Specimen Temperature Research Articles

Linewidth reduction laser thermal-transferred carbon nanotube wirings on plastic film by heat propagation suppressing

Abstract We have developed a technique to decrease the linewidth of multi-walled carbon nanotube (MWNT) wirings on the surface of a plastic film fabricated using the laser thermal transfer method. In this method, the MWNT film deposited on a polyethylene (PE) film was irradiated with laser light, resulting in the intermixing of MWNT and PE at the interface. To control the linewidth, the heat propagation in the MWNT film was suppressed by decreasing the laser spot size and the specimen temperature. The minimum wiring width was approximately 90 μm. Furthermore, the linewidth could be reduced without increasing resistivity by suppressing the heat propagation. Simulation results showed our proposed methods caused different heat propagation and different temperatures at the center region of the MWNT/PE film. Experimental and simulation results suggest that suppressing heat propagation in the MWNT/PE film was effective. This method could be utilized for the miniaturization of carbon devices.

Thermodynamic coupling performance analysis and simulation of aerated oil medium steel-BMC joint surface

In order to study the thermal coupling properties of aerated oil medium steel-basalt mineral composite (BMC) joint surface and establish an accurate and convenient simulation analysis method. The calculation method of the actual contact area ratio weight matrix of the aerated oil medium steel-BMC joint surface was studied. The virtual material theory model of the thermal coupling performance of the aerated oil medium steel-BMC joint surface was established by combining it with the virtual material theory. Based on the virtual material method, the thermodynamic coupling performance of the aerated oil medium steel-BMC joint surface was studied by finite element simulation, and compared with the experiment and numerical simulation methods of fractal theory. The results show that the temperature and strain changes of BMC specimen with virtual material method have a good coincidence with the experimental results, and the relative error is minimal. At the same time, the virtual material simulation model is simple, less computation and higher efficiency. It is proved that the method in this paper has better precision and convenience.

Experimental analysis of intumescence fireproofing coating on base material of substation frames

In order to improve the fire resistance of the substation frame, an intumescence fireproof coating for the base material (Q235 steel and stainless steel) of substation frame was developed in this paper. The experiments of pull-out test, fire resistance test and electron microscope scanning were carried out to observe the mechanical properties, fire resistance properties and microphysical and chemical properties of the fireproof coating or base material. The main conclusions are summarized as follows: The bond strength of the Q235 steel to the intumescence fireproof coating is 1.26 MPa, which is greater than that of stainless steel at 0.506 MPa. Moreover, the variations of backside temperature and internal temperature of specimens with fireproofing coating are apparently different from those for conditions without fireproofing coating. For conditions with fireproofing coating, the backside temperature and internal temperature of specimens increase in the initial stage, while after the fireproofing coating is expanded and the insulation layer is formed on the surface, the rise rate of the temperature decreases. The average thermal insulation efficiencies of Q235 carbon steel and stainless steel are 240.32 min and 223.22 min, while the average values of fire resistance limit are 250.8 min and 244.2 min, respectively. The expansion multiples of the fireproofing coating for the two materials after being heated are between 50 and 60. Furthermore, the pull-out test would cause certain damage to the fireproof coating on the surface of steel components, and the damage to the Q235 steel sample was greater than that to the stainless steel sample. At the same time, the fireproof coating would undergo chemical reactions leading to expansion when heated, resulting in a dense surface and porous structure inside, which could reduce heat transfer to a certain extent.

Evaluation of Reusable Thermal Protection System Materials Using a High-Velocity Oxygen Fuel Torch.

We studied a candidate TPS (thermal protection system) material for reusable re-entry space vehicle applications. The material was based on a high-temperature-resistant material called Cerakwool. A total of six specimens were fabricated with substrate densities of 0.45 g/cm3, 0.40 g/cm3, and 0.35 g/cm3, with two specimens for each density. All specimens were coated with high-emissivity TUFI (toughened unpiece fibrous insulation), with coating thicknesses ranging from 445 to 1606 µm. The specimens were tested using an HVOF (high-velocity oxygen fuel) material ablation test facility. For each density specimen pair, one specimen was tested at 1 MW/m2 and the remaining one was tested at 0.65 MW/m2. The average stagnation point temperature for specimens tested at 1 MW/m2 was ~893 °C, approximately 200 °C higher than those tested at 0.65 MW/m2. This suggests a ~200 °C increase in stagnation point temperature for a 0.35 MW/m2 rise in incident heat flux. During the tests, internal temperatures were measured at three locations. For all tested specimens, regardless of heat flux test conditions and density, the temperature at ~40 mm from each specimen's stagnation point remained around or below 50 °C, well within the 180 °C design limit set for the TPS back face temperature. Post-test visual inspections revealed no signs of ablation or internal damage, confirming the material's reusability.

