Unprocessed Material Research Articles

The use of chain extenders as processing aids in the valorization of single-use polylactide (PLA) products by rotomolding

Biodegradable plastics in single-use products have increased in popularity as a way to reduce the negative environmental impact of conventional plastics and meet the tightening law regulations. However, their recyclability needs to be assessed, as the environmental behavior of single-use plastics, even if compostable, is not negligible. Polylactide (PLA) is susceptible to thermal, oxidative, hydrolytic, and mechanical degradation during reprocessing, so the conditions of such cycles must be accurately controlled. The necessity of using additives to reduce such degradations during rotational molding, a process with long cycle times and oxidizing atmosphere, has been demonstrated. Chain extenders based on a carbodiimide (Bioadimide® 100 - KI), a methylene diphenyl diisocyanate (MDI), and a polystyrene-acrylic copolymer (Joncryl® ADR-4368c - J) have been added to post-consumer PLA wastes. It has been demonstrated that these three chain extenders enabled obtaining a higher molecular weight of the reprocessed polymer, compared to the ∼50% reduction for the neat PLA. The use of carbodiimide yielded the most similar performance to that of unprocessed raw material. All samples provided adequate thermal stability and processing parameters for the rotational molding. Carbodiimide is considered the most efficient additive, as it increases the molecular mass of the polymer as it remains unchanged after processing. Similarly, KI-modified PLA rheological behavior remains unchanged after processing, which means this compound can reduce thermooxidative and hydrolytic degradation reactions. Thus contributing to the achievement of improved processability and better performance; in particular, impact strength increased from 1.06 ± 0.56 for PLA to 8.12 ± 2.28 kJ/m2 for KI-modified PLA, and toughness of 5.36 ± 1.61 to 61.49 ± 8.01 J/mm3, respectively, leading to rotomolded items without structural defects. On the opposite, the use of Joncryl® and MDI led to structural defects in the rotomolded parts despite a higher molecular weight of the polymer, which resulted in poor mechanical properties, although better than PLA without any additive. All three chain extenders resulted in an amorphous PLA structure with increased glass transition temperature and improved thermal stability, which correlated with the reduced emissions of volatile compounds compared to neat recycled PLA. The presented findings significantly contribute to a better understanding of PLA and its modifications at a molecular scale required for its efficient and possibly environmentally burden-free reprocessing. Gathered knowledge will be crucial for optimizing its environmental performance and widening its applications, particularly in a process with long cycle times and oxidative character, such as rotational molding.

The Mechanical Properties of Orthodontic Aligners of Clear Aligner After Intraoral Use in Different Time Periods.

Although the technique of orthodontic aligners has risen in popularity, their mechanical properties have not been thoroughly investigated. The aim of this study was to evaluate the mechanical properties of the orthodontic aligners Clear Aligner after intraoral use for 7, 10 and 14 days, and to compare them with as-received aligners (0 days). It was also sought to examine the properties of the unprocessed raw material (polyethylene glycol terephthalate) used to manufacture these aligners. Thirty-two aligners by four patients were evaluated and studied at 0, 7, 10, 14 days of use. Each aligner was divided into three segments (two posterior and one anterior), which resulted in 96 samples. Also, 16 samples of unprocessed material were studied. For all samples, elastic modulus, ultimate tensile stress (UTS) and yield stress were calculated by conducting tensile testing. Additionally, material hardness was tested. The two-tailed Mann-Whitney test was performed, having set the level of significance at p = 0.05. Analysis of the measurements indicated a statistically significant decrease in elastic modulus between days 0 and 14 of use, of UTS between days 0 and 7, 7 and 10, and of yield stress between days 0 and 7. For hardness, in every period, posterior segments demonstrated significantly higher values than anterior segments. All properties of the unprocessed material were statistically significantly higher than the processed samples. The unprocessed material presented significant differences in every property tested in comparison to the processed aligners. The processed material showed further deterioration over time during use. The present study provides evidence that thermoforming and ageing affect the mechanical properties of the aligners.

