Number Of Voids Research Articles

Single-point incremental formability of Monel 400: Coupled grey relational and principal component analyses

This study reports the effects of single-point incremental forming (SPIF) process variables like vertical step down (0.2, 0.4, 0.6 mm), tool diameter (6, 8, 10 mm), feed rate (300, 600, 900 mm/min), spindle speed (300, 450, 600 rpm), lubricant (dry, oil, grease) and sheet thickness (0.6, 0.8, 1.0 mm) on the formability of Monel 400. Based on the varying wall angle tests conducted, it was found that the vertical step down was the parameter most influential in achieving maximum wall angle. The forming limit diagram constructed with the data obtained from straight groove tests revealed the parameter combination for low, moderate, and high formability while forming along different directions (0°, 45°, 90°). Also, it was observed that the formability has been positively influenced by increased tool diameter in the case of 0° orientation, spindle speed in the case of 45° orientation, and vertical step down in the case of 90° orientation. Based on the fractography study, it is concluded that more number of voids enhanced the forming limit. This may be due to the coalescence of voids and their slow aggregation. Based on the combined grey relational analysis and principal component analysis, it is obtained that the order of influencing parameters is vertical step down, tool diameter, sheet thickness, spindle speed, lubricant, and feed rate for obtaining the maximum sum of strains (0°, 45° 90°) and maximum wall angle.

Comparative study of blending techniques in polylactic acid/cellulose nanofibrils green composites for benchtop 3D printing filaments

AbstractAdditive manufacturing for polylactic acid (PLA) reinforced with cellulose nanofibrils (CNF) could unlock fabrication of specialized and user‐specific biomedical devices. However, the process of combining PLA and CNF is challenging and proves complicated with possible irreversible CNF agglomeration and organic solvents leftover, particularly when involving solvent‐casting technique. Direct melt‐blending can mitigate these issues, but there are few reports of a single‐step melting and extrusion process to produce ready‐to‐use 3D printing filaments. This study compares the distribution of CNF fillers within the PLA matrix in PLA/CNF composites made by direct melt‐blending into filaments using a benchtop filament maker, and by solvent‐casting followed by extrusion into filaments. The filaments were 3D‐printed via fused deposition modeling (FDM), followed by tensile testing, morphology, and other characterizations. Uneven filament diameters were observed for the composite filaments prepared via solvent‐casting because of severe agglomeration, resulted in poor printability and tensile properties of filaments and 3D‐printed samples. Direct melt‐blended filament diameters were consistent, resulted in only slight decrease of tensile properties compared to pure PLA, contributing to the highest maximum tensile strength of 3D‐printed sample of 51.47 ± 1.73 MPa at 5% CNF loading. Morphology revealed good integration of CNF into PLA matrix starting at 3% CNF loading. Direct melt‐blending was comparable to the conventional methods, which enables simpler PLA/CNF composite preparation especially for 3D printing.Highlights Better dispersibility achieved by direct melt‐blending than by solvent‐casting. PLA/CNF filaments produced via solvent‐casting suffered severe agglomeration. Direct melt‐blended PLA/CNF5% yielded the highest maximum tensile strength. Morphology reveals good CNF‐PLA integration starting at 3% of CNF loading. Worsened agglomeration causing increased number of voids observed at 10% CNF.

Crack arrest characteristics and dynamic fracture parameters of moving cracks encountering double holes under impact loads

Brittle materials such as rock or concrete contain a large number of micro-cracks, voids, and other defects. Under external impacting loads, the interaction between fissures and holes affects the bearing capacity and stability of Engineering structures. To study the interaction mechanism between moving cracks and circular holes, A large-size semi-circular notched with a fissure and double circular hole (SNFDH) specimen was suggested in this research, and the dynamic fracture tests were carried out on the SNFDH specimens with different double circular hole spacing (35mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, and 70 mm) using a drop hammer impact test device. Crack propagation gauges were employed to track the time and velocity at which the crack propagated along its trajectory. Dynamic Drucker-Prager yield criterion and the cumulative damage failure criterion were used in the numerical simulation of SNFDH concrete materials. The program AUTODYN was employed to simulate the crack growth characteristics when a crack encounters the double hole. The program ABAQUS was applied to calculate the dynamic fracture parameter of cracks. The test results manifest that the crack propagating trajectory has three different characteristics according to the double hole spacing; the double circular hole has an arresting function for a moving crack; the size of the double hole spacing has a significant effect on the crack propagating velocity, crack propagating length, dynamic stress intensity factor and dynamic energy release rate; the configuration of the SNFDH specimen can be used to investigate the crack arrest mechanism when moving crack encountering double holes.

