Search Results (109)

To improve the low-temperature impact toughness of Q235B steel, this paper adopts a heat treatment method combining quenching and spheroidizing annealing to enhance its microstructure and properties and conducts a detailed analysis of the evolution of the microstructure of Q235 steel under the spheroidizing annealing process. The results show that spheroidizing annealing at 700 °C has a significant spheroidizing effect on the pearlite structure: after 6 h of annealing, the room-temperature tensile strength reaches 522 MPa, the elongation is 31.28%, and the impact energy is 323.14 J; as the impact temperature decreases, the impact toughness of Q235B steel decreases, but the impact energy can still remain at 291.62 J under service conditions of −20 °C. This is attributed to the spherical cementite formed by spheroidizing annealing, which has better dispersibility and can reduce stress concentration, thereby improving the low-temperature impact toughness. Full article

The purpose of this study was to demonstrate the feasibility of using spheroidal cellulose powders with different particle sizes (2 and 7 µm) in face creams and to evaluate their effect on selected physicochemical and performance properties of these products. A series of prototypes of facial creams with spheroidal cellulose were prepared. The following tests were carried out: stability, dynamic viscosity, texture analysis, degree of skin hydration, and evaluation of sensory appeal by consumers. It was observed that none of the creams showed instability over time. The addition of powdered spheroidal cellulose was found to increase dynamic viscosity and hardness and reduce the adhesion strength of the tested emulsions to the base face cream. A positive effect of the presence of polymeric raw materials on the level of skin hydration was observed. The most favorable results were obtained for the E4 cream prototype containing spheroidal powders of both 2 and 7 µm particle size at a weight ratio of 2.5 to 2.5. In addition, according to the members of the sensory panel, the E4 face cream was best evaluated and showed sensory benefits. The study concluded that spheroidal cellulose powders are a promising biodegradable alternative to microplastics in cosmetics. Full article

Nodular cast iron is one of the most widely used materials in the machine building industry. The main reasons for this are its strength, elongation, and competitive price compared to other steels and metals. The possibility to have a high strength and elongation together is thanks to the spheroidal shape of the graphite inserts in the metal structure of the iron. To exploit these advantages, special treatments such as adding magnesium are used after the melting process but before pouring the metal in the casting mold. Classic technology is called tundish/sandwich technology when ferrosiliconmagnesium alloy in bulk is placed at the bottom of a ladle before filling it with liquid cast iron. In the present article, an alternative technology will be presented where a fesimg alloy is filled in a steel wire and inserted automatically into a ladle. The advantages of this technology will be described in detail. Full article

Ti₂AlNb-based alloys are widely used in aerospace applications due to their excellent high-temperature mechanical properties. This study aims to investigate the texture, microstructural evolution, and phase transformation behavior of Ti₂AlNb-based alloy sheets during heat treatment and their effects on tensile properties. During heat treatment, B2 → O phase transformation occurs at 550 °C and 650 °C, while Ostwald ripening takes place at 700 °C and 850 °C. The α₂ phase undergoes spheroidization around 1000 °C due to grain boundary separation and recrystallization. Additionally, the B2, O, and α₂ phases all exhibit strong textures. The B2-phase texture follows a cubic orientation ({100}<001>), rotated ~30° around the normal direction (ND). The O-phase texture consists of a strong {100}<010> rolling texture and a weaker texture component <001>//RD, influenced by the B2-phase texture, rolling deformation, and variant selection during O-phase precipitation. Each B2 grain generates four variants, forming distinct O-phase textures within the same grain. The α₂-phase texture exhibits typical rolling textures, [0001]//TD, <$\overline{1}$2$\overline{1}$0>//ND, and {11$\overline{2}$0}<01$\overline{1}$0>, remaining stable after heat treatment. Tensile tests show that the rolled sheet has better ductility along the rolling direction (RD), while the transverse direction (TD) demonstrates higher yield strength (up to 1136 MPa). The anisotropy in tensile properties is mainly attributed to the O-phase texture, with minor contributions from the α₂-phase and B2-phase textures. These findings provide a theoretical basis for optimizing the mechanical properties of Ti₂AlNb-based alloys. Full article

