Search Results (38)

Sliding bearing alloy layers must combine excellent tribological performance with reliable metallurgical bonding, but conventional fabrication methods often suffer from coarse grains, chemical segregation and poor interface adhesion. Annular coaxial laser wire-feed cladding, by providing more uniform heat input and rapid solidification, is expected to mitigate these deficiencies; however, systematic studies of this technique applied to tin-based Babbitt alloy layers remain limited. In this work, Babbitt layers produced by conventional casting and by annular coaxial laser wire-feed cladding were compared in terms of microstructure, phase constitution, hardness and tribological behavior. The results indicate that laser cladding can produce continuous, dense and well-bonded coatings and markedly refine the SnSb phase, reducing grain size from approximately 100 μm in the cast material to 10-20 μm. Hardness increased from 25.3 HB to 27.6 HB, while tribological performance improved substantially: the coefficient of friction decreased by about 38.19% and the wear volume was reduced by approximately 10.46%. These improvements are attributed mainly to the rapid solidification, low dilution and more uniform phase distribution associated with annular coaxial laser cladding, demonstrating the strong potential of this process for fabricating high-performance tin-based Babbitt bearing layers. Full article

Background/Objectives: Integrating behavioral health and primary care services is a national public health priority in the US, especially in underserved settings like northern Arizona. This healthcare delivery model is crucial to meet the mental and physical health needs of people with SU/SUDs, particularly those belonging to culturally diverse populations. In collaboration with a behavioral health center in northern Arizona, the current study aimed to assess the perspectives of providers and administrative staff on the implementation of integrated primary care (IPC) services for people with SU/SUDs. Methods: In February 2023, twelve healthcare providers and administrative staff from diverse educational backgrounds were recruited using purposive sampling to capture a range of perspectives on IPC implementation at the behavioral health center. Participants completed individual, semi-structured interviews conducted via Zoom, which were audio recorded and lasted approximately 30 min. The interview recordings were transcribed verbatim using Trint Software, and analyzed on Google Docs using applied thematic analysis. Two researchers coded the transcripts, iteratively developing and refining themes through multiple cycles of review and team discussions. Additional team members provided feedback and verified the themes, with consensus reached through collaborative meetings. This rigorous, iterative approach ensured the reliability and validity of the final thematic framework. Results: We found that IPC supports SU/SUDs recovery by providing holistic care that integrates medical, mental health, and addiction services while addressing social and co-occurring needs. It fosters an empathetic environment where clients do not need to repeatedly disclose their SU/SUDs, improves access to preventive care, and offers continuous support and education. Implementation barriers included workforce shortages, limited internal communication, and insufficient interdisciplinary training. Gaps in culturally centered care were identified, including reliance on Western models, limited representation of Native American and sexual and gender minority staff, and inconsistent use of inclusive practices such as pronouns, traditional healing, and trauma-informed approaches. Additionally, community partnerships with multisectoral organizations help clients access supportive resources beyond the facility, including vision care, clothing, and dental services. Conclusions: The implementation of IPC was seen as important to support the behavioral health center in northern Arizona to foster an empathetic environment where clients with SU/SUDs can have their mental, physical, and social needs addressed, either within the facility or through community partnerships, thereby supporting their recovery. However, progress is hindered by barriers such as workforce shortages, limited internal communication, and insufficient interdisciplinary care training. Additionally, despite regular cultural competency training, gaps remain in culturally centered care for underserved populations, particularly Native American and sexual and gender minority clients. Full article

This study investigates the fabrication and performance of a novel composite material by infiltrating SnSb11Cu6 babbitt alloy into an open-cell AlSn6Cu-SiC matrix. The composites, produced via a multi-stage liquid-state processing route, were comprehensively characterized for their microstructural, mechanical, and tribological properties. The inclusion of 5 wt.% silicon carbide reinforcement resulted in a significant improvement in tribological performance under dry-sliding conditions. Specifically, the reinforced composite exhibited a 24.8% reduction in wear and a 10.8% reduction in the coefficient of friction compared to its unreinforced counterpart. Crucially, this enhancement in wear resistance was achieved while the bulk compressive mechanical properties and ductile deformation behavior remained virtually identical to the unreinforced material. Microstructural analysis confirmed that the high-hardness SiC particles act as primary load-bearing agents, shielding the softer metallic matrix from severe wear. These findings demonstrate the successful development of a high-performance composite with enhanced tribological durability without a mechanical trade-off, making it a promising candidate for advanced bearing applications. Full article

