentration by matrix volatilization

The paper discusses the development of optical-emission and mass-spectral with inductively coupled plasma (ICP-OES/MS) analysis procedures for determination of traces in cadmium. These procedures are based on the preliminary concentration of traces by selective volatilization of cadmium in vacuum through the film of its own oxide and the subsequent ICP-OES/MS analysis of concentrate. The relative concentration coefficient for the entire array of the experimental data is at least 150. The trace limits of detection (LODs) have been evaluated for the developed ICP-OES and ICP-MS analysis procedures. The ICP-OES method allows to determine 43 traces (Ag, Al, As, Au, B, Ba, Be, Ca, Ce, Co, Cr, Cu, Dy, Er, Fe, Ga, Gd, Hf, Ho, K, La, Li, Lu, Mg, Mn, Mo, Nb, Ni, Pb, Re, Sb, Sm, Sn, Sr, Ta, Tb, Ti, V, W, Y, Yb, Zn, Zr) at the concentration level from 0.1 to 40 ng·g−1. At the same time implementation of the ICP-MS method provides data about 41 impurities (Ag, Al, As, Au, B, Ba, Be, Bi, Ce, Co, Cr, Cu, Dy, Er, Ga, Gd, Hf, Ho, In, La, Lu, Mn, Mo, Nb, Ni, Pb, Re, Sb, Sm, Sn, Sr, Ta, Tb, Te, Ti, V, W, Y, Yb, Zn, Zr) with LODs from 0.002 to 10 ng·g−1.

Contact potential difference of alloy steel after heat treatment

Introduction. The paper considers an actual issue of the development and application of a non-destructive method for controlling the quality of surfaces of steel products (Kelvin probe method). The work objective is to establish the magnitude of the contact potential difference (CPD) of steel 107WCR5 after heat treatment. Materials and Methods. The object of study is alloy tool steel 107WCR5. The chemical composition of the samples was refined through the optical emission analysis method. To carry out the statistical processing, there were three samples in three series. We chose different heat treatment modes for each series, i.e., quenching with low tempering, strengthening and normalization. The end surfaces of the samples were polished and then one of them was treated with a solution of nitric acid. Further, the measurement of the contact potential difference and statistical data processing were carried out. Results. The data obtained show that the CPD value of steel 107WCR5 samples changes after heat treatment. With an increase in tempering temperature, the contact potential difference of the polished surface and the hardness, decrease almost linearly. Exposure to acid causes a significant decrease and equalization of the contact potential difference for all structures. The contact potential difference of steels 107WCR5 and CT105 is compared. Alloying steel by the elements with the work function values of the electron higher than that of iron causes a decrease in the CPD between the standard and the sample. The CPD behavior under a change in the composition of the steel depends strongly on the presence of alloying elements. The dependence of CPD on the dispersion of the structure is seen in both cases; however, it is more pronounced for 107WCR5 steel. The electron work function of the martensite, troostite, and sorbitol structures obtained as a result of heat treatment of steels 107WCR5 and CT105 is calculated. Discussion and Conclusions. The dependence of the contact potential difference on the structure, chemical and phase composition was experimentally established; the electron work function of steels 107WCR5 and CT105 was calculated. This technique is more sensitive to alloy steel samples than to carbon steel. It seems possible to conclude that the measurement of the contact potential difference can be used to control surfaces exposed to active media or elevated temperatures as a non-destructive express diagnostic method.

A comparison of two cold atmospheric helium plasma devices which utilise the same RF power generator

PurposeThis research was conducted to analyse and compare a Renuvion hand piece and TheraDep's deposition device at various gas flow rates and power settings. Both devices were powered by an Apyx Ultimate Electrosurgical generator. MethodsCurrent, voltage, optical emission spectroscopy (OES) and thermal imaging were used to investigate the resulting plasma intensities and species being ionised. It was found that the Renuvion device could deliver 5.6 to 8.2 W of power whereas the Deposition Accessory was significantly less at between 1.9 and 4.2 W depending on the power setting selected. Differences in the OES results were also observed which are thought to have resulted from variations in the atmospheric entrainment between the two devices. ResultsTaken in combination, the electrical, optical emission and thermal data analysis has demonstrated that the addition of the Deposition Accessory transforms the Renuvion electrosurgical tool from a device that operates in the coagulation and cutting arena into a device with a dramatic reduction in the energy delivered to the target tissue. Consequently, this limits the localised heating of adjacent tissue and results in a device that has controlled coagulation capability and one which is not capable of cutting tissue. ConclusionsThis offers significant potential to allow clinicians to evaluate applications in plasma medicine using an FDA cleared electrosurgical power source.

Hesperidin mediated synthesis, structure and optical emission analysis on nanocrystalline CuO

Abstract Nanocrystalline Copper (II) oxide was synthesized through hesperidin mediated phytochemical reduction method and post annealed at 600 °C for 4 hrs. Various analytical results obtained after characteristic measurements such as XRD, FESEM, UV–visible spectroscopy and Photoluminescence studies have been discussed. The crystallographic plane reflections obtained in X-ray diffraction pattern was found to be analogous with the monoclinic end centered phase of copper (II) oxide with Halder-Wagner crystallite size 18 nm. The formation of spherical grains via agglomerated crystallites was apparent from the surface morphology obtained through FESEM images. Tauc’ plot of UV–visible spectrum employing Kubelka-Munk function provided a direct optical band gap of 1.61 eV. The photoluminescence spectrum using 280 nm optimal excitation wavelength and the related CIE plot revealed that the optical emission occurs at blue region as indicated by the chromaticity coordinates.