Advances in mechanical and physicochemical performances of recycled carbon fiber reinforced PEKK composites

In recent years, waste storage and recycling have been important issues. All efforts shown in these fields aim to help resolve concerns related to climate change. In this study, recycled CF/PEKK thermoplastic composite materials were reviewed to reduce the environmental impact of materials during the production phase as well as economic costs and ensure product continuity. Comparisons between unprocessed or virgin material and recycled materials were performed by bending and interlaminar shear strength (ILSS) analyses. In addition to mechanical tests, physicochemical tests such as differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and fiber void ratio (FVC)-porosity tests were conducted. Images of the samples were observed by scanning electron microscopy (SEM) to interpret changes in the structure before and after the recycling. According to the experimental results, it was found that the virgin thermoplastic composite showed 68.05% higher flexural strength and 7.85% higher flexural modulus compared to the recycled thermoplastic composites. The average ILSSs were measured as 81.8 MPa and 64.7 MPa for the virgin and the recycled thermoplastic composites, respectively. Hence, it is obvious that the recycled composites could be used for applications that require less strength and durability. Finally, it was concluded that recyclable materials can be reused in the aero structures.

The Influence of Multi-Pass Friction Stir Processing on the Microstructure Evolution and Mechanical Properties of IS2062 Steel

The motive of present work is to explore the variation in the material characteristics of steel upon multi-pass friction stir processing. Steel plates (IS2062) that were 3 mm thick, were subjected to friction stir processing in a multi-pass manner. The selected transverse speed was 150 mm/min, along with a tool rotation of 800 RPM when using a tungsten carbide tool (shoulder diameter—10 mm). Steel plates were processed using the single-pass, double-pass, and triple-pass travel of the rotating tool to observe the impact of multi-pass processing on the properties of steel plates. Multi-pass friction stir processing resulted in a higher micro-hardness of 175 VHN after the second pass, in comparison to the unprocessed metal, which had a micro-hardness of 130 VHN, owing to the collective effect of the plastic flow of the material due to the rotation of the tool and frictional heat, which also leads to grain refinement. The second pass evidenced an average grain size of 22 microns, whereas the unprocessed material had an average grain size of 57 microns. The results of EBSD and SEM characterization showed reasonably improved material properties of the processed work materials.

Autonomous construction of lunar infrastructure with in-situ boulders

Significant infrastructure is required to establish a long-term presence of humans on the lunar surface. In-situ resource utilization (ISRU) is a fundamental approach to ensure the viability of such construction. Here, we investigate the feasibility of constructing blast shields as one example of lunar infrastructure using unprocessed lunar boulders and an autonomous robotic excavator. First, we estimate the volume of unprocessed material required for the construction of blast shield segments. Secondly, we quantify the amount of available boulders in two exploration zones (located at the Shackleton-Henson Connecting Ridge and the Aristarchus Plateau pyroclastic deposit) using LRO NAC images and boulder size-frequency distribution laws. In addition, we showcase an alternative approach that relies on Diviner rock abundance data. Thirdly, we use a path planning algorithm to derive the distance, energy, and time required to collect local material and construct blast shield elements. Our results show that our construction method requires two orders of magnitudes less energy than alternative ISRU construction methods, while maintaining realistic mission time and payload capacity margins.

Characteristics of in-situ automated fiber placement carbon-fiber-reinforced low-melt polyaryl ether ketone laminates part 1: Manufacturing influences

This study presents an investigation into mechanical and thermal properties, as well as the microstructure of Automated Fiber Placement-manufactured laminates using a novel carbon fiber-reinforced low-melt polyaryl ether ketone polymer material. The material’s lower melting temperature and lower melt viscosity as compared to established high-temperature thermoplastic materials as PEEK, promises favourable characteristics for the Automated Fiber Placement process. This work aims at in-situ consolidation and the influence of a heated tooling and a post process tempering step, which both turned out to be promising in previous investigations. Laminates were manufactured using a cold tooling, a heated tooling configuration, a cold tooling with a subsequent tempering process step and a hot-pressed reference laminate. Differential Scanning Calorimetry showed that crystallinity values more than doubled for the heated tooling and post process tempering configurations, compared to the cold tooling, reaching 24% and 30%, respectively. Mechanical strength values showed an increase in interlaminar shear strength and compression strength but did not increase to the same extent as was expected from the increase in crystallinity. With Scanning Electron Microscopy differences in the microscopic structure of the polymer matrix could be detected. While the post process tempering step leads to a mostly lamellar crystalline structure, the heated tooling configuration and the post process hot pressing induce a predominance of crystalline spherulites, which might positively affect the mechanical performance. Computed Tomography scans revealed a high amount of porosity in the in-situ-manufactured samples and unprocessed tape material, which likely mitigated the positive effect of increased crystallinity.

