Tensile Strength Values Research Articles

Composite cellulose/bismuth/PVA nanocrystal for high-performance X-ray radiation shielding

The strong penetrating power of X-rays causes serious health problems. Longer exposure to radiation that penetrates normal cells can result in gene mutations, cancer, and even death. Protection against radiation exposure is necessary to prevent negative impacts from occurring. This research aims to make apron samples using a simple method based on cellulose as a matrix, bismuth as a filler with concentrations of 1 g, 0.75 g, 0.25 g and PVA acts as a binder that helps bind cellulose and bismuth particles into an effective X-ray radiation shield. The characterization carried out includes Fourier transform infrared (FTIR) to determine the functional groups and chemical composition of the sample, x-ray diffraction (XRD) to analyze the crystal size of the sample, and mobile x-ray with energies of 60, 70, and 80 keV to determine the radiation shielding performance. The findings of this study highlight that the optimal shielding properties were attained by employing a sample with the highest concentration of bismuth filler, specifically at 1 g. This material exhibits outstanding characteristics, including a high linear attenuation coefficient and mass attenuation coefficient of 0.68 cm−1 and 2.24 cm2/g respectively for an energy of 60 keV and especially low HVL (1.01 cm) and TVL (3.36 cm) values. These findings have significant implications for developing high-performance X-ray radiation shielding materials, particularly in industries where radiation exposure is a concern, such as the medical industry, research, and laboratories. The high tensile strength (2.83 N/mm2) and elongation (12.09 %) values as well as the low Young's modulus (0.108 N/mm2) values also indicate the flexibility of the resulting material, which could be beneficial for applications that require flexible shielding materials. The practicality of this research makes the audience feel that the findings are applicable and useful in real-world scenarios.

Effects of lignocellulose structure on single fiber tensile characteristics portrayal: a case of enset fiber

Fiber-leveltensile characteristics are vital for micromechanical analysis and mechanical modellingof materials and their composites. This portrayal depends on diameter estimation accuracy, as the applied load is determined from the testing machine. Inline, natural fibers possess an internal cavity; the diameter found using microscopy denotes the external diameter which is larger than the diameter pertaining to actual load-carrying cross-section. This study presents a new approach that estimates diameter considering lignocellulose structure and hydrophilicity, thereby enabling the portrayal of more accurate tensile strength values. First, the fibers’ diameter is measured using a laser microscope, on various spots axially and the internal cavity was then considered to determine the actual diameter. Thedensity of milled fibers is measured using Pycnometry. The diameter which relates to a solid load-carryingcross-section is identified using the relationship between density, mass and volume. The experiment design was framed and analyzed using Python and JMP Pro 13. The measured density of Enset is 1.38 g/cm3. The average overestimation of microscopy result issignificant; it is 27.7μm which is about 21.8%. This underrates the actual tensile strength of Enset fiber by about 37.5%. That is σext=0.627σact. This, in turn, would affect micromechanical analyses and mechanical modelling. Thus, the need to consider lignocellulose structure for testing the tensile strength of Enset fiber is inevitable and the method utilized in this study can be used forother natural fibers of the same nature customizing the context.

Use of Fruit Waste as Natural Dyes in pH-Sensitive Colorimetric Sensors for Tilapia Fillets Quality Decline

