Post-treatment Process Research Articles

Regulating material wettability through surface plastic deformation post-processing via friction modification

The wettability of engineering materials significantly influences their cleaning and antifreeze properties, making it a key consideration in aerospace applications. Methods for controlling surface plastic deformation can alter the wettability of materials and contribute to a certain level of strengthening effect, thereby presenting significant application potential. This study aimed to modify the wetting characteristics of aviation titanium alloys in harsh environments through adjustments in surface roughness via peening treatments (such as laser shock peening with coating and mechanical shot peening). The impact of various peening processes on wetting characteristics was investigated through comprehensive surface energy, macro, and nano morphology analyses. Static contact angle measurements were quantified, followed by evaluating other properties, such as surface free energy. Through adjustments in post-treatment processes and control of surface roughness, tailored acquisition of wetting characteristics was achieved. This study elucidates the beneficial effect of surface plastic deformation post-processing on controlling material wettability and introducing strengthening effects. Additionally, the study indicates the importance of accurately determining the sampling range for precise characterization of material wettability.

Direct Growth Graphene Via Atmospheric Pressure Chemical Vapour Deposition

The integration of graphene in field-effect transistor (FET) has aroused tremendous attention in the field of sensor technology, particularly for electronic biosensors. However, transferring graphene from metal substrates has destructive effects on the electrical characteristics of the graphene film, leading to severe impurities and defects. Here, we investigated a new approach of technique to synthesis direct- growth semiconducting graphene via atmospheric pressure chemical vapour deposition (APCVD) method. In this study we observe the effects of different reaction times, carbon concentrations and temperatures on the carbon arrangement in graphene. The synthesised graphene was characterised by Raman spectroscopy and field emission scanning electron microscopy (FESEM) to observe the quality of graphene formation. From the Raman analysis, the I2D/IG ratio < 1 indicates the formation of graphene in multiple layers. The ID /IG ratio < 1 was also observed, indicating that the graphene has less disorder of defects. Based on the electrical measurement of the material at estimated distance of 250 μm, a higher I2D/IG ratio leads to a higher resistance. Full width at half maximum (FWHM) of 2D band shows graphene with the highest I2D/IG ratio has the lowest value of FWHM. As the conclusion, these directly grown semiconducting graphene layers can be efficiently integrated into biosensors without any complex post-treatment process.

Remineralization of desalinated water: Duality roles of H2SO4 and CO2 injection during calco-carbonic equilibrium of osmosis water

In a desalination station, the remineralization step of osmosis water (OW) is essential to return to produced water its calco-carbonic equilibrium. For this, the use of calcite CaCO3 or lime Ca(OH)2 for water equilibrium in post-treatment processes needs the utilization of both CO2 and/or H2SO4 in osmosis water. For this reason, we describe here in detail, the effect of H2SO4 and CO2 on the remineralization process in a post-treatment desalination plant, especially with using hydrated lime Ca(OH)2 and calcite contactor (CaCO3)·In this paper, the different cases were discussed and investigated, by monitoring several indicator parameters such as pH, Ca2+ content, alkalinity, Langelier Index, etc. After the remineralization stage, we have shown that the efficiency of the remineralization process by CaCO3 or Ca(OH)2 depends on CO2 or H2SO4 content. Remineralization by CaCO3 (limestone) coupled with CO2 acidification is easy and more operator-friendly compared to the process using Ca(OH)2 (lime); it provides a clean environment for people working in the plant. In addition, the H2SO4 injection in the pretreatment stage followed by CaCO3 contact could lead to great results and correct calco-carbonic equilibrium. In the end, a comparative study of the investment cost in each process shows that the acidification of raw water with sulfuric acid (pretreatment) is the cheapest one, according to many studies. But on the other hand, the direct injection of CO2 is the easiest one to use for water balancing.