Unveiling solid-solid contact states in all-solid-state lithium batteries: An electrochemical impedance spectroscopy viewpoint

All-solid-state lithium batteries (ASSLBs) are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety. The solid-solid contact between lithium metal and solid electrolyte plays a vital role in the performance of working ASSLBs, which is challenging to investigate quantitatively by experimental approach. This work proposed a quantitative model based on the finite element method for electrochemical impedance spectroscopy simulation of different solid-solid contact states in ASSLBs. With the assistance of an equivalent circuit model and distribution of relaxation times, it is discovered that as the number of voids and the sharpness of cracks increase, the contact resistance Rc grows and ultimately dominates the battery impedance. Through accurate fitting, inverse proportional relations between contact resistance Rc and (1 − porosity) as well as crack angle was disclosed. This contribution affords a fresh insight into clarifying solid-solid contact states in ASSLBs.

To Compare and Evaluate Rotary and Manual Techniques in Biomechanical Preparation of Primary Molars to Know Their Effects in Terms of Cleaning and Shaping Efficacy.

The introduction of the rotary file system for children was a revolution in the field of pediatric endodontics. These files are cost-effective and help in consistent obturations with shorter instrumentation time. The present randomized controlled trial (RCT) was planned for a comparative evaluation of rotary and manual techniques in biomechanical preparation of primary molars to determine their effect in terms of cleaning and shaping efficacy, working time, quality of obturation, and postoperative pain. A randomized clinical trial study was conducted in 75 children aged 5-9 years requiring pulpectomy. Each tooth was randomly assigned to one of the three treatment groups: Kedo-S files, rotary K-Flex files, and hand instruments group. It was observed that Kedo-S files and rotary K-Flex files were more effective in cleaning and shaping of root canals compared to hand H/K files. The postbacterial count for hand files was higher compared to rotary files. Shorter working time was seen with rotary files (3.88-5.04 minutes) compared to hand files (15.68 minutes). Rotary files showed a reduced number of voids, with Kedo-S files in 92% of cases and rotary K-Flex files in 80% of cases. Apical seal and extent of fill were maximum with rotary files, having a grade C rating in 92% of cases. Kedo-S files and rotary K-Flex files showed a significant reduction in postoperative pain compared to hand files. The present study showed a significant reduction in bacterial count, working time, quality of obturation, and postoperative pain with rotary files. Moudgalya MS, Tyagi P, Tiwari S, et al. To Compare and Evaluate Rotary and Manual Techniques in Biomechanical Preparation of Primary Molars to Know Their Effects in Terms of Cleaning and Shaping Efficacy. Int J Clin Pediatr Dent 2024;17(8):864-870.

Microwave self-healing characteristics of the internal voids in steel slag asphalt mixture subjected to salt-freeze-thaw cycles