As the cross-sectional size of bearing steel increases, maintaining a uniform microstructure becomes more difficult. To address this issue in large-section 1.0C-1.5Cr bearing steel, the behavior of carbides during isothermal spheroidization annealing at different positions within the steel was investigated. Quantitative metallography was used to measure the mean diameter of carbides (D), the number of carbides per area (n), and the carbide particle size distribution at both the 1/2 position and the center position of the steel. The results of the study showed good spheroidization of carbides in all the specimens except for the presence of lamellar pearlite organization in the specimens with austenitizing temperatures of 760 °C and 880 °C. As the austenitizing and second annealing temperatures and times increased, the mean diameter of carbides (D) became larger, while the number of carbides per area (n) decreased. It is worth noting that the carbides in the center position are smaller than in the 1/2 position, although the center position had a higher density of carbides. Based on the measured values of D and n, a model was developed to describe the relationship between them. In addition, the mechanical properties were influenced by this uneven carbide distribution: as the carbide size increased, tensile strength decreased, while elongation followed a similar trend. Additionally, tensile strength was higher at the center position than at the 1/2 position, whereas elongation was greater at the 1/2 position. Full article

While a tensile test revealing joint fracture at the base material may indicate good joint quality under certain circumstances, this conclusion might overlook the importance of examining the joint interface because exceptions can occur when one side is significantly softer. This study investigates the fabrication of a 316L/CuCrZr bimetal structure using the laser powder bed fusion (LPBF) process. Cracks were observed at the joint interface. The microhardness measured approximately 200 HV at the cracked interface and 100 HV on the CuCrZr side. Tensile testing showed that fractures occurred on the CuCrZr side, despite the presence of cracks at the bonding interface of the 316L/CuCrZr bimetal joint. Spheroids of 316L and Cu were found at the interface due to the Fe-Cu immiscibility system. This immiscibility was the main reason for the formation of cracks. This highlights the need for a thorough microstructural examination of the bonding to ensure a comprehensive quality assessment. The LPBF-fabricated 316L/CuCrZr bimetal joint exhibits a yield strength of 203.0 MPa, a UTS of 287.5 MPa, and an elongation of 15.3%. Full article

This study developed a new heat treatment method, normalizing and stress relief (NSR), to increase productivity compared to spheroidizing annealing (SA). The influence of different microstructures resulting from these heat treatments was investigated in cold-forged steel. Despite a shorter heat treatment time, the mechanical properties of the NSR alloy were found to be similar to those of the SA alloy. The factors influencing the mechanical properties of the experimental alloys were analyzed using the Hall–Petch equation, and the predicted values closely matched the measured strength of hyper-eutectoid steels. The primary factors affecting mechanical properties were microstructure and dislocation density. In the case of the SA alloy, the microstructure was associated with lower strength due to the spherical cementite structure. In contrast, the NSR alloy had lower strength because of a reduced dislocation density. This was achieved via stress-relief heat treatment below the A₁ temperature after phase transformation. Based on the mechanical properties, cold forging simulations showed that the effective stress during cold forging of the NSR alloy was similar to that of the SA alloy. Full article

The Ti-62222 (Ti-6Al-2Sn-2Zr-2Mo-2Cr) alloy has considerable potential for structural applications in the aerospace industry owing to its exceptional fracture resistance and specific strength. This study investigates the influence of local strain parameters and solution treatment and aging (STA) on the microstructure, texture evolution, and microhardness of a hot-forged Ti-62222 alloy. The strain distribution was simulated using the finite element method (FEM). The results showed that in the specimens before heat treatment, the morphology of the primary Ti α phase grains elongated perpendicular to the compression direction as the strain increased. In contrast, the post-heat-treated specimens (PHTSs) exhibited similar aspect ratios, regardless of the strain level, owing to grain spheroidization induced by the STA heat treatment process. Spheroidal primary Ti α phase and acicular Ti α’ phase were observed in the specimens before and after heat treatment. Texture analysis revealed that the specimens subjected to heat treatment had a weaker texture than the before-heat-treatment specimens. The near ($11\overline{2}0$)//FD texture tended to develop along the direction perpendicular to the forging direction. The microhardness analysis results indicated that strain had no significant effect on the microhardness of either the as-forged specimen or the PHTS. After heat treatment, the specimens showed consistent microhardness values regardless of the strain level. The PHTS exhibited increased microhardness, attributed to the aging process during STA. Full article

