Properties Of Samples Research Articles

Exploring the use of averaged thermal kinetic parameters in luminescence thermochronometry

In luminescence thermochronometry, the thermal stability of feldspar minerals is conventionally constrained from isothermal decay experiments. However, despite recent refinement of the measurement protocol, measurements take several days and are routinely done for each individual sample. Following that most other thermochronometric methods usually use only a single reference set of thermal kinetic parameters, and that recent studies on direct physical probing of feldspar sample properties have shown that trap depth and band-tail width are broadly similar despite large variations in chemical composition, we sought to optimise luminescence thermochronometry measurements by exploring whether a single set of thermal kinetic parameters can describe luminescence thermal decay in feldspar. We explored the effect of using averaged thermal kinetic parameters rather than sample-specific thermal kinetic parameters to model luminescence signal accumulation under different thermal conditions. A set of K- and Na-feldspar minerals extracted from all over the world were analysed after being measured with a multi-elevated temperature protocol, comprising four different IRSL signals at 50, 100, 150, and 225 °C. Comparisons were done between the thermal kinetic parameters of each IRSL signal depending on different variables such as geographic region, transect, lithology, or mineralogy of the analysed feldspar grains. Even though it is not possible to generalise the thermal kinetic parameters between IRSL signals measured at different temperatures, the variance between the thermal kinetic parameters of different samples measured at the same IRSL temperature is consistent with the uncertainties on the individual parameters (i.e., <2–10%), suggesting that averaged, rather than sample-specific values may be appropriate. We then explored the effect of using these averaged parameters to model luminescence signal accumulation under different synthetic and natural thermal conditions. For our dataset, results show minimal impact on the obtained cooling histories and exhumation rates. We therefore propose the use of averaged rather than sample-specific thermal kinetic parameters for rapid investigation of luminescence thermochronometry samples. Based on careful initial characterisation of a few samples to verify the validity of using averaged thermal kinetic parameters, this would reduce measurement times by ca. 50% (i.e., 3–4 days per sample), allowing higher resolution sampling and measurement.

The Role of Overflow on the Mechanical Propert ies of 3D Printed PLA

3D printing is a technology used on an ever-increasing scale, which makes it easier to obtain parts with complex geometry. The printing process is very complex because, in addition to the variables introduced by the various materials that are used, there is a multitude of process parameters: printing direction, layer thickness, infill level, filament feed rate, printing temperature, printing bed temperature, etc. Each process parameter influences the mechanical properties of the 3D-printed structure, which is why it is necessary to define the range of possible values where the effect is maximum. In this paper it was studied the effect of process parameters variation on the roughness and mechanical properties of the 3D-printed samples. Using a commercially PLA filament (produced by Prussia), we made six sets of 3D-printed samples, using six different overflow (OF) values: 90%, 95%, 100%, 105%, 110%, 115%. The test samples (realized according to ISO 572-2) were subjected to tensile tests on an Instron 3382 machine, and the results were interpreted comparatively. It has been observed that there are variations of the mechanical properties, dependent on the chosen values of the overflow and, in addition, this process parameter has an important role for the achieving the desired structure.

Evolution of early hydration in mortar by using waste dolomite powder as a micro-aggregate

The evolution of early hydration in cement – based material is always one of important issues for investigating their engineering application. This study investigated the early hydration reaction of mortars containing different waste dolomite powder (WDP) contents. Compared to the reference sample (WDP0), the hydration process, hydration products, pore structure and mechanical properties of samples prepared by WDP were studied at the early stage. For the hydration process, the 1H low – field nuclear magnetic resonance (NMR) and chemical shrinkage testing results indicated that the process of early hydration of cement could be significantly accelerated by incorporating WDP. Meanwhile, the quantities of hydration products (Portlandite and calcite) in samples with WDP have a significant variation by X-ray diffraction results and thermogravimetric analysis. In addition, the WDP40 has denser pore structure and higher mechanical properties than WDP0. After curing 3 d, the pore volume of WDP40 has a reduction of 17.84 %, the flexural and compressive strength of WDP40 were increased by 6.6 % and 18.06 %, respectively. Based on the mechanism analysis, the filling effect and nucleation effect of WDP in mortars contributed to the improvement of early cement hydration. This study is meaningful to evaluate the impact of WDP on the evolution of early cement hydration, which is expected to offer a reliable reference for the application of inert materials in cement – based materials.