Facile one-pot synthesis of Cu-SSZ-39 catalysts with excellent catalytic performance in NH3-SCR reaction

Nitrogen oxide (NOx) emission from diesel vehicles has caused severe pollution to the atmospheric environment. Selective catalytic reduction of NOx with NH3 (NH3-SCR) technology has been widely used to remove NOx from diesel vehicle exhaust. Cu-SSZ-39 zeolites have exhibited excellent NH3-SCR catalytic activity and hydrothermal stability, giving them promise for practical application. A facile one-pot synthesis method to prepare Cu-SSZ-39 zeolites was developed, with complete crystallization achieved in 24 h. Moreover, the Cu content could be controlled by adjusting the amount of Cu-TEPA added without the need for complex post-treatment processes. Cu-SSZ-39 catalysts synthesized through the one-pot synthesis method exhibited excellent NH3-SCR activity and hydrothermal stability. The one-pot-synthesized Cu-SSZ-39 catalysts contained in situ generated CuO species, which can act as sacrificial sites to protect Cu2+ under sulfidation conditions. Considering their efficient synthesis process, excellent NH3-SCR activity, hydrothermal stability and sulfur resistance, one-pot-synthesized Cu-SSZ-39 catalysts hold great promise for future applications.

Hybrid peroxymonosulfate/activated carbon fiber-sequencing batch reactor system for efficient treatment of coking wastewater: Establishment and influential factors

Coking wastewater contains high concentrations of toxic and low biodegradable organics, causing long hydraulic retention times for its biological treatment process. This study developed a pretreatment method for coking wastewater by using activated carbon fiber (ACF) activated peroxymonosulfate (PMS) to improve the treatment performance of subsequent biological post-treatment process, sequencing batch reactor (SBR). The results showed that, after optimization of treatment processes, the removal efficiency of chemical oxygen demand (COD), phenol, and chroma in coking wastewater reached to 76, 98, and 98%, respectively, with a significantly improved biodegradability. Compared with the sole SBR system without any pretreatment that could remove 73% of COD, the ACF/PMS+SBR system removed over 97% of COD in coking wastewater. Moreover, this pretreatment method facilitated the growth of functional bacteria for organics biodegradation, indicating its high potential as a highly efficacious pretreatment strategy to improve the overall treatment efficiency of coking wastewater.

Supercritical CH3OH-Triggered Isotype Heterojunction and Groups in g-C3N4 for Enhanced Photocatalytic H2 Evolution.

The structure tuning of bulk graphitic carbon nitride (g-C3N4) is a critical way to promote the charge carriers dynamics for enhancing photocatalytic H2-evolution activity. Exploring feasible post-treatment strategies can lead to effective structure tuning, but it still remains a great challenge. Herein, a supercritical CH3OH (ScMeOH) post-treatment strategy (250-300 °C, 8.1-11.8 MPa) is developed for the structure tuning of bulk g-C3N4. This strategy presented advantages of time-saving (less than 10 min), high yield (over 80%), and scalability due to the enhanced mass transfer and high reactivity of ScMeOH. During the ScMeOH post-treatment process, CH3OH molecules diffused into the interlayers of g-C3N4 and subsequently participated in N-methylation and hydroxylation reactions with the intralayers, resulting in a partial phase transformation from g-C3N4 into carbon nitride with a poly(heptazine imide)-like structure (Q-PHI) as well as abundant methyl and hydroxyl groups. The modified g-C3N4 showed enhanced photocatalytic activity with an H2-evolution rate 7.2 times that of pristine g-C3N4, which was attributed to the synergistic effects of the g-C3N4/Q-PHI isotype heterojunction construction, group modulation, and surface area increase. This work presents a post-treatment strategy for structure tuning of bulk g-C3N4 and serves as a case for the application of supercritical fluid technology in photocatalyst synthesis.

Surface self-assembly via one-pot polymerization to construct high-strength and antibacterial polyethylene fabric

An increasing number of hospital-acquired infections (HNIs) confirms the urgency of medical protective fiber material (MDPF), which possesses high strength, low toxicity and excellent hydrophobicity and is considered as an effective method to deal with HNIs. However, the current performance of MDPF mainly relies on a single physical barrier mechanism, and pathogenic and contagious bacteria or virus attached on the surface barrier layer are one of the important paths for secondary infection. Therefore, research on the fabrication of highly effective antibacterial MDPF is of great significance for preventing contagious infections. Herein, high-strength, environment-friendly and antibacterial PE@PDA@ZnO-Ag (PE@PDAZA) nonwoven fabric was successfully prepared through a simple one-pot coating method. The functional fabric exhibits antibacterial rate up to 99.9 % against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) with low amount of antibacterial agent additions. Moreover, the fabric exhibits tested tensile strength of 35.4 ± 2.9 MPa. This work provides a new strategy for preparing high-strength and automatically-protective MDPF, which can reduce hospital-acquired contagious infections through a simple post-treatment process and has great potential for large-scale production.