The mechanical properties of music wire are contingent upon its microstructure, which in turn influences its applications in music. Chinese stringed instruments necessitate exacting standards for comprehensive performance indexes, particularly with regard to the strength, resilience, and rigidity of the musical steel wires, which differ from the Western approach to musical wire. In this study, SWP-B music wire was selected for investigation through metal heat treatment, which was employed to regulate its microstructure characteristics. Furthermore, a spectral analysis was conducted to evaluate the musical expression, encompassing attributes such as pitch and timbre. In conclusion, the governing law of the impact of the microstructure of music wire on its musical expression was established. The results demonstrate that steel wire subjected to a 200 °C annealing treatment for cementite spheroidization can effectively reduce stress concentration, thereby reducing the probability of fracture and consequently improving tonal uniformity and richness while increasing tensile strength from 2578 MPa to 2702 MPa. Conversely, the high-temperature annealing treatment alters the crystalline structure of the material and refines the grain structure, thereby improving the material’s performance and sound quality. The fine microstructure of the music steel wire displays enhanced uniformity. As the annealing temperature increases, the strength of the ferrite phase <110>//ND (<010>//ND, indicating that the <010> direction of the crystal is parallel to the normal direction of the material) and the cementite phase <010>//ND demonstrates a gradual decline. However, this also results in a more pronounced harmonic performance, which, in turn, affects the overall music expression. Full article

Spheroidal graphite cast iron, which is commonly used in a variety of applications, is subject to sliding wear and tear during operation. This damage can be prevented by increasing its strength value. In this study, 0%, 0.191%, and 0.304% niobium-reinforced spheroidal graphite cast irons were produced. Specimens for hardness, compression, and abrasion tests were produced in accordance with the standards for the tests of the sand mold cast specimens. In order to compare the results of the tests, test specimens reinforced with 0.191% and 0.304% niobium, as well as 0% (unreinforced), were also produced. The hardness and compression strength of the niobium-reinforced and unreinforced specimens were tested in accordance with the standards. In addition, wear tests were carried out at 5 N, 10 N, and 15 N loads for 0%, 0.191%, and 0.304% niobium reinforcements, respectively. In the hardness tests, the highest measured value was observed in the sample reinforced with 0.304% niobium, with an average of 272 HB. Since Nb is an element with high hardness, the hardness values of the samples increased with the increase in Nb reinforcement. With an average value of 1411 MPa, the niobium-reinforced sample with 0.191% niobium reinforcement exhibited the highest compression strength. When analyzing the results of the compression tests, an increasing trend was observed with increasing reinforcement ratio, as was the case with the results of the hardness tests. In the wear tests, the changes in wear volume, wear rate, and friction coefficients were examined at loads of 5 N, 10 N, and 15 N. When the test specimens with the same reinforcement ratio were examined, it was found that the wear volume loss values increased with the increase in load. As the wear resistance increases with increasing hardness value, it becomes more difficult to detach the particles from the wear surfaces. The wear volume of the samples, therefore, decreases as the hardness value increases. At the end of the experimental study, a microstructural analysis of the surfaces subjected to sliding wear was carried out. It was observed that wear marks and pits had formed on the surfaces subjected to sliding wear. Full article

This study presents an advanced integration of Multi-modal Raman Light Sheet Microscopy with zero-shot learning-based computational methods to significantly enhance the resolution and analysis of complex three-dimensional biological structures, such as 3D cell cultures and spheroids. The Multi-modal Raman Light Sheet Microscopy system incorporates Rayleigh scattering, Raman scattering, and fluorescence detection, enabling comprehensive, marker-free imaging of cellular architecture. These diverse modalities offer detailed spatial and molecular insights into cellular organization and interactions, critical for applications in biomedical research, drug discovery, and histological studies. To improve image quality without altering or introducing new biological information, we apply Zero-Shot Deconvolution Networks (ZS-DeconvNet), a deep-learning-based method that enhances resolution in an unsupervised manner. ZS-DeconvNet significantly refines image clarity and sharpness across multiple microscopy modalities without requiring large, labeled datasets, or introducing artifacts. By combining the strengths of multi-modal light sheet microscopy and ZS-DeconvNet, we achieve improved visualization of subcellular structures, offering clearer and more detailed representations of existing data. This approach holds significant potential for advancing high-resolution imaging in biomedical research and other related fields. Full article