Behaviours of novel prefabricated RAC-HSC composite beams subjected to fire: An experimental and numerical study

The combination of different types of concrete in prefabricated concrete structures may have promising potential in optimizing both structural mechanics and fire performance. Therefore, the fire-resistance tests of proposed U- and C-types recycled aggregate concrete (RAC) - high-strength concrete (HSC) composite concrete beams were carried out. Their thermal and structural behaviours were extensively analyzed and compared with those of monolithic beams. Subsequently, a sequential thermal-mechanical analysis model was developed. The test results revealed that the novel composite RAC-HSC beams exhibited lower mid-span deflection and less damage than the monolithic HSC beams under fire exposure. The internal temperatures of specimens with RAC were significantly lower than that of specimens without RAC. Based on the numerical analysis, the predicted fire resistance limits for the novel RAC-HSC composite beam were approximately 30 min longer than that for the monolithic HSC beam. The thickness of the RAC section in RAC-HSC composite beams was suggested by parametric studies. Generally, this study proved that the fire performance of the proposed novel RAC-HSC composite beams was better than that of HSC and RAC monolithic beams.

Analysis of Thermal Isotropy of Parallelepiped Shape of Bronze Samples for Mechanical Engineering Applications

Objective: The need to find out whether the specimens are ‘thermally thin’ or not is the basis for applying the law of conservation of energy or the Fourier differential equation of heat conduction in finding the time dependence of the specimen temperature. The aim of this study is to find out the thermal field distribution in a parallelepiped shaped bronze specimen and to verify the Bio number. Methods: A number of external variables make it difficult to maintain a monotonic change in sample temperature during the ‘heating’ stage. These factors led to the use of the cooling method to study tiny samples with low inertia of the thermal process. We used the cooling method to experimentally verify the isotropy of the thermal field in the sample and to study the kinetics of cooling relative to the sample axes over a wide range of temperatures. Results: It was found out that in natural air cooling the main mechanisms are conductive, convective and radiative heat transfer. The contribution of thermal radiation to the cooling process is noticeable at high temperatures. It was found that the typical cooling time increases with sequential radiative, conductive and convective heat transfer. By extending the temperature study area to, for the first time, we were able to observe each component of the heat transfer process independently. The values of the typical cooling time on all axes correspond to the experimental error bounds. It was found that the temperature value of the sample is independent of the coordinates and depends only on time. In this case, the law of conservation of energy can be used to explain the dependence of body temperature on cooling time. Conclusion: It is shown that the sample under study is ‘thermally thin’, i.e. the thermal field is constant in all directions. In this situation, the thermal balance equation should be applied rather than the Fourier differential equation of heat conduction, since the temperature gradient inside the body is practically zero. The results obtained are of great importance for the study of cooling processes of metallic products in thermal power engineering, heat engineering and thermophysics.

Self-heating curing and its influence on self-sensing properties of ultra-high performance concrete with hybrid stainless steel wires and steel fibers

This study aims to develop ultra-high performance concrete (UHPC) with self-heating curing and self-sensing properties by incorporating hybrid stainless steel wires (SSWs) and steel fibers (SFs) to advance the safety, function/intelligence, and resilience of infrastructures. 0.2 vol% SSWs with micro diameter can already form overlapped conductive network inside UHPC together with SFs to decrease the electrical resistivity and enhance high-efficiency conversion rate from electric energy to Joule heat. As 20 W input power is applied and sustained, the electrical resistivity of UHPC with hybrid 0.2 vol% SSWs and 1.6 vol% SFs (W02F16) first decreases from 45.1 Ω∙cm to 8.3 Ω∙cm and then to 7.88 Ω∙cm due to the field emission effect and the microscopic thermal expansion of SSWs. The surface temperature of W02F16 specimens reaches 78.6 ℃ for 73 minutes self-heating with an average heating rate of 0.821 ℃/min and a temperature difference lower than 11.6 ℃. Meanwhile, the fractional change in electrical resistivity and sensitivity corresponding to peak flexural stress of W02F16 after 8 h self-heating curing can reach 58.3 % and 3.22 %/MPa, higher 2.1 and 3.6 times than that after 28 d standard curing. Furthermore, self-heating curing UHPC composites at 28 d possesses more stable and sensitive self-sensing performance especially within pre-peak flexural stress period, resulting from the coarsening effect of direct current on SSWs’ interface to regulate and control of conductive pathway in concrete. This is the innovative demonstration that self-heating curing process can endow hybrid SSWs and SFs reinforced UHPC with stable/high self-sensing sensitivity to rapidly fabricate multifunctional/smart infrastructures with the abilities of structural health monitoring, snow and ice self-melting, and indoor heating.