Catalytic post-treatment of homogeneous Ag–S2O8 and Cu–H2O2 advanced oxidation processes: Revealing the importance of capacitive-Faradaic electrochemical structure of Pt/AC

Implementation of homogeneous advanced oxidation processes (HAOPs) catalysed by Cu and Ag metals is limited due to high residual concentrations of oxidants and dissolved metals. The proposed post-treatment process starts with recirculation of H2-enriched HAOP-treated water through the Pt-loaded activated carbon (AC). Hydrogen oxidation reaction (HOR) on Pt results in degradation of oxidants while silver and/or copper ions are reduced and deposited on the catalytic media. The subsequent aeration of the catalyst results in oxygen reduction reaction (ORR) and oxidation of the metals back into ionic forms. This allows the homogeneous metal catalysts to be reused in multiple HAOP cycles.The capacitive-Faradaic electrochemical structure of the Pt/AC catalyst with Pt acting as a Faradaic electrode and AC as a capacitive electrode plays an important role in the process. The HOR on Pt/AC results in accumulation of electrons in electrical double layer of AC. These electrons can be effectively used in a subsequent H2-free reduction of metal ions and oxidants. Thus, the degradation of H2O2 and S2O82− and reduction of Cu2+ and Ag + ions proceed much faster if the H2-step of the process is split into two sub-processes: (i) hydrogenation of Pt/AC catalyst in an inert Na2SO4 solution to pre-charge the Pt/AC with electrons originating at HOR, followed by (ii) catalytic reduction of oxidants and metal ions by the capacitively stored electrons.The process was investigated using Ag–S2O82− ([S2O82−]0 = 25 mM; [Ag+]0 = 50 mg/L) and Cu–H2O2 ([H2O2]0 = 100 mM, [Cu]0 = 635 mg/L) solutions. Total degradation of oxidants was achieved within <2 h and complete metals’ recovery was obtained. Several cycles of HAOP experiments were performed for the degradation of 1,4-dioxane (10 mg/L) and phenol (25 mg/L) using Ag– S2O82− and Cu–H2O2 HAOPs, respectively. The residual oxidants were completely degraded in all experiments. The reactivation of Pt/AC catalysts inhibited by phenol derivatives was achieved by hydrogenation in Na2SO4 solution (i.e., using the pre-charge approach).

Investigations towards nanoscale precise polishing of Nb3Sn thin films for SRF applications

The superconducting radio frequency performance of Nb3Sn is significantly impacted by its near-surface composition and nanostructure. In this study, an innovative polishing technique for Nb3Sn thin films with nanoscale precision is proposed. Systematic angle-resolved X-ray photoelectron spectroscopy (ARXPS) analysis reveal that the mechanism of this polishing process involves the formation of a few nanometer-thick oxide layer on the film's surface, followed by the uniform removal of the oxide layers with HF rinse. It is approximated that the polishing depth achieved in a single cycle can reach several nanometers. Advanced material characterization demonstrates that optimized polishing process effectively eliminates compulsive tin droplets and potential tin-rich phases with poor superconductivity generated on the surface during the preparation of Nb3Sn thin films. Simultaneously, no additional impurity phase will be formed on the surface, and the surface roughness will remain undamaged. Meanwhile, the results of magnetic and electrical analysis show that the superconducting properties of the polished films are not affected. This polishing technique is anticipated to ease the stringent coating conditions for the preparation of high-performance Nb3Sn thin film superconducting cavity, and will be a valuable addition to the post-treatment process of Nb3Sn thin films.