Graphical Abstract Highlight Research 1. The use of dragon fruit peel, mangosteen peel and onion peel waste as natural dyes in colorimetric sensors was analyzed in this study. 2. Natural dyes are added to bioplastics with kappa carrageenan polymer, a mixture of corn starch and kappa carrageenan, and corn starch to determine the characteristics of the best bioplastic to be used as a colorimetry sensor. 3. The quality of the fish fillet compared to the color changes in colorimetry sensor was analysed in this study. 4. Mixture of kappa carrageenan and corn starch as bioplastic with casting method was analyzed in this study. Abstract Tilapia fillet aimed to prolonging shelf life, may still experience quality deterioration posing food safety risks. Colorimetric pH indicators offer a simple and affordable solution to the food industry to evaluating fish spoilage. Natural dyes reduce potential health risks associated with synthetic dyes. Anthocyanin sources haven’t been explored like dragon fruit rind, mangosteen rind, and red onion skin serve as real time quality and safety assessment tools for consumers. This study explores the potential of anthocyanin extracted from dragon fruit rind, mangosteen rind, and red onion skin as colorimetric sensors for evaluating the quality and safety of tilapia fillets. The anthocyanin-based sensors developed using kappa carrageenan and corn starch polymers to achieve sustainability fisheries program and were characterized according to the Japanese Industrial Standard for bioplastics. The results show that anthocyanin from dragon fruit skin exhibited the best color change in response to pH changes in the tilapia fillet, indicating its potential as a reliable indicator of spoilage. This research highlights the feasibility of using natural dyes as colorimetric sensors, reducing the risk of health hazards associated with synthetic dyes. This study also shows that different polymers give different characteristic of bioplastic. Carrageenan bioplastic shows best thickness values of 0,118 mm; Carrageenan and corn starch bioplastics shows best tensile strength values of 20,62 MPa; Carrageenan bioplastic shows best elongation values of 254%; and All polymers shows the same biodegradation rate values of 14,29%. Further studies are needed to explore other natural dyes and optimize the polymers for optimal bioplastic characteristics.

Comparison of Bond Strength of Soft Denture Liner on the Denture Base Materials Produced by Different Methods and Effect of Thermocycling

Aim: This study set out to determine the tensile bond strength between denture bases (produced by 3D printing technology, conventional technique, and computer-aided design and computer-aided manufacturing [CAD/CAM] milled) and silicone-based soft lining material. The consequence of thermocycling on the bonding strength was also investigated. Materials and Methods: The bonding between denture foundation materials produced through three distinct techniques (conventional, CAD/CAM milled, and 3D printed) and silicone-based soft lining material was examined. Before tensile testing, half of the samples underwent thermocycling (5–55°C, 5,000 cycles) in 37°C distilled water for 48 hours. A universal testing apparatus employed a crosshead speed of 5 mm/min. The failure type was identified visually, and the maximum tensile strength was noted. The Shapiro-Wilk test and analysis of variances ( P = .05) were used to assess the statistics. Results: CAD/CAM milled denture base material (1.56 ± 0.62/1.36 ± 0.16 MPa) showed higher bond strength values than the other denture bases in the tensile test conducted before and after thermocycling ( P < .001). The denture base material made conventionally had the lowest bond strength (1.02 ± 0.24/0.77 ± 0.1 MPa) ( P < .001). The tensile bond strength values of the conventional and 3D printing groups showed a statistically significant drop before and after thermocycling ( P = .001). Regardless of thermocycling, adhesive failure was primarily seen in all groups (76.6%). Conclusion: Compared to conventionally produced denture bases, the bond strength of soft relining materials to CAD/CAM milled and 3D printed denture base is different. In denture base materials that are conventionally, CAD/CAM and 3D printed, the thermocycling method reduced bonding strength values.

Edible Coating from Breadfruit Starch and Chitosan for Food Packaging

Lectures that encompass Education for Sustainable Development (ESD) can encourage awareness about sustainable development by integrating current issues, such as the potential of breadfruit starch and chitosan for making edible coatings for food packaging. This work aimed to study the development of edible coating from breadfruit starch (BS) and chitosan (CH) for food packaging based on SDGs aspects and as preliminary research to develop worksheets for prospective chemistry teacher students. BS-CH edible film developed by solvent evaporation method, thickness measurement, and physical properties for application on chili, carrot, and sweet potato which. The results showed that the optimal comprehensive properties of the film were obtained when the mass ratio of 3% AS to 1% CH was 7:3. The solubility test results show that the addition of CH ratio increases the swelling of the film before the dissolution process. The tensile strength and elongation of the film increased with the addition of CH until the optimum condition with tensile strength values of 3.01 MPa and 58.26%. The optimum mass ratio was applied through the coating of carrot, chili, and sweet potato which can prevent mass weight and mushroom. Apart from that, student opinion data was generated in the form of potential edible coating topics in the theme of ESD issues. In addition, student opinion data was generated in the form of expectations of edible coatings topics in ESD-laden chemistry learning, including understanding and applying ESD principles and the context of edible coatings and introducing the potential of edible coatings in society so that it is expected to improve 21st-century skills. The results of this research show the need to integrate the topic of edible coating of breadfruit starch and chitosan in worksheets for prospective chemistry teacher students.

