Shape Retention Research Articles

Zr and V-doped effect on Martensitic transformations and magnetic properties of NiMnIn shape memory alloy

In this study, the elements vanadium (V) and zirconium (Zr) were doped separately as a fourth element to the ternary NiMnIn Heusler magnetic shape memory alloy and the alloys were produced as ingots by arc-melting method. The shape memory properties, microstructures, magnetic and microstructural changes of these new alloys were investigated in detail. The vanadium (V) and zirconium (Zr) elements doped into the alloy caused a decrease in the transformation temperature values of the alloy, but did not cause a significant change in its magnetic properties. The master sample, which has low hysteresis, undergoes a phase transition from the martensite phase to the austenite phase due to an increase in the nucleation of austenite phases at the twinning boundaries. Here, the vanadium and zirconium doping of the alloy caused an increase in the strength and ductility values of the alloy and this caused the formation of the second phase. Due to the increase of this phase formation in the alloy, it can be said that there is a slight decrease in the shape retention of the alloy.

Optimizing the design parameters for chamotte particle‐reinforced geopolymers

AbstractThis study delved into the utilization of chamotte particles in varying contents (0–50 wt%) as reinforcing agents in both fresh and hardened states within potassium‐based geopolymer (KGP) composites. Although the previous research predominantly underscored the high‐temperature stability of chamotte in composites subjected to extreme conditions, this study focuses on expanding their potential applications at ambient temperature. The experimental findings showed that the flowability of the pastes experienced a slight reduction up to 20 wt% chamotte, followed by a substantial decrease, ultimately resulting in complete shape retention at 50 wt%. Squeeze flow and standard rheological tests supported these observations, revealing elevated work‐to‐squeeze values peaking at 1.3 J. X‐ray diffraction data showed that crystallinity prevailed in chamotte, establishing its efficacy as a nonreactive reinforcement. In the hardened state, the inclusion of chamotte enhanced the mechanical properties of the composites, specifically compressive, flexural, and splitting tensile strengths, reaching up to 61.7, 13.2, and 5.6 MPa, respectively. Young's modulus (E) and shear modulus (G) also exhibited an upward trend with increasing chamotte content, reaching values of up to 17.7 and 7.7 GPa at 50 wt%, respectively. Scanning electron microscopy (SEM) analysis validated particle interlocking and crack‐bridging mechanisms. In general, this study highlights the effectiveness of chamotte particles in improving the mechanical properties of KGP composites at room temperature. It also emphasizes the necessity of considering the mentioned parameters in the design of particulate‐reinforced geopolymer compositions for diverse applications.

The application of dairy products and their derivatives as edible inks in 3D printing technology: A review

SummaryThree‐dimensional (3D) printing technology digitally designs and manufactures objects through computer‐controlled processes. It requires raw materials with specific rheological properties for extrusion and shape retention. Dairy products hold promise for 3D printing due to their ability to form structures and their nutritional value. However, the quality of 3D printing with dairy products relies on the properties of the printing ink and printer parameters, presenting challenges for practical applications. This work provided a summary of the suitability of dairy‐based 3D printed products, discussing physicochemical modifications and additives to enhance their suitability and nutritional properties. The internal structure and composition of printing inks derived from dairy products are closely linked to their printing performance. Physicochemical modifications and additives effectively improve printability and the nutritional aspects of dairy inks. The 3D printing suitability of dairy inks can be enhanced through physical, chemical or enzymatic treatments. The gel properties of dairy products can be improved by mixing them with hydrophilic gels, introducing calcium, and incorporating lipids to enhance the 3D printing performance of dairy products. 3D printing technology enables the customisation of dairy products with personalised control of nutritional content, meeting the increasing consumer and market demand for healthier foods. In the future, 3D printed dairy products are expected to constitute convenient and quick nutritious food and enter home kitchens.