Enhancing thermal conductivity of sinterized bronze (Cu89/Sn11) by 3D printing and thermal post-treatment: Energy efficiency and environmental sustainability

Enhancing the thermal conductivity of bronze is essential to enhance the efficiency of heat transfer and reduce energy consumption in systems such as heating, cooling, and heat exchangers systems. This study investigates the feasibility of producing sinterized bronze (Cu89/Sn11) using low-cost 3D printing Fused Deposition Modeling (FDM) technology and thermal post-treatment processes. The intention is to identify optimal printing parameters and sintering temperatures to maximize thermal conductivity, while focusing on minimizing energy consumption, raw material usage, and environmental impact. The thermal conductivity of twenty-seven samples was evaluated according to the ASTM E1530:2019 standard. A statistical analysis revealed significant effects of nozzle diameter and flow rate on thermal conductivity and density. The optimal results were obtained with a sintering temperature of 845 °C, a 1.0 mm nozzle diameter, and a 110 % flow rate. These conditions yield the highest thermal conductivity (87.61 W/m·K) and density (7.52 g/cm3). The lowest values were observed at a sintering temperature of 865 °C, a 0.6 mm nozzle diameter, and a 100 % flow rate. A Life Cycle Assessment (LCA) using the ReCiPe Endpoint (E) methodology was employed to compare the environmental impact of the resulting thermal conductivities. The results suggest that sintered bronze produced by FDM and thermal post-treatment provide superior performance and a smaller environmental impact than conventional methods. This study underscores the potential for more efficient and sustainable manufacturing practices in the production of sintered bronze.

Effect of Ni content on microstructure and mechanical properties evolutions of 9Cr high Si heat resistant steel deposited metals

This work presents the effect of Ni content on the morphology of microstructure and changes of mechanical properties of high Si 9Cr heat resistant steel deposited metals with different states: as-welded, as-post weld heat treated (750 °C/2.5 h) and as-aged (550 °C/3000 h). With the increase of Ni content, the martensitic laths are refined improving the overall mechanical properties. δ ferrite deteriorates the impact toughness. During aging process, Ni facilitates the formation of M6X. Therefore the overall mechanical properties of deposited metal decreases as the Ni content increases after long-term aging owing to the formation of chain-like precipitates consisted mainly of M6X. The process of post weld heat treatment improves the negative effect of small-sized δ ferrite on impact toughness.

In Vivo Investigation of 3D-Printed Calcium Magnesium Phosphate Wedges in Partial Load Defects.

Bone substitutes are ideally biocompatible, osteoconductive, degradable and defect-specific and provide mechanical stability. Magnesium phosphate cements (MPCs) offer high initial stability and faster degradation compared to the well-researched calcium phosphate cements (CPCs). Calcium magnesium phosphate cements (CMPCs) should combine the properties of both and have so far shown promising results. The present study aimed to investigate and compare the degradation and osseointegration behavior of 3D powder-printed wedges of CMPC and MPC in vivo. The wedges were post-treated with phosphoric acid (CMPC) and diammonium hydrogen phosphate (MPC) and implanted in a partially loaded defect model in the proximal rabbit tibia. The evaluation included clinical, in vivo µ-CT and X-ray examinations, histology, energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) for up to 30 weeks. SEM analysis revealed a zone of unreacted material in the MPC, indicating the need to optimize the manufacturing and post-treatment process. However, all materials showed excellent biocompatibility and mechanical stability. After 24 weeks, they were almost completely degraded. The slower degradation rate of the CMPC corresponded more favorably to the bone growth rate compared to the MPC. Due to the promising results of the CMPC in this study, it should be further investigated, for example in defect models with higher load.

Post-Treatment and Hybrid Techniques for Prolonging the Service Life of Fused Deposition Modeling Printed Automotive Parts: A Wear Strength Perspective

