Post-sintering Process Research Articles

The impact of sintering temperature on the thermoelectric performance of Cu2Se synthesized by solid state reaction method

In this study, copper selenide (Cu2Se) compounds were synthesized using a solid-state reaction technique and post-sintering processes (573 ​K–973 ​K). The mass density of the Cu2Se compounds decreased with increasing sintering temperatures due to changes in grain morphology and an increase in the number and size of pores in the samples. The sintering temperature also affected carrier generation mechanisms, which directly impacted the electrical transport characteristics and thermal properties. The α→β phase transition at around 400 ​K was observed in all samples. The low thermal conductivity was mainly attributed to the low lattice thermal conductivity (κlattice). As the result, the sample sintered at 773 ​K showed an outstanding ZT value of 1.44 ​at 773 ​K, with a power factor of 12.1 μWm−1K−2 and the thermal conductivity of 0.65 Wm−1K−1. The sintering temperature dependence of thermal conductivity was elucidated in terms of the growth of microstructural pores.

A cold spray-based novel manufacturing route for flexible electronics

In this research, we propose a cold spray-based novel manufacturing route that enables the custom production of flexible electronics (FE) at high spatial resolution without a need of high-temperature post-sintering process. The proposed manufacturing route sequentially comprises: (1) cold spray metallization; (2) femtosecond laser machining; and (3) ultrasonic plastic welding. First, the flexible polymer (i.e., PET) surface is metallized by cold spray direct writing of Tin (Sn) particles under vacuum-and mask-free conditions. The as-metallized polymer film is then precisely cut into arbitrarily designed high-resolution electrodes (i.e., 500 μm linewidth) by femtosecond laser machining. Lastly, the laser-cut electrodes are joined onto a base polymer substrate via ultrasonic plastic welding to constitute mechanically resilient and conformal FE. In this way, the proposed route enables exploiting the unique features of cold spray deposits in FE (e.g., strong adhesion, high conductivity, minimal thermal input). The resultant printings show excellent electrical conductivity (1.08 × 106 S·m−1), flexibility (60 % elongation), and adhesion strength without significantly compromising intrinsic polymer and functional coating properties. Moreover, a serpentine-shaped flexible microheater (10 × 10 mm2) is also fabricated to demonstrate the viability of the introduced platform in flexible microelectronics. This work potentially provides a promising route toward the rapid, scalable, and cost-effective production of high-resolution and high-performance FE in a mechanically resilient and conformal manner.

Cold spray-based rapid and scalable production of printed flexible electronics

Flexible electronics (FE) is attracting great attention from both scientific and industrial communities, and plays a crucial role in smart device applications. Despite great promise, traditional printing approaches ( e.g. , screen printing, ink-jet printing, etc.) often need a high-temperature post-sintering process to produce FE with desired electrical conductivity and adhesion strength. The post-sintering processes, however, often lead to fast oxidation of the functional coating while limiting the use of low-thermal budget substrates. Exponential advance of FE in a large-scale and energy-efficient manner relies on rationally eliminating the post-sintering processes. To this end, with the aim of uncovering process-structure-properties relationships, we employ the emerging cold spray (CS) technique for rapid and scalable production of FE without a need for high-temperature post-sintering. In this regard, micron-scale Tin (Sn) particles are directly written on a flexible polymer substrate (PET) by cold spraying under ambient conditions. The effect of CS process parameters on the resultant coatings is comprehensively characterized in terms of microstructure, film thickness, electrical conductivity, linewidth, and adhesion strength. The resulting electrodes show excellent electrical conductivity (6.98×10 5 S.m -1 ), adhesion strength, long-term stability, and flexibility without significant conductivity loss after 1,000 bending cycles. By leveraging the CS operational settings, a resistive macro-heater (12×15 cm 2 ) and an LED circuit (2.5 cm×18 cm) are fabricated to demonstrate the applicability of the CS in printed FE. Moreover, to address the low-spatial resolution of CS writing, a case study on sequential CS and femtosecond laser machining is performed, which further led to ultra-high resolution ( i.e. , 30 µm linewidth) custom-designed flexible electrodes. Thus, the present study reveals the immense potential of the CS technique for rapid and scalable production of FE without the need for post-sintering. • Cold spray deposition is employed in printed flexible electronics (FE). • Tin (Sn) particles are directly written on a flexible substrate (PET) at ambient conditions. • Flexible electrodes with excellent electrical conductivity (6.98×10 5 S.m -1 ) are achieved. • The resultant electrodes are constructed into FE applications such as a resistive heater. • Cold spray is found to be promising for rapid and scalable production of printed FE.

