The Vale do Caí region - RS is an important hub for the production of red ceramics and charcoal. It is essential for environmental and social sustainability that solid waste arising from these activities is properly managed. Red ceramic fines have a pozzolanic action comparable to Portland cement. Replacing this with brick waste in mortar formulations comes up against the need for alkali activation, greater water consumption and controlled curing temperature to maintain compressive strength similar to Portland cement. Charcoal, in turn, has adsorbent properties. Therefore, the objective of this study was to incorporate these residues in order to replace 25% of Portland cement in formulations of six different mixing proportions of charcoal and brick fines to produce mortar at room curing temperature. The evolution of the compressive strength of the samples was evaluated at 7 curing ages, between 1 and 90 days. The formulation with 20% brick fines and 5% charcoal showed greater mechanical resistance to compression than the mortar without added residue, from 28 days of age. Thermogravimetric and X-ray fluorescence analyzes demonstrated that charcoal does not behave as a pozzolanic material, but due to its adsorbent capacity, it allowed the supply of water during the pozzolanic reaction of brick fines with Portland cement.

Over the years, the production of plastic has grown rapidly, and this material has become the most widely used by humans today. As a result, the pollution of this material in the soil, water and air has become a major problem, as it takes years to degrade. Its degradation can lead to microplastics that can cause the death of birds and fish, as well as increasing the chance of a heart attack in humans. Due to their size, removing microplastics from water is a major challenge. Therefore, in order to retain microplastics present in water, and thinking of a simple and low-cost device, the aim of the work was to develop a ceramic filter based on clay and glass waste, evaluating the effects of adding a porogenic agent (ilex paraguariensis waste - after infusion). We used 0, 10 and 20% yerba mate residue, keeping 10% glass residue in all the formulations. The raw materials were milled, sieved, humidified (8% water - by mass), pressed at 20 MPa, dried and sintered at low firing temperatures of 900 and 950 °C with a heating rate of 1.6 °C/min and a plateau of 5 min. Rectangular ceramic filters were obtained to evaluate the characteristics of the firing process, such as loss on firing and linear shrinkage, and the physical properties of the filters, such as water absorption, apparent porosity, apparent density and flexural strength. Circular samples were made to evaluate the filters in terms of mass flow by applying different pressures, leaching of elements with sodium and potassium and retention of microplastics, and an apparatus was developed for these tests. The surface structure of the filters was also checked using optical microscopy (50x magnification). The microplastic suspension was prepared with 0.2 g of polystyrene (PS) in 400 mL of distilled water, and its retention by the ceramic filter was checked using turbidity analysis. The results obtained showed that the apparent porosity and water absorption of the formulation containing 20% yerba mate and sintered at 900 °C were higher than the other formulations, but showed low mechanical strength and generated fractures in its structure when pressure above 100 kPa was applied. The porosity of the material also influenced a higher mass flow rate and resulted in a lower retention of microplastics (97.30%). The formulation with the lowest porosity, i.e. without the addition of the porogenic agent, achieved 99.77% retention. The leaching of sodium and potassium elements from the ceramic filter developed was insignificant. It can therefore be concluded that a simple ceramic filter can retain microplastics well, as long as the filtration pressure and the amount of porosity are optimized to achieve the best results.

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Among the various types of discarded materials, electronic waste (ewaste) has been exponentially increasing in recent years due to its perceived obsolescence within a short time frame. In this context, the objective of this study is to evaluate the feasibility of producing a filament for use in 3D printing using polymer residues derived from CRT monitor and television casings. Spectroscopic characterization of the e-waste revealed differences in Polymer identification in the casings compared to the results obtained from the analysis. Thermal and rheological properties were found to be similar to virgin Acrylonitrile Butadiene Styrene (ABS). The ABS residues were extruded under the same conditions as the virgin material, yielding satisfactory results. However, the postextrusion cooling method introduced high porosity into the filament. The fused deposition modeling (FDM) printing process of the test specimens proved to be efficient using the recycled filament, although porosity was observed in the printed parts. Overall, the printed parts using the recycled filament exhibited inferior mechanical properties compared to those printed with virgin ABS. The identified voids in the print had the most significant influence on the mechanical response of the samples produced with the recycled filament, resulting in na approximately 83% reduction in impact strength. The filament produced from ewaste is suitable for 3D printing applications that require good dimensional tolerance without the need for high mechanical properties.