Microwave heating technology can be used to repair freeze-thaw (F-T) cycle damage and cracks caused by the use of snow melting salts and de-icers in winter. This study utilized three different gradations of asphalt mixtures: AC-13, SMA-13, and OGFC-13, and enhanced their microwave absorption performance with steel slag (SS). The heating uniformity was evaluated through surface and internal temperature tests. Additionally, the mechanisms of damage and healing of the asphalt mixtures under salt freeze-thaw (S-F-T) damage conditions were explored using S-F-T cycles test and X-ray computed tomography scans (CT). The results showed that OGFC-13 exhibits a significantly higher rate of temperature increase compared to the other two types due to its stronger wave absorption capacity. The thermal hysteresis caused by steel slag leads to uneven spatial temperature distribution. The study recommends an optimal microwave heating time of 40 s for SS asphalt mixtures, which has minimal impact on the mixture structure, by defining an evaluation method for the uniformity index and local overheat ratio. After undergoing S-F-T cycles, the porosity of all three asphalt mixtures increased, particularly at the top and bottom of the specimens. Among them, OGFC-13 exhibited the poorest durability under S-F-T conditions, with the S-F-T cycles having a significant impact on medium-sized voids (0.15–0.6 mm). After microwave heating, AC-13 and SMA-13 showed good repair effects, with porosity levels returning to their initial states. For large voids (>2.36 mm) in OGFC, microwave heating may not effectively reduce the number of voids. Additionally, the healing rate of mixture specimens at certain mid-height ranges is higher due to elevated surface temperatures in these areas, making it especially effective in repairing F-T damage. This study shows that microwave heating of SS asphalt mixtures can improve the durability of pavement in cold regions. However, implementation challenges include the need for specialized equipment and potential uneven heating. Future research should explore optimizing microwave heating techniques to minimize local overheating and investigate the long-term performance of microwave-repaired asphalt pavements under various environmental conditions.

Additive Manufacturing of Waste Electrical and Electronic Equipment (WEEE) Produced From Acrylonitrile Butadiene Styrene (ABS)

Objective: To evaluate the feasibility of producing recycled acrylonitrile-butadiene-styrene (r-ABS) filaments from waste electrical and electronic equipment (W EEE) casings, specifically discarded monitors and televisions, and to compare their properties with those of virgin ABS. Theoretical Framework: The research was based on a literature review of additive manufacturing, WEEE recycling, and the thermal, mechanical, rheological, and microscopic characterizations of recycled polymers, with an emphasis on fused deposition modeling (FDM). Method: WEEE casings were collected and mechanically recycled to produce r-ABS filaments. These filaments were characterized and compared with virgin ABS filaments using infrared spectroscopy (FTIR), thermal analyses (TGA and DSC), rheological, mechanical, and microscopic evaluations. Results and Conclusion: The results indicated that r-ABS filaments exhibit properties comparable to those of virgin ABS. FTIR analysis revealed the presence of the main functional groups of ABS in the recycled samples. Thermal analysis showed similar behavior between the recycled and virgin materials, with a single thermal decomposition event. Rheological analysis demonstrated that r-ABS possesses viscoelastic properties suitable for the FDM process, and mechanical characterization showed that r-ABS exhibited tensile strength close to virgin ABS. Microscopic analysis revealed good layer adhesion and a low number of voids, factors that contribute to the quality of the printed objects. Research Implications: This study contributes to the valorization of polymeric waste, promoting the use of recycled materials in additive manufacturing processes, which can benefit both the environment and the 3D printing industry. Originality/Value: The research addresses a topic still underexplored in the literature, especially concerning the recycling of WEEE casings for the production of ABS filaments.

A Method of Images to Study Plate-Impact-Induced Cavitation in Aluminum through Molecular Dynamics Simulation

The tensile stress generated by the superposition of two reflection waves in the target plays a critical role in explaining plate-impact-induced spalling. A method of images is proposed to simulate the physical process of wave superposition and this method is applied in order to study the cavitation mechanism in single-crystal Al through molecular dynamics simulation. The critical impact-load velocity for the cavitation obtained by this method is as small as 400 m/s, which is much lower than the result (650 m/s) obtained by the conventional piston-load method. The new cavitation mechanism found is distinctively different from the conventional dislocation-entanglement-induced cavitation under high-velocity impact. The new mechanism involves two key events: firstly, a crack-like defect is formed and its relevant atomic bonds are broken under high tensile stress, resulting in a great momentum of related atoms; and secondly, previous high-momentum atoms collide with the atoms in their running way, resulting in the destruction of the original FCC structure locally and nanovoids or penny-shaped voids being formed. Additionally, the cavitation region, the number of voids, and delamination surfaces increases with the impact-load rate.