Study on quality of treated wastewater for urban agriculture use in Addis Ababa, Ethiopia

Non-conventional water supplied from Bole Lemi Industrial Park (BLIP) in Addis Ababa, Ethiopia is treated to remove contaminants, but never has been analyzed for its quality for urban agriculture (UA) use. The objective of this study is to analyze the quality of treated wastewater (TWW) using treated wastewater quality index (TWWQI). Treated wastewater samples were taken at the influent and effluent of the wastewater treatment plant located within BLIP. The physico-chemical properties of the water samples from BLIP were analyzed at the third-party laboratory. The result showed that the aggregate TWWQI value falls under the category of very poor water for urban irrigation agriculture (UIA) use. This very poor water quality grade attributes 85 % to the presence of heavy metals, 4 % to nutrients load, 8 % to saline condition contributors and 4 % to miscellaneous contaminants. Discrete analyses of the indices for heavy metals, nutrient loads, saline condition contributors and miscellaneous contaminants shifted the water quality from very poor to very polluted, excellent, poor and good for UIA use respectively. Though the aggregate TWWQI is of very poor category for UIA use, the treatment plants of BLIP exhibited contaminants removal efficiencies of between 30 and 100 % with aggregate removal efficiency of 58 %. Results also revealed that there were contaminants that exhibited higher effluent values than influent after treatment indicating the failure of BLIP’s treatment plants to remove these contaminants. In conclusion, treated wastewater from BLIP, falls under very poor water category for use in irrigation agriculture where Cr+3, Cl− and TDS have contributed most in that order. Therefore, BLIP should upgrade and optimize its treatment plants to increase the removal efficiency for the respective contaminants. Moreover, BLIP should enhance the capacity of the experts through training and continually monitor the quality of the water to protect the environment and ensure its contribution to the building of a resilient city.

Multi Response Modelling and Optimisation of Copper Content and Heat Treatment Parameters of ADI Alloys by Combined Regression Grey-Fuzzy Approach

This paper deals with the austempering of ductile iron (ADI) and clarifies the influential austempering parameters during the production of ADI. During the austempering process, the heat treatment parameters can be varied, thus influencing the final microstructure and, of course, the mechanical properties of ADI. To appropriately conduct experiments and obtain good results, an experimental plan was developed using the Design Expert 13 software. Along with the heat treatment parameters, the influence of the copper content on the ADI toughness, tensile strength, and elongation was determined. The obtained results from this experiment were used to develop unique mathematical models which describe the influences of heat treatment and copper content on the observed mechanical properties of ADI samples. These mathematical models can be applied to predict the analysed mechanical properties of ADI in the dependence of heat treatment parameters and copper content in base ductile iron. For the multi response optimisation of toughness, tensile strength, and elongation, a hybrid grey-fuzzy technique was presented as a significant contribution to the enhancement of the analysed mechanical properties. Consequently, the copper content and heat treatment parameter levels that resulted in the maximal mechanical properties’ functions were defined.

Limitations of quartz extracted from Antarctica sediments for luminescence dating

Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) properties of quartz samples extracted from soil of Fisher Island (76° 13ʹ 23.9ʺ E, 69° 23ʹ 31.9ʺ S) in Antarctica were studied. The nature of signals indicated presence of a dominant slow component in the OSL signal. The widely utilized Single Aliquot Regenerative (SAR) protocol for dose recovery was found unsuitable for this particular sample due to the dominating slow component in the OSL signal. Efforts to minimize the effect of slow component in dose recovery by adopting procedures like, bleaching with blue light, and early background subtraction were carried out. Additionally, thermally transferred OSL (TT-OSL) studies were conducted on the natural sample and dose estimation using the TT-OSL SAR protocol was carried out.