The present study presents a surface coating with polytetrafluoroethylene (PTFE) and molybdenum disulfide (MoS2) on the cutting edges and on surfaces of the channel of Auger Bits twist drills used for drilling in wood, mainly Pinus elliottii, widely used in civil construction. The chemical characterization of the functional groups of the coating layer was carried out by Fourier transform infrared spectroscopy (FTIR), the tool life evaluation through bench tests, and the latter torque variation during the drilling process. The films and substrates' hardness were verified by Vickers durometer, and the metallography was performed to identify the drill microstructure and the film thicknesses. All analyzes were performed comparatively between the variations of samples with PTFE, MoS2, and uncoated standard samples. The tests were carried out in the laboratory with controlled parameters after the characterization of the samples concerning dimensional, heat treatment, and coating applied. In the analyses compared to the uncoated samples, the drills with PTFE obtained reductions of up to 38% in roughness, reduced drilling torque in the tip and channel region, required less power and energy from the screwdriver obtained low levels of layer peeling. On the other hand, the MoS2 samples showed a roughness reduction of up to 30% in some regions. Still, an increase of 66% in the channel region, presented an increase in drilling torque of more than 22%, an increase in consumed power of 16% in the channel region, and an 18% increase in energy consumption, in addition, to completely peeling off the coating layer in the cutting edges. The torque in samples with PTFE was lower than MoS2 in all cut regions of the drill. The core drills microstructures were martensitic, and due to the coating process, the core hardness on the HRC scale decreased. In general, PTFE-coated samples showed the best results when compared to MoS2 but, actually, had been observed a changing in the drills performances, which still needs to be further evaluated to improve tool life

In recent times, the issue of plastic recycling has become one of the leading issues of environmental protection and waste management. Polymer materials are found applied in many areas of daily life and industry. Along with their extended use, the problem of plastic waste appeared because, after withdrawal from use, they became persistent and noxious wastes. The possibility of reusing polymeric materials enables waste utilization to obtain consumable products. The 3D printing market is a well-growing sector. Printable filaments can be made from various thermoplastic materials, including those from recycling. This paper studies the thermal-mechanical properties of recycled polylactic acid (PLA) material filaments obtained from 3D-printed specimens. The analysis was first with the virgin filament (PLA N) and, subsequently, two recycling cycles (PLA 1 and PLA 2). There were thermal properties evaluations for the three processing types, as follows: differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and tensile test for both specimens and filaments. The glass transition temperatures (Tg) remained at their typical values. The same happened with the melting temperature (Tm). In the TGA, the PLA thermal stability remained constant. The FTIR presented the functional groups unaltered for the recycled samples. In the second filament recycling, the tensile strength decreased by 26%, and the maximum strain was 40%, compared to PLA N. The same occurred to PLA 2 specimens; the maximum stress and strain decreased by 45% and 31%, respectively. In terms of crystallinity, this presented a variation of 86% of the virgin material for the second recycling cycle, which correlated to tensile strength shows a weakness in the PLA recycled structure, decreasing the strain until the fracture and the tensile strength.

Mechanical components for critical applications demand solid properties, which are
directly related to the material chemical composition and microstructure. Equipment
used in oil and gas wells require special attention, because errors on their building
might lead to failures or even catastrophes. In these cases, high corrosion resistance
alloys such as stainless steels, are widely used. Furthermore, heat treatments are
essential to achieve application purposes. When a material does not meet the specified
properties, in many cases the heat retreatment is performed in order to adjust the
features that have not been met. Although this process is commonly used, there are
only a few sources of literature about the effects of metals heat retreatment. Thus, this
investigation analyses the supermartensitic stainless steel quenched and tempered,
which is one of the most used metallic alloys for building oil and gas well completion
equipment. Therefore, samples of this material were heat treated and retreated from
one to six times in order to map the morphological characteristics of microstructure and
mechanical properties resulting from this process. Once done, metallographic
analyses, tensile tests and Charpy impact tests were performed on each retreated
sample. The analyses over microstructure showed a grain refinement after each heat
retreatment and a non-linear variation of retained austenite portion and of mechanical
properties. The conclusion is that each heat retreatment promotes two main changes
in the resulting microstructure, the grain refinement and the variation in the content of
retained austenite. As the latter is not linear, the results of mechanical properties are
different for each heat retreatment. The variations observed in the grain size and in the
contents of retained austenite can result in different behaviors of other important
properties of the material, such as its resistance to some corrosion methods, its
susceptibility to hydrogen embrittlement and its fluency resistance.