Effect of the brass waste recycling process on mechanical properties with investment casting for gear materials

This study is an experimental research to analyze the characteristics and mechanical properties of the casting process of recycled brass alloy, which will be used as a material for gears. Currently, the remaining production and waste from brass alloys continue to increase. Another thing is the increase in the need for brass gears, so environmentally friendly material engineering is needed to provide good quality and efficient energy use, especially during the casting process. The casting process uses an electric furnace that melts brass alloys at 526 up to 900 °C within 1 hour and molds to make test specimens. The results of microstructural testing for grain size in recycled brass alloys range from 74.63 μm to 84.57 μm. The maximum tensile strength produced is up to 225.2 MPa, the maximum yield strength is up to 179.8 MPa, and the maximum elongation is up to 7.3 %. The roughness of recycled brass alloys has a maximum Ra value (average roughness) of up to 0.836 μm. Validation was carried out by comparing the mechanical properties of CAC 302 brass products and the study results. The data shows that recycled brass's maximum yield strength value is 179.8 MPa and CAC 302 brass material is 175 MPa, but for the ultimate tensile strength value, the value of recycled brass is far below CAC 302 products. These results can be a consideration for the industry to be able to use recycled brass alloys for gear products because the yield strength value is not far from CAC 302 brass products. The impact result of this study produces recycled brass alloys that are environmentally friendly, efficient in smelting energy consumption, and have good yield strength. The results of this research can benefit the manufacture of gear components made of brass alloys.

Comparative Study of the Dehydrothermal Crosslinking of Electrospun Collagen Nanofibers: The Effects of Vacuum Conditions and Subsequent Chemical Crosslinking.

Collagen nanofibrous materials have become integral to tissue engineering due to their exceptional properties and biocompatibility. Dehydrothermal crosslinking (DHT) enhances stability and maintains structural integrity without the formation of toxic residues. The study involved the crosslinking of electrospun collagen, applying DHT with access to air and under vacuum conditions. Various DHT exposure times of up to 72 h were applied to examine the time dependance of the DHT process. The DHT crosslinked collagen was subsequently chemically crosslinked using carbodiimides. The material crosslinked in this way evinced elevated Young's modulus values and ultimate tensile strength values, a lower swelling rate and lower shrinkage ratio during crosslinking, and a higher degree of resistance to degradation than the material crosslinked solely with DHT or carbodiimides. It was shown that the crosslinking mechanism using DHT occupies different binding sites than those using chemical crosslinking. Access to air for 12 h or less did not exert a significant impact on the material properties compared to DHT under vacuum conditions. However, concerning longer exposure times, it was determined that access to air results in the deterioration of the properties of the material and that reactions take place that occupy the free bonding sites, which subsequently reduces the effectiveness of chemical crosslinking using carbodiimides.

Evaluating the Effectiveness of the "Double Finish Line Technique" on Full-Crown Retention for Short Abutments: An In Vitro Study.

Achieving clinically adequate retention for cast crowns in prepared short abutments represents a major challenge for practicing dentists. Despite the important developments with adhesive cement, only a few teeth can be treated this way, and conventional preparation techniques are still employed for most crowns. Numerous options for auxiliary features exist; however, there is no consensus about one preferred method. This study aimed to evaluate the effect of a new innovative technique called the "double finish line technique" on full-crown retention for short abutments and to compare it with another modified preparation method. A comparative in vitro experimental study was conducted at the Department of Fixed Prosthodontics, Damascus University. The study sample consisted of 30 chromium-cobalt abutments and 30 metal crowns. The sample was divided into three equal groups. The first group was a control group (CG) with a 20-degree total occlusal convergence, 3 mm height, and a 0.5 mm chamfer finish line. The second group had a reduced total occlusal convergence (TOC) in the cervical 1.5 mm of the axial wall from 20 to 8 degrees. The third group implemented the so-called "double finish line technique," adding another 0.5 mm chamfer finish line 1 mm above the first finish line (DFL group). The metal crowns were cemented to metal dies with zinc-phosphate cement. Pull-off tests were applied until failure. Data were analyzed, and the differences between the three groups were detected using one-way ANOVA followed by Bonferroni's post-hoc tests (p<0.05). The mean tensile strength values for the specimens were 115.36 (SD=14.59), 149.60 (SD=11.10), and 42.46 (SD=11.54) for the TOC, DFL, and CR groups, respectively. The reduced total occlusal convergence and double finish line techniques effectively increased full crown retention and resistance cemented on short abutments.