Influence of dry density and wetting–drying cycles on the soil–water retention curve of compacted loess: experimental data and modeling

AbstractIn this paper, the EC-5 water sensor and the MPS-6 water potential sensor were used to measure water content and suction, respectively, to investigate the evolution of soil–water retention properties of compacted loess samples prepared at different dry densities and subjected to different numbers of wetting–drying cycles. The water retention data were integrated with a detailed microstructural investigation, including morphological analysis (by scanning electron microscopy) and pore size distribution determination (by nuclear magnetic resonance). The microstructural information obtained shed light on the double porosity nature of compacted loess, allowing the identification of the effects of compaction dry density and wetting–drying cycles at both intra- and inter-aggregate levels. The information obtained at the microstructural scale was used to provide a solid physical basis for the development of a simplified version of the water retention model presented in Della Vecchia et al. (Int J Numer Anal Meth Geomech 39: 702–723, 2015). The model, adapted for engineering application to compacted loess, requires only five parameters to capture the water retention properties of samples characterized by different compaction dry densities and subjected to different numbers of wetting–drying cycles. The comparison between numerical simulations and experimental results, both original and from the literature, shows that only one set of parameters is needed to reproduce the effects of dry density variation, while the variation of only one parameter allows the reproduction of the effects of wetting and drying cycles. With respect to the approaches presented in the literature, where ad hoc calibrations are often used to fit density and wetting–drying cycle effects, the model presented here shows a good compromise between simplicity and predictive capabilities, making it suitable for practical engineering applications.

Elucidation of annealing effects on austenite–martensite and magnetic phase transitions in Mn2Ni1.6Sn0.4 ribbons synthesized from bulk alloys prepared by RF induction melting

We investigate the consequences of annealing on the structure, microstructure, magnetic, and electrical transport of Mn2Ni1.6Sn0.4 ribbons. The 40–60 μm thick ribbons were formed by melt spinning of the bulk ingot synthesized by RF induction melting. Ribbons were annealed at 600 °C for 12 hrs and the other at 800 °C for 2 hrs in vacuum. All ribbons crystallize into a cubic symmetry (space group F4¯3m). The orthorhombic phase appears as the secondary one. In ribbons annealed at 600 °C, the crystallite size decreases from ∼ 47 nm to ∼ 29 nm, and annealing at 800 °C doubles the crystallite size to ∼ 96 nm. The least amount of microstrains (17x10−4) in the as-synthesized ribbon is consistent with the occurrence of the superlattice peaks (111) and (200). Lower intensities of the superlattice peaks in 600 °C and 800 °C ribbons are consistent with higher microstrains (25x10−4 and 24x10−4). Hence, a higher degree of Ni-Mn ordering improves magnetic properties in annealed samples. The as-synthesized ribbon has an austenite-phase Curie temperature of TCA∼303K, which enhances to TCA∼320K and TCA∼310K after annealing at 600 °C and 800 °C. The ribbon annealed at 600 °C has the highest saturation moment. All the ribbons show the exchange-bias (EB) effect, and the most pronounced effect is seen in the 800 °C annealed ribbon. Microstructure uniformization and relative strengths of the Ni-Mn and Mn-Mn interactions improve the magnetics. Near TC, MT=M0TC-Tβ is satisfied (β = 0.31, 0.36, and 0.37, for as-synthesized, 600 °C and 800 °C annealed ribbons). The low-temperature spontaneous magnetization obeys the Bloch law MT=M01-AT32, with a deviation in 600 °C annealed ribbon due to spin freezing. The ρ-T has been fitted in the different temperature ranges using the various combinations in ρT=ρ0+AphT+BsdTα. At T < 85 K, the resistivity of the as-synthesized ribbon follows ρT=ρ0+BsdTα, with α≈1.47, while for the 600 °C annealed ribbon, α≈1.49. The exponent α∼1.5 supports the existence of the spin glass state in the lower temperature region of as-synthesized and 600 °C annealed ribbons. In the high-temperature range, the linear ρ-T behavior is described by ρT=ρ0+AphT and consistent with the electron–phonon scattering.