Babbitt alloys are among the most commonly used materials for sliding bearings. However, with the high speeds and heavy loads of modern machinery, as well as the demands of extreme working conditions, the temperature resistance, strength, and hardness of traditional Babbitt alloys are often insufficient to meet these requirements. To address this issue, it is essential to improve the properties of Babbitt alloys, particularly their performance at high temperatures. The present study explored a technical approach for incorporating copper powder to improve the high-temperature performance of Babbitt alloys. Copper powder was added to the traditional Babbitt alloy in mass percentages of 1, 2, 3, and 4%. After fabrication, the samples were examined using metallographic structure analysis, high-temperature compression testing, and friction and wear testing. The experiments investigated the effects of copper powder addition on the properties of the Babbitt alloy and determined the optimal amount of copper powder required to enhance its performance. Full article

Enhancing the durability and tribological performance of babbitt alloys is critical for high-stress applications in automotive, marine, and industrial machinery. The present study explores the electrodeposition of chromium coatings on SnSb11Cu6 alloys to improve their microstructural, mechanical, and tribological properties. The coatings were applied through an electrolytic process and systematically characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy to evaluate their morphology, composition, and wear performance. The chromium coating exhibited a uniform thickness of 20.2 µm and significantly improved the surface hardness to 715.2 HV, far surpassing the matrix and intermetallic phases of the uncoated alloy. Tribological testing under dry sliding conditions demonstrated a 44% reduction in the coefficient of friction (COF) and a 54% decrease in mass wear for the coated alloy, highlighting the protective role of the chromium layer against abrasive and adhesive wear. To further analyze the frictional behavior, a deep learning model based on a one-dimensional convolutional neural network was employed to predict COF trends over time, achieving excellent accuracy with R² values of 0.9971 for validation and 0.9968 for testing. Feature importance analysis identified coating hardness as the most critical factor influencing COF and wear resistance, followed by matrix hardness near the coating. These findings underscore the effectiveness of chromium coatings in mitigating wear damage and improving the operational lifespan of SnSb11Cu6 alloys in high-stress applications. This study not only advances the understanding of chromium coatings for babbitt materials but also demonstrates the potential of machine learning in optimizing tribological performance. Full article

Primate species differ drastically from most other mammals in how they visually perceive their environments, which is particularly important for foraging, predator avoidance, and detection of social cues. Background/Objectives: Although it is well established that primates display diversity in color vision and various ecological specializations, it is not understood how visual system characteristics and ecological adaptations may be associated with gene expression levels within the primary visual cortex (V1). Methods: We performed RNA-Seq on V1 tissue samples from 28 individuals, representing 13 species of primates, including hominoids, cercopithecoids, and platyrrhines. We explored trait-dependent differential expression (DE) by contrasting species with differing visual system phenotypes and ecological traits. Results: Between 4–25% of genes were determined to be differentially expressed in primates that varied in type of color vision (trichromatic or polymorphic di/trichromatic), habitat use (arboreal or terrestrial), group size (large or small), and primary diet (frugivorous, folivorous, or omnivorous). Conclusions: Interestingly, our DE analyses revealed that humans and chimpanzees showed the most marked differences between any two species, even though they are only separated by 6–8 million years of independent evolution. These results show a combination of species-specific and trait-dependent differences in the evolution of gene expression in the primate visual cortex. Full article

In this paper, the ultrasonic vibration treatment (UVT) technique was used to prepare a SnSbCu11-6 alloy semi-solid slurry, and the effects of ultrasonic power on its microstructure size, distribution and properties were studied. The results show that the UVT technique significantly refines the Cu6Sn5 phase and SnSb phase and improves their distribution uniformity. Interestingly, the second SnSb phase is also well refined to nearly 100 °C below the melting point; furthermore, the morphology is transformed from coarse petal-like to fine regular cubic, and the average grain size is refined to 48.8 ± 8.8 μm. The alloy’s comprehensive properties are best when the ultrasonic power is 1200 W. The yield strength, tensile strength, elongation and microhardness reach 60.6 MPa, 70.3 MPa, 4.9% and 27.4 HV, respectively, which represent increases of 4.7%, 6.0%, 113% and 23.4%, respectively, compared with conventional liquid casting. This may be attributed to the grain size refinement and distribution uniformity enhancement of the Cu6Sn5 phase and the SnSb phase. This work provides a feasible and effective method for the preparation of high-performance tin-based babbitt alloys by UVT technology. Full article