Comparison of the quality of three obturation techniques in primary anterior teeth using cone-beam computed tomography: An in vitro study

Background: This study aimed to compare the number of voids of primary anterior teeth obturated with Endoflas by using three different obturation techniques, namely, endodontic pressure syringe, modified disposable syringe, and reamer using cone-beam computed tomography (CBCT). Materials and Methods: Thirty-six single-rooted primary incisors and canines with lengths ranging within 15–22 mm were randomly divided into three groups (12 teeth/group) according to the obturation techniques used. Group A, endodontic pressure syringe; group B, modified disposable syringe; and group C, reamer. A single operator instrumented and obturated all teeth by using Endoflas. An independent evaluator analysed the quality of the obturation techniques by using CBCT imaging to determine the number of voids in the root canals. Fisher's exact test and multiple pairwise comparisons adjusted by the Dunn–Bonferroni method were used to statistically assess the results. Results: All study groups showed no statistically significant difference in the number of voids (P > 0.05). Comparing the thirds of each group, the coronal and middle thirds of group A contained the maximum number of voids, followed by groups B and C, with no statistically significant difference. For the apical third, voids were highly presented in group C followed by group B. Meanwhile, group A was found to have no voids. Conclusion: Within the limitations of the current research, we concluded that voids existed in all techniques used; however, they were the least when using endodontic pressure syringes. Thus, an endodontic pressure syringe used with an Endoflas obturation material may be preferred as an obturation technique.

Adaptation and Biomechanical Performance of Custom-Fit Mouthguards Produced Using Conventional and Digital Workflows: A Comparative InVitro Strain Analysis.

The use of different models for the fabrication of custom-fit mouthguards (MTGs) can affect their final thickness, adaptation, and shock-absorption properties. This study aimed to evaluate the adaptation, thickness, and shock absorption of ethylene-vinyl acetate (EVA) thermoplastic MTGs produced using conventional plaster or three-dimensional (3D) printed models. A typical model with simulated soft gum tissue was used as the reference model to produce MTGs with the following two different protocols: plast-MTG using a conventional impression and plaster model (n = 10) and 3DPr-MTG using a digital scanning and 3D printed model (n = 10). A custom-fit MTG was fabricated using EVA sheets (Bioart) plasticized over different models. The MTG thickness (mm), internal adaptation (mm) to the typodontic model, and voids in the area (mm2) between the two EVA layers were measured using cone-beam computed tomography images and Mimics software (Materialize). The shock absorption of the MTG was measured using a strain-gauge test with a pendulum impact at 30° with a steel ball over the typodont model with and without MTGs. Data were analyzed using one-way analysis of variance with repeated measurements, followed by Tukey's post hoc tests. The 3DPr-MTG showed better adaptation than that of the Plast-MTG at the incisal/occlusal and lingual tooth surfaces (p < 0.001). The 3DPr-MTG showed a thickness similar to that of the Plast-MTG, irrespective of the measured location. MTGs produced using both model types significantly reduced the strain values during horizontal impact (3DPr-MTG 86.2% and Plast-MTG 87.0%) compared with the control group without MTG (p < 0.001). The MTGs showed the required standards regarding thickness, adaptation, and biomechanical performance, suggesting that the number and volume of voids had no significant impact on their functionality. Three-dimensional printed models are a viable alternative for MTG production, providing better adaptation than the Plast-MTG at the incisal/occlusal and lingual tooth surfaces and similar performance as the MTG produced with the conventional protocol.