The effect of printing parameters on the mechanical properties of fiber-reinforced PA6 matrix composites in material extrusion-based additive manufacturing

PurposeThis study aims to understand the effect of the use of different proportions and types of fibers in the polyamide 6 (PA6) matrix during material extrusion-based additive manufacturing (MEX) and the effect of the manufacturing parameters on the mechanical properties. The mechanical, thermal and morphological properties of PA composites that are reinforced with carbon fiber (CF), glass fiber (GF) and as well as hybrid fiber (HF) were investigated.Design/methodology/approachIn this study, the effect of nozzle temperature and layer thickness on the mechanical properties of composite samples was investigated in terms of their behavior under tensile, impact and compression loads, manufacturing parameters as well as fiber ratio and type. The results were also consolidated by scanning electron microscopy.FindingsAt 20 Wt.% CF reinforcement PA6 samples, a tensile strength value of 125 MPa was obtained with a 60% increase in tensile strength value compared to neatPA6. The HF-reinforced ones also measured a tensile strength value of 106.69 MPa. This corresponds to an increase of 38% compared to neatPA6. The results also show that HF reinforcement can be an important component for many composites and a suitable material for use under compression loading.Originality/valuePA6, an engineering polymer, can be produced by MEX, which offers several advantages for complex geometries and customized designs. There are studies on different carbon and GF ratios in the PA6 matrix. Using these fibers together in a HF, the examination of their mechanical properties in the MEX method and the examination of the effect of GF reinforcement in the hybrid structure, which has a cost-reducing effect, has been an innovative approach. In this study, the results of the optimization of the parameters affecting the mechanical properties in the production of samples reinforced with different ratios and types of fibers in the PA6 matrix by the MEX method are presented.

Influence of Solution Treatment Process on the Properties of Duplex Stainless Steels: A Comparative Study on Microstructure and Corrosion Properties of UNS S32205 and UNS S32760

The study investigated the effect of the solution treatment process on the corrosion behavior and microstructure of the duplex stainless steel. It was also aimed to reveal this effect comparatively depending on the chemical composition and alloying element content. For this purpose, UNS S32205 and UNS S32760 alloys were treated at 1000 °C, 1020 °C and 1040 °C for an hour. A solution treatment temperature was determined according to Thermo-Calc analysis. The examined samples were characterized by an optical microscope, scanning electron microscope, and XRD analysis. Also, electrochemical impedance spectroscopy and potentiodynamic polarization analyses revealed the corrosion properties of solution-treated samples. Microstructural studies showed that enhanced solution treatment temperature increased ferrite content for both alloys. A lower solution treatment temperature caused the formation of sigma in the microstructure of S32760 alloy. On the other hand, the charge transfer resistance of the passive layer was reduced after solution treatment at 1000 °C and 1020 °C, indicating decreasing corrosion resistance. A higher austenite ratio in S32205 led to pitting, while corrosion resistance improved with higher treatment temperatures. The presence of the sigma phase in S32760 significantly impacted corrosion properties by increasing ion transfer on the surface, leading to reduced corrosion resistance. It was determined that solution treatment at 1040 °C was appropriate for both alloys to achieve the desired microstructure and corrosion properties.