Study of freeze-thaw deterioration of saturated and unsaturated hydraulic concrete based on measured strain

In actual concrete water projects, areas such as the back surface, above-water surface, and even areas where the water level fluctuates are in the unsaturated freeze-thaw state. The complexity of freeze-thaw tests of unsaturated hydraulic concrete has thus far prevented a sound understanding of the mechanisms at work in freeze-thaw deterioration of unsaturated hydraulic concrete. Given this situation, this study first compares three different unsaturated hydraulic concrete freeze-thaw test processes (polyurea seal, paraffin seal, and vacuum-bag seal) and then uses the vacuum-bag seal method to implement freeze-thaw tests of unsaturated hydraulic concrete. Afterward, three test schemes (unsaturated sealed freeze-thaw, water-freeze-thaw without air-entraining agent, and water-freeze-thaw with air-entraining agents) are conducted and the mechanisms of freeze-thaw deterioration of saturated and unsaturated hydraulic concrete are evaluated based on the measured temperature and strain of the concrete specimens. The results reveal a continuous and irreversible deterioration leading to the freeze-thaw damage of unsaturated sealed freeze-thaw specimens and water-freeze-thaw specimens with and without an air-entraining agent. After 200 freeze-thaw cycles, the cumulative residual strain of the aforementioned three test schemes reach 47 με, 616 με, and 273 με, respectively. The thermal expansion coefficient of concrete remains relatively constant with increasing freeze-thaw cycles. Water-freeze-thaw specimens without air-entraining agents have a greater thermal expansion coefficient than those with air-entraining agents, and unsaturated sealed freeze-thaw specimens have the smallest thermal expansion coefficient. The frost heave coefficient increases with increasing freeze-thaw cycles, and water-freeze-thaw specimens without air-entraining agents have greater frost heave coefficients than those with air-entraining agents.

Experimental Study and Neural Network Predictions of Early-Age Behavior of Microexpansion Concrete in Large-Diameter Steel Tube Columns

The improved mechanical performance of concrete-filled steel tube (CFST) components has led to their widespread application in megastructures. Therein, CFST hybrid arch bridge has become an optimal selection of large span bridges. Nonetheless, for massive concrete poured in CFST members with large diameter, the thermal cracking and sustained rising temperature caused by early hydration heat of core concrete are urgently required to be studied. The two large-diameter CFST columns in this work, each having a diameter of 2.1 m, had their temperature and strain fields recorded in-situ. An existing CFST arch bridge served as the model for the two CFST columns’ design. Additionally, early-age characteristics of several scaled CFST columns with varying diameters were documented. A multi-field finite element (FE) model that combines linked chemical (hydration), heat, and mechanical fields is suggested in order to properly characterize the evolutions of temperature and strain fields. The model is validated by comparing the in-situ measurements with the numerical results. Finally, to investigate the affect factors on the hydration temperature of core concrete in CFST columns, early-age hydration behaviors of CFST columns was simulated using the validated FE models input parameters as water to cement ratio (w/c), cement dosage, heat release of cement and diameter of CFST columns. Based on the numerical results under the input parameters mentioned, the LSTM neural network was constructed, and the hydration temperature variances computed by FE models were selected as the input dataset. Afterwards, the temperature variance of core concrete of CFST columns was predicted using the established LSTM network. It is discovered that the LSTM neural network that was previously constructed was able to predict the peak temperature of CFST columns as well as the hydration temperature of CFST specimens with respect to time.