Novel Fast Cure Silicone Inks for Single‐Step, Support‐Free 3D Printing of Tall, Overhanging, and High Aspect Ratio Structures

AbstractSilicone elastomers have a broad variety of applications, such as soft robotics, biomedical devices, and structural metamaterials. The extrusion‐based method known as direct ink write (DIW) has enabled the production of additively manufactured silicone structures. However, this method is limited to manufacturing mostly planar or pseudo‐3D structures. Due to the low self‐supporting capabilities of extruded strands for traditional silicone‐based “inks,” obtaining tall or overhanging structures, or structures comprised by thin walls is not feasible. Here, a novel Fast Cure silicone‐based ink is demonstrated that enables manufacturing of complex 3D structures. The Fast Cure ink is a two‐part mixture and silicone structures are produced by inline mixing and coextrusion of a part containing a catalyst (part A) and a part containing a crosslinker (part B). By the virtue of crosslinking, the extruded strands rapidly rigidize, increasing their self‐supportive capacity. Hence, structures can be obtained with superior shape retention and previously unobtainable parts are realized that are tall, with aspect ratios higher than 3, and have overhanging features, achieving inclination angles smaller than 35° with respect to the printing plane. These minimal sag parts are achieved without requiring extra curing or mechanisms, support structures, or suspension baths.

Scaffold providing spatial guidance enhances the healing of osteochondral defects and reduce adverse bone-cartilage crosstalk

Despite previous attempts using multiphasic scaffolds to organize cells and bioactive elements, osteochondral repair still faces challenges, such as thin cartilage layers and uneven bone-cartilage interfaces. These issues are likely exacerbated by detrimental biochemical interactions and the formation of new blood vessels within the osteochondral unit, impacting tissue repair quality. In this study, we devised a novel freeze-welding technique to create a unified porous scaffold. Chitosan was chosen as the primary material due to its structural and compositional similarity to glycosaminoglycans in the ECM. In particular, by meticulously adjusting freezing and solute conditions, we engineered the scaffold to have an axially aligned porous structure in the cartilage layer and a radially aligned porous structure in the subchondral layer (scaffold A/R), each designed to meet the unique repair needs of the respective tissues. This scaffold showed enhanced mechanical compressibility, shape retention, and interfacial bonding capabilities. The results demonstrated that this unique spatial scaffold structure offers significant advantages over purely axial scaffolds in guiding osteochondral regeneration. These advantages were evident in its ability to independently promote cartilage and bone growth, reduce undesirable bone-cartilage crosstalk, particularly in the context of vessel invasion in the cartilage layer, and optimize the remodeling of the osteochondral interface. This study offers valuable insights into the structural design patterns for osteochondral regeneration, highlighting the potential importance of structural scaffold design in guiding endogenous tissue remodeling during heterogeneous tissue regeneration.

Properties and microstructure of a low-carbon clinker-free cementitious binder and its extrusion-based printing performance

The extensive use of cement binders in the construction industry limits the progress of carbon emission reduction. A low-carbon clinker-free cementitious binder (CFCB) was developed by using wet grinding to activate granulated blast furnace slag (GGBS), combining fly ash (FA) spheres as rheology-modified material and calcium carbide slag (CS) together with sodium metasilicate (NS) powder as the compound activator. The effects of FA content and CS/NS ratio on the hydration, performances, and microstructure were systematically investigated. The printability and mechanical anisotropy of extrusion-based printed CFCB were also analyzed. The results show that lower fly ash content and CS/NS ratio positively influenced the yield stress and improved rheology and thixotropy within a certain range. The compressive strength of the CFCB mortar reaches a maximum of 46.6 MPa at 28 days. At the same time, the decrease in the CS/NS ratio is conducive to the development of the hydration process, generating a higher amount of hydration and forming a denser microstructure. The FA20-CS18 group shows suitable extrudability, buildability, and shape retention ability with a height loss of only 0.8 %. The existence of interlayer property differences causes the extrusion-based printed mortar to exhibit anisotropic mechanical properties, with the highest flexural and compressive strength in the Z-direction. The anisotropy coefficient was below 0.25 before 7 days.