Precipitation behaviors and the related strengthening mechanism in 2219 Al alloy fabricated by wire arc additive manufacturing

Normally, a large number of dislocations could be introduced into the metallic component in the additive manufacturing process. The effects of these thermal stress-induced dislocations on the precipitation of 2219 Al alloy have thus far not been comprehensively studied. In the present study, the precipitation behaviors of 2219 Al alloys fabricated by wire arc additive manufacturing are investigated in detail by multi-scale experimental methods, including transmission electron microscopy, scanning electron microscopy, and X-ray diffraction analyses. Our study suggests that the stress-induced dislocations could act as the heterogenous nucleation sites, facilitating the precipitation of θ′ and θ′′ phases in the deposition process. During the subsequent artificial aging, θ′ and θ′′ phases are present in the 160°C peak-aged sample. Raising the aging temperature from 160°C to 180°C could facilitate the transformation of θ′′ to θ′ phases. Moreover, for the 200°C peak-aged sample, the number density of θ′ phases appears to decrease with accompanied coarsening. An evident improvement occurs in the comprehensive mechanical properties of the as-deposited sample by appropriate heat treatment (540℃/3 h-180℃/14 h). The ultimate tensile strength significantly increases from 238 MPa to 408 MPa, exhibiting an enhancement of approximately 70 %, while the elongation increases from 14 % to 15 %. Additionally, a quantitative correlation is established between the precipitate characteristics and mechanical properties.

Estimation of the conditional tail moment for Weibull‐type distributions

AbstractWe consider the estimation of the conditional tail moment at extreme levels for the class of Weibull‐type distributions. A two‐step procedure is introduced where in the first stage one estimates the conditional tail moment at an intermediate level, followed by an extrapolation in the second stage. The asymptotic properties of the estimators introduced in the two stages are derived under suitable assumptions. The finite sample properties of the proposed estimator are examined with a simulation experiment. We conclude with two applications on real life data: wind speed measurements collected at an offshore wind farm and air pollution data.

Investigation of influence of technological parameters on the properties of SiC samples fabricated by selective laser sintering. Part 1

Investigation of influence of technological parameters on the properties of SiC samples fabricated by selective laser sintering. Part 1

Three-Dimensional Bioprinted Skin Microrelief and Its Role in Skin Aging.

Skin aging is a complex physiological process, in which cells and the extracellular matrix (ECM) interreact, which leads to a change in the mechanical properties of skin, which in turn affects the cell secretion and ECM deposition. The natural skin microrelief that exists from birth has rarely been taken into account when evaluating skin aging, apart from the common knowledge that microreliefs might serve as the starting point or initialize micro-wrinkles. In fact, microrelief itself also changes with aging. Does the microrelief have other, better uses? In this paper, owing to the fast-developing 3D printing technology, skin wrinkles with microrelief of different age groups were successfully manufactured using the Digital light processing (DLP) technology. The mechanical properties of skin samples with and without microrelief were tested. It was found that microrelief has a big impact on the elastic modulus of skin samples. In order to explore the role of microrelief in skin aging, the wrinkle formation was numerically analyzed. The microrelief models of different age groups were created using the modified Voronoi algorithm for the first time, which offers fast and flexible mesh formation. We found that skin microrelief plays an important role in regulating the modulus of the epidermis, which is the dominant factor in wrinkle formation. The wrinkle length and depth were also analyzed numerically for the first time, owing to the additional dimension offered by microrelief. The results showed that wrinkles are mainly caused by the modulus change of the epidermis in the aging process, and compared with the dermis, the hypodermis is irrelevant to wrinkling. Hereby, we developed a hypothesis that microrelief makes the skin adaptive to the mechanical property changes from aging by adjusting its shape and size. The native-like skin samples with microrelief might shed a light on the mechanism of wrinkling and also help with understanding the complex physiological processes associated with human skin.

The influence of secondary raw materials of grain processing on the rheological properties of the dough

The development of technologies and new recipes for bakery products with increased nutritional value is a promising direction for the food industry. The expansion of the assortment is due to the introduction of additional raw materials, one of the options of which is rice and buckwheat flour. Rice and buckwheat flour contain a wide range of biologically active substances that, when added to food, have a beneficial effect on the human body. The main objects of research were flour composite mixtures obtained by mixing wheat flour of the first grade, rice, and buckwheat flour in a percentage ratio of 95:2:3, 90:3:7, 85:4:11, 80:5:15, 75:6:19, accordingly. The aim of the study was to study the influence of secondary raw materials of grain processing on the rheological properties of the dough to justify their introduction into the production of bakery products for functional purposes. The study of semifinished product samples was carried out using the following devices: Chopin alveograph (NG with the prefix alveolink) and Mixolab 2 (CHOPIN Technologies, France). The study of the rheological properties of the test samples under study showed that the introduction of secondary raw materials of grain crops – rice and buckwheat flour into the formulation of wheat bread in a dosage of 4% - 11%, respectively, improved the rheological and physico-chemical properties of the dough, which contributed to the development of the formulation and technology of a new type of enriched bread.