&lt;div&gt;This study aims to explore the wear characteristics of fused deposition modeling (FDM) printed automotive parts and techniques to improve wear performance. The surface roughness of the parts printed from this widely used additive manufacturing technology requires more attention to reduce surface roughness further and subsequently the mechanical strength of the printed geometries. The main aspect of this study is to examine the effect of process parameters and annealing on the surface roughness and the wear rate of FDM printed acrylonitrile butadiene styrene (ABS) parts to diminish the issue mentioned above. American Society for Testing and Materials (ASTM) G99 specified test specimens were fabricated for the investigations. The parameters considered in this study were nozzle temperature, infill density, printing velocity, and top/bottom pattern. The hybrid tool, i.e., GA–ANN (genetic algorithm–artificial neural network) has been opted to train, predict, and optimize the surface roughness and sliding wear of the printed parts. Results disclose that the minimum surface roughness obtained with GA–ANN was 1.05482 μm for infill density of 68%, nozzle temperature of 230°C, printing velocity of 80 mm/sec, and for concentric type of top/bottom pattern. In extension of this study, annealing was performed on the specimens printed on the optimized results obtained from the analysis at three different temperatures of 110°C, 150°C, and 190°C and for a fixed period of time of 60 min as a post-treatment process to further study the impact of annealing on the surface roughness and wear rate. The surface roughness of the samples showed a discernible improvement as a result of annealing, which can further make significant inroads in automotive industries.&lt;/div&gt;

Application of local fatigue strength approach to assess and optimise the impact of deep rolling on the fatigue performance of railway axles

Deep rolling is a frequently used post-treatment process to increase the service life of railway axles. Through the process application, the surface roughness is reduced, the surface is work-hardened and compressive residual stresses are introduced in the near surface region in a controlled manner. These three effects have a positive impact on service life, and in the investigated case of railway axles, the introduced residual stress state constitutes the most significant potential. The compressive residual stresses introduced near the surface, which are responsible for the positive lifetime effect, are inevitably balanced by compensating tensile residual stresses below the surface. Therefore, it is generally challenging to estimate the actual potential of the process application properly. Classical design methods consider only the condition at the surface and are thus not suitable for a surface layer-based analysis. In the present publication, the concept of local fatigue strength is applied for the fatigue strength assessment of deep rolled railway axles. The locally permissible fatigue strength at each surface-layer depth of the railway axle is determined as a function of local properties and compared with the locally occurring load. This allows a proper fatigue design in depth and, at the same time, the estimation of the critical point at which the potential of crack initiation and thus failure occurs. Based on the methodology presented, it is possible to determine the fatigue benefit achieved by deep rolling railway axles considering the influence of various deep rolling parameters, and to further systematically optimise the significant process parameters. An increase in fatigue strength of 4.7 % can be proven by deep rolling the railway axle with reference parameters compared with the not deep rolled state. By applying the proposed optimisation, fatigue strength can be further increased up to 10.4 %.

Review on the Tensile Properties and Strengthening Mechanisms of Additive Manufactured CoCrFeNi-Based High-Entropy Alloys

The advent of high-entropy alloys (HEAs) provides new possibilities for the metallurgical community. CoCrFeNi-based alloys have been widely recognized to demonstrate superior mechanical properties, amongst the high-entropy alloy systems; in particular, they possess an outstanding tensile ductility and work-hardening capacity. Additive manufacturing (AM) uses a layer-by-layer material deposition approach to build parts directly from computer-aided design models, which are capable of producing near-net-shape HEAs with superior mechanical properties, surpassing traditional manufacturing methods that require a time-consuming post-treatment process, such as cutting, milling, and molding. Moreover, the rapid solidification inherent in AM processes induces the formation of high-density dislocations, which are capable of enhancing the mechanical properties of HEAs. This review comprehensively investigates and summarizes the diverse strengthening mechanisms within CoCrFeNi-based alloys produced using AM technologies, with a specific focus on their influence on tensile properties. A correlation is established between the AM processing parameters and the resultant phases and microstructures, as well as the mechanical properties of CoCrFeNi-based HEAs, which provide guidelines to achieve a superior strength–ductility synergy.

Laser shock peening of laser melting deposited TiAl alloy for enhancing its corrosion resistance

Laser shock peening (LSP), as a post-treatment process, was employed to improve the corrosion resistance of Ti45Al8Nb alloy fabricated via laser melting deposition (LMD). Microstructure analysis indicated that nanograins and nanotwins structures were formed on the surface layer of LSP-treated Ti45Al8Nb alloy, accompanied by high-density dislocations and stacking faults. Electrochemical results showed that LSP improves the corrosion resistance of Ti45Al8Nb alloy. The formation of nanograins, nanotwins and compressive residual stress during LSP was conductive to dense oxidation films, thus improving the corrosion resistance of the as-deposited Ti45Al8Nb alloy.