Utilization of hazelnut oil oleogels for the preparation of milk couverture type compound chocolates: Composition, properties, and sensory evaluations

AbstractThe aim of this study was to use oleogels in compound chocolates. A control sample with cocoa butter (CNT) and two compound chocolates with hazelnut oil‐sunflower wax oleogel (SWO‐CC), and polyglycerol stearate oleogel (PGSO‐CC) were prepared with the same recipe. The main properties and compositions of the samples were quite similar. While CNT sample included only 37.97% of total unsaturated fatty acids, it was 74.19 and 63.08% in the SWO‐CC and PGSO‐CC, respectively. The melting peak temperatures were 32.1, 25.4, and 23.8°C for CNT, SWO‐CC and PGSO‐CC. The samples had 11.75%, 74.25%, and 74.25% shape retention index values at 60°C. Clearly compound chocolates melted at lower temperatures, but retained their shape at higher temperatures. After 15‐day temperature fluctuation storage, no fat bloom was developed. Rheological data showed that the PGSO‐CC sample was stiffer among all, and the compound chocolates melted slowly up to 40°C, but CNT melted sharply at 38°C. Further, the PGSO‐CC sample showed a lubricating behavior. Although CNT sample included 7 volatile aromatics, SWO‐CC and PGSO‐CC samples had 17 and 14 compounds, respectively. Trained panel described the samples with 13 attributes, and most profoundly the compound chocolates had lower shape, surface gloss, coffee, bitter, cooling, hardness scores, and higher coating scores. Consumer test revealed that compound chocolates had lower appearance scores, and equal aroma scores. The flavor score and acceptability were highest for the PGSO‐CC sample. Overall, this study proved that heat stable and sensorially acceptable compound chocolates could be prepared from the oleogels.

Effect of sand gradations on the fresh properties of 3D printable concrete

Sand is frequently used as a fine aggregate in concrete mixtures, but the performance of concrete can be considerably impacted by regional variations in sand gradation. In this work, the effect of sand gradations on the fresh properties of three-dimensionally printable concrete (3DPC) mixtures was systematically investigated. The binder combinations (cement, fly ash, silica fume, limestone powder, ground granulated blast-furnace slag) and the water/binder ratio were kept constant throughout the trials. The sands used in the mixtures were standard Ennore sand (ES) (grades I, II and III) and locally available river sand (RS). The mini-slump heights and flow values of mixes made with RS and with optimal packing of binary and ternary combinations of the standard ESs were evaluated and compared with those of the unary packing of ESs and RS. A correlation between the fineness modulus of different sand gradations and printable flow time was determined. The influence of sand gradations and fineness modulus on buildability, shape retention, open time and extrudability were evaluated. It was found that the performance of the fresh 3DPC was influenced by the aggregate's gradation and grain size in addition to its fineness. In conclusion, different fine aggregate specifications must be chosen depending on the various 3D printing building conditions and design requirements.

Single-Cell Screening through Cell Encapsulation in Photopolymerized Gelatin Methacryloyl

This study evaluated the potential of gelatin methacryloyl (GelMA) for single-cell screening compared to polyethylene glycol diacrylate (PEGDA). GelMA photopolymerized at 1000–2000 mJ/cm2 produced consistent patterns and supported HeLa cell viability. GelMA (5%w/v) facilitated better cell collection within 2 days due to its shape retention. GelMA demonstrated biocompatibility with HeLa cells exhibiting exponential proliferation and biodegradation over 5 days. The average cell displacement over 2 days was 16 µm. Two targeted cell recovery strategies using trypsin were developed: one for adherent cells encapsulated at 800 mJ/cm2, and another for floating cells encapsulated at 800 mJ/cm2, enabling the selective removal of unwanted cells. These findings suggest GelMA as a promising biomaterial for single-cell screening applications, offering advantages over PEGDA in cell encapsulation and targeted recovery.