Simple and low‐cost preparation of functionalised graphene by microwave expansion combined with ball milling grafting

AbstractThe preparation of functionalised graphene often involves consuming significant amounts of organic solvents, complicated steps, and expensive equipment. This study presented a simple, low‐cost, and efficient method for preparing well‐dispersed functionalised graphene. This method involved the microwave heating of commercial graphene precursors and ball milling of grafted expanded graphite, resulting in a short and straightforward preparation process without requiring large amounts of organic solvents. This process enabled the preparation of few‐layer graphene with a thickness of only 3.5 ± 0.5 nm. During this process, the majority of the surface oxygen‐containing groups were replaced by polyetheramine (D2000) at a grafting rate of up to 5.14%, which improved the interface adhesion strength between the graphene and the epoxy resin. The fabricated altered graphene notably enhanced the mechanical characteristics of the epoxy resin., that is, the toughening effect reached up to 171% with a graphene content of only 0.3 wt%, while the Young's modulus and tensile strength values increased by 54% and 39%, respectively. This process is cost‐effective, easy to operate, and highly efficient, making it suitable for the large‐scale production of well‐dispersed functionalised graphene.Highlights Pioneers mechanical chemical energy in graphene, a new materials science direction. First ball milling on microwave graphene, merging milling benefits with graphene. Ball milling cuts D2000 grafting time on graphene, boosting efficiency. Reduces organic solvent use, cutting costs and environmental effects. Ball milling lowers costs and impacts, aiding graphene material commercia‐lization.

Friction weldability of ultrafine-grained titanium grade 2

The paper presents the results of an experimental study of the friction weldability of Titanium Grade 2 with ultrafine-grained (UFG) microstructure obtained by hydrostatic extrusion and rotary swaging (HE+RS). High-speed friction welding with different rotational speed (n) values was used as a joining method. The best properties were obtained for n=7000 rpm. Metallographic observations confirmed the formation of a continuous friction joint with a changed microstructure of the base material in the thermal-mechanical affected zone (TMAZ) and a friction weld (FW). The results of the mechanical properties showed the greatest decrease in hardness in the TMAZ. The friction welded joint had an 18 % lower tensile strength value than initial state UFG Titanium Grade 2 after the HE+RS process (with UTS=1050 MPa).

Nanocomposites based on MWCNT and nanoclay: Effect of acrylated epoxidized soybean oil on curing and composite properties

UV and thermal-curing hybrid epoxy adhesives are generally developed with a combination of epoxy acrylates and thermal-curing epoxy resin. This study modified bisphenol-A type epoxy resin (ER) with acrylated epoxidized industrial crop soybean oil (AESO) to obtain a dual-curable epoxy system. Hydroxylated multi-walled carbon nanotube (MWCNTOH) and montmorillonite-type nanoclay (NC) first was used as nano reinforcement in this system. Both thermal and UV-curing were applied to composites. Tensile and hardness tests, thermogravimetric analysis (TGA), and four-point probe electrical conductivity measurements were used for the nanocomposite characterization. Although (UV+thermal) curing increased the thermal strength of the nanocomposites, it caused a decrease in their electrical conductivity and moisture absorption. The highest tensile strength values were obtained as 107 MPa and 97 MPa for thermally cured 1.5 wt% MWCNTOH and 2 wt% NC composites, respectively. The effect of the AESO ratio on UV curing of nanocomposites was investigated and 10 % was found to be the most suitable. MWCNTOH composites also exhibited the highest electrical conductivity with a percolation threshold of 1.5 wt%. The effect of hydrothermal aging on thermal and electrical conductivity properties showed that only T5 and T10 values of thermally or (UV+thermally) cured MWCNTOH and NC composites decreased, T50 values did not change significantly.

