Post Heat Research Articles

4D printing and annealing of PETG composites reinforced with short carbon fibers

In this study, for the first time, post-heat treatment was applied to improve the stress recovery of short carbon fiber reinforced PETG (SCFRPETG). PETG and SCFRPETG composite were printed under optimal conditions, and constrained and free shape memory cycles were applied under compression and three-point bending loadings to assess shape and stress recovery. The results of the free shape memory test for both vertical and horizontal patterns showed that PETG composite also has a higher shape memory effect (SME) compared to PETG. The SME was significantly improved by performing heat treatment. The stress recovery values for pure PETG, reinforced PETG before and after annealing are 2.48 MPa, 3.04 MPa and 3.18 MPa, respectively. It showed that the addition of 1.5% carbon fiber increases the stress recovery by 22%. The increasing trend reaches 28% by performing post-heat treatment. Additionally, altering the printing pattern affects the programming and stress recovery values. For the SCFRPETG composite samples before and after annealing, changing the printing pattern from horizontal to vertical, resulted in a 16% and 7% increase in recovery stress, respectively. SEM results confirm that the annealing process removes the layered structure, micro-holes caused by shrinkage and 4D printing mechanism. Using the controlled heat treatment method can be a practical solution to solve the problem of adhesion and reduce the anisotropy of FDM 3D printed layers.

Tailoring fluoride networks to precipitate hexagonal Ln1-yMyF3-y nanocrystals in glass: Towards short-wavelength upconversion PL of lanthanides

The AlF3-MF2-LnF3 (M = Ca; Sr; Ba; Ln = Yb/Tm) based pure fluoride GCs are essentially ideal candidates for the realization of PL in UV and VIS spectral region. However, the pure fluoride glasses are prone to precipitation of undesired nano-crystals while quenching and post annealing due to their poor chemical stability. Therefore, the development of such glass systems requires strict adherence to composition control right from the outset. This research employed extensive molecular dynamics (MD) simulations and incorporated the results into the experimental design to develop an efficient multicomponent fluoride glass system. Vivid simulation of M-F-Ln and M-F-Al nano-cluster formation via MD are observed in the glass matrix. These nano-clusters serve as the structural origins of the precipitated nano-crystals in GCs post heat treatment. Through meticulous manipulation of the Al/M ratio, it became feasible to theoretically forecast the transformation of the glass matrix from a cubic M1-xLnxF2+x to a hexagonal Ln1-yMyF3-y nano-crystal precipitated GCs, which could conceivably be manufactured experimentally. This transformation offers superior luminescent performance for Ln1-yMyF3-y containing GCs enabling short-wavelength PL realisation in near UV (∼361 nm with 8-fold enhancement) and VIS (∼478 nm with 1.7-fold enhancement) from Yb3+/Tm3+ transitions, in comparison to its cubic M1-xLnxF2+x counterpart. Hence, we propose an effective fluoride glass system for short-wavelength upconversion luminescent applications through the integration of MD simulations and experimental research.

An additively manufactured precipitation hardening medium entropy alloy with excellent strength-ductility synergy over a wide temperature range

Modern engineering has long been in demand for high-performance additive manufactured materials for harsh working conditions. The idea of high entropy alloy (HEA), medium entropy alloy (MEA), and multi-principal-element alloy (MPEA) provides a new way for alloy design. In this work, we develop a Co42Cr20Ni30Ti4Al4 quinary MEA which exhibits a superiority of mechanical properties over a wide temperature ranging from 77 to 873 K via selective laser melting (SLM) and post-heat treatment. The present MEA achieves an excellent ultimate tensile strength (UTS) of 1586 MPa with a total elongation (TE) of 22.7 % at 298 K, a UTS of 1944 MPa with a TE of 22.6 % at 77 K, and a UTS of 1147 MPa with a TE of 9.1 % at 873 K. The excellent mechanical properties stem from the microstructures composed of partially refined grains and heterogeneously precipitated L12 phase due to the concurrence of recrystallization and precipitation. The grain boundary hardening, precipitation hardening, and dislocation hardening contribute to the high YS at 298 and 77 K. Interactions of nano-spaced stacking faults (SFs) including SFs networks, Lomer–Cottrell locks (L–C locks), and anti-phase boundaries (APBs) induced by the shearing of L12 phase are responsible for the high strain hardening rate and plasticity at 77 K. Our work provides a new insight for the incorporation of precipitation hardening and additive manufacturing technology, paving the avenue for the development of high-performance structural materials.