Analysis of bioactive compounds in Cordyceps militaris fruiting bodies and dietary supplements: in vitro bioaccessibility determination in artificial digestive juices

SummaryIn recent years, Cordyceps militaris has garnered increased attention in both scientific research and popular culture, exemplified by references in the entertainment industry, such as ‘The Last Of Us’. This study aims to investigate the qualitative and quantitative composition of bioactive compounds (such as cordycepin, ergothioneine, L‐phenylalanine, lovastatin, sterols, indole and phenolic compounds) in various samples. These samples encompass commercially available dietary supplements (in the form of capsules or powder), featuring standardised extracts or non‐standardised C. militaris material. Additionally, fruiting bodies cultivated in Poland and China were examined. The bioactive compounds were subsequently analysed after extraction into artificial digestive juices. Each sample underwent extraction, evaporation and dissolution in methanol, followed by qualitative and quantitative analyses using RP‐HPLC (with UV and DAD detectors) for the determination of bioactive compounds. The results of this analysis revealed that extracts with cordycepin contents of 7% and 1% exhibited the highest cordycepin concentrations, as well as significant ergothioneine levels (4405 and 928 mg/100 g d.w. and 234 and 77.6 mg/100 g d.w. respectively). However, on analysis of simulated digestive juices, it became evident that the fruiting bodies of C. militaris are superior sources of bioactive compounds. Consequently, this study underscores the efficacy of unprocessed material, such as fruiting bodies, as the preferred form of supplementation for potential consumers of C. militaris.

Processing of reactive Ni−Al powders via the LabRAM**

AbstractReactive Ni−Al materials have been developed using a variety of methods, with high energy ball milling (HEBM) being one of the most common means for tailoring reaction behavior. Powder production limitations associated with HEBM, including the addition of process control agents, have inspired the exploration of an alternate manufacturing technique: acoustic dry milling with the Resodyn Laboratory Resonant Acoustic Mixer (LabRAM). The influence of acoustic milling time, intensity, and media size with respect to microstructure and reactive behavior of Ni−Al powders were evaluated in this work. After just 20 min of milling, a reactive composite Ni−Al microstructure was produced. Milling intensity and media size were directly proportional to the formation of more homogeneous composite powders. The reaction onset temperature was decreased to 446 °C, or ≈200 °C lower than that of unprocessed material. The method shows promise for the production of reactive powder for a host of applications.

The Treatment of Natural Calcium Materials Using the Supercritical Antisolvent Method for CO2 Capture Applications

The potential of the supercritical antisolvent micronization (SAS) technique was evaluated for the production of CaO-based particles with a size and a physical structure that could enable high performance for CO2 capture through the calcium looping process. Two sources of calcium derivative compounds were tested, waste marble powder (WMP) and dolomite. The SAS micronization of the derivate calcium acetate was carried out at 60 °C, 200 bar, a 0.5 mL min−1 flow rate of liquid solution, and 20 mg mL−1 concentration of solute, producing, with a yield of more than 70%, needle-like particles. Moreover, since dolomite presents with a mixture of calcium and magnesium carbonates, the influence of the magnesium fraction in the SAS micronization was also assessed. The micronized mixtures with lower magnesium content (higher calcium fraction) presented needle-like particles similar to WMP. On the other hand, for the higher magnesium fractions, the micronized material was similar to magnesium acetate micronization, presenting sphere-like particles. The use of the micronized material in the Ca-looping processes, considering 10 carbonation-calcination cycles under mild and realistic conditions, showed that under mild conditions, the micronized WMP improved CaO conversion. After 10 cycles the micronization, WMP presented a conversion 1.8 times greater than the unprocessed material. The micronized dolomite, under both mild and real conditions, maintained more stable conversion after 10 cycles.