Ice templated honeycomb-like porous copper foam to improve the anisotropic thermal transfer property of phase change composites

This study explores the use of copper foam (CF) as a thermally conductive scaffold for phase change materials (PCMs), enhancing shape stability. Employing the ice template method (ITM), we fabricate a CF with a low-density, honeycomb structure and anisotropy from flake copper powders. The resulting phase change composites (PCCs), infused with paraffin wax (PW), showcase high thermal conductivity and shape retention compared to pure PW, with anisotropic heat flow due to directional channels in the CF. With a 34.4 wt% filling ratio, the PCCs achieve axial and lateral thermal conductivities of 2.85 W m−1 K−1 and 1.51 W m−1 K−1, respectively, and a thermal storage enthalpy of 158.18 J g−1. This work presents a novel method for advanced thermal energy storage and management, indicating the promise of ITM-derived CF in high-performance PCCs for diverse applications.

3D-printed photocatalytic scaffolds of BiVO4 by direct ink writing for acetaminophen mineralization

A novel methodology to obtain 3D printable BiVO4 precursor scaffolds (3DM-BiVO4) via robocasting, showing excellent periodicity, shape retention, and mechanical stability, is disclosed for the first time. The ceramic pastes (solids at 70 wt.-%) comprised of BiVO4 precursor, SiO2NPs, and a solution of deionized water: ethylene glycol (volume ratio 1:2, DI water: EG) exhibited enhanced rheology for the 3D printing of self-supported structures (3DM-BiVO4). The thermal treatment induced a monoclinic scheelite phase, and the ethylene glycol contributed to achieving a unique square flake-like particle morphology. 3DM-BiVO4 scaffolds were used as reusable monolithic photocatalysts, showing 72% acetaminophen mineralization at 240 min and pH = 9. This innovative approach opens avenues for designing 3D printable ceramic pastes, offering potential applications in tailoring-made monolithic photocatalyst fabrication by using SiO2NPs as an inorganic binder.

Acoustic velocity and stability of tissue-mimicking echogenic materials for ultrasound training phantoms

Purpose. High-fidelity mannequins are increasingly used to train the medical staff on many medical procedures. Lately, a new challenge regarding echogenic materials to build ultrasound-responding phantoms has emerged. The challenge is to find materials with a suitable combination of ultrasound velocity and consistency to the touch. Methods. Bibliographic research was performed to identify materials with promising stiffness, shape retention, and ultrasound velocity combinations. As-standardized-as-possible specimens were realized and tested using an A-mode ultrasound machine to evaluate the US velocity through them. Four differently doped silicones, five gelatin-based materials, five synthetic gelatins, and a 3D printable resin were included in the study. After being tested, the materials were monitored for 12 days to assess their durability and shape retention and tested again to evaluate the ultrasound velocity’s stability. In the paper, the results of the characterization and follow-up of the materials are presented. Results. Outcomes show that gelatins are exceptional soft tissue-mimicking materials in terms of ultrasound velocity and consistency to the touch, but are poor in terms of overtime stability and therefore suitable for disposable short-term phantoms only. Doped silicones present lower ultrasound velocity compared to the reference value of 1540 m/s found in the literature, but excellent overtime stability, and shape retention properties. Values close to biological ones were also given by the Elastic 50A and by polyvinyl chloride plastisol. Conclusion. The paper gives a quantitative overview of the fidelity of both already-in-use and non-conventional materials, focusing on the ultrasound velocity value through them and their longevity in terms of macroscopically observed dehydration, shape retention, and bacterial onset.