Void number counts as a cosmological probe for the large-scale structure

ABSTRACT Void number count (VNC) indicates the number of low-density regions in the large-scale structure (LSS) of the Universe, and we propose to use it as an effective cosmological probe. By generating the galaxy mock catalogue based on Jiutian simulations and considering the spectroscopic survey strategy and instrumental design of the China Space Station Telescope (CSST), which can reach a magnitude limit $\sim$23 AB mag and spectral resolution $R\gtrsim 200$ with a sky coverage of 17 500 deg2, we identify voids using the watershed algorithm without any assumption of void shape and obtain the mock void catalogue and data of the VNC in six redshift bins from $z=0.3$ to 1.3. We use the Markov chain Monte Carlo method to constrain the cosmological and VNC parameters. The void linear underdensity threshold $\delta _{\rm v}$ in the theoretical model is set to be a free parameter at a given redshift to fit the VNC data and explore their redshift evolution. We find that the VNC can correctly derive the cosmological information, and the constraint strength on the cosmological parameters is comparable to that from the void size function method, which can reach a few per cent level in the CSST full spectroscopic survey. This is because, since the VNC is not sensitive to void shape, the modified theoretical model can match the data better by integrating over void features, and more voids could be included in the VNC analysis by applying simpler selection criteria, which will improve the statistical significance. It indicates that the VNC can be an effective cosmological probe for exploring the LSS.

Investigation of aggregate gradation on air voids distribution in porous asphalt concrete using X-ray CT scanning images

Porous asphalt concrete (PAC) is typically used as a paving material for porous asphalt pavement in rainy areas due to its abundant interconnected pores structure. Not all interconnected pores in PAC are valid for permeability, mainly influenced by the composition of aggregate gradation. The main purpose of this paper is to investigate the effect of aggregate gradation on pores structure distribution in PAC by X-ray computed tomography (CT) system and digital image processing (DIP) techniques. The distributions of porosity, number and average equivalent diameter of air voids in middle part are much more evenly compared to the both ends in PAC specimens, accounting for about 70 % of the total of specimen height. The average equivalent diameter of interconnected air voids mainly ranges from 0.5 mm to 5 mm in PAC, accounting for about 80 % of the total numbers. For PAC with similar porosity, the larger the normal maximum aggregate size (NMAS), the less the number and the larger the average equivalent diameter of air voids (interconnected air voids), the smaller the difference between the interconnected porosity and porosity. For PAC with same NMAS, as the porosity increase, the number and average equivalent diameter of air voids (interconnected air voids) are respectively decreased and increased gradually, the difference between the interconnected porosity and porosity is also showed a decreasing trend. And then, the correlated equation is established among porosity, interconnected porosity and the composition of aggregate gradation. The distribution of air voids (interconnected air voids) size could be well described by the two-parameter Weibull model, and the relationships are explored and developed between Weibull model parameters and the composition of aggregate gradation.

Phase stability of precipitate-hardened CoCrFeNiTi high entropy alloys fabricated via laser-directed energy deposition under high-temperature irradiation

This study investigated the irradiation response of precipitate-hardened CoCrFeNiTi high entropy alloys (HEAs) fabricated by laser-directed energy deposition (LDED). These HEAs were in-situ irradiated with 1 MeV krypton ions (Kr2+) at 400 °C and 600 °C up to 10 displacements per atom (dpa) at the IVEM-Tandem Facility at Argonne National Laboratory. Transmission electron microscopy (TEM) characterized precipitate stability and defect evolution under irradiation. At 400 °C and 10 dpa, precipitates showed high phase stability, while irradiation at 600 °C caused intense dissolution mainly due to its annealing effect. A high density of faulted dislocation loops formed at 400 °C. The annihilation rate of dislocation loops seemed higher at 600 °C. Increasing the dose increased the number and size of voids in the face-centered cubic (FCC) matrix.

Study on the Plastic Deformation Mechanism of Void‐Containing Twin‐Crystal Magnesium with Symmetric Tilt Grain Boundary Angles

AbstractA twin‐crystal magnesium (Mg) model with 9 different symmetric tilt grain boundary (STGB) angles (20°–80°) with preset nanohole defects is established by atomsk and lammps software. The mechanical behavior of grain boundary (GB) angles on twin‐crystal Mg with cavity defects and its cavity evolution are simulated by the molecular dynamics method with embedded atomic potential, and the plastic deformation mechanism is revealed. The results show that the yield stress decreases with the increase of the STGB Angle during the stretching process. When the GB Angle increases from 20° to 80°, the yield stress decreases from 2.28 to 1.42 Gpa. This is because the larger the STGB Angle is, the larger the Schmidt factor is, and the easier it is to start dislocation slip during the stretching process. On the other hand, the larger the Angle of STGB, the more the number of atomic voids at the interface, and the more the number of dislocation nucleation points. The larger the Angle of STGB, the lower the strength of twinning Mg but the better the plasticity to avoid fracture. The plastic deformation mechanism mainly includes the nucleation of Shockley incomplete dislocation at STGBs, dislocation slip generates stacking faults (SFs), GB migration, and base plane dislocations.