Tata Kelola Persediaan Bahan Baku Usaha Djamoe Van Java untuk Meningkatkan Efisiensi Pembuatan Jamu

Raw material inventory is unprocessed basic material provided by the company for later use in the company's production process. Raw materials are important in production companies. Limited or excess supplies of raw materials can be a problem for the company. A shortage of raw materials can result in problems with company activities, especially in the production process, while excess supplies of raw materials can lead to excessive costs in maintaining raw materials and the value of raw materials will decrease over time (Anista & Widiyastuti, 2016). The method used in this research is quantitative descriptive. According to Winartha (2006: 155), the quantitative descriptive method is analyzing, describing and summarizing various conditions and situations from various data in the form of numbers collected from the results of analysis and interviews or observations regarding the problems being studied that occur in the field. Based on the calculation results, the optimal quantity of raw material orders for the Djamoe Van Java business is 10 Kg. Based on the results of the research and discussion described previously, it can be concluded that to obtain optimal raw material inventory management for the Djamoe Van Java business, the quantity The economic purchase (EOQ) that the company must provide is 10 kg. The results of calculations that have been carried out in Total Inventory Cost (TIC) show that after implementing an appropriate and optimal inventory control system, the company can save costs of IDR 150,000. Companies should determine Reorder Points in carrying out raw material inventory control to anticipate possible delays in ordering raw materials.

Assessing the Effects of Refuse-Derived Fuel (RDF) Incorporation on the Extrusion and Drying Behavior of Brick Mixtures

This study explores the potential benefits of incorporating Recycled Demolition Waste (RDF) as an additive in ceramic mass for the brick industry, with a focus on applications such as thermoblocks. The research underscores the significance of sustainable waste management practices and environmental conservation by diverting waste from landfills. RDF, exhibiting combustion properties above 550 °C, emerges as a valuable candidate for enhancing clay-based materials, particularly in the brick production process where firing temperatures exceed 850 °C. Conducted in two phases, the research initially concentrated on RDF preparation, RDF integration with clay materials, and its influence on extrusion and drying phases. Employing innovative techniques involving brick and tile industry machinery coupled with sand incorporation yielded promising results. The grounding of RDF particles to less than 1 mm not only facilitated the mixing process but also ensured stable grinding temperatures within the hammer mill, reducing operational costs. During extrusion, challenges associated with unprocessed RDF material were addressed by utilizing ground RDF, leading to a more efficient and cost-effective process with enhanced plasticity and reduced water requirements. Practical implications for brick plant operations were identified, promoting resource and energy savings. Drying behavior analysis revealed the positive impact of RDF integration, showcasing reduced sensitivity, decreased drying linear shrinkage, and improved density properties. RDF’s role as an inert additive resulted in a 5% reduction in density, enhancing porosity and thermal insulation properties, particularly in thermoblock applications. In the brick industry, where durability, thermal performance, and cost-efficiency are paramount, this study emphasizes the potential benefits of incorporating RDF into clay-based materials. While further research is needed to address the firing procedure of RDF as a brick mass additive, the initial findings underscore the promise of this approach for sustainable and environmentally responsible brick production. This study contributes to the literature by shedding light on the advantages and challenges of integrating RDF into clay-based products, supporting sustainability and waste reduction in construction and manufacturing. The findings provide valuable insights into the performance and feasibility of these mixtures, offering crucial information for industries striving to adopt eco-conscious production methods. This article not only outlines the applied methodology and experimental setup but also presents results related to the behavior of RDF-inclusive clay block mixtures in the production environment. Anticipated to exert considerable influence on future practices and policies, this research contributes to the growing body of knowledge concerning eco-friendly and sustainable manufacturing processes.