International standards and original equipment manufacturers (OEM) procedures usually define wear tests in organic friction materials focusing on the brake lining temperature. The current work presents an approach combining different brake pads temperatures, vehicle speeds, and brake pressures for analyzing their effects and interactions in the friction material wear through dynamometer tests. Therefore, mechanical properties were evaluated, where internal shear strength had the most significant influence on wear; furthermore, compressive strength and flexural strength did not considerably change with variations on the test parameters. A 2³ factorial design of the experiment (DOE) showed that the brake temperature alone was not the main factor for increasing wear, and the primary wear mechanism was abrasion. Furthermore, higher vehicle speed (80 km/h) along with greater brake pressure (3 bar) promoted the highest friction material mass loss (10.8 g).

This research project aims to develop new equipment for quantification of retained
austenite in heat-treated martensitic steels, in a fast and non-destructive way: a
balance that relates the magnetic response of a specimen, with the quantity of phase
present. The higher the percentage of retained austenite there is in the steel, the less
will be its magnetic response. The device was developed using low-cost material, and
simplified construction allocated over an electromagnetic plate. To authenticate the
equipment was manufactured and head treated square section specimens with 20 x
20 mm using SAE 5160 steel, with different thicknesses and heat treatment
temperatures, i.e., raw, quenched, quenched and tempered, and quenched and double
tempered, with the purpose to get different retained austenite fractions. Also, were
selected parts manufactured by a factory, to test the equipment with parts with different
sections. The specimens and parts were quantified on the conventional method to
obtain retained austenite fraction (x-ray diffraction, quantitative metallography, and
feritoscope) and then in the device developed in this project. To analyze the results
was utilized the analysis of variance method (ANOVA), using the design of the
experiment in randomized blocks. The electromagnetic balance is quantified in a fast
and effective way with the square section specimens, regardless of their thickness,
according to ANOVA analysis, the percentage of retained austenite acquired does not
differs statistically from the results obtained with the conventional methods. In the end,
the aim of this study, to develop equipment that applies a non-destructive quantification,
was not reached, because the equipment only worked in specimens with square
sections. So, for the next research, there is a need to improve the device so that it
works in other geometry situations.

Polyoxymethylene has good tensile strength, low friction coefficient, excellent dimensional stability. Polyoxymethylene has good tensile strength, low coefficient of friction and excellent dimensional stability. Thermoplastic elastomers have a rubbery, tacky surface and can be overmolding into a rigid substrate to increase friction and slip resistance. To obtain adhesion between the two materials, it is necessary that they are compatible and that the formation of polymeric blends is possible. The objective of this work is to evaluate the influence of the mechanical and thermal properties of polymeric blends with a polyoxymethylene matrix, after the addition of different percentages by weight of thermoplastic elastomer and the incorporation of a compatibilizing additive for subsequent overmolding of thermoplastic rubber and evaluation of adhesion between the materials. After the formation of the blends, it can be evidenced by the analysis of infrared spectroscopy by Fourier transform that there were interactions and miscibility between the materials, mainly in the samples that contained compatibilizing agent. The blends showed changes in morphology after scanning electron microscopy analysis of fractured samples in the impact strength test. The degree of crystallinity of the blends reduced with the incorporation of thermoplastic elastomer or the presence of the compatibilizing agent. The mechanical properties showed a reduction in tensile strength and elastic modulus with increasing percentage by weight of thermoplastic elastomer added to the mixture. The blends selected to receive the thermoplastic elastomer overmolding showed better adhesion in the mixtures that contained the compatibilizing agent, due to their chemical interactions and better interphase with the overmolding thermoplastic elastomer

In this work, extractor pins of thermoplastic polymer injection molds, originally produced in AISI H13 steel and gas nitrided, were coated with a thin film of DLC (Diamond Like Carbon), making a tribological pair with extractor bushings of AISI P20 and AISI H13 steels quenched and tempered. The DLC thin film was deposited in a PECVD (plasma enhanced chemical vapour deposition) chamber with electrostatic confinement. A device that simulates the extraction system of an injection mold was used to test the wear behavior of the proposed pin-bushing pairs, as a function of the increase in the number of cycles. Different materials and lubrication conditions were tested, looking for more efficient alternatives to the current system that uses gas nitrided pins and white grease for molds as a lubricant. Optical microscopy and Scanning Electron Microscopy (SEM) were used for the microstructural characterization of the samples and analysis of the DLC layer. Wear on the pins was quantitatively evaluated by mass loss and by measuring the layer thickness in SEM after 100,000 cycles. Analysis of the roughness variation of the topography of the samples by SEM was carried out to verify the impacts of the wear test on the surface of the samples. The hardness and adhesion of the DLC film were measured through nanohardness and nanoscratch tests, respectively. In addition, the samples were analyzed by nanohardness, GDOES (glow-discharge optical emission spectroscopy), and the friction coefficient, by scratching test. The mass loss results show that for the samples without the use of lubricating grease, the wear rate was considerably lower. The pins with the least wear were those of the PS and HS sets, both without the use of grease, which showed a mass loss of 5,400 and 5,467 mg, respectively. These results prove the possibility of using DLC coated pins without the use of lubricating grease in injection mold extractor systems and that this still provides a considerable reduction in the wear rate. The DLC film presented a uniform layer, with an average thickness of 3.34 μm and no gaps between the film and the substrate after its deposition. The main wear mechanism for DLC lubricated systems was abrasion, due to the abrasive paste created with DLC particles and the grease. Therefore, the condition of pins with DLC without the grease had a better performance in the bench tests.