3D-printable construction and demolition waste-based geopolymer: Investigating the effects of additives on engineering properties

This paper focuses on the investigating the effects of various additives on the engineering properties of construction and demolition waste (CDW)-based geopolymer mortars. In this study, low-activity CDW-based precursors, specifically brick waste (BW) and concrete waste (CW), were employed. Additionally, industrial waste-based precursors such as slag (S) and silica fume (SF) were utilized to enhance the overall composition. To facilitate activation, a 5 M solution of NaOH was used. To address the efflorescence issue prevalent in geopolymer mixtures and to eliminate potential cracks that may arise due to the dimensional stability problem of 3D-printed CDW-based geopolymer, various kind of additives including calcite, polypropylene fiber, nano SiO2, Al2O3, and TiO2, carbon nano tubes (CNTs), graphene nanoplatelet (GNP), methyl cellulose (MC), Na2SiO3, calcium oxide (CaO), calcium aluminate cement (CAC), and Ca(OH)2 were incorporated into the matrix. The research utilized a comprehensive testing methodology, allowing for a detailed exploration of various properties and the performance of the geopolymer mixtures. The results indicated that nano SiO2 and Al2O3, Na2SiO3, BW, and CAC were recognized for their positive impact on improving the mechanical properties of the geopolymer. Notably, the geopolymer exhibited an impressive compressive strength of 29.8 MPa and a flexural strength of 5.4 MPa following a 28-day ambient curing (23 ± 2 °C and 50 ± 5% relative humidity). Furthermore, the inclusion of nano SiO2 and Al2O3, GNP, MC, Na2SiO3, CaO, CAC, and Ca(OH)2 proved effective in preventing efflorescence, while MC, Na2SiO3, CaO, CAC, and Ca(OH)2 successfully mitigated cracks formation. The results also demonstrated that the CDW-based geopolymer mixture is suitable for 3D printing, displaying satisfactory buildability, shape retention, and extrudability. A thorough testing approach highlighted the effectiveness of additives in shaping the properties of CDW-based geopolymer, positioning them as promising for improvement and addressing challenges.

Preparation of shape memory polyurethane composite materials by grafting PCL onto CNFs with different carboxyl content

This study describes the preparation of cellulose nanofibers (CNFs) with varying amounts of carboxyl groups from rice straw pulp using the TEMPO/NaBr/NaClO oxidation system. The resulting CNFs were found to be in the form of nanofibers with an average diameter of 6 nm and an average length of 160 nm. To further enhance their properties, the CNFs were grafted with polycaprolactone (PCL) to create CNFs-g-PCL, which was then blended with shape memory polyurethane (SMPU) to produce CNFs-g-PCL/SMPU composites. It was observed that as the carboxyl content in CNFs increased from 0.35 to 1.14 mmol/g, the graft ratio of PCL on CNFs decreased from 24.6 to 10.7%. Consequently, the hydrophobicity of the grafted product (CNFs-g-PCL) also decreased. When 10% CNFs-g-PCL was added to the SMPU matrix, the elastic modulus and tensile stress of the resulting composite were both higher than those of the pure SMPU, increasing by up to 54.4% and 67.3%, respectively. Additionally, the shape retention and shape recovery rates of the composite remained stable after addition of CNFs-g-PCL. In conclusion, incorporating CNFs-g-PCL into SMPU can improve its mechanical properties while maintaining its shape memory properties.Graphical abstract

Development of 3D printable stabilized earth-based construction materials using excavated soil: Evaluation of fresh and hardened properties

Soil excavated during construction and demolition can be utilized to reduce the demand for natural sand in 3D printed constructions. This research attempts to systematically develop 3D printable stabilized earth-based materials using excavated soil (clay content of 42.5 %) as 25 % and 50 % replacement of natural sand, and examine their compressive strength, water permeable porosity, and moisture sensitivity. The effectiveness of two binder systems – Ordinary Portland Cement (OPC) and a combination of OPC and ground granulated blast furnace slag (GGBS used to replace 30 % OPC by mass), was investigated. Non-expansive clay in the soil leads to a steeper reduction in apparent viscosity, 12–15 % higher flow retention, and 50–60 % lower plastic viscosity of soil-based mixes, thus contributing to superior extrusion quality at 35–40 mm lower initial flow than OPC-sand and OPC-GGBS-sand mixes. The addition of GGBS, due to its irregular particle morphologies and interlocking effects, further enhances the shape retention of the printed layers by 8–26 % compared to OPC-soil mortars. The structural build-ups in OPC-soil and OPC-GGBS-soil mortars increase with the increase in clay content, which enabled buildability up to a height of 1.2 m compared to only 0.51–0.55 m for OPC-sand and OPC-GGBS-sand mortars. Higher water demand due to the addition of natural clay increases the porosity of 3D printed OPC-soil mortars, thereby lowering compressive strength and increasing moisture sensitivity. However, a blend of OPC and GGBS substantially reduces the moisture sensitivity of the printed mortars at 28-day age, attributed to better stabilization of clay through hydraulic and pozzolanic action of GGBS. 28-day wet compressive strength of 14–25 MPa is obtained for the printed soil-based mixes depending on the soil dosage and loading direction. In summary, the study provides a feasible solution for the 3D printing of stabilized earth structures with lower demand for natural sand and OPC.