3D printing of hierarchically porous monolithic TS‐1 catalyst for one-pot synthesis of ethylene glycol

Structured monolithic catalysts have attracted increasing attention in the petrochemical industry due to their advantages of high heat and mass transfer rate, easy scale-up, and reusability. Herein, we put forward a strategy for one-step preparation of SiO2-based monolithic TS-1 catalysts with optimal hierarchical scaffolds by combining the flow field simulation of the reactor and 3D printing technology. Tunable hierarchical porosity from nano to micro scales, suitable pore characteristics, and numerous active sites have been obtained by innovatively combining the spherical porous structure of TS-1/SiO2 material, direct ink writing (DIW) and post-sintering processes. Combined with computational fluid dynamics (CFD) analysis, the effects of different channel offset angles, axial and radial channel sizes on the 3D printed monolithic TS-1 in the catalytic reaction of one-step oxidation of ethylene to ethylene glycol (EG) were verified. 3D-printed monolithic TS-1 catalysts exhibited superior crush strengths (135.11 N/cm) and extraordinary catalytic efficiency, in which the yield of EG reached 82.7%, and the utilization of hydrogen peroxide reached 85.3%. Moreover, the 3D printed TS-1 monolith maintained high catalytic performance over 5 reusable cycles, which solved the problem that traditional catalysts are difficult to be manufactured, separated, and recycled, and presented considerable prospects in reactions requiring fluid agitation.

Aerosol Jet® Printing of Poly(3,4-Ethylenedioxythiophene): Poly(Styrenesulfonate) onto Micropatterned Substrates for Neural Cells In Vitro Stimulation.

In neural tissue engineering (NTE), topographical, electrical, mechanical and/or biochemical stimulations are established methods to regulate neural cell activities in in vitro cultures. Aerosol Jet® Printing is here proposed as enabling technology to develop NTE integrated devices for electrically combined stimulations. The printability of a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS) commercial ink onto a reference substrate was firstly investigated and the effect of the process parameters on the quality of printed lines was analyzed. The study was then extended for printing thick electrodes and interconnects; the print strategy was finally transferred to a silicon-based wafer with patterned microchannels of proven cellular adhesion and topographical guidance. The results showed values of electrical resistance equal to ~16 Ω for printed electrodes which are ~33 μm thick and ~2 mm wide. The electrical impedance of the final circuit in saline solution was detected in the range of 1 – 2 kΩ at 1 kHz, which is in line with the expectations for bioelectronic neural interfaces. However, cells viability assays on the commercial PEDOT: PSS ink demonstrated a dose dependent cytotoxic behavior. The potential cause is associated with the presence of a cytotoxic co-solvent in the ink’s formulation, which is released in the medium culture, even after a post-sintering process on the printed electrodes. This work is a first step to develop innovative in vitro NTE devices via a printed electronic approach. It also sheds new insights the transfer of AJ® print strategies across different substrates, and biocompatibility of commercial PEDOT: PSS inks.

Biaxial Flexural Strength of Different Monolithic Zirconia upon Post-Sintering Processes.