Rapid densification of nanocrystalline zirconia: Pressureless versus pressure-assisted spark plasma sintering

Spark plasma sintering (SPS) is the most straightforward way to rapidly sinter nanoceramics, but the applied pressure prevents sintering of additively manufactured ceramics. Therefore, fast firing techniques such as “pressureless” SPS and ultra-fast high-temperature sintering, based on intense thermal radiation, are gaining interest. Here we compare pressure/current-assisted and pressureless SPS techniques for the rapid heating (∼300 °C/min, 5 min) of nanocrystalline zirconia with high sintering activity. The applied pressure and current indeed contributed to the lowestr temperatures needed for full densification of nanocrystalline zirconia, retaining very fine grain size, but also induced tetragonal phase transformations in the final sintering stages. When the radiative heat transfer was “decoupled” (pressureless SPS), a pronounced temperature difference between graphite crucible wall and simulated specimen temperature along with non-steady-state conditions during dwell were observed. Nevertheless, high heating rates facilitated fine and dense microstructures even in the absence of pressure/current.

Effect of Graphene Oxide on the Electrothermal and Pressure-Sensitive Properties of Carbon Fiber Cementitious Composites.

The application of carbon fiber in cement matrix has some disadvantages, such as poor dispersion and poor interfacial adhesion. In order to improve the interaction between carbon fiber and cement matrix and improve the properties of cement-based composites, carbon fiber was modified by electrophoretic deposition of nano-graphene oxide (GO). In this paper, the effects of doping CF into the cement matrix before and after GO modification are studied comparatively in terms of electrical conductivity, electrothermal warming effect, and pressure-sensitive properties of the cement matrix. It was found that the GO-modified CF reduces both the electrical resistivity of cementitious composites and the required level of fiber incorporation compared to CF. The percolation threshold is 0.7 wt% for CF and 0.5 wt% for GO-CF. The GO-modified CF is more effective than CF as a conductive filler to enhance the electrothermal warming performance of the cement matrix. When the GO-CF doping rate is 0.5%, the specimen temperature increases most rapidly, and the temperature rise value reaches a maximum of up to 30.45 °C, which is twice that of the CF group. When the fiber content is 0.7%, the pressure sensitivity of the sample was the best. When the fiber content is 0.5%, GO-CF can improve the pressure sensitivity of cement mortar specimens, and increase the resistance change rate of the cement mortar specimens by 5.7%.

Experimental and numerical simulation studies of electrical resistance of cementitious materials under varying temperature history

Many in-service concrete structures are normally exposed to varying temperature condition. The time-dependent and non-uniform temperature distribution in concrete structures could affect the accurate assessment of their electrical properties. Therefore, the influences of temperature change over time and the spatial variation in temperature on the measured electrical resistance of cementitious materials are still in need of investigation. The coupled thermal-electrical responses of two types of cementitious materials under varying temperature history were investigated by a series of thermal and electrical tests in this study. Then a coupled thermal-electrical finite element (FE) model was developed to simulate the coupled thermal-electrical responses. The results show that the input direct current has a minor effect on the measured electrical resistance by embedded four-probe method and the specimen temperature when it is no greater than 3 mA. The relationship between the measured temperature at 10-mm depth of the specimen and the apparent resistance is well captured by a linear equation. The coupled thermal-electrical finite element model can predict well the developments of specimen temperature and apparent electrical resistance under varying temperature history. The FE results reveal that the non-uniform temperature variation results in the redistribution of electrical current within the tested specimen. However, electrical field between the two inner electrodes is always uniform when the embedded four-probe method is used, which is not affected by the non-uniform temperature variation.

Calibrating cryogenic temperature of TEM specimens using EELS

Cryogenic Scanning/Transmission Electron Microscopy has been established as a leading method to image sensitive biological samples and is now becoming a powerful tool to understand materials' behavior at low temperatures. However, achieving precise local temperature calibration at low temperatures remains a challenge, which is especially crucial for studying phase transitions and emergent physical properties in quantum materials. In this study, we employ electron energy loss spectroscopy (EELS) to measure local cryogenic specimen temperatures. We use the temperature-dependent characteristics of aluminum's bulk plasmon peak in EEL spectra, which shifts due to changes in electron density caused by thermal expansion and contraction. We successfully demonstrate the versatility of this method by calibrating different liquid nitrogen cooling holders in various microscopes, regardless of whether a monochromated or non-monochromated electron beam is used. Temperature discrepancies between the actual temperature and the setpoint temperatures are identified across a range from room temperature to 100 K. This work demonstrates the importance of temperature calibrations at intermediate temperatures and presents a straightforward, robust method for calibrating local temperatures of cryogenically-cooled specimens in electron microscopes.