Surface and subsurface material modifications and graded material properties in sheet steel 1.0338 (DC04) and their influence on forming processes

For bulk material it is very well known, that the material properties differ between the material near the surface and the inner material (i.e. segregations). However, for sheet material a gradient of material properties in depth direction and its influence on forming processes was not yet investigated. Within experiments on sheet steel 1.0338 (DC04) a gradient in material properties was proven by hardness measurements for both unprocessed material as well as after conducting forming and milling processes. The characterisation shows a gradient in material hardness over the entire sheet thickness. The experimental results regarding forming processes, such as rolling and bending, additionally show an increase of the materials hardness due to work hardening. The problem from the inhomogeneous material properties leads to an inaccurate prediction of the forming behaviour of the workpiece in further processing. Machining experiments were conducted for transferring the knowledge of modified surface and subsurface layers onto forming processes and their simulation. The bending experiments and the corresponding process simulation of the spring back behaviour show, that the implementation of an inhomogeneous material property increases the prediction accuracy. Notably the prediction of the spring back behaviour of thinner sheet metals is highly improved. Therefore, an analysis of sheet metal properties in thickness direction and their consideration in forming process simulations is inevitable for the implementation of accurate material models.

Production of inclusion complexes containing corticosteroids by SAA process

Slightly water-soluble drugs are frequently coprecipitated with a suitable carrier to speed up active principle ingredient (API) dissolution, improving its bioavailability. In this work, combined systems constituted by a corticosteroid and a cyclodextrin were micronized by Supercritical Assisted Atomization (SAA). When SAA processes corticosteroids alone, it is impossible to obtain micronized powders. The selected corticosteroids were prednisolone and dexamethasone, and a derivative of β-cyclodextrin was chosen as the carrier. The drug:cyclodextrin molar ratio and the initial solution concentration were varied to verify their influence on the powders’ particle size and particle size distribution. At all ratios and concentrations assessed, spherical micrometric particles were obtained. Under the optimized process conditions, compared to the unprocessed material, the dissolution time decreases from 18 h to 4 h in the case of prednisolone and from 22 h to 5 h in the case of dexamethasone.

ПРАВОВОЕ РЕГУЛИРОВАНИЕ ТОРГОВЛИ ЛЕКАРСТВЕННЫМИ РАСТЕНИЯМИ В ИНДИЙСКОЙ ЭКОНОМИЧЕСКОЙ СИСТЕМЕ

Issues of legal and trade regulation of the market of medicinal plants are relevant in the modern economy of India. The increasing demand of medicinal plants in the world is causing an adverse impact on Indian medicinal plant resource. There is an urgent need to organize medicinal plant trade sector by sustainable use 
 of wild population of plants, increased cultivation of medicinal plants and moving to export from unprocessed raw material to finished drugs suitable for international standards. Besides this conservation of Indian medicinal plant wealth is utterly necessary to favour the international trade.

Experimental investigation of the recycling of carbon fiber polyetherketoneketone thermoplastic composite

The increasing usage of composite materials due to their lightness and high strength came along with a problem which is the accumulating waste of this material. Recycling is one of the sustainable waste management methods for composites. However, recycling of composite materials is a complicated process due to the complex nature of these materials where reinforcement and matrix are different components with different characteristics. In the evaluation of recycling methods for thermoplastic composites, many factors such as environmental effects and economic efficiency are taken into consideration. In this study, mechanical recycling of carbon fiber polyetherketoneketone (CF/PEKK) thermoplastic composite is carried out to show the feasibility of recycling by comparing the recycled and unprocessed material in terms of mechanical and thermal properties. Waste CF/PEKK materials are shredded and consolidated in a press and samples taken from the final product to carry out mechanical and thermal tests such as tensile, three-point bending test, dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Results indicate unprocessed thermoplastic composite shows 61% higher tensile strength and 79% fracture strength where recycled material shows a loss of 33% in flexural modulus.

Assessment of the energetic efficiency of friction stir welding/processing

This paper scrutinizes and goes beyond previously published results on the analysis of the energy flow during friction stir welding/processing (FSW/P). An in-depth scientific method was used to assess the individual energetic contribution arising from the main components within the FSW/P system. This investigation was performed during FSW/P of AA7075 with different tool rotations and travel speeds. The main contributors to energy losses during the FSW/P process include the FSW/P tool, anvil, unprocessed base material, and the surrounding environment. It was found that only about 25 % of the total energy is effectively used to perform the welding/processing, while the remaining energy dissipates through heat into the tooling and clamping system. Additionally, around 6 % of the energy is lost towards the base material, forming the heat-affected zone (HAZ). These results suggest that proper selection of the anvil material offers a promising opportunity to enhance effective energy efficiency, considering that approximately 60 % of the total energy input is lost through this component. Addressing this substantial energy loss becomes essential for achieving a more energetically sustainable industrial application of the FSW/P process.