Development of a pH-responsive system based on starch and alginate-pectin hydrogels using coaxial 3D food printing

This study developed and optimized a 3D food printing (3DFOODP) process of a complex hydrogel system, consisting of a starch core and a pH-responsive alginate-pectin (Al–P) shell for potential encapsulation purposes. A coaxial nozzle setup was employed to print such a complex hydrogel structure. The 3D printability of inks (i.e., starch and Al–P) was first optimized for the best shape retention. By varying the concentrations of these biopolymers (i.e., 10–12 wt% for starch and 2–4 wt% for Al–P) in the ink solutions, it was found that a 2 wt% Al–P and an 11 wt% starch concentration provided the best printability. The printability of Al–P was significantly enhanced with the use of 0.02 M calcium chloride solution during the ink formation. The rheological properties of the inks were characterized in detail, where the shear experienced by the inks in the coaxial nozzle was also calculated. XRD and FTIR analyses of the 3D-printed hydrogel system showed a reduction in crystallinity and no covalent chemical interactions, respectively. Finally, SEM images displayed a porous structure ideal for encapsulation purposes.

Modulating fat crystallization behavior in ice cream with mono- and diglycerides: Influence on microstructure and shrinkage

Ice cream commonly experiences volume shrinkage, especially during storage and transportation with temperature fluctuations. The 3D semi-crystalline fat network supports the spatial structure of ice cream, preventing the coarsening of elements like foams and ice crystals during temperature fluctuations, ultimately reducing volume shrinkage. This study investigates the impact of fat crystallization behavior on the formation of the fat network, examining the correlation between ice cream shrinkage and fat crystallization induced by mono- and diglycerides. Techniques include differential scanning calorimetry, polarization microscopy, contact angle measurement and oscillatory thermorheometry. Shape retention is assessed through melting and freeze-thaw tests, and ice cream microstructure is observed using microscopy. Results shown mono- and diglycerides significantly impacted fat crystal wettability and emulsified fat crystallization kinetics, altering the ice cream microstructure, and contributing to heat shock-induced shrinkage. Saturated monoglyceride formed a two-dimensional crystalline layer at fat globule interface, causing fat network absence and significant shrinkage. Slightly unsaturated monoglycerides increased nucleation dimensions (n from 2.22 to 2.71), forming large fat aggregates (around 39 μm), supporting a rigid network, and reducing the shrinkage rate (from 36% to 23%). Highly unsaturated monoglycerides increased crystal growth rate (kz from 0.72 to 0.84), elevating solid fat content, and creating protrusions that damaged air bubbles, leading to a 45% shrinkage rate. Additionally, saturated emulsifiers with diglycerides reduced crystal growth rates, increased fat crystal nucleation dimensions, and hydrophobicity (kz from 0.72 to 0.63 and n from 2.22 to 3.12), forming smaller fat aggregates (around 7 μm) and minimizing shrinkage to 6%.