Color and reflective properties of magnesium phosphate cement grouting material for cooling pavement

In order to reduce the absorption of solar radiation by asphalt pavement in plateau permafrost regions and protect the underlying permafrost subgrade, the aim of this research was to develop a dark high near-infrared (NIR) reflective material using magnesium phosphate cement (MPC) and chrome black T, and to construct reflective grouting compound pavement (RGCP) by grouting the material into large void asphalt mixture. The optimal magnesium (M)/phosphate (P) ratio of MPC was determined to be 10 through solar spectral reflectance test, with a NIR reflectance of 71.74 %. A series of experiments, including chromaticity characteristics, reflectance test, SEM-EDS analysis, and strength test, were conducted to characterize the impact of chrome black T content on the reflection and mechanical properties of MPC. The results indicated that the chrome black T particles were uniformly distributed on the surface of MPC and filled in its pores, which not only effectively colored the MPC, but also improved its mechanical strength. Since the reflectivity of chrome black T was lower than that of MPC, its incorporation also reduced the NIR reflectivity of MPC to a certain extent. Overall, MPC with 1 % chrome black T content had a color similar to asphalt and a NIR reflectance of 43.91 %, making it a suitable dark NIR reflective material. An indoor irradiation experiment verified that RGCP can maintain a lower temperature under solar radiation. Compared with the control group, the surface temperature of the RGCP specimen was reduced by 4.5 °C.

Numerical Analysis on Frictional Heat Effect in Polyether-Ether-Ketone (PEEK)/Steel Pair by using OpenFOAM Model

The PEEK material has been applied to a sliding bearing system in a power plant system because of its high mechanical durability. In the solid friction of the PEEK materials, the frictional heat becomes the important factor because the temperature increase due to the frictional heat causes the rapid increase of the frictional coefficient of the specimen. To maintain the low frictional coefficient of the PEEK materials, an effective cooling method for the PEEK materials needs to be developed. In this study, the passive cooling method, which attaches the heat sink to the PEEK materials, was suggested. For evaluating the suggested cooling method of the PEEK materials, the calculation model adopting OpenFOAM, which is open-source software, has been developed. Adopting some functions and libraries of OpenFOAM, the frictional heat, heat resistance, and heat transfer coefficient on the heat sink were modelled. The sliding bearing experiment was conducted and time variation of the temperature and friction coefficient in the ring specimen were measured. The temperature variation in the ring specimen was compared with the calculation result. From the numerical calculation results, the developed calculation model could simulate the temperature-time variation of the ring obtained in the experiment, when the variation of the frictional coefficient, heat resistance, and heat transfer coefficient was modelled appropriately. Based on the friction and wear test results, by applying a heat dissipation mechanism to the ring test piece, the calorific value of the PEEK material can be reduced, and it is stable. It was suggested that the friction was maintained.

Influencing factors of the temperature rise of direct electric curing concrete and its effect on concrete properties

Direct electric curing (DEC) is one of concrete's most promising rapid curing methods. However, the factors influencing temperature variations in concrete specimens during the curing process have not yet been fully elucidated. This study investigates the impact of electric voltage, specimen dimensions, energized cross-sectional area, and water-to-cement ratio on the temperature rise of concrete during the DEC process. It also examines the pore structure and strength development of specimens with different water-to-cement ratios under various curing voltages. The temperature rise mechanism is explored through the Joule heating effect, cement hydration heat, and specimen heat dissipation. Research findings reveal that, during the DEC curing process, the peak temperature of specimens gradually rises in conjunction with increasing curing voltage and energized cross-sectional area. The impact of the water-to-cement ratio on the temperature variation of DEC concrete depends on the voltage of DEC. Higher voltages tend to promote Joule heating. Adjusting the water-to-cement ratio contributes to achieving a higher temperature rise in the paste. At lower voltages, the opposite effect is observed. The electrical current of specimens under various curing conditions demonstrates an initial increase followed by a subsequent decrease over time. DEC facilitates early strength enhancement, with different water-to-cement ratios yielding varying curing efficiencies. Through DEC, the 1-day strength of the specimens shows a remarkable increase of up to 89.89 % compared to the standard curing methods. MATLAB simulations using Joule heating, heat dissipation formulas, and the equivalent age function effectively model temperature variations during curing. This study provides a reference for designing lower-carbon, more efficient, and intelligent DEC regimes.