Influence of casein on the degradation process of polylactide-casein coatings for resorbable alloys

This study used the dip-coating method to develop a new biocompatible coating composed of polylactide (PLA) and casein for ZnMg1.2 wt% alloy implants. It evaluated its impact on the alloy's degradation in a simulated body fluid. After 168 h of immersion in Ringer's solution, surface morphology analysis showed that the PLA-casein coatings demonstrated uniform degradation, with the corrosion current density measured at 48 µA/cm2. Contact angle measurements indicated that the average contact angles for the PLA-casein-coated samples were below 80°, signifying a hydrophilic nature that promotes cell adhesion. Fourier-transform infrared spectroscopy (FTIR) revealed no presence of lactic acid on PLA-casein coatings after immersion, in contrast to pure PLA coatings. Pull-off adhesion tests showed tensile strength values of 7.6 MPa for pure PLA coatings and 5 MPa for PLA-casein coatings. Electrochemical tests further supported the favorable corrosion resistance of the PLA-casein coatings, highlighting their potential to reduce tissue inflammation and improve the biocompatibility of ZnMg1.2 wt% alloy implants.

KAJI NUMERIK GROUND PAD SHOE KENDARAAN TEMPUR DENGAN MODEL MATERIAL HYPERELASTIC

One of the important components on a combat vehicle is the ground pad shoe (GPS) or track pad. GPS that has been developed at this time mostly uses rubber material. Rubber raw materials themselves are found in Indonesia in large amount. Indonesia left 3 million tonnes of natural rubber unprocessed in 2018. On the other hand, natural rubber research is quite expensive and takes a long time to become a product. To make rubber products is needed special molds and tests. To solve the high costs and long time involved in rubber research, it is necessary to carry out numerical research. In this study, a numerical study of GPS rubber for combat vehicles was carried out with a hyperelastic material model. The research was conducted experimentally and numerically. Tensile testing is carried out on imported GPS samples which are then used as comparison data for numerical studies. The Mooney-Rivlin, Neo-Hookean, Yeoh, and Ogden hyperelastic models were varied to get the stress and strain values ​​closest to the experimental test. The results of the numerical study show that the best hyperelastic model for the imported GPS rubber model is the Neo-Hookean model. The tensile strength of GPS according to the experimental tensile test results is 16.93 MPa, while the result of the finite element method (FEM) is 16.75 MPa. The GPS modulus 200% according to the experimental tensile test results is 14.7 mm/mm, while the FEM result is 15.3 mm/mm. The difference between the FEM and experimental test values ​​for tensile strength and modulus 200% are below 5%. Maximum stress on GPS is 4,4 MPa and safety factor 3,8.

Effect of graphene oxide on mechanical, deformation and drying shrinkage properties of concrete reinforced with fly ash as cementitious material by using RSM modelling

The industrial production of cement contributes significantly to greenhouse gas emissions, making it crucial to address and reduce these emissions by using fly ash (FA) as a potential replacement. Besides, Graphene oxide (GO) was utilized as nanoparticle in concrete to augment its mechanical characteristics, deformation resistance, and drying shrinkage behaviours. However, the researchers used Response Surface Methodology (RSM) to evaluate the compressive strength (CS), tensile strength (TS), flexural strength (FS), modulus of elasticity (ME), and drying shrinkage (DS) of concrete that was mixed with 5–15% FA at a 5% increment, along with 0.05%, 0.065%, and 0.08% of GO as potential nanomaterials. The concrete samples were prepared by using mix proportions of design targeted CS of about 45 MPa at 28 days. From investigational outcomes, the concrete with 10% FA and 0.05% GO exhibited the greatest CS, TS, FS, and ME values of 62 MPa, 4.96 MPa, 6.82 MPa, and 39.37 GPa, on 28 days correspondingly. Besides, a reduction in the DS of concrete was found as the amounts of FA and GO increased. Moreover, the development and validation of response prediction models were conducted utilizing analysis of variance (ANOVA) at a significance level of 95%. The coefficient of determination (R2) values for the models varied from 94 to 99.90%. Research study indicated that including 10% fly ash (FA) as a substitute for cement, when combined with 0.05% GO, in concrete yields the best results. Therefore, this approach is an excellent option for the building sector.

A novel biodegradable film based on chicken gelatin and κ-carrageenan cross-linked with oxidized phenolic compounds.