Cavitation behavior of poly(4‐methyl‐1‐pentene)/polypropylene/poly(4‐methyl‐1‐pentene) tri‐layer film: Influence of annealing and stretching temperature

AbstractIn this work, poly(4‐methyl‐1‐pentene)/polypropylene/poly(4‐methyl‐1‐pentene) tri‐layer films were prepared. The microstructure of the film was adjusted by annealing in the temperature range of 150–237.5°C. Afterward, the influence of annealing and stretching temperature on the cavitation behavior of the film was investigated by small‐angle x‐ray scattering (SAXS). Results showed that for the “butterfly” scattering in the early stage, the radius of gyration () and maximum dimension () of voids were ca. 75 and 200 nm, which were hardly influenced by annealing. Whereas, the volume fraction of voids was enlarged obviously, suggesting that more voids were formed; for the “streak” scattering in the late stage, the length of voids () grew gradually with stretching, and the ultimate value of was 432.5 nm for un‐annealed film and 176 nm for film annealed at 230°C. Simultaneously, the misorientation of voids was reduced from 0.33 to 0.18. As the stretching temperature was elevated from 30 to 45 and 60°C, and maintained at 75 and 200 nm, and was enlarged to 434 and 432 nm. At the same time, the number of voids was reduced obviously. As the stretching temperature was 90°C, the voids were suppressed.

Analysis of the mechanical behavior of porous materials containing two populations of voids under dynamic spherical loading

A computational homogenization analysis is performed on three-dimensional representative volume elements (RVE) that contain two distinct populations of voids, to demonstrate the influence of the interaction between cavities. RVEs are constructed as cubic elastic perfectly-plastic matrices embedding two families of spherical voids, and subjected to dynamic loading under homogeneous kinematic boundary conditions. Multiple microstructure models are considered by varying the number, position, and size of voids to evaluate the micro-inertia contribution to the overall macroscopic stress. Velocity fields within numerical RVEs are investigated to reveal the interaction of voids and their key role in the dynamic macroscopic response of the porous material. Based on numerical simulation results, a homogenization analytical model considering void interaction is proposed to describe the mechanical behavior under dynamic loadings. This model relies on adjusting the strain rate level at the boundary of unit cells composing the porous material. Comparison between our numerical and analytical results with those obtained using the classical Taylor homogenization scheme highlights the limitations of the Taylor model in the case of porous materials under dynamic loading.

Preparation and Performance Characterization of Low-Density 3D-Printed Expanded Perlite–Foam Concrete

Traditional lightweight foam concrete typically introduces a large number of voids into the concrete using surfactants to reduce density. However, in 3D printing, the instability of lightweight foam concrete can affect the workability of the slurry. Additionally, the lower strength of foam with more pores also reduces its mechanical performance. This study found that by replacing sand with expanded perlite in 3D-printed foam concrete, the stability of the foam is improved, enhancing the workability of the mixture and increasing the constructability of printed concrete. Furthermore, analyses of mechanical properties, porosity, and pore size distribution showed that at the same dry density, foam concrete with a higher expanded perlite replacement ratio exhibited higher compressive strength, with a maximum strength increase of up to 39%. Moreover, the introduction of expanded perlite optimized the pore distribution of the foam concrete, resulting in a more uniform material structure. The 3D-printed expanded perlite–foam concrete (3DPFC) prepared in this study provides new insights for the preparation of lightweight 3D-printed concrete, which is of significant importance for the sustainable development of the construction industry.

