Results in Materials最新文献

Adhesive bonded joints hold significant importance across various industrial sectors in modern engineering, owing to their lightweight nature and myriad advantages. The rising demand for trimaterial joints underscores their utility and versatility. In these joints, the choice of materials for both adherends greatly influences their strength, structural reliability, and overall characteristics. While numerous researches have extensively analyzed stress distributions, their effects, and behaviors, many have relied on a one-factor-at-a-time approach, focusing solely on individual design variables' effects. However, recognizing the intricate interplay among various material combinations and their collective impact on overall performance, this study employs various types of White-box, Black-box, and Grey-box machine learning algorithms to identify an optimized ML model as well as predict stress distributions for any random combinations of upper and lower adherend materials. Dataset of total 178 random material combinations were utilized for the training phases with 5-fold cross validation and model tuning. However, the decision tree regressor emerged as the optimized model by comparing the quantitative metrics of accuracy benchmark as well as the prediction outcomes obtained through all the machine learning models. The maximum prediction accuracy attained was an impressive 99.97 %, while the minimum recorded was 89.74 %. This research aims to identify tailored machine learning model specifically for trimaterial bonded joints where nano layer of resin is utilized as the adhesive.

The liquid breeding blanket concept of a fusion reactor is based on the employment of the eutectic Lead-Lithium solution (LLE), where Lithium, enriched in ⁶Li, has the purpose of regenerating Tritium by reacting with neutrons, while Lead enhances the process acting as neutrons multiplier. Anyway, despite the huge interest on this binary system, LLE is not characterized yet by a fully consolidated description of its basic thermophysical properties and, in many cases, the spread of values reported so far in literature remains still significant. The purpose of this paper is hence to check again the many data available in literature, with a special attention to the ones more recently published, trying to explain and solve their inhomogeneity. Taking into account the general features of the Pb-Li interaction and particularly the not ideal behaviour of the Pb-Li liquid solutions, the following thermophysical properties of the LLE are dealt in detail: specific heat; density and volumetric thermal expansion coefficient; thermal conductivity and diffusivity; electrical resistivity; Sieverts' constant of Hydrogen. Based on the deep analysis of all the reported experimentation and through the adoption of several comparison criteria, the most trustable correlation is sought for each of the above properties; additionally, when a robust correlation couldn't be retrieved, a new, optimized, one has been proposed, capable also to foresee correctly the effect of small composition variations and to assure the internal coherence among linked properties.

Specific heat and density values resulted at the end accurately described and not needing for additional experimentation; thermal properties and electrical resistivity can be evaluated with decent confidence, even if their uncertainty could be somehow reduced by future investigations; for Sieverts' constant it has not possible yet to identify a unique, trustable correlation, anyway the range of values correctly assumed up to 900K has been significantly restricted.

Magnetic fluid hyperthermia (MFH) is one of the new methods for personalizing cancer treatment. In this study, ${20\text{SiO}}_2‐50\text{FeO}‐15\text{CaO}‐15{\text{Na}}_{2}O$ glass ceramics was selected as the base glass and the effect of adding different $P_2{O}_5$ percentages on the magnetic properties and bioactivity of the samples were investigated. Phase studies showed that maghemite, hematite, sodium calcium silicate, and iron calcium silicate phases have crystallized in glass ceramics. Structural studies showed that $P_2{O}_5$ acted as a nucleation agent in glass ceramics and reduced the size of maghemite and hematite crystals. By increasing $P_2{O}_5$ to 2 wt%, the magnetic saturation of the samples increased to 22.5emu/g and decreased in higher percentages. The highest increase in temperature also belonged to these samples, and its value was measured as 13 $°C$. Study the samples immersed in the simulated body fluid (SBF), it was seen that hydroxyapatite with cauliflower morphology was crystallized on the surface of the samples.

The generation of waste from the demolition of old structures poses a significant environmental challenge. Recycling these materials as aggregates in concrete offers a potential alleviation of environmental impact. While recycled aggregates offer promise as a remedy, they are not without drawbacks. However, innovative approaches have been developed to overcome these limitations. Among these, plastic coating stands out as a particularly sustainable solution. This study investigates the influence of plastic coating temperature on recycled concrete brick aggregates (RCBA), which serve as coarse aggregates. The RCBA were coated with locally sourced polyethylene terephthalate (PET) at varying temperatures, such as 250 °C, 300 °C, 350 °C, and 400 °C. Then the physical properties of the plastic-coated recycled aggregates (PCRA) were assessed. Additionally, concrete specimens incorporating PCRA were fabricated to evaluate their influence on the mechanical properties of concrete. The results indicate that higher coating temperatures positively influenced the physical properties of the aggregate. Furthermore, at elevated temperatures, the plastic became sufficiently malleable to penetrate deeper into the permeable pores, reinforcing the weak mortar interface and thereby enhancing the mechanical properties of the concrete made with it. Additionally, mathematical models have been proposed to predict the influence of plastic coating temperature on both the physical properties of the RCBA and the mechanical properties of the concrete.