Application and safety of pectin substances from vegetable raw materials in bread production

Currently, pectin substances and their compounds are often used in cooking as an anionic surfactant. In the technology of food preparation, such properties of pectin substances as swelling, thickening, gel-forming, crystalforming, water-absorbing ability, and emulsifying ability are of great importance. Like any gel-forming fiber, pectin helps remove heavy metals from the body such as lead, mercury, cadmium, etc. MCP may be better suited for these purposes, as it has been used in four clinical studies of heavy metal detoxification. Considering the accumulation of radioactive elements, heavy metal salts and pesticides in the environment and the human body, Jerusalem artichoke, which is rich in pectin substances, carotene and dietary fiber, is of particular interest. It is also economically beneficial as it is a domestic raw material. The goal of scientific research is to obtain a new type of functional bread with the addition of vegetable pectin. In this article, it was determined that the addition of pectin to dough has an effect on biochemical, colloidal, as well as microbiological processes. It also affects the physicochemical and rheological properties and reduces the content of contaminants. The work investigated that when pectin substances are added to the dough, its initial acidity increases. Acidity varied 2.2-2.4. It was also noted that in the test sample the fermentation process was more active; the activity of the fermentation process was associated with the addition of sugar along with pectin. As a result of this work, in order to improve the quality of bread and extend shelf life, pectin from raw materials of plant origin was added, the properties of bread samples with Jerusalem artichoke pectin with high performance were studied, and their organoleptic, physicochemical and safety indicators were studied. It was revealed that pectin reduces the content of some toxic elements by up to 100%. Practical significance: the conducted studies showed that the obtained samples of functional bread can be recommended for introduction into production to expand the range of bakery products.

The Study of Composite Materials Properties Based on Polymers and Nano-Additives from Industrial Wastes from Kazakhstan.

This research is aimed at studying the properties of polymer anticorrosion coatings based on ED-20 resin widely used in practice and industrial wastes. In this work, three basic types of nanoscale nanofillers were chosen: dispersed particles-microsilica, microspheres obtained at Kazakh enterprises, and carbon nanotubes. Physicochemical research methods were used in the research: a laser analyzer for studying the dispersibility of industrial waste and spectrometric research methods. The properties of materials were investigated by standardized methods. The obtained results show that the introduction of microsilica and microspheres obtained at Kazakhstani enterprises, used as additives, improves both the physical and mechanical properties of epoxy composites compared to the standard (control) material. The results of experiments have shown that the optimal content of additives of microsilica and microspheres provides an improvement in the physical and mechanical properties of epoxy composites in comparison with the standard (control) material. Studies have shown that the introduction of microspheres into ED-20 polymer increases impact toughness. The introduction of microsilica into the matrix contributes to the increase of elastic modulus. Experimental studies of optical properties of samples of carbon composite polymer films based on polystyrene (PS) with additives of carbon nanotubes C60 and C70 and multilayer carbon nanotubes were also carried out. The experimental results obtained for the optical properties of polymer composites based on basic polymers from solid waste and carbon nanotubes showed that the optical properties of polymer composites undergo noticeable changes.