The parent bodies of CR chondrites and their secondary history

AbstractRenazzo‐type (CR) chondrites are a relatively rare group of carbonaceous chondrites with the vast majority having escaped thermal alteration. This means that CRs are composed of relatively unprocessed material, depending on the extent of aqueous alteration they have experienced. Hydration in CRs ranges from incipient alteration of matrix glass, up to nearly complete replacement of the rock by hydration products. The extent of secondary processes is often difficult to assess in these meteorites, due to their heterogeneity and diversity of alteration products. Yet, this is crucial in order to understand the extent of geological processing that occurred on the primary parent body. Additionally, the parent asteroids of CRs remain a mystery, mainly because terrestrial oxyhydroxide signatures dominate the reflectance spectra of CRs. In this work, we have conducted optical and IR reflectance and transmission spectra of 25 CR chondrites in order to (i) better evaluate the extent of aqueous alteration that occurred on the CR parent body, and (ii) find possible parent body candidates. Terrestrial oxyhydroxides were removed from 12 samples, as these tend to interfere with the optical‐IR spectra of CRs. Our results suggest, among other, that (i) aqueous alteration in most of our CRs was limited to the matrix and (ii) most CRs may stem from a continuum of X‐to‐C complex asteroids, depending on their extent of aqueous alteration. More specifically, the endmembers being Xk/Xn types and Cgh/Ch types. This has strong implication in regard to what we can expect from the Psyche mission.

Study of unidirectional torsion of samples with different internal structures manufactured in the MEX process

PurposeManufacturing of products loaded with torque in an incremental process should take into account the strength in relation to the internal structure of the details. Incremental processes allow for obtaining various internal structures, both in the production process itself and as a result of designing a three-dimensional computer-aided design model with programmable strength. Finite element analysis (FEA) is often used in the modeling process, especially in the area of topological optimization. There is a lack of data for numerical simulation processes, especially for the design of products loaded with torque and manufactured additive manufacturing (AM). The purpose of this study is to present the influence of the internal structure of samples produced in the material extrusion (MEX) technology on the tested parameters in the process of unidirectional torsion and to present the practical application of the obtained results on the example of a spline connection.Design/methodology/approachThe work involved a process of unidirectional torsion of samples with different internal structures, produced in the MEX technology. The obtained results allowed for the FEA of the spline connection, which was compared with the test of unidirectional torsion of the connection.FindingsThe performance of the unidirectional torsion test and the obtained results allowed us to determine the influence of the internal structure and its density on the achieved values of the tested parameters of the analyzed prototype materials. The performed FEA of the spline connection reflects the deformation of the produced connection in the unidirectional torsion test.Originality/valueThere are no standards for the torsional strength of elements manufactured from polymeric materials using MEX methods, which is why the industry often does not use these methods due to the need to spend time on research, which is associated with high costs. In addition, the industry is vary of unknown solutions and limits their use. Therefore, it is important to determine, among others, the strength parameters of components manufactured using incremental methods, including MEX, so that they can be widely used because of their great potential and thus gain trust among the recipient market. In addition, taking into account the different densities of the applied filling structure of the samples made of six prototype materials commonly available from manufacturers allowed us to determine its effect on the torsional strength. The presented work can be the basis for constructors dealing with the design of elements manufactured in the MEX technology in terms of torsional strength. The obtained results also complement the existing material base in the FEA software and perform the strength analysis before the actual details are made to verify the existing irregularities that affect the strength of the details. The analysis of unidirectional torsion made it possible to supplement the material cards, which often refer to unprocessed material, e.g. in MEX processes.