This study investigates and compared various properties of high-quality foundry sands on the surface quality of castings, whose cores are produced using the col-box method. Methods such as the measurement of flushable fraction, sieve analysis, electron and optical microscopy, pH and electrical conductivity measurements were used to monitor the physico-chemical properties of silica and non-silica sands. 5 core mixtures were prepared from individual sands by adding 1.6 % of organic binder based on phenol-formaldehyde formed from resin and hardener using an MR100 mixer. The produced cores were placed in moulds made of a uniform bentonite mixture and cast (15 test castings). In all the tested sand samples, the dust content was visible at a 300× magnification, but the share of flushable content is not exceeded 3 %, which is one of the fundamental conditions for moulding. All the tested sands are heat resistant at 1600 °C and had a low flushable fraction in the range 0.05–0.3 %. The results indicate that the occurrence of surface defects in high-quality foundry sands is not related to the flushable fraction content, to the average grain size value d₅₀, to the electrical conductivity, to the shape of the sand grains and to the flexural strength. The surface roughness is related to the average grain size, to the grain shape and to the flexural strength.

It was considered the forming multilayer heat-resistant coatings that work under conditions of elevated temperatures and long-term oxidation. The issue of increasing the service life of the parts by strengthening their bulk and surface is considered. The issue of determining the level of the thermophysical properties is also considered. The thermophysical properties of carbonyl iron reinforced with carbon fibers (CF) pre-clad with nickel are investigated. Unclad and nickel clad carbon fibers were produced. The thermal conductivities of the samples are determined depending on the conditions of their production. The thermal conductivity characteristics of polymer composite materials based on CF with ceramic hollow microspheres and carbonyl iron from CF depending on the conditions of their production were determined. It is shown that heat transfer mechanisms related to the electron-lattice interaction can function in these systems. Heat transfer can occur by various transport mechanisms, such as collisions or diffusion. Nevertheless, the increase in thermal conductivity can be related to the electronic mechanism. The thermal conductivity of materials based on carbonyl iron with nickel-plated CF is 1.2 times higher compared to unclad CF, which is due to better adhesive interaction between the coated carbon fibers and iron was established.

A surface modification process for steel rods based on atmospheric-pressure nitrogen plasma (APP) at room temperature was developed. Steel rods were irradiated with APP generated by dielectric-barrier discharge in a nitrogen atmosphere. Elemental analysis using an electron-probe microanalyzer revealed strong nitrogen signals at the top surface, which suggests the formation of a modified layer due to the generation of excited nitrogen sources by APP. However, no noticeable nitrogen diffusion into the steel was observed. This is because the excited nitrogen sources reacted with elemental iron emitted by APP and nitrides were deposited on the surface of the steel. The proposed APP treatment is a promising approach for modifying the surface of steel rods without heat treatment.

The recycling of polyvinylchloride (PVC) from waste electrical cables in blends with low-density polyethylene (LDPE) is here explored, focusing on the material's mechanical and physical responses. Factors influencing these responses were identified, and reasonable ranges of variability were estimated for each factor. A comprehensive test plan was subsequently devised to develop optimal PVC/LDPE blends. The samples were produced by melt-blending the polymers in a counter-rotating internal mixer followed by compression molding. The effects of suitable coupling additives were also evaluated to enhance phases adhesion. The study investigated the impact of various processing parameters on thermomechanical properties using ANOVA, while a specific focus on optimizing material toughness was pursued. This optimization aimed to maximize both elastic modulus and elongation at break, through the application of genetic algorithms. Introducing a 5 % compatibilizer significantly enhances the interface, resulting in a complex fracture surface facilitated by its presence. Higher mixing temperatures promote better dispersion and distribution of PVC and the compatibilizer within the LDPE matrix, yielding a more uniform and interconnected structure. Increased PVC content correlates with reduced elastic modulus in the blend. The inclusion of a compatibilizer plays a vital role in counteracting the negative effects of PVC particles on stiffness, acting as a bridge to enhance interactions with the matrix and thereby improving interfacial adhesion and overall structure. The study offers insights into enhancing the recyclability of PVC from waste cables and optimizing the mechanical performance of the resultant materials.

In the present work, we have made a comparative investigation on the structural, elastic, electronic, thermos-physical, and optical properties of cubic binary lave phase intermetallic compound with the common formula HfX₂ (X = Cr, Mo and W) based on Density Functional Theory (DFT) using CASTEP. The result of geometrical optimization has been strongly agreed with the experimental results. The HfW₂ compound exhibits larger lattice parameters and volumes than HfMo₂ and HfCr₂ because of the variation of atomic radii of the exhibiting elements in the studied compounds. The elastic properties show that each of the compounds in the ground state is mechanically stable and has a highly ductile nature. Band structures and energy densities of states have been studied to learn more about electronic properties. These compounds display metallic properties in their electrical band structures. They also have high machinability, a low Debye temperature, low bond hardness, and a remarkably high melting point. Our investigation thoroughly examined the reflectivity, absorption coefficient, refractive index, dielectric function, optical conductivity, and loss function of these metals. The optical absorption, reflectivity spectra, and refractive index of HfX₂ (X = Cr, Mo, and W) indicate their potential for use as solar reflectors in the IR-Vis region and UV–Vis absorbers.