Research on the forming and demolding process of shape memory self-demolding mold

The molding method is highly anticipated in engineering fields and has been preliminarily applied. However, traditional demolding methods introduce subtle deviations in demolding direction, leading to demolding defects and reduced forming accuracy. To address this, we developed an innovative Shape Memory Polymer (SMP) mold. Through finite element simulation, we extensively investigated the effects of diaminodiphenylmethane (DDM) addition, temperature, and load on the template forming and shape recovery processes. Finally, we experimentally verified the feasibility of the self-demolding of the template. The findings demonstrate that as the amount of DDM added increases, the glass transition temperature of SMP progressively elevates. This can be attributed to the enhanced crosslinking triggered by the addition of DDM. Consequently, during the stage of preserving shape in mold formation, SMP exhibits a heightened storage modulus and diminished shape recovery. Notably, when 1.5 g of DDM is added, the shape memory template exhibits the least shape recovery, with a shape retention rate of 78.2%. Conversely, employing 1.6 g of DDM generates the highest shape recovery but only achieves a shape retention rate of 59.5%. Augmenting the amount of DDM is advantageous in accomplishing template demolding. Higher temperatures expedite the initiation of the shape recovery process, facilitating template demolding during the shape recovery stage. Moreover, increasing the load can minimize template rebound and enhance the precision of mold formation. However, it also intensifies the complexity of self-demolding. Consequently, it is imperative to sensibly determine and implement suitable process parameters in applications.

Strong and densified 3D metal-ceramic composite with strengthened layer structure by material extrusion additive manufacturing

Material extrusion (MEX) of high-filled polymers with metal or ceramic powders has showed great potential in fabricating 3D structure combined via the powder metallurgy route. However, defects between deposited layers adversely affect the final performance of 3D components. Here, we introduced a high-flow filling approach based on effective viscosity control and optimized printing strategies for preparing high-density NiFe2O4-based cermet. We investigated the influence of powder loading and filling paths on both green and sintered samples regarding density, microstructure and mechanical properties. Polyformaldehyde (POM)-based feedstocks were developed with powder loading of 62 vol% and 56 vol%. 3D cermet with high powder loading demonstrated good shape retention but contained periodic pores due to low-flow filling between adjacent filament. Cermets with high relative density were achieved using 56 vol% POM-based feedstock because of satisfactory fluidity and high-filling effect during deposition. Filling paths determined the distribution and size of the pores, with cermet based on the (45°, 135°) trace exhibiting the most uniform and dense structure. Cermets using 62 vol% feedstock showed significant differences in flexural strength depending on the filling path, much lower than those achieved with the high-flow filling approach. Finally, 3D NiFe2O4-based cermets utilizing 56 vol% feedstock demonstrated an optimal average flexural strength of 173.5 MPa, close to 178.4 MPa of conventional injection molded samples. Hence, high-qualified metal-ceramic composites can be fabricated using MEX via the high-flow filling approach, with potential applications in complex-shaped anode, cutting tools and wear-resistant parts.

Relationship between Shape Retention and X-ray Absorption Value of the Tip of Microcatheters in Neuroendovascular Treatment.

Objective We noticed that the X-ray absorption value of the tip of each microcatheter used for aneurysm treatment varied from product to product. We hypothesized that the differences were caused by variations in the metal's density braid, which could be related to the ability of the tip to retain its shape. Methods The X-ray absorption value of each microcatheter tip was measured. Next, heat forming was performed using a shaping mandrel at 6 mm and 90 degrees to determine whether there was a correlation between the X-ray absorption value and the forming angle. Next, the optimal mandrel angle for forming each microcatheter at 90 degrees was investigated. We also examined the shape retention after 20 times wire insertions into each microcatheter. Conclusion It was found that the higher the X-ray absorption value, the harder it was for the microcatheter to be formed. The mandrel angle required to form 90 degrees was determined by the X-ray absorption value. The higher the X-ray absorption value, the higher the shape retention of the tip shape. The heat formation and shape-retention conditions of the microcatheter tip were correlated with the X-ray absorption value of the metal braid. Even for unknown microcatheters, the optimum shaping conditions can be inferred from the X-ray absorption value.