The Mechanical and Tribological Properties of Epoxy-Based Composites Filled with Manganese-Containing Waste

Epoxy Composites with Post-Production Gray Cast-Iron Powders

Processing of cast-iron castings by machining is associated with a large amount of post-production waste in the form of cast-iron chips, which constitute up to about 5% of the weight of the entire casting. In the case of serial production, this generates large amounts of post-production waste, constituting a constantly growing scale of environmental problems. The aim of this research was to develop a simple and cheap method of utilizing post-production waste of gray cast-iron chips from the machining process for the production of small structural elements of water supply fittings. The analysis of the state of knowledge indicates that the simplest method of managing waste chips is to use them as a starting material in the process of manufacturing polymer composites. The most frequently chosen material for the matrix of polymer composites reinforced with metal powders is epoxy resin. The epoxy composite was produced by the vacuum-assisted casting method. This paper presents the results of tests of morphological, mechanical, and corrosion properties of epoxy composites filled with grey cast-iron powder with a grain size below 0.075 mm and a mass content in the composite of 65%. The composite cured at 130 °C for 90 min had the best mechanical properties. The sample cured at 130 °C for 90 min was observed to have the optimum effect, with a tensile strength of 28.35 MPa, a flexural strength of 55.4 MPa, and a compressive strength of 53.8 MPa. All tested composites were characterized by very good thermal resistance and, in comparison to gray cast iron, over 2.5 times lower weight and an over three times lower corrosion rate in the tap water environment.

Influence of Gamma-Phase Aluminum Oxide Nanopowder and Polyester-Glass Recyclate Filler on the Destruction Process of Composite Materials Reinforced by Glass Fiber

Recycling of composite materials is an important global issue due to the wide use of these materials in many industries. Waste management options are being explored. Mechanical recycling is one of the methods that allows obtaining polyester-glass recyclate in powder form as a result of appropriate crushing and grinding of waste. Due to the fact that the properties of composites can be easily modified by adding various types of fillers and nanofillers, this is one of the ways to improve the properties of such complex composite materials. This article presents the strength parameters of composites with the addition of fillers in the form of polyester-glass recyclate and a nanofiller in the form of gamma-phase aluminum nanopowder. To analyze the obtained results, Kolmogorov-Sinai (K-S) metric entropy was used to determine the transition from the elastic to the viscoelastic state in materials without and with the addition of nanoaluminum, during a static tensile test. The tests included samples with the addition of fillers and nanofillers, as well as a base sample without any additives. The article presents the strength parameters obtained from a testing machine during a static tensile test. Additionally, the acoustic emission method was used during the research. Thanks to which, graphs of the effective value of the electrical signal (RMS) were prepared as a function of time, the parameters were previously identified as extremely useful for analyzing the destruction process of composite materials. The values obtained from the K-S metric entropy method and the acoustic emission method were plotted on sample stretching graphs. The influence of the nanofiller and filler on these parameters was also analyzed. The presented results showed that the aluminum nanoadditive did not increase the strength parameters of the composite with recyclate as a result of the addition of aluminum nanofiller; however, its addition influenced the operational parameters, which is reflected in a 5% increase in the UTS value (from 55% to 60%).

Acoustic Emission and K-S Metric Entropy as Methods to Analyze the Influence of Gamma-Aluminum Oxide Nanopowder on the Destruction Process of GFRP Composite Materials

Composites are materials that are widely used in industry, including yachting, railway and aviation. The properties of these materials can be modified by changing the type of reinforcement, the type of matrix, as well as the use of additives in the form of fillers and nanofillers that improve their mechanical or specific parameters. Due to the fact that these materials are often used for important structures, computational models using FEM tools may not be sufficient to determine the actual strength parameters, and what is more, to check them during operation. When designing structures made of composite materials, it is necessary to use high safety factors due to their behavior under several different types of loads, which is still difficult to determine precisely. This situation makes these structures much heavier and characterized by much higher strength properties than those that would actually be needed. In this article, the Kolmogorov-Sinai (K-S) metric entropy was used to determine the transition from the elastic to the viscoelastic state in GFRP (glass fiber reinforced polymer) composite materials without and with the addition of nanoaluminum, during a static tensile test. Additionally, the acoustic emission method was used during the research. This signal was further processed, and graphs were made of the number of events and the amplitude as a function of time. The obtained values were plotted on tensile graphs. The influence of the nano-filler on these parameters was also analyzed. The presented results show that it is possible to determine additional parameters affecting the strength of the structure for any composite materials.