Mitochondrial holocytochrome c synthase (HCCS) is an essential protein in assembling cytochrome c (cyt c) of the electron transport system. HCCS binds heme and covalently attaches the two vinyls of heme to two cysteine thiols of the cyt c CXXCH motif. Human HCCS recognizes both cyt c and cytochrome c₁ of complex III (cytochrome bc₁). HCCS is mutated in some human diseases and it has been investigated recombinantly by mutational, biochemical, and reconstitution studies in the past decade. Here, we employ structural prediction programs (e.g., AlphaFold 3) on HCCS and its two substrates, heme and cytochrome c. The results, when combined with spectroscopic and functional analyses of HCCS and variants, provide insights into the structural basis for heme binding, apocyt c binding, covalent attachment, and release of the holocyt c product. Results from in vitro reconstitution of purified human HCCS using cyt c and cyt c₁ peptides as acceptors are consistent with the structural modeling of substrate binding. Reconstitution of HCCS and cyt c₁ provides an approach to studying cyt c₁ assembly, which has been refractile to recombinant in vivo reconstitution (unlike HCCS and cyt c). We propose a structural basis for release of the holocyt c product from HCCS based on in vitro studies and on cryoEM structures of the bacterial cyt c synthase (CcsBA) active site. We analyze the kinetoplastid mitochondrial synthase (KCCS), and hypothesize a molecular evolutionary path from mitochondrial endosymbiosis to the current HCCS. Full article

A Babbitt alloy SnSb11Cu6 with 0–2.0 wt.% Co was synthesized using the induction melting process. This study examined the effect of cobalt (Co) on the microstructure, tensile properties, compressive properties, Brinell hardness, and wear properties of SnSb11Cu6 using optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), a universal tensile testing machine, a Brinell hardness tester, and a wear testing machine. The results indicate that the optimal quantity of Co can enhance the microstructure of the Babbitt alloy and promote microstructure uniformity, with presence of Co₃Sn₂ in the matrix. With the increase in Co content, the tensile and compressive strength of the Babbitt alloy first increased and then decreased, and the Brinell hardness gradually increased with the increase in Co content. The presence of trace Co has a minimal effect on the dry friction coefficient of the Babbitt alloy. When the Co content exceeds 1.5 wt.%, the friction properties of the Babbitt alloy deteriorate significantly. The optimized Babbitt alloy SnSb11Cu6-1.5Co was subsequently fabricated into wires, followed by conducting cold metal transfer (CMT) surfacing experiments. The Co element can promote the growth of interfacial compounds. The microstructure at the interface of the Babbitt alloy/steel is dense, and there is element diffusion between it. The metallurgical bonding is good, and there are serrated compounds relying on the diffusion layer to extend to the direction of the additive layer with serrated compounds extending and growing from the diffusion layer to the additive layer. Overall, Babbitt alloys such as SnSb11Cu6 exhibit improved comprehensive properties when containing 1.5 wt.% Co. Full article

Tin-based Babbitt alloy/steel bimetallic castings were prepared by compound casting with different coating surface modification treatment. The defects of modified coating surface are effectively controlled, while the unmodified interface has a considerable number of micropores. In consequence, the additional composite surface modifier greatly increased the integrity of the bimetal interface and led to a significant improvement of shear strength to ~55.61 MPa, in comparison to its counterpart with no surface modifier of ~7.04 MPa. Based on extensive experimental investigation and theoretical analysis, the role of coating surface modifiers in the interfacial strengthening was revealed. Meanwhile, the diffusion behavior of the bimetal interface connection was analyzed by first-principles calculations. These results will shed new light on the understanding of the liquid–solid connection of bimetallic composites and improve defect control at the interface. Full article

Tin-based Babbitt alloys are a widely used bearing bushing material which have good comprehensive properties. However, problems such as high-temperature softening and insufficient bearing capacity occur during their use, so the optimization of tin-based Babbitt alloys has become a research hotspot. In this paper, ZChSnSb11-6 alloy was mainly prepared by the gravity casting method, and different amounts of Zn were added to the alloy (the mass fraction values were 0 wt.%, 0.05 wt.%, 0.1 wt.%, 0.15 wt.%, and 0.2 wt.%, respectively). Through the hardness test, the tensile test, the friction and wear test, and the microstructure observation of the prepared alloy, the influence of Zn on the organization and properties of the ZChSnSb11-6 alloy was analyzed. The results show that the size of the SnSb hard phase changed with the increasing content of Zn. The size of the hard phase of the SnSb tended to increase first and then decrease, and the number of phase particles increased first and then decreased, resulting in changes in performance. Through comparison, it was learned that the addition of Zn can effectively improve the hardness, tensile strength, yield strength, and wear resistance of the alloy, but the elongation rate was reduced. When the Zn content was 0.1 wt.%, the hardness value of the alloy reached the maximum value, 25.82 HB, which increased by 7.3% when compared with the sample without Zn. The hardness of the Zn, 0.15 wt.%, is close to that of the Zn, 0.1 wt.%. Compared to the sample without Zn, the tensile strength and elongation of the alloy were maximized at a Zn content of 0.15 wt.%. Compared to the sample without the Zn, the tensile strength was increased by 21.29%, and the elongation rate was increased by 46%. An analysis showed that the alloy has good comprehensive mechanical properties when the Zn content is 0.15 wt.%. Full article