Effect of βSn grain orientations on the electromigration-induced evolution of voids in SAC305 BGA solder joints

The electromigration (EM) failure of solder joints is closely related to the development of voids during EM. In this paper, an integrated approach combining experimentation and finite element simulation was employed to reveal the evolution of voids in solder joints under current stress. The results indicate that the quantity and volume of voids near the cathode consistently increase, while those close to the anode decrease. These asymmetric evolutions of voids are mainly due to the Sn flux, which is controlled by both current density and βSn grain orientation. The magnitude of Sn flux increases with higher current densities and larger angles γ between the c-axis of βSn and the current direction. The direction of Sn flux is more significantly influenced by the current direction rather than the βSn orientation, due to the weak anisotropic self-diffusion of Sn. Voids near the anode tend to shrink while those close to the cathode expand, parallel to the substrate, due to higher Sn flux distributions at the waists of voids, where current crowding is seen. Void splitting related to rapid Cu diffusion has been observed, leading to an abnormal increase in the number of voids near the cathode. This study enhances the understanding of the electromigration failure mechanisms involving void evolution in solder joints.

Effects of rotational speed of the classifying wheel during jet milling on magnetic properties and thermal stability of sintered Nd-Fe-B magnets

Sintered Nd-Fe-B magnets with different grain sizes are prepared by adjusting rotational speed of the classifying wheel during the jet milling process. The microstructures of the magnets, the element contents of the magnets, the relationship between powder particle size and grain size and the magnetic properties of the magnets are studied by X-ray diffracton (XRD), scanning electron microscopy (SEM), optical microscopy (OM), electron backscattered diffraction (EBSD), inductively coupled plasma (ICP) and permanent magnet tester. The effect of grain size on thermal stability is characterized by the temperature coefficient of coercivity from room temperature to working temperature and the irreversible magnetic flux loss of the magnet at high temperature. The results show that the particle size of the alloy powder decreases with the increase of the rotational speed of the classifying wheel. When the alloy powder is formed and sintered, it is found that the grain size of the prepared magnet decreases with the decrease of the particle size of the alloy powder. The finer the grain size of the magnet, the clearer the grain boundary. As the grain size of the magnet decreases, the coercivity of the magnet increases, the remanence of the magnet decreases slowly and the thermal stability of the magnet becomes better. For the magnet with a rotational speed of the classifying wheel of 4900 r/min, the average grain size of the magnet is 4.70 μm, the coercivity (Hcj) is 15.47 kOe, and the remanence (Br) is14.09 kGs. At a temperature of 80 °C, the coercivity temperature coefficient of the magnet reaches −0.745 %/°C, and the irreversible loss of magnetic flux hirr is 16.49 %. In addition, the magnet prepared by the tail material produced a large number of voids and pores due to the high oxygen content. Tail material is not good enough in terms of magnetic property as well as thermal stability.

Enhancing the functionality of sugar palm (Arenga Pinnata) fibre reinforced polylactic acid composite filament of fused deposition modelling through Taguchi method

Constructing functional components using Fused Deposition Modelling (FDM) is challenging due to various processing factors that influence the quality of the final product. The main reason for this is the many processing parameters involved, which have the ability to impact the quality of the produced components. The aim of this research is to use the Taguchi technique in attempt to improve the printing variables for attaining the best possible mechanical and physical qualities in the three-dimensional (3D) printed product made from sugar palm fibre reinforced polylactic acid (SPF/PLA). The layer thickness, infill density, and printing speed are characteristics that directly affect the mechanical qualities, surface roughness, and dimensional accuracy of FDM products. The research applied Taguchi’s L9 array, consisting of 9 experimental trials, with each trial including 5 duplicated specimens. Thus, a total of 45 specimens were generated by altering various processing settings. The most effective printing settings for FDM using SPF and PLA were found to be a layer thickness of 0.1 mm, infill density set to 100%, and a printing speed of 25 mm s−1. The microscopic images reveal a significant rise in the number of voids as the layer thickness is raised. Additionally, the printing speed has a substantial impact on the nead structure, making it more resilient. Overall, the results will provide a significant collection of data in the area of 3D printing, improving the utilization of indigenous plant fibres in additive manufacturing technology.