Retracted: “Fabrication and Characterization of Magnesium-Based WE43/TiC Nanocomposite Material Developed Via Friction Stir Processing and Study of Significant Parameters” [ASME Journal of Engineering Materials and Technology, 2023, 145(3), p. 031007; DOI: 10.1115/1.4062321

Abstract Magnesium metal matrix composites (MMMCs) have exceptional mechanical and metallurgical characteristics, which have drawn the interest of researchers across the world. In the present research study, an attempt has been made to fabricate WE43 magnesium (Mg) based nanocomposites using friction stir processing (FSP) after incorporating nano-titanium carbide (TiC) as a reinforcement. Further, the impact of different FSP variables such as transverse speeds (40 mm/min and 80 mm/min), and tool rotation speeds (900 rpm and 1800 rpm) over the metallurgical, wear, and mechanical performance has been studied. The large thermal energy generated by the rotating FSP tool gives rise to the mechanism of dynamic recrystallization and plastic deformation. This contributes to refining the microstructure and improvement in microhardness as per Hall–Patch relation—contributing to prominent grain size refinement and Orowan mechanism strengthening, due to the dispersion of reinforcement particulates. The outcome of the results depicts that the nanocomposite fabricated at a tool rotation speed of 1800 rpm and 80 mm/min transverse shows better mechanical and tribological characteristics than other developed composites and the base alloy. More specifically, the grain size was reduced nearly 12 times, microhardness was 2.58 times higher, and ultimate tensile strength (UTS) was 2.08 times higher when contrasted to the base alloy. Moreover, the unprocessed base material was characterized by an adhesive wear mechanism whereas the presence of scratches depicts the abrasive wear mechanism was dominant for WE43/TiC nanocomposite.

The noble gas and nitrogen relationship between Ryugu and carbonaceous chondrites

Carbonaceous chondrites are considered to have originated from C-type asteroids and represent some of the most primitive material in our solar system. Furthermore, since carbonaceous chondrites can contain significant quantities of volatile elements, they may have played a crucial role in supplying volatiles and organic material to Earth and other inner solar system bodies. However, a major challenge of unravelling the volatile composition of chondritic meteorites is distinguishing between which features were inherited from the parent body, and what may be a secondary feature attributable to terrestrial weathering. In December 2020, the Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) successfully returned surface material from the C-type asteroid (162173) Ryugu to Earth. This material has now been classified as closely resembling CI-type chondrites, which are the most chemically pristine meteorites. The analysis of material from the surface of Ryugu therefore provides a unique opportunity to analyse the volatile composition of material that originated from a CI-type asteroid without the complications arising from terrestrial contamination. Given their highly volatile nature, the noble gas and nitrogen inventories of chondrites are highly sensitive to different alteration processes on the asteroid parent body, and to terrestrial contamination. Here, we investigate the nitrogen and noble gas signature of two pelletized grains collected from the first and second touchdown sites (Okazaki et al., 2022a), to provide an insight into the formation and alteration history of Ryugu. The concentration of trapped noble gas in the Ryugu samples is greater than the average composition of previously measured CI chondrites and are primarily derived from phase Q, although a significant contribution of presolar nanodiamond Xe-HL is noted. The large noble gas concentrations coupled with a significant contribution of presolar nanodiamonds suggests that the Ryugu samples may represent some of the most primitive unprocessed material from the early solar system. In contrast to the noble gases, the abundance of nitrogen and δ15N composition of the two Ryugu pellets are lower than the average CI chondrite value. We attribute the lower nitrogen abundances and δ15N measured in this study to the preferential loss of a 15N-rich phase from our samples during aqueous alteration on the parent planetesimal. The analyses of other grains returned from Ryugu have shown large variations in nitrogen concentrations and δ15N indicating that alteration fluids heterogeneously interacted with material now present on the surface of Ryugu. Finally, the ratio of trapped noble gases to nitrogen is higher than CI chondrites, and is closer to refractory phase Q and nanodiamonds. This indicates that Ryugu experienced aqueous alteration that led to the significant and variable loss of nitrogen, likely from soluble organic matter, without modification of the noble gas budget, which is primarily hosted in insoluble organic matter and presolar diamonds and is therefore more resistant to aqueous alteration.