Effect of solution treatment on the microstructure, phase transformation behavior and functional properties of NiTiNb ternary shape memory alloys fabricated via laser powder bed fusion in-situ alloying

Post-heat treatment is commonly employed to improve the microstructural homogeneity and enhance the mechanical performances of the additively manufactured metallic materials. In this work, a ternary (NiTi)91Nb9 (at.%) shape memory alloy was produced by laser powder bed fusion (L-PBF) using pre-alloyed NiTi and elemental Nb powders. The effect of solution treatment on the microstructure, phase transformation behavior and mechanical/functional performances was investigated. The in-situ alloyed (NiTi)91Nb9 alloy exhibits a submicron cellular-dendritic structure surrounding the supersaturated B2-NiTi matrix. Upon high-temperature (1273 K) solution treatment, Nb-rich precipitates were precipitated from the supersaturated matrix. The fragmentation and spheroidization of the NiTi/Nb eutectics occurred during solution treatment, leading to a morphological transition from mesh-like into rod-like and sphere-like. Coarsening of the β-Nb phases occurred with increasing holding time. The martensite transformation temperature increases after solution treatment, mainly attributed to: (i) reduced lattice distortion due to the Nb expulsion from the supersaturated B2-NiTi, and (ii) the Ti expulsion from the β-Nb phases that lowers the ratio Ni/Ti in the B2-NiTi matrix, which resulted from the microstructure changes from non-equilibrium to equilibrium state. The thermal hysteresis of the solutionized alloys is around 145 K after 20% pre-deformation, which is comparable to the conventional NiTiNb alloys. A short-term solution treatment (i.e. at 1 273 K for 30 min) enhances the ductility and strength of the as-printed specimen, with the increase of fracture stress from (613 ± 19) MPa to (781 ± 20) MPa and the increase of fracture strain from (7.6 ± 0.1)% to (9.5 ± 0.4)%. Both the as-printed and solutionized samples exhibit good tensile shape memory effects with recovery rates >90%. This work suggests that post-process heat treatment is essential to optimize the microstructure and improve the mechanical performances of the L-PBF in-situ alloyed parts.

Recovery of Ni-Co-Mn Oxides from End-of-Life Lithium-Ion Batteries for the Application of a Negative Temperature Coefficient Sensor

This study demonstrates the current advancements in battery management systems (BMSs), emphasizing the need for precise temperature monitoring within battery packs to enhance safety and performance through efficient thermal management. The increased demand for lithium-ion batteries (LIBs) has driven the development of temperature sensors with improved accuracy and stability. In particular, Ni-Co-Mn-based spinel oxides are commonly used due to their stable negative temperature coefficient (NTC) behavior. However, challenges arise in manufacturing due to the high cost and uncertain supply of critical cathode components (e.g., Co, Ni, and Mn) for LIBs. This research focuses on developing spinel-type (Ni0.6Co0.4Mn2)O4 using recycled Ni-Co-Mn oxides obtained from end-of-life (EOL) LIBs, demonstrating temperature resistance behavior suitable for temperature sensing. The oxides are prepared through hydrometallurgy, oxalate synthesis, and post-heat treatment. Successful integration into spinel-type NTC thermistors suggests broader applications in various industrial fields. A systematic investigation into the synthesis and characterization of recovered Ni-Co-Mn oxides from EOL LIB cathode materials (Li(Ni0.33Co0.33Mn0.33)O2) is presented for NTC thermistor application. Thermogravimetric analysis-derivative thermogravimetry (TGA-DTG) identifies the optimal post-heat treatment temperature. The X-ray diffraction (XRD) patterns confirm a cubic spinel structure of the Ni-Co-Mn oxides, supported by scanning electron microscope (SEM) images showing a uniform microstructure. Also, energy dispersive X-ray spectroscopy (EDS) mapping confirms homogeneous element distribution. Recovered oxide pellets from the sintering process exhibit a single spinel structure, with X-ray photoelectron spectroscopy (XPS) analysis revealing changes in the valence states for Ni and Mn. Resistivity measurements demonstrate semiconductive behavior, which shows a B value (3376.92 K) suitable for NTC thermistor applications. This study contributes valuable insights to black powder recycling from EOL LIBs and its potential in temperature-sensitive electronic devices.

