Papers by Keyword: Materials Science

Abstract: High-entropy alloys (HEAs) are a new and rapidly developing area of materials science, characterized by their high entropy content. High-entropy alloys have received considerable attention in recent years because of their properties, such as high tensile strength, corrosion resistance and excellent heat resistance. These materials have the potential to broaden material utilization in aerospace, automotive, energy, and other industries. There are three main manufacturing technology group to produce high entropy alloys. These groups are melting and casting, powder metallurgy, and deposition techniques. The manufacturing processes is essential to optimize the properties of the final product and meet the requirements of the application. The paper summarizes the four core effects and the production methods for high-entropy alloys.

Abstract: The achievements and discoveries of chemical science have firmly established themselves in all branches of humanity. One of the most significant chemistry possibilities is the polymerization and polycondensation of compounds, which, in turn, are methods for producing polymers. Polymers are high molecular weight compounds consisting of many units (monomers) linked by chemical bonds. Unique polymer compounds are the basis of plastics, chemical fibers, rubber, paints, and varnishes, adhesives [8]. Polymers are used for the manufacture of removable prostheses, materials for fillings and inlays, orthodontic appliances, artificial teeth, dental implants, as well as in the creation of artificial heart valves, artificial kidney devices, artificial circulation, artificial heart [6].

Abstract: The journey toward foundry and the increasing implementation of Powder Metallurgy are evoking replacing traditional Sand Casting, thus, creating new challenges and opportunities. To take advantage of these opportunities and deal with the challenges, we must gain a holistic understanding of the emerging technical interactions and apply new approaches and methods when introducing new technologies and designing Powder Metallurgy. In this paper, we present the findings of a systematic literature review, consisting of quantitative and qualitative data, focusing on investigating Powder Metallurgy, as an alternative to traditional Sand Casting, by comparing certain characteristics of either process to synthesize the existing information of each method and to present an overview of manufactured materials. Although results indicate an increasing current trend in research publications, showing Powder Metallurgy with many advantages over traditional casting, the latter continues to be implemented as the preferred option in industries with low-level casting production. Given that the studies indicate greater advances in Powder Metallurgy methods over traditional casting, we identified the need for more research on the former under different contexts and therefore recommend it as an approach for future studies of metal casting. This review both reorganizes the available knowledge on Powder Metallurgy, as well as it makes an important methodological contribution by applying a review in Materials science, where there is little to no systematic research, which often means failure to provide sufficient help to implement Powder Metallurgy. Based on these findings, we point to future research needs, highlighting the need for further empirical evidence and improved collaboration between the topics of Mechanical Engineering, Manufacturing Processes, and Materials science, as well as with practitioners.

Abstract: The aim of this paper is to review the literature on Materials science to identify the current research and to provide direction for future research in thermal properties of the concrete block composite, either with Polyethylene Terephthalate (PET) or Polystyrene (PS), presenting the opportunity to make an important methodological contribution by applying systematic review in three areas of Materials science: Composites, Building Materials, as well as Testing and Evaluation of Materials. This is a growing interdisciplinary field since there are no current comparative papers addressing both PET and PS in the same research for concrete composites. Papers investigating to what extent, what type and how academic publications are integrated on the analysis of the characteristics of the two recycled polymers (PET and PS), to improve the thermal properties of the concrete block and contribute to the research of sustainable thermal comfort in homes. They were reviewed, keywords were identified within a framework of composites, building materials, as well as testing and evaluation of materials, and a lexical analysis of the papers was conducted. The results of current research show that both forms of recycling (PS and PET), combined with concrete, have sustainability in thermal comfort. The analysis reveals that previous research has focused on PET-Concrete (i.e., concrete-PET polymer composite) since it is more viable, due to its large amount of recycling. While this has benefited home builders in their ability to respond with some thermal comfort with higher construction efficiency, it also clarifies that there has been research done on PS-Concrete (i.e., concrete-PS polymer composite), presenting greater thermal comfort, because it has lower thermal conductivity. This finding suggests the need for further research within this narrow field, with absence of data, since most prescriptive recommendations have not been tested and lack practical applications, which is why the need for more empirical and experimental studies are identified. Based on the novelty of the PET or PS recycling concepts, we highlight the need of better collaboration between academic disciplines, such as engineering and architecture to provide better experimental evidence for recycling of polymers, including empirical approaches for the different types of composites and aggregate distributions, which can be made with concrete to improve thermal insulation performance and energy savings for manufacturers.