Rare earth elements recovery and mechanisms from coal fly ash by column leaching using citric acid

Rare earth elements (REEs) play an irreplaceable role in supporting the advancement of the global economy and technology, but their limited supply drives researchers to devise effective strategies for the recovery of REEs from alternative sources, including coal fly ash (CFA). In this work, a new column leaching method using citric acid as the lixiviant was proposed to enhance the recovery of REEs from CFA at room temperature. The mechanism of column leaching was investigated based on sample properties, leaching results, and the adsorption characteristics and complexation of citric acid. REEs in the CFA were found to be hosted into the amorphous aluminosilicate matrix in the form of oxides and fluorides using SEM-EDS. Compared to the maximum recovery of total REEs (TREEs, < 30 %) in the conventional agitation leaching tests, the recovery of TREEs in the column leaching tests increased significantly to 64.8 %, while the leaching rate of impurities (Al, Ti, and Fe) was less than 13.7 %. Results of the Zeta potential measurements showed that the citric acid and rare earth cations were adsorbed on the surface of CFA particles. These adsorption phenomena may make REEs bind to the CFA surface, thereby resulting in low leaching recoveries of REEs. Rare earth-citrate complexes in the lixivium were isolated by antisolvent precipitation, demonstrating that rare earth cations can be complexed by citrate. During the column leaching process, the leached rare earth ions were complexed with citrate and then carried away with the flowing liquid phase, which improved the recovery of REEs.

Optimizing the composition of barium-borate glasses for enhancing thermal neutron shielding efficiency: Monte Carlo simulation

A transparent window with thermal neutron shielding properties was an important part of the stations of the nuclear reactors and the particle accelerators. The borate glass with a high neutron cross section was a candidate as a glass network for the neutron shielding window. In order to slow down thermal neutrons, they were trapped by boron and subsequently emitted secondary radiation, such as alpha particles and gamma-ray radiation. This work was to optimize the content between a ratio of borate with a high cross-section neutron interaction and barium for shielding alpha and gamma ray. The barium-borate glasses were successfully synthesized using the melting technique in the atmosphere. Measurements of mechanical and optical glass properties were presented. The measured results showed that an increase in barium oxide content in the glass ratio enhanced the glass density and the transmittance at a visible wavelength. In the calculation of radiation shielding properties, FLUKA code based on Monte Carlo Simulation was demonstrated. The calculated results revealed that an increase in the barium oxide content in the glass composition reduced the thermal neutron shielding properties of the glass samples. In contrast, the glass with barium contents enhanced the photon-shielding efficiency, as indicated by the mass attenuation coefficient and half-value layer. Not only the ratio of the barium and borate contents affected the shielding properties, but the increased glass thickness also enhanced the shielding properties. Thus, the utilization of cooperative borate glasses and barium with appropriate thickness could potentially serve as a viable option for simultaneously protecting against thermal neutrons and photons. The barium-borate glasses with our composition might be used as a window in a thermal neutron station as well as for photon radiation.

Effects of Low-Temperature Heat Treatment on Mechanical and Thermophysical Properties of Cu-10Sn Alloys Fabricated by Laser Powder Bed Fusion.

This study investigated the impact of low-temperature heat treatments on the mechanical and thermophysical properties of Cu-10Sn alloys fabricated by a laser powder bed fusion (LPBF) additive manufacturing (AM) process. The microstructure, phase structure, and mechanical and thermal properties of the LPBF Cu-10Sn samples were comparatively investigated under both the as-fabricated (AF) condition and after low-temperature heat treatments at 140, 180, 220, 260, and 300 °C. The results showed that the low-temperature heat treatments did not significantly affect the phase and grain structures of the Cu-10Sn alloys. Both pre- and post-treatment samples displayed consistent grain sizes, with no obvious X-ray diffraction angle shift for the α phase, indicating that atom diffusion of the Sn element is beyond the detection resolution of X-ray diffractometers (XRD). However, the 180 °C heat-treated sample exhibited the highest hardness, while the AF samples had the lowest hardness, which was most likely due to the generation of precipitates according to thermodynamics modeling. Heat-treated samples also displayed higher thermal diffusivity values than their AF counterpart. The AF sample had the longest lifetime of ~0.19 nanoseconds (ns) in the positron annihilation lifetime spectroscopy (PALS) test, indicating the presence of the most atomic-level defects.