Effect of Heat Exposure Time on Tensile Properties in Cold Rolled Steel

This paper presents the effect of heat exposure time on tensile strength of cold rolled specimens. Welding and process annealing are applied to the specimens to investigate their implications. The two processes involve heat and time but in differential amounts. In welding the temperature raises to levels far beyond the melting point of the specimens and cools quickly. The case is different in process anneal the specimen temperature increases slowly to the subcritical level and cools slowly after a specific soaking time. Welded and process annealed in the form of tensile specimens are tested in the tensile machine until fracture. The test results showed that welding and process annealing caused a decrease in yield strength by one third and almost two thirds respectively compared with the as rolled. The fracture of the welded specimen was localized at the heat affected zone near the weld line but was random in all other specimens. Percentage elongation was lowest in the welded specimen compared with other patches of specimens.

Influence of high fluence irradiation on reference temperature of VVER-440 RPV surveillance specimens

Master curve (MC) testing of VVER-440 RPV surveillance specimens treated for 27 years (∼200,000 h) in a surveillance channel of Metsamor-NPP was performed to investigate the influence of long term high fluence irradiation on RPV embrittlement. The surveillance chain consisted of both thermal aged specimens (above the core level) and irradiated specimens (inside the core). The reference temperature (To) values obtained from irradiated specimens are compared with the results from thermal aged specimens to characterize irradiation induced shifts in To values for both base and weld metal specimens. It was found that the high fluence irradiation up to a nominal fluence of 3.2 × 1025 n.m-2 at E > 0.5 MeV resulted large embrittlement with To shift values greater than 300 °C for both base and weld metal specimens. The obtained shifts in To values at these high fluence values were used to compare with the predictions from PNAE procedure in the Russian regulatory guide outside its validity range. It was found that the measured shift in reference temperature for the weld metal was well below the predicted value while, the shift in reference temperature for base metal was largely under-predicted at these high fluence values.

Oxygen diffusion in freestanding body centered cubic tantalum structural thin films in air and in high vacuum

Sensors and actuators constructed from freestanding tantalum thin films show promise for micromachining applications and for the study of thin film mechanical behavior. To assess this promise, it is necessary to gain further understanding of the performance of Ta as a structural material. We first evaluate the coefficient of thermal expansion, αTa, using micromachined bent beams, which amplify displacement compared to linear expansion. The value for αTa is 6.8 × 10−6 m/m °C, in good agreement with the bulk value. This validation enables the study of interstitial oxygen diffusion in Ta, for which literature values of activation energy vary widely, from 0.60 to 1.98 eV. Displacement in air due to oxygen diffusion becomes measurable after 30 min exposure at 180 °C. We extract an activation energy for interstitial oxygen in Ta of 0.53 eV/atom. Analysis indicates that lattice rather than grain boundary diffusion is the associated mechanism. To inhibit the oxidation, we construct a thermal stage that controls specimen temperature in 10−5 Pa vacuum. Then, after a 24 h hold, oxidation is suppressed up to 400 °C. This result is discussed in terms of O dissolution from its native oxide, coupled with further absorption from background gases.

Knowing the spectral directional emissivity of 316L and AlSi10Mg PBF-LB/M surfaces: gamechanger for quantitative in situ monitoring

For a deep process understanding of the laser powder bed fusion process (PBF-LB/M), recording of the occurring surface temperatures is of utmost interest and would help to pave the way for reliable process monitoring and quality assurance. A notable number of approaches for in-process monitoring of the PBF-LB/M process focus on the monitoring of thermal process signatures. However, due to the elaborate calibration effort and the lack of knowledge about the occurring spectral directional emissivity ε′λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\varepsilon }^{\\prime}}_{\\lambda }$$\\end{document}, only a few approaches attempt to measure real temperatures. In this study, to gain initial insights into ε′λ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\varepsilon }^{\\prime}}_{\\lambda }$$\\end{document} occurring in the PBF-LB/M process, measurements on PBF-LB/M specimens and metal powder specimens were performed for higher temperatures up to T = 1290 °C by means of the emissivity measurement apparatus (EMMA) of the Center for Applied Energy Research (CAE, Wuerzburg, Germany). Also, measurements at ambient temperatures were performed with a suitable measurement setup. Two different materials—stainless steel 316L and aluminum AlSi10Mg—were examined. The investigated wavelength λ ranges from the visible range (λVIS\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\lambda }_{VIS}$$\\end{document} = 0.40–0.75 µm) up to the infrared, λ = 20 µm. The influence of the following factors were investigated: azimuth angle φ, specimen temperature TS, surface texture as for PBF-LB/M surfaces with different scan angles α, and powder surfaces with different layer thicknesses t\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$t$$\\end{document}.