Stem cell-based therapy holds promise for cartilage regeneration in treating knee osteoarthritis (KOA). Injectable hydrogels have been developed to mimic the extracellular matrix (ECM) and facilitate stem cell growth, proliferation, and differentiation. However, these hydrogels face limitations such as poor mechanical strength, inadequate biocompatibility, and suboptimal biodegradability, collectively hindering their effectiveness in cartilage regeneration. This study introduces an injectable, biodegradable, and self-healing hydrogel composed of chitosan–PEG and PEG–dialdehyde for stem cell delivery. This hydrogel can form in situ by blending two polymer solutions through injection at physiological temperature, encapsulating human adipose-derived stem cells (hADSCs) during the gelation process. Featuring a 3D porous structure with large pore size, optimal mechanical properties, biodegradability, easy injectability, and rapid self-healing capability, the hydrogel supports the growth, proliferation, and differentiation of hADSCs. Notably, encapsulated hADSCs form 3D spheroids during proliferation, with their sizes increasing over time alongside hydrogel degradation while maintaining high viability for at least 10 days. Additionally, hADSCs encapsulated in this hydrogel exhibit upregulated expression of chondrogenic differentiation genes and proteins compared to those cultured on 2D surfaces. These characteristics make the chitosan–PEG/PEG–dialdehyde hydrogel–stem cell construct suitable for direct implantation through minimally invasive injection, enhancing stem cell-based therapy for KOA and other cell-based treatments. Full article

Human serum albumin (HSA) corona formation on polymer microparticles of a spheroidal shape was studied using dynamic light scattering and Laser Doppler Velocimetry (LDV). Physicochemical characteristics of the albumin comprising the zeta potential and the isoelectric point were determined as a function of pH for various ionic strengths. Analogous characteristics of the polymer particles were analyzed. The adsorption of albumin on the particles was in situ monitored by LDV. The stability of the HSA-functionalized particle suspensions under various pHs and their electrokinetic properties were also determined. The deposition kinetics of the particles on mica, silica and gold sensors were investigated by optical microscopy, AFM and quartz microbalance (QCM) under diffusion and flow conditions. The obtained results were interpreted in terms of the random sequential adsorption model that allowed to estimate the range of applicability of QCM for determining the deposition kinetics of viruses and bacteria at abiotic surfaces. Full article

Geopolymers are binder materials that are produced by a chemical reaction between silica or aluminum compounds with an alkaline activating solution. Foamed geopolymer materials are increasingly being cited as a viable alternative to popular organic insulation materials. Since the foaming process of geopolymers is difficult to control, and any achievements in improving the performance of such materials are extremely beneficial, this paper presents the effect of the addition of basalt powder on the properties of foamed geopolymers. This paper presents the results of physicochemical studies of fly ash and basalt, as well as mechanical properties, thermal properties, and structure analysis of the finished foams. The scope of the tests included density tests, compressive strength tests, tests of the thermal conductivity coefficient using a plating apparatus, as well as microstructure tests through observations using light and scanning microscopy. Ground basalt was introduced in amounts ranging from 0 to 20% by mass. It was observed that the addition of basalt powder contributes to a reduction in and spheroidization of pores, which directly affect the density and pore morphology of the materials tested. The highest density of 357.3 kg/m³ was characterized by samples with a 5 wt.% basalt powder addition. Their density was 14% higher than the reference sample without basalt powder addition. Samples with 20 wt.% basalt addition had the lowest density, and the density averaged 307.4 kg/m³. Additionally, for the sample containing 5 wt.% basalt powder, the compressive strength exceeded 1.4 MPa, and the thermal conductivity coefficient was 0.1108 W/m × K. The effect of basalt powder in geopolymer foams can vary depending on many factors, such as its chemical composition, grain size, content, and physical properties. The addition of basalt above 10% causes a decrease in the significant properties of the geopolymer. Full article

In this study, the induction plasma spheroidization (IPS) technique was adopted to improve the microstructure and properties of the traditional agglomerated ZrO₂-7wt%Y₂O₃ (YSZ) powders used in thermal barrier coating (TBC) applications. Compared with agglomerated YSZ powders, IPS-treated powder has a more desirable microstructure, and the overall performance of the spray powders for TBC preparation is significantly improved. Specifically, IPS-treated powder has a dense, solid, defect-free, and chemically uniform microstructure, and its apparent density, flowability, and powder strength are significantly improved, which is believed to substantially enhance the coating performance when prepared with this IPS-treated powder. Full article