Metal structures made of carbon steel are widely used in civil construction and are susceptible to corrosion. In this sense, improving the strength of the material is essential to prevent deterioration of the metallic structure. One of the ways to prevent the corrosive process of steel from occurring is through corrosion inhibitors. The study of corrosion inhibitors from renewable and biodegradable natural resources becomes relevant for being an environmentally friendly, efficient and low-cost method for anticorrosive protection. Thus, this work proposes to evaluate the inhibitory effect of the natural extract of bergamot bark (Citrus reticulata) against the corrosive process of carbon steel ASTM A36. For this purpose, mass loss tests were performed on specimens by immersion in a corrosive medium of HCl, combined with electrochemical techniques. In addition, adsorption isotherms were built in order to determine physicochemical parameters related to the adsorptive process. The results obtained demonstrate a high efficiency of inhibition against corrosion compared to the process induced in the absence of the inhibitor, and the inhibition increases with the relative concentration of the extract. Furthermore, the greatest inhibition efficiency was observed after 72 hours of contact, decreasing with longer exposure times. Thus, the results obtained suggest that the bergamot extract has the potential to be used in the protection against corrosion of carbon steel ASTM A36 in an acidic medium.

Poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA) is fluoropolymer that has an extensive application area, ranging from medical and aerospace industry, to household utensils. As a result, large volumes of waste (or residues) are generated during its processing, and its reincorporation is necessary not only because of the environmental appeal, but also because of its economic value. The objective of this study is to evaluate the viability of reincorporation of PFA’s residues, generated by the extrusion process, in to neat PFA (PFAv). The results showed that the reincorporation of up to 10% of reprocessed PFA (10PFAr) proved to be adequate to produce extruded tubes. In this sample, the thermal and chemical properties appeared to be stable, in addition it has not been found significant differences in the mechanical properties evaluated in comparison with the neat PFA sample. Besides that, higher concentration of PFAr (˃50%) promoted a reduction in tensile strength and elongation at break, in addition an increase in elastic modulus and hardness. The samples showed a yellowing effect, which was more evident with the increase of the PFAr content.

Glass is a widely used material, however, it is far from being recycled in its entirety. A good alternative to glass recycling is its incorporation in ceramic masses, since in these glass acts as a flux. Several studies investigate the addition of residual glass in ceramic mass for the production of bricks, tiles, blocks and even porcelain tiles, but there are no studies that deal with the addition of residual glass in an interlocked clay floor. Therefore, the present study proposes the incorporation of residual glass in interlocked clay pavement characterized by its rustic appearance and natural coloration. To this end, the present research investigates the physical and mechanical behavior of specimens as a function of glass residue composition and firing temperature. Three ceramic paste formulations were used. One is composed entirely of kaolin clay (100C), the second has 60% kaolin mass and 40% glass waste (60C40WG), and the third is 40% kaolin and 60% glass waste (40C60WG). The samples were burned at 900, 950 and 1000 ºC. The properties of shrinkage, water absorption, flexural strength (RMF) and compression (RMC), density and chemical attack were evaluated. The morphology and composition were analyzed by scanning electron microscopy (SEM) and dispersive energy spectroscopy (EDS). In addition, the visual aspect of kaolin and red clay pavements with colorless, green and amber glass additions was investigated. StatPlus software was used for variance analysis and tukey test. Based on the results, it can be concluded that ceramic masses with incorporation of 40 and 60% of glass dust burned at 950ºC are technically suitable for the manufacture of interlocked clay floor for industrial floor application, light traffic and pedestrians In addition, parts formulated with 60% glass waste and burned at 950 ° C still fit for use in heavy vehicular traffic.