Natural and renewable polymers are gradually replacing petroleum-based plastics, mostly as a result of environmental concerns. Moreover, upcycling industrial food waste into new added-value products is a creative approach that is crucial for cleaner and more sustainable manufacturing. The aim of this study was to obtain an environmentally friendly biodegradable film using a combination of k-carrageenan (KCAR) and chicken gelatin (CGEL), which obtained from poultry by-products. The effects of varying concentrations of KCAR (0-2%) on the physical, permeability, textural, thermal, and microstructural properties of CGEL/KCAR composite films were evaluated. The findings demonstrated that an increase in KCAR enhanced the lightness and opacity levels of the films. Water vapor permeability (WVP) values reduced as the KCAR concentration increased. The lowest WVP value (0.0012g.mm/h.m2.kpa) was seen in the treatment with 2% KCAR. Tensile strength (TS) values increased with increasing KCAR. The films' thermal stability was increased by the addition of KCAR. Microstructure assessments revealed a more compact and smooth structure in the KCAR-containing treatments, indicating improvements in WVP, thermal stability, and TS. Compared to the commercial cattle gelatin film, the CGEL film had higher TS and lower water solubility (WS). Overall, this study showed that the physical, mechanical, barrier and thermal and microstructural qualities of gelatin-based films may be enhanced by combining CGEL and KCAR to create an effective biodegradable film. Moreover, the comparison study between commercial cattle and chicken gelatin films revealed that cross-linked chicken gelatin films would be a suitable alternative for bovine gelatin films in the production of biodegradable film.

High-performance ultra-lean biodegradable Mg–Ca alloys and guidelines for their processing

High-performance ultra-lean binary Mg–Ca alloys are engineered by intelligent alloying and thermo-mechanical processing using hot-extrusion. With Ca-alloying contents as low as 0.2-0.6 wt.%, remarkable room-temperature tensile properties are obtained with tensile strength values as high as 380–420 MPa, or ductility values reaching a maximum of 36 %. By means of multiscale structural and chemical analysis using electron microscopy and energy dispersive X-ray spectroscopy, we show that multimodal strengthening mechanisms can be activated by modifying the spatial distribution of Ca as secondary phase. Our results indicate that strong precipitation strengthening is achieved when Mg2Ca phase particles are dispersed within the grains. On the other hand, preferential distribution of the Mg2Ca precipitates along grain boundaries imparts substantial grain-boundary strengthening by the Hall-Petch effect. Apart from secondary-phase precipitation, the role of Ca as solute atoms is paramount in promoting homogeneous deformation. The presence of Ca directly alters the intrinsic stacking fault energies and modifies the cross-slip energy barriers such that the slip-transition probability from pyramidal-to-basal and vice-versa becomes comparable. Both effects ensure competitive activation of basal and non-basal slip, thereby reducing the mechanical anisotropy. The mechanical performance in the current work, when compared to earlier reported studies of Mg alloys with similar or higher alloying content, shows a 2 to 10-fold increase in tensile strength without compromising ductility.

The Evaluation of the Use PET and HDPE Plastic Waste as Coarse Aggregate of Lightweight Concrete

The use of goods with plastic-based materials is familiar to society in general. Good for wrapping food, drinks, groceries, and others. Because of so much use, the problem of plastic waste cannot be avoided. Therefore, the purpose of this study is to overcome environmental land problems due to plastic waste. This research focuses on how to apply PET (Poly-Ethylene Terephthalate) and HDPE (High Density Polyethylene) plastic waste to concrete mixtures. PET plastic waste that has been chopped is then heated until melted then poured into molds and allowed to cool and harden. Then crushed and substituted as much as 5%, 10%, 15% and 20% replace the coarse aggregate to improve the characteristics of concrete. The results showed that the use of PET and HDPE in concrete resulted in decreased fill weight, lighter concrete weight, reduced compressive strength, and gave an optimum value of tensile strength at a variation of 10%. The use of PET plastic has a greater absorption value than HDPE, while the tensile strength value of PET is smaller than HDPE. Overall, it is concluded that PET and HDPE plastics have a big role in reducing the problem of plastic waste in the community

Pemanfaatan Abu Cangkang Kopi Sebagai Substitusi Semen Untuk Bahan Beton Ringan Menggunakan Bahan Tambah Sikament NN