Synthesis of Air@Co@Co7Fe3@Fe3O4 composite with enhanced electromagnetic wave absorption performance

Electromagnetic pollution prevention and military stealth technology requirements for wave absorbing materials gradually increased, therefore, the research and development of absorbing materials with the merits of low reflection loss, wide effective absorption bandwidth, and lightweight is of great significance. In this work, Air@Co@Co7Fe3@Fe3O4 hollow spherical particles have been successfully synthesized via a simple chemical plating method combined with a post heat treatment. It reveals that the Air@Co@Co7Fe3@Fe3O4 particles with a loading of 50 wt % exhibits an optimum reflection loss (RL) value of −20.77 dB at 15.52 GHz and broad effective absorption bandwidth (EAB, RL ≤ −10 dB) of 4.56 GHz with a thickness of 1.4 mm. Compared to Air@Co hollow spherical particles, Air@Co@Co7Fe3@Fe3O4 particles with natural resonance and eddy current loss, as well as the interlayer interfacial polarization mechanism of the multilayer structure, exhibit superior electromagnetic wave(EMW) absorption capabilities. The Air@Co@Co7Fe3@Fe3O4 hollow spherical particles could be a new highly efficient absorbing material for electromagnetic waves.

Preparation and application research of composites with low vacuum outgassing and excellent electromagnetic sealing performance

Abstract Electromagnetic interference (EMI) shielding rubber effectively fills gaps in electronic devices to prevent electromagnetic (EM) leakage. However, research on the potential application of EMI shielding rubber in the field of space is limited. This study explores the optimal amount of silver-coated aluminum powder (SCA) in SCA/ methyl vinyl silicone rubber (MVQ) composites to balance the electrical and mechanical properties of EMI shielding rubber. The EMI shielding effectiveness (SE) of 41.8 vol% SCA/MVQ composite exceeded 90 dB in the frequency range between 100 and 1,200 MHz with a compression set of only 14%. To address the outgassing characteristics of silicone rubber in a vacuum environment, both pre-heating and post-heating treatments for reducing rubber volatility are explored, proving that silicone rubber followed by 4 h of post-heating treatment at 200°C, is an appropriate solution to reduce silicone rubber volatility, leading to the SCA/MVQ composite with a total mass loss of only 0.2%, and a collected volatile condensable material of only 0.02%. In addition, high reliability is crucial for EMI shielding materials. SCA/MVQ composite exhibits excellent adaptability to vacuum temperature cycles, with the EMI SE maintained at 90 dB after cycles. At room temperature, after 30 days of storage, the EMI SE of the composite remains at 90 dB. These findings indicate that SCA/MVQ composites exhibit broad potential applications in the field of EM sealing for aerospace electronic devices.

Extending the mechanical property regime of laser powder bed fusion Sc- and Zr-modified Al6061 alloy by manipulating process parameters and heat treatment

Highly dense compositionally modified Al6061 alloys with Sc and Zr (Al6061MOD) were fabricated using the laser powder bed fusion. The as-built AL6061MOD alloy exhibits a bimodal grain size distribution consisting of coarse columnar grains and ultrafine grains, which is tunable by either varying the printing parameters or post-heat treatment. A high laser energy density along with a lower cooling rate, leaving more time for nucleating primary Al3Sc particles, triggers a higher area fraction of ultrafine grains. The heat treatment-induced evolution of microstructure and mechanical properties is jointly influenced by the size of grains and (Al,Si)3(Sc,Zr) particles. The conventional T6 heat treatment triggers coarsening of grains (∼5.3 μm) and (Al,Si)3(Sc,Zr) particles (∼42 nm), lowering the yield strength (∼280 MPa) compared with that of as-built counterparts. On the contrary, direct aging enhances the yield strength (∼383 MPa) due to the precipitation of nano-sized secondary Al3(Sc,Zr) particles (∼5 nm) as well as retaining the grain size (∼690 nm) of ultrafine grains. Concurrent with the tunable strength, the plasticity behaviors (Lüders band and Portevin-Le Chatelier effect) are manipulated correspondingly with varying microstructure. The broad tailoring of microstructure and mechanical property regime can shed light on designing Al alloys targeting the desired applications by manipulating the printing parameters and heat treatment.