Influence of Citrus Fruit Waste Filler on the Physical Properties of Silicone-Based Composites

Silicones have been used as protective coatings due to their resistance to hydrolytic degradation and UV (ultraviolet) degradation. There is a growing problem with managing organic waste, which can be used as fillers in composites. This research demonstrated the use of organic waste from citrus peels, including grapefruit, lime, lemon, and orange peels. Silicone-based composites were prepared by gravity-casting using 2.5, 5, and 10 wt.% waste filler. Samples made from the composite panels were subjected to static tensile, density, hardness, pin-on-disc, and Schopper-Schlobach abrasion tests. The test results showed that lower tensile strength values characterized the composite materials compared to the silicone used as a filler. All materials had greater hardness than the silicone without the addition. At the same time, composites with a mass density of the filler of 2.5 and 5 wt.% showed more excellent abrasion resistance than the silicone used as a matrix. This research showed that the samples containing 2.5 wt.% grapefruit filler had the best mechanical properties and the lowest abrasive wear.

Progress in comprehensive utilization of electrolytic manganese residue: a review

Electrolytic manganese residue (EMR) is a solid waste produced in the process of electrolytic manganese metal (EMM) production. In recent years, the accumulation of EMR has caused increasingly serious environmental problems. To better understand the state of EMR recycling in recent years, this paper used a comprehensive literature database to conduct a statistical analysis of EMR-related publications from 2010 to 2022 from two perspectives: harmless green treatment and resource utilization. The results showed that the research on the comprehensive utilization of EMR mainly focused on the fields of chemical hazard-free treatment and manufacturing building materials. The related studies of EMR in the fields of biological harmlessness, applied electric field harmlessness, manganese series materials, adsorbents, geopolymers, glass-ceramics, catalysts, and agriculture were also reported. Finally, we put forward some suggestions to solve the EMR problem, hoping that this work could provide a reference for the clean disposal and efficient utilization of EMR.

Multiobjective Optimization of Composite Wind Turbine Blade

When designing a wind turbine, the main objective is to generate maximum effective power with the lowest possible production costs. The power of a wind turbine depends primarily on the aerodynamic properties of its blades. Moreover, the cost of making a blade for a wind turbine, and therefore also for the entire wind turbine, depends on the materials used for its production. Therefore, wind turbine blades are the most studied element of a wind turbine. By selecting the optimal material and geometric properties of the wind turbine blade, it is possible to reduce the costs of making the entire wind turbine. These rationales led the authors to investigate composite wind turbine blades. A two-criteria optimization task was formulated, which allowed for the simultaneous consideration of two criteria: minimizing the mass and minimizing the vertical deflection of the wind turbine blade. Geometric properties of the blade, influencing the considered criteria, were assumed as decision variables. The weighted sum method was used. The results obtained allowed us to determine the optimal geometric and material properties of a wind turbine blade.

Influence of Graphite as a Filler on Selected Mechanical and Structural Properties of Layered Composites with Polyester-Glass Recyclate

The search for recycling methods of composite materials indicated the possibility of using composites with polyester-glass recyclate as structural elements. The main aim of the article was to analyse the influence of the graphite percentage content on the mechanical and structural properties of such composites. Composite materials were made by hand laminating with 10% polyester-glass recyclate and graphite nano-additive. Samples for the static tensile test were prepared, which was carried out in accordance with the applicable standard on a universal testing machine. The obtained results showed that with the increase in the amount of graphite, the properties of the composite decrease; however, disproportionately to the % of its content.

Analysis of Strength Parameters at Tension of Epoxy-Glass Composites with Rubber Recyclate Addition

The aim of the research was to analyze the strength parameters of epoxy-glass sandwich composites with the addition of rubber recyclate. Material samples were subjected to a static tensile test performed on a universal testing machine in accordance with the current standard for fiber-reinforced composite materials. The test results showed that the addition of rubber recyclate increases the plastic parameters of the composite, which allows considering the use of the tested material for structures loaded with the vibration and noise scale. The use of rubber recyclate to modify the strength parameters of the composite allows to reduce the amount of rubber waste and ensures the durability of the new material.