Babbitt alloy is a bearing material with excellent properties, including good anti-friction wear resistance, embeddedness, corrosion, and compliance, as well as sufficient bearing capacity. However, with the development of engines to have high speed and heavy load, the use of Babbitt alloy as a bearing material exposes its weaknesses of low bearing capacity, insufficient fatigue strength and a sharp decline in mechanical properties with an increase in working temperature. Therefore, its application scope is gradually narrowed and subject to certain limitations. Improving the tensile strength and wear resistance of tin-based Babbitt alloy is of great significance to expanding its application. In this study, tin-based Babbitt alloy was taken as the main research object; the particle size, microstructure, mechanical properties, and friction were systematically studied after the single addition of Y-Cu composite in tin-based Babbitt alloy liquid. The wear performance and the strengthening, toughening and wear mechanisms of tin-based Babbitt alloy were investigated under the action of Y in order to prepare a high-performance tin-based Babbitt alloy for bimetallic bearing. It was found that when rare-earth Y was added to the Babbitt alloy body, the wear properties were greatly improved. Full article

This article presents the research results of depositing anti-friction coatings (Babbitt) using three different casting methods: static casting, flame soldering, and clad welding. Babbitt alloy coatings deposited with different casting methods are discussed and explained in terms of changes in the coating properties, such as the microstructure, hardness, strength, and chemical composition. The results showed significant differences in the aforementioned properties, depending on the chosen coating deposition method. The results of the tests confirmed the importance of using shielding gas during deposition to ensure the chemical composition of the coating. The analysis revealed that decreases in the amounts of antimony and copper in the Babbitt coating compared with the initial concentrations were influenced by selective evaporation, oxidation, and the coating process parameters associated with different coating methods. To maintain the desired balance of mechanical properties in Babbitt coatings, it is important to control the antimony and copper contents. Clad welding deposition using a non-consumable tungsten electrode and argon shielding gas achieved a chemically stable coating quite close to the initial chemical composition of the Babbitt alloy. Full article

This paper discusses the results of a study to determine the effect of the chemical composition of two tin-based bearing alloys (B89 and B83) on their tribological properties. The tribological properties were tested using a T05 block-on-ring tester under technically dry and wet friction conditions. The research includes the determination of the wear rates, loss of mass, coefficients of friction, and changes in the coefficient of friction as a function of the process and material parameters. A study of the microstructure and base properties of such alloys, which affect the tribological properties and wear, are also presented. The study showed that chemical composition has a significant effect on the tribological properties; increasing the proportion and changing the morphology of the SnSb precipitates to rhomboidal in the B83 alloy results in an increase in wear resistance represented by loss of mass. Decreasing the size and proportion of these precipitates results in a stabilization of the frictional force variation and a slight decrease in the coefficient of friction. The research showed that SnSb phase precipitation is mainly responsible for the wear resistance of the investigated bearing alloys. Full article

Considering the problem of the weak bonding interface structure between the rolling mill oil and film bearing bushings of Babbitt alloy and steel substrate, a numerical simulation of the layered bimetallic ZChSnSb8Cu4/steel by tungsten inert gas (TIG)-metal inert gas (MIG) hybrid welding process was carried out using Simufact Welding software (version 2020). In this study, the TIG-MIG hybrid welding process was simulated to obtain the temperature field and the stress field distributions. The residual stress and the deformation of the weldment were also analyzed using the calculated results. The results showed that the temperature gradient and the thermal stress were reduced in TIG-MIG hybrid welding compared to the conventional MIG welding preparation of layered bimetal ZChSnSb8Cu4/steel, which resulted in an improvement in the structural stability of the weldment. The temperature field and deformation of TIG-MIG hybrid welding of Babbitt alloy were studied under different controlled electrode spacings and TIG welding currents, and it was found that as electrode spacing increased, so did heat loss. Furthermore, with increased TIG welding current, compressive stress increased and tensile stress at the weld decreased, and the maximum thermal efficiency of welding was with a preheating current of 60 A. Full article