Investigation of optical and spectroscopic properties of neodymium doped oxyfluoro-titania-phosphate glasses for laser applications

Nd3+-doped oxyfluoro-titania-phosphate glasses with a chemical combination, P2O5–CaF2–BaF2–TiO2–Nd2O3 (PCfBfTiNd), were synthesized by the regular melt-quenching method. These glass samples were investigated through optical absorption, emission, decay curves and spectroscopic ellipsometry analysis. Non-linear refractive index (n2) is evaluated using the Boling method and it was found to be as low as 3.68 × 10−16 cm2/W (1.36 × 10−13 esu). Emission spectra of Nd3+-doped glasses were obtained by laser excitation at a wavelength of 808 nm. Results were endorsed that the 0.5 mol% Nd3+-doped PCfBfTiNd05 glass could be a suitable gain media for the development of high-energy high-peak power lasers.

Luminescence properties of europium doped oxyfluorosilicate glasses for visible light devices

Europium (Eu3+)-doped oxyfluorosiliacte (SALfSfEu: SiO2 + Al2O3 + LiF + SrF2 + Eu2O3) glasses have been fabricated by usual melt-quenching technique. These glasses were characterized through optical absorption, excitation, emission and decay curve analysis. The Judd-Ofelt (JO) parameters have been evaluated from the refractive index and luminescence spectrum of the 1.0 mol% Eu3+-doped glass. The quantitative radiative properties including branching ratio, radiative lifetime and stimulated emission cross-sections of the fluorescent levels were predicted by using the JO parameters. Luminescence intensity increases as for as 0.5 mol% and then decreases with further increasing Eu3+ ion concentration. Photoluminescence quantum yield found to be as high as 74% for 0.05 mol% of Eu3+ ion concentration and decreased by increasing concentration. Luminescence intensity ratio is found to be 3.17 for 1.0 mol% Eu3+-doped SALfSfEu1.0 glass which suggest that the occupation of high degree of symmetry by the Eu3+ ions. Fluorescent decay curves of the emitting level exhibit an exponential behaviour. Lifetime of 5D0→7F2 transition was decreased slightly with increasing Eu3+ ion concentration, however, not significant for 5D1→7F1 transition. Luminescence properties reveal that the red emission at 612 nm found to be suitable for developing the lasers and display devices in the visible region.

Extremely high-power-density atmospheric-pressure thermal plasma jet generated by the nitrogen-boosted effect

In this study, the effect of N2 addition to an atmospheric-pressure Ar thermal plasma jet (TPJ) on ultrarapid heating was investigated. With increasing N2 flow rate, a boost of arc voltage to ∼36 V was observed, which significantly improved heating characteristics. As a result, a drastic power density increase from 10 to 125 kW/cm2 was achieved with the addition of 2.0 L/min N2 to 3.0 L/min Ar. The results of optical emission analysis and heating characteristics evaluation implied that dissociation and recombination of N2 molecules and the high thermal transport property of nitrogen gas play important roles in the increase in TPJ power density. Furthermore, we obtained TPJ extension with N2 addition that reached 300 mm, and it showed spatial enhancement of heat transport characteristics.

Theoretical Analysis of Optical Absorption and Emission in Mixed Noble Metal Nanoclusters.

In this work, we studied theoretically two hybrid gold-silver clusters, which were reported to have dual-band emission, using density functional theory (DFT) and linear and quadratic response time-dependent DFT (TDDFT). Hybrid functionals were found to successfully predict absorption and emission, although explanation of the NIR emission from the larger cluster (cluster 1) requires significant vibrational excitation in the final state. For the smaller cluster (cluster 2), the Δ H(0-0) value calculated for the T1 → S0 transition, using the PBE0 functional, is in good agreement with the measured NIR emission, and the calculated T2 → S0 value is in fair agreement with the measured visible emission. The calculated T1 → S0 phosphorescence Δ H(0-0) for cluster 1 is close to the measured visible emission energy. In order for the calculated phosphorescence for cluster 1 to agree with the intense NIR emission reported experimentally, the vibrational energy of the final state (S0) is required to be about 0.7 eV greater than the zero-point vibrational energy.

Assessment of optical emission analysis for in-process monitoring of powder bed fusion additive manufacturing

ABSTRACTDeveloping methods which allow real-time monitoring of powder bed fusion (PBF) additive manufacturing (AM) processes is key to enabling in situ assessments of build quality (e.g. lack of fusion and porosity). Here, we investigate the use of optical emission spectroscopy and high-speed (100 kHz) measurement of select wavelength emissions, based on a line-to-continuum approach, to determine if a correlation between PBF AM process inputs, sensor outputs, and build quality exists. Using an open protocol system interfaced with a 3D Systems ProX 200 machine, sensor data were synchronised with the scanner position and the laser state during the buildup of Inconel-718 components under varying powers, scan speeds, and hatch spacing parameters. Sensor measurements were then compared against post-build computed tomography scans. We show evidence that sensor data, when combined with appropriate analyses, are related to both processing conditions and build quality.