Objective Different post-sintering processes are expected to be a reason for alteration in the strength of zirconia. This study evaluated the effect of post-sintering processes on the flexural strength of different types of monolithic zirconia. Materials and Methods A total of 120 classical- (Cz) and high-translucent (Hz) monolithic zirconia discs (1.2 mm thickness and 14 mm in Ø) were prepared, sintered, and randomly divided into four groups to be surface-treated with (1) as-glazed (AG); (2) finished and polished (FP); (3) finished, polished, and overglazed (FPOG); and (4) finished, polished, and heat-treated (FPHT) technique ( n = 15). Biaxial flexural strength (σ) was determined on a piston-on-three ball in a universal testing machine at a speed of 0.5 mm/min. Statistical Analysis Analysis of variance, and post hoc Bonferroni multiple comparisons were determined for significant differences ( α = 0.05 ). Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristic strength (σ 0 ). The microstructures were examined with a scanning electron microscope and X-ray diffraction. Results The mean ± standard deviation value of σ (MPa), m, and σ 0 were 1,626.43 ± 184.38, 9.51, and 1,709.79 for CzAG; 1,734.98 ± 136.15, 12.83, and 1,799.17 for CzFP; 1,636.92 ± 130.11, 14.66, and 1,697.63 for CzFPOG; and 1,590.78 ± 161.74, 10.13, and 1,663.82 for CzFPHT; 643.30 ± 118.59, 5.59, and 695.55 for HzAG; 671.52 ± 96.77, 3.28, and 782.61 for HzFP; 556.33 ± 122.85, 4.76, and 607.01 for HzFPOG; and 598.36 ± 57.96, 11.22, and 624.89 for HzFPHT. The σ was significantly affected by the post-sintering process and type of zirconia ( p < 0.05), but not by their interactions ( p > 0.05). The Cz indicated a significantly higher σ than Hz. The FP process significantly enhanced σ more than other treatment procedures. Conclusion Post-sintering processes enabled an alteration in σ of zirconia. FP enhanced σ, while FPOG and FPHT resulted in a reduction of σ. Glazing tends to induce defects at the glazing interface, while heat treatment induces a phase change to tetragonal, both resulted in reducing σ. Finishing and polishing for both Cz and Hz monolithic zirconia is recommended, while overglazed or heat-treated is not suggested.

Tribological behavior of metallo-ceramic composites for high friction and high temperature applications

The development of materials for high temperature application posed challenges at all time. The present work deals with the development of copper – iron based material for brake pads preferably where the kinetic energy of vehicle is more at the time of halt. The copper powder approximately 60% of the composition along with iron, silicon carbide, graphite and barium sulphate are mixed thoroughly in a ball mill. These are new family of materials which possess same strength as ceramics and also possess good fracture toughness equal to that of metal. It is then compacted and sintered. After post sintering process the material is machined suitably and the test specimens are prepared for the wear test. The composite performs better at higher temperature and at lower sliding distance. The coefficient of friction shows a very gradual increase with the increase in time.

Hierarchically porous alumina catalyst carrier with biomimetic vein structure prepared by direct ink writing

Biomimetic porous ceramics have great application potential in the petrochemical industry; their biomimetic porous structure is conducive to mass transfer, energy exchange and catalytic reactions. However, it is challenging to produce biomimetic porous ceramics with complex shapes using conventional processes. Herein, we demonstrate a novel structural bionic and 3D printing strategy and a pseudo-boehmite-based slurry for fabricating hierarchical alumina ceramic carriers with biomimetic vein structures. Tuneable hierarchical porosity from nm to mm scales, high specific surface area, and superior strength have been achieved by innovatively combining dehydroxylation and peptisation of pseudo-boehmite, direct ink writing (DIW), and post-sintering processes. The effects of post-sintering temperature and impregnation treatment on the crush strength, porosity, and specific surface area were systematically investigated. The optimised porous ceramics exhibited a crush strength of 54.453 ± 7.359 N/cm, specific surface area of 109.870 ± 0.143 m2/g, and porosity of 60.03 ± 2.72%. The catalytic test for dry reforming of methane was conducted on biomimetic catalysts loaded with nickel (Ni) and phosphorus (P). The biomimetic catalyst had a remarkable methane conversion of 41.27%, in addition to mass transfer and coke inhibition effects. Through the integrated biomimetic design of macro–micro structures, monolithic alumina catalyst carriers with biomimetic vein structures prepared by DIW can potentially be used more efficiently in industrial catalytic reactions.

Fracture toughness of different monolithic zirconia upon post-sintering processes.

BackgroundSurface treatments are expected to be a reason for alteration in fracture resistance of zirconia. This study evaluated the effect of post-sintering processes on the fracture toughness of different types of monolithic zirconia. Material and MethodsClassical- (Cz) and high-translucent (Hz) monolithic zirconia discs (1.2 mm thickness, 14 mm in Ø) were prepared, and randomly divided