Abstract: The integral-differential equation of the cascade process for ions was solved using the Laplace transform and the method of successive approximations, taking into account the energy loss during the formation of primary-knocked-on atoms (PKA) in a one-dimensional model of an elementary atom. It is shown that the solution includes a cascade-probability function (CPF) for these particles. The main properties of CPF are considered and its graphical dependencies on the depth of registration are presented. It is shown that with the specific ionization loss coefficient k = 0, the FQM turns into the simplest cascade-probability function. When λ₀→ 0, λ₀→∞ and n→∞, the KV-function is equal to 0. The sum of the probabilities for all possible collisions from 0 to ∞ is 1. As the detection depth h increases, for all values of n, the CRF increases, reaches a maximum and then decreases . With increasing n, the curves shift to the right.

Abstract: Renewable energy sources, such as solar energy, could potentially provide an affordable alternative to conventionally generated electricity, especially in locations like the Caribbean which tend to have an abundant solar resource, but also high cost for electricity. Thin film and hybrid solar devices, including Dye-Sensitized Solar Cells (DSSCs), are especially promising energy solutions, due to the low cost of materials and equipment required for their fabrication. In this paper, we investigate the effect of doping titanium dioxide based DSSC photoanodes with lanthanum, cerium, and praseodymium species on the overall performance of the cell, along with results from optimization of the best performing cell formulation according to sintering time and sintering temperature, giving a maximum 39% increase in device efficiency.

Abstract: Innovative materials and structures are analyzed in this paper. Multicomponent formulation of polyvinyl chloride materials containing various functional additives requires assessment of their influence on polymer stability while processing and operating. According to the nature, particulate fillers widely used in plasticized and liquid compositions based on polyvinyl chloride may have different impact on thermal resistance of materials. This paper presents the study of organic and nonorganic dispersed waist as filler in polyvinyl chloride formulation and determines key parameters of their influence on thermal resistance of composition. Polyvinyl chloride stabilization course by means of polyfunctional fillers-modifiers in different mechanisms, such as: chemical stabilization – chloride hydride acceptance, replacement of chlorine labile atom in polymer macromolecule, adjoining conjugated defective ethylenic bonds, recombination macroradicals and physical stabilization – chloride hydride sorbing, reduction of mechanical destruction by oiling, etc. have been considered. Contribution into stabilization course in various mechanisms depending on chemical nature, dispersion rate and mineral content of fillers is evaluated.

Abstract: This article describes the results ofthe research on determination of activity and sorption capacity of modified zeolites. Activation processes of sorbents were compared including thermal dehydration and ion-plasma treatment of zeolites. Mineralogical composition of investigated zeolites as well as the results of ion-plasma treatment on the structure of natural zeolites are presented. The obtained results have shown high effectiveness of ion-plasma treatmentof sorbents compared with thermal treatment method.

Abstract: Nowadays, modification of the bitumen by sulfur is considered as an effective way to enhance the properties of materials for road construction. By means of using the sulfur we eliminate the need to reconstruct existing production facilities for asphalt concrete. There is a plenty of research had already been performed for investigation of the sulfur-extended asphalt. Still, formation of new compounds in sulfur-bitumen systems depends on many factors, including mixture and thermal conditions. In the present work we have carried out both experimental and theoretical examination of the specific sulfur-bitumen binder made of grade 60/90 petroleum bitumen and technical sulfur at temperatures that are typical for ordinary asphalt concrete technology. The obtained results indicate that there is no noticeable formation of new chemical products in sulfur-bitumen melts at temperatures below 145 °C. Sulfur is partially dissolved in bitumen during the technological operations; the limiting concentration of dissolved sulfur is near 10%. Later in the course of cooling, the crystallization of the sulfur takes place, accompanied with formation of a separate solid phase.

Abstract: Innovative materials and structures are analyzed in this paper. On the basis of provisions of the systems analysis the principles and approaches to modeling of processes of contact and condensation curing of silicate materials are developed. The mechanism of contact and condensation process on macro - and mesolevels of system is presented. There are provisions of synergetic at its base: formation of an infinite cluster of a framework of a raw from the power links connected by a contact condensation crossing point as a result of redistribution of an unstable phase calcium-silicate knitting between sources and drains of structure-forming elements. Theoretical modeling of intergrain condensation at the base of which there are submodels of the squeezed deposit and a capillary porous body is executed. The nanosized filler has a polyfunctional influence on the structure and properties of calcium-silicate and cement materials, takes part in the formation of new chemical compounds and the structure of pore walls.