High-Efficiency Pure-Red CsPbI3 Quantum Dot Light-Emitting Diodes Enabled by Strongly Electrostatic Potential Solvent and Sequential Ligand Post-treatment Process.

Efficient pure-red emission light-emitting diodes (LEDs) are essential for high-definition displays, yet achieving pure-red emission is hindered by challenges like phase segregation and spectral instability when using halide mixing. Additionally, strongly confined quantum dots (QDs) produced through traditional hot-injection methods face byproduct contamination due to poor solubility of metal halide salts in the solvent octadecene (ODE) at low temperatures. Herein, we introduced a novel method using a benzene-series strongly electrostatic potential solvent instead of ODE to prevent PbI2 intermediates and promote their dissolution into [PbI3]-. Increasing methyl groups on benzene yields precisely sized (4.4 ± 0.1 nm) CsPbI3 QDs with exceptional properties: a narrow 630 nm PL peak with photoluminescence quantum yield (PLQY) of 97%. Sequential ligand post-treatment optimizes optical and electrical performance of QDs. PeLEDs based on optimized QDs achieve pure-red EL (CIE: 0.700, 0.290) approaching Rec. 2020 standards, with an EQE of 25.2% and T50 of 120 min at initial luminance of 107 cd/m2.

Introduction to subpressure-driven soft deformation method for removing inherent voids in green components manufactured by material extrusion

This study introduces a post-treatment process, the subpressure-driven soft deformation method, to reduce inherent voids in Material Extrusion (MEX) components. By subjecting printed green components to heat treatment under subpressure, the process enhances viscosity, effectively filling voids formed between deposited tracks. The average porosities of the samples sintered from the green components without and with soft deformation are calculated to be 3.55% and 2.36%, respectively. A comparison of the tensile strengths and fracture surfaces of the sintered samples with and without soft deformation treatment indicated that the sintered samples with soft deformation treatment exhibited narrower standard deviation for the various mechanical properties. Capillary rheometer calculations indicate feedstock viscosity to be between 450.34 and 1018.31 Pa s under subpressure, diminishing inter-track voids without sizeable dimensional changes. Molecular dynamics simulation demonstrates a 3.7-fold increase in bond strength, indicating intertrack voids effectively eliminated. Reduced inter-particle distances facilitate necking, grain growth, and improved sintered density.

Non-heat source forming technology of binder jetting metal powder and its post-treatment process

Non-heat source forming technology of binder jetting metal powder and its post-treatment process

Solution Blow Spinning of the Benzimidazole-Containing Aramid Nanofibers for Separators of Lithium-Ion Batteries.

Nanofibers based on high-performance polymers are much highlighted in recent studies toward advanced lithium-ion batteries. Herein, we demonstrate one scalable poly(ethylene oxide) (PEO)-assisted solution blow spinning strategy for the preparation of heterocyclic aramid (HA) nanofibers of poly(p-phenylene-benzimidazole-terephthalamide). The incorporation of PEO is essential to improve the spinnability of the HA solution achieved directly through the low-temperature-solution copolymerization process. Additionally, the flexible PEO with a strong H-bonding affinity is also utilized as the molecular zipper to adjust the pore size of the nanofiber membrane during the post-treatment process. The obtained membrane combines the good wettability of PEO to the liquid electrolytes, with outstanding mechanical strength, modulus, toughness, and environmental resistance of HA. The nonwoven separator membranes with a porosity of 83.6% exhibited excellent comprehensive performance, which could be seen not only on the high tensile strength (68.2 MPa), modulus (3.0 GPa), and toughness but also on the high thermal stability (Td > 405 °C) and flame retardancy, as well as the high electrolyte uptake (302.4%). The ion conductivity of the porous separators reached 0.83 mS/cm, with the bulk resistance dropping to 1/4 of the reference polypropylene separator. In the assembly of the Li/LiFePO4 half battery, the HA separators displayed improved discharge specific capacity and high retention in both rate capability and cycling tests, providing the potential industrial preparation for advanced lithium-ion batteries.