The chemical reaction of cement and water produces compounds that are alkaline and react with various acids so that they can reduce the quality of concrete. To minimize this effect, pozzolanic materials need to be added. Organic pozzolan materials such as coffee shell ash waste can be used as material for making lightweight foam concrete which can be applied to non-structural buildings such as lightweight bricks. This research was conducted to see the effect of coffee shell ash substitution for cement on the properties of fresh concrete and the mechanical properties of lightweight foam concrete and to find the most optimal substitution composition for coffee shell ash for cement as well as lightweight foam concrete with FAS 0.5. Substitution of coffee shell ash for cement weight was carried out with variations of 0% BBN, 5% BBAAK1, 10% BBAAK2, and 15% BBAAK3 using 1% superplasticizer additive. The test object used is a cylinder with dimensions of 15 cm x 30 cm. The number of test objects used was 24 pieces. Tests for compressive strength and split tensile strength were carried out at the age of 28 days. The results of compressive strength tests carried out at 28 days for the lightweight foam concrete variations BBN, BBAAK 1, BBAAK 2 and BBAAK 3 were respectively 15.29 MPa, 12.21 MPa, 18.29 MPa and 19.52 MPa. The greater showing variation in the percentage of coffee shell ash substitution used, the greater the resulting compressive strength and split tensile strength values. This is because Sikament NN also plays a role in increasing the compressive strength of concrete

Unraveling the interrelation between process parameters and defects to enhance the strength of laser additively manufactured CuZrAlTi bulk metallic glass

Laser powder bed fusion (LPBF) enables the production of large and intricately shaped bulk metallic glasses (BMGs); however, the current strength of LPBF-fabricated BMGs is significantly lower than their cast counterparts due to defects generated during the LPBF process in the as-built BMGs. In this study, considering the viscosity characteristics of BMG melts and their impact on melt pool characteristics, we investigated the relationship between LPBF parameters, structural characteristics, and defects in a selected Cu45Zr45Al6Ti4 BMG. Our findings revealed a transition of the melt pool from conduction mode to keyhole mode and subsequently to extended mode with increasing laser power. Furthermore, we explored how melt pool characteristics influence defects such as pores, heat affected zone (HAZ), and crystalline phase in the as-built Cu45Zr45Al6Ti4 BMG. Under optimized LPBF parameters, we successfully fabricated nearly fully amorphous Cu45Zr45Al6Ti4 BMG samples with high density (>99%) and absence of cracks. The printed samples exhibited a compressive strength of 1839 MPa comparable to their cast counterparts while achieving an impressive tensile strength value of 920 MPa, currently the highest reported for CuZr-based BMGs. This study enhances our understanding of the intrinsic relationship between LPBF parameters, melt pool characteristics, defects, and mechanical properties of LPBF-fabricated BMGs while providing a new parameter optimization strategy for reducing defects and achieving high strength in BMGs.

Enhancing the mechanical properties of CF-reinforced epoxy composites through chemically surface modification of carbon fibers via novel two-step approach by addition of epichlorohydrin

The chemical surface modification was carried out in this study to improve the interface connection between carbon fiber (CF) and epoxy matrix to study the mechanical and fracture behavior of CF-reinforced epoxy composites. Finite element analysis was carried out by using ABAQUS software to simulate the variation of the tensile strength (TS), interfacial shear strength (IFSS), and interlaminar shear strength (ILSS). The chemical surface modification was carried out by the chemical oxidation by nitric acid and subsequently, addition of monomer resin of epichlorohydrin in a solution at 80 °C. The Raman spectroscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy were carried out to ensure the successful surface modification of CFs. Subsequently, surface-modified CF-reinforced epoxy composites were prepared through the hand lay-up method with the volume fraction of 20 wt.%, and curing was carried out at 80 °C for 4 h. The TS, IFSS, and ILSS values equaled 462.82 MPa, 156 MPa, and 4.1 MPa for modified CF/epoxy composites were achieved, respectively, which are improved remarkably compared to unmodified ones (380, 81, and 2.9 MPa). These improvements are attributed to the successful surface modification of CFs by epichlorohydrin. The surface modification causes the increase in wettability of CFs and the formation of mechanical interlocking and interaction between CFs and epoxy matrix was achieved through uniform and homogenous distribution of epichlorohydrin on the surface of CFs. Fractography was carried out, which indicated the sound and uniform adhesion between CF and epoxy matrix. Achieved results are consistent with simulated results.