Multi-scale hybrid reinforced super duplex stainless steel matrix composites with high strength and ductility via laser powder bed fusion and an in-situ synthesis strategy

The emergence of nanoparticle-reinforced metal matrix composites represents a promising method for efficiently enhancing material strength without significant compromise in ductility. Nevertheless, the homogeneous distribution of nanoparticles in matrix remains a technical challenge. To address this issue, this study designed an advanced method to create a multi-scale hybrid to reinforce super duplex stainless steels (SDSSs) by coupling laser powder bed fusion (LPBF) technique with an in-situ synthesis strategy and optimizing post heat treatment. For as-built composites, both TiCxNy and M23C6 nanoparticles were generated in-situ by the introduction of micron-sized TiC particles into SDSSs, and their microstructure was mainly composed of fine ferrite grains. The post quenching treatment enabled heat-treated composites to possess micro-duplex matrix grains with a multi-scale hybrid, including micron-sized TiC, in-situ sub-micron M23C6 particles, and in-situ TiCxNy nanoparticles. Particularly, the obvious agglomeration phenomenon of in-situ TiCxNy nanoparticles was not observed. In comparison with heat-treated SDSSs (ultimate tensile strength (UTS): ∼839 MPa; uniform elongation (UE): ∼20.6 %), heat-treated composites processed by 1090 °C obtained a higher UTS (∼992 MPa) with only 0.8 % reduction in UE. The great ductility of heat-treated composites was primarily attributed to their relatively high strain hardening rate, facilitated by grain refinement and the formed multi-scale hybrid. The successful creation of a multi-scale hybrid sets the stage for producing high-performance metallic components via LPBF and in-situ strategy.

Influence of Scanning Strategy and Post-Treatment on Cracks and Mechanical Properties of Selective-Laser-Melted K438 Superalloy

The feasibility of manufacturing high-performance components with complex structures is limited due to cracks in some superalloys fabricated by selective laser melting (SLM). By controlling the main process parameters such as scanning strategy, the adverse effects of cracks can be effectively reduced. In this paper, the effects of two different SLM scanning strategies with island and ‘back-and-forth’ and post-heat treatment on the cracks and mechanical properties of selective-laser-melted (SLMed) K438 alloy were investigated. The results show that the SLM method of the ‘back-and-forth’ scanning strategy had better lap and interlayer rotation angles and a more uniform distribution of laser energy compared with the island scanning strategy. The residual stress accumulation was reduced and crack formation was inhibited under this scanning strategy owing to the cooling and shrinkage process. In addition, the dislocation motion was hindered by the formation of uniformly dispersed MC carbides and γ’ phases during the SLM K438 alloy process, which resulted in the density of the as-built SLMed K438 alloy being up to 99.34%, the hardness up to 9.6 Gpa, and the tensile strength up to 1309 MPa. After post-heat treatment, the fine secondary γ’ phases were precipitated and dispersed uniformly in the Ni matrix, which effectively improved the Young’s modulus and tensile strength of the alloy by dispersing the stress-concentrated area.

In-situ synchrotron X-ray diffraction investigation of martensite decomposition in Laser Powder Bed Fusion (L-PBF) processed Ti–6Al–4V

Laser powder bed fusion (L-PBF) processed Ti–6Al–4V components present two substantial challenges: the presence of tensile residual stress and brittleness of the as-fabricated component due to the formation of the martensite (α′) phase. Industrially, post-heat treatment is performed to improve the quasi-static mechanical properties of the Ti–6Al–4V component through martensite (α′) decomposition and residual stress relaxation. However, detailed insights into the martensite decomposition and stress relaxation mechanisms are still lacking. To address this, in-situ high-energy synchrotron x-ray diffraction (HEXRD) was employed to simultaneously track: (I) martensite (α′) decomposition into a mixture of hexagonal α and body-centered cubic β phases, (II) residual stress relaxation process during heating. Rietveld refinement of 2D diffraction patterns recorded over a temperature range spanning from 25 to 1000°C revealed a three-stage evolution in the α′ unit cell parameters. Unit cell parameter analysis combined with the phase fraction analysis based on the diffraction patterns and the chemical composition profiles predicted by Thermocalc simulation gave detailed insight into the martensite (α′) decomposition process. In Stage 1 (until 375°C), the α′ phase unit cell exhibited linear expansion without indications of any phase transformation or stress relaxation. Upon commencement of stage II at 375°C, an increased expansion rate of the martensite (α′) unit cell was observed, attributed to the enhanced outward diffusion of vanadium (V), succeeded by β phase nucleation at 575°C. Simultaneously, during stage II, residual stress relaxation was observed at both macro and micro scale, culminating in a stress-free state achieved at approximately 750–800°C. Lastly, α-to-β phase transformation was observed in stage 3. The thermal evolution of the hexagonal unit cell dimensions was compared between martensitic and mill-annealed α+β microstructures. This comparison unraveled the link between the initial microstructure and the thermal expansion behavior of the hexagonal α′ and α phase.

Grainy properties of post–heating fermented milk with different particle sizes

Post–heating operation is crucial to produce ambient yogurt, which is also a direct cause of sensory defects, especially graininess. Consumers’ perception of graininess varies based on individual sensitivities. Accurate evaluation of graininess is a prerequisite for improving the sensory quality of ambient yogurts. The purpose of this study was to propose a method to discriminate consumers' sensitivity to grainy perception of post–heating (55 °C–85 °C, 25 s) fermented milk, and to further determine the volume proportion threshold required to produce different graininess intensities by blending fermented milk with different particle sizes. The results suggested that increasing the post–heating temperature induced various graininess by promoting different microgel aggregation. Fermented milks with microgel aggregate sizes of ∼14–∼20 μm, ∼27 μm, and ∼46–∼65 μm were classified as “weak”, “moderate”, and “strong” graininess, respectively. This result was obtained by approximately 81% of the panelists with moderate and high sensitivity on the perception of graininess. Furthermore, the graininess can be modulated by regulating the fermented milks with larger microgels and with smaller microgels; however, the blending volume of the latter must exceed 50% to reduce the graininess of the former by 1–2 sensory intensity ranks.

Effect of Heat Treatment on Fatigue Performance of 316L Stainless Steel Fabricated by Laser Powder Bed Fusion

Abstract The 316L stainless steel part built by laser powder bed fusion has attracted much attention in recent years. However, current studies have not systematically revealed the influence of post-heat treatment on fatigue performance. In this study, we utilized two common heat treatment processes (450 °C anneal treatment and 1050 °C solution treatment) for 316L stainless steel and then discussed their influence on fatigue life and crack growth rate. It can be found that both the heat treatment processes led to a decrease in fatigue life. The 1050 °C solution treatment can decrease crack growth rate. This can be attributed to the increase in grain size and decline of carbide at the grain boundary. The former can lead to a longer propagation path. The latter may cause more and deeper secondary cracks along the propagation path, which exhaust more energy.

Effect of Secondary Phase on Electroless Ni Plating Behaviour of Super Duplex Stainless Steel SAF2507 for Advanced Li-Ion Battery Case.

The development of Li-ion battery cases requires superior electrical conductivity, strength, and corrosion resistance for both cathode and anode to enhance safety and performance. Among the various battery case materials, super duplex stainless steel (SDSS), which is composed of austenite and ferrite as two-phase stainless steel, exhibits outstanding strength and corrosion resistance. However, stainless steel, which is an iron-based material, tends to have lower electrical conductivity. Nevertheless, nickel-plating SDSS can achieve excellent electrical conductivity, making it suitable for Li-ion battery cases. Therefore, this study analysed the plating behaviour of SDSS plates after nickel plating to leverage their exceptional strength and corrosion resistance. Electroless Ni plating was performed to analyse the plating behaviour, and the plating behaviour was studied with reference to different plating durations. Heat treatment was conducted at 1000 °C for one hour, followed by cooling at 50 °C/s. Post-heat treatment, the analysis of phases was executed using FE-SEM, EDS, and EPMA. Electroless Ni plating was performed at 60-300 s. The plating duration after the heat treatment was up to 300 s, and the behaviour of the materials was observed using FE-SEM. The phase analysis concerning different plating durations was conducted using XRD. Post-heat treatment, the precipitated secondary phases in SAF2507 were identified as Sigma, Chi, and CrN, approximating a 13% distribution. During the electroless Ni plating, the secondary phase exhibited a plating rate equivalent to that of ferrite, entirely plating at around 180 s. Further increments in plating time displayed growth of the plating layer from the austenite direction towards the ferrite, accompanied by a reduced influence from the substrate. Despite the differences in composition, both the secondary phase and austenite demonstrated comparable plating rates, showing that electroless Ni plating on SDSS was primarily influenced by the substrate, a finding which was primarily confirmed through phase analysis.

How to characterise the anisotropy of laser powder bed fusion-processed parts? Towards a surrogate, non-destructive indentation-based approach

This work proposes a non-destructive indentation (NDI)-based surrogate mechanical testing framework for anisotropy and mechanical property evaluation of LPBF processed Inconel 718 superalloy. A Knoop-hardness tester was employed to develop the surrogate framework. Further post-heat treatments (PHTs) were performed at various cooling rates. The as-printed and PHT (SA, SB, SC, and SD) samples were characterized using X-ray diffraction (XRD) optical microscopy (OM), scanning electron microscopy (SEM), and electron back-scattered diffraction (EBSD) techniques. The yield locus plots show strong anisotropy for the as-printed sample. The IPF maps and pole figures for the as-printed samples showed elongated columnar grains with strong fiber texture along the (001) plane parallel to the build direction. They corroborated sufficiently with XRD, grain boundary map (GBM), and Kernel average misorientation (KAM) analysis. The yield locus shape of samples subjected to homogenization treatment becomes a nearly uniform ellipse with a reduction in the difference between σx and σy values, which can be attributed to the recrystallization of grains as observed by the transition from low-angle grain boundaries (LAGBs) to high angle grain boundaries (HAGBs). The PHT samples show a further increase in yield loci size due to the precipitation of γ’ and γ” strengthening phases due to aging treatment and corroborated with higher Taylor factor and dislocation density than the as-printed samples. The yield loci were sensitive to the PHT's cooling rates. Notably, among PHT ones, ‘SA’ samples exhibited a strong correlation (R2 ≈ 97.5 %) between the Taylor factor and yield locus. It was attributed to slower cooling rates (furnace cooled) with noticeably enhanced precipitation of strengthening phases, an increase in the volume fraction of recrystallized grains (from grain orientation spread (GOS) map), corroborating with higher dislocation density due to local strain as inferred from EBSD analysis. The proposed NDI surrogate approach was initially validated on an as-printed Inconel 718 stator blade. The yield locus showed a strong correlation between the stator blade and the as-printed sample, indicating the effectiveness of the proposed methodology.

“Whey protein nanoparticles obtained by water in oil emulsification followed by heating: Influence of surfactant type on the stability, rheology and interfacial properties”.

Whey protein isolate (WPI) nanoparticles were synthesized through water-in-oil (W/O) emulsions followed by heating. The aqueous phase containing 12% WPI was encapsulated within the emulsion droplets. During heat treatment at 80 °C for 15 min, the protein underwent gelation, leading to the formation of nanoparticles with different size and morphology depending on the emulsifier used. The examined surfactants were Polyglycerol Polyricinoleate (PGPR), Sorbitan monooleate 80 (Span 80), and a 3:1 mixture of Span 80/Polyoxyethylene sorbitan monooleate (SPTW). The study focused on understanding their interactions at the oil-water interface. Emulsions were assessed for stability, size, and optical properties, with analysis via confocal microscopy and rheology, both pre- and post-heat treatment. The resulting nanoparticles were examined using scanning electron microscopy (SEM). Interface analysis revealed similar behavior between PGPR and SPTW. However, PGPR exhibited superior stability in emulsions and was the only surfactant capable of producing nanoparticles upon thermal treatment. Conversely, emulsions containing Span 80 and SPTW experienced coalescence, leading to gelation of the aqueous phase and formation of large protein aggregates. These aggregates resulted in increased viscosity and elastic modulus of the heated emulsions. PGPR proved to be the only surfactant able to generate nanoparticles with a controlled size and shape, of approximately 300 nm.

Self-assembled titanium-based macrostructures with hierarchical (macro-, micro-, and nano) porosities: A fundamental study

This study details the novel self-assembly of sodium titanate converted Ti-based microspheres into hierarchical porous 3D constructs, with macro-, micro-, and nanoporosity, for the first time. Ti6Al4V microspheres were suspended into 5 M NaOH (60 °C/24 h) solutions, with extensive variations in microsphere:solution ratios to modify microsphere interaction and initiate self-assembly through proximity merging of titanate surface dendritic growth. The formed structures, which either produced 1) unbonded, sodium titanate-converted microspheres; 2) flat (non-macroporous) scaffolds; or 3) open, hierarchically porous scaffolds, were then assessed in terms of their formation mechanism, chemical composition, porosity, as well as the effect of post-heat treatments on compressive mechanical properties. It was found that specific microsphere:solution ratios tended to form certain structures (<⅓ powder, 0.5 to 3 porous, >3 flat non-macroporous, >8 powder) due to a combination of microsphere freedom of movement, H2 gas bubble formation, and exposed surface reactivity. This promising discovery highlights the potential for lower temperature, simplistic production of 3D constructs with modifiable chemical properties due to the ion-exchange potential of titanate structures, with clear applications in a wide-range of fields, from medical materials to catalysts.

Additive manufacturing of Invar 36 alloy

Invar 36 alloy, renowned for its ultra-low coefficient of thermal expansion (CTE), is a functional Fe–Ni alloy that finds wide applications in aerospace and precision instruments. Additive manufacturing (AM), as a rapid digital manufacturing process, can efficiently and flexibly fabricate Invar 36 alloy parts with complex geometric and exceptional properties. Considering the advantages of AM and the increasing interest and demand for Invar 36 alloy parts fabrication by AM in recent years, it is imperative to provide a comprehensive summary of the current research status and technological advancements pertaining to AM Invar 36 alloy. Firstly, an overview of the AM processes currently employed for fabricating Invar 36 alloy is provided, including laser powder bed fusion, selective laser sintering, directed energy deposition, cold spray additive manufacturing, wire arc additive manufacturing, and binder jetting. Additionally, the microstructure, mechanical properties, and CTE of Invar 36 alloy manufactured by AM are summarized. Even eliminating the post heat treatment, the as-printed Invar 36 alloy can achieve excellent low CTE and mechanical properties, comparable to or exceeding traditional manufacturing processes. Moreover, the advantages and research progress of AM Invar 36 alloy composites are introduced. Enhancing mechanical properties while reducing CTE is a common challenge for both AM Invar 36 alloy and Invar composites. Finally, the technical gaps, research trends, and potential applications of AM Invar 36 alloy are summarized and prospected.

Determination of minimum individual cow colostral immunoglobulin G concentration required to provide adequate total immunoglobulin G mass in pooled colostrum fed to Jersey calves.

Quantify the minimum individual cow colostral immunoglobulin G (IgG) concentration required for pooling to achieve adequate transfer of passive immunity in calves. 201 Jersey cows. Colostrum was collected from 28 pools and heat treated before being fed to calves or stored. Parity, total number of cows contributing to the pool, individual cow colostral volume contributions, and total volume of each colostrum pool were recorded. Colostrum IgG concentrations in individual and pooled (pre- and post-heat treatment) samples were analyzed by radial immunodiffusion and Brix refractometry. Colostral IgG concentration of ≥ 50g/L was considered the current recommended dairy industry standard for acceptable colostrum quality. Multivariable models were performed to determine factors affecting pooled colostral IgG concentrations. The minimum colostral IgG concentration required for pooling to achieve the recommended total mass of at least 200g IgG to be fed to a calf was calculated. Total pool volume and the number of cows contributing to the pool were significant factors affecting IgG concentration. Colostrum pools from ≤ 7 cows, with a minimum pool IgG concentration of 70.4 g/L (22.9% Brix) or colostrum pool volume ≤ 40 L, with a minimum pool IgG concentration of 66.2 g/L (21.8% Brix) achieved the recommended total mass of at least 200g IgG in 4L of colostrum. When feeding pooled colostrum, IgG concentrations higher than the industry standard of 50 g/L is recommended to reduce the risk of failure of transfer of passive immunity in calves.

Comparison of the Microstructural, Mechanical and Corrosion Resistance Properties of Ti6Al4V Samples Manufactured by LENS and Subjected to Various Heat Treatments.

In this paper, the influences of two post-heat treatments on the structural, mechanical and corrosion resistance properties of additively manufactured Ti6Al4V alloys were discussed in detail. The materials were produced using the laser engineering net shaping (LENS) technique, and they were subjected to annealing without pressure and hot isostatic pressing (HIP) under a pressure of 300 MPa for 30 min at temperatures of 950 °C and 1050 °C. Annealing without pressure led to the formation of a thin plate structure, which was accompanied by decreasing mechanical properties and increasing elongation and corrosion resistance values. For the HIP process, the formation of a thick plate structure could be observed, resulting in the material exhibiting optimal mechanical properties and unusually high elongation. The best mechanical and corrosion resistance properties were obtained for the material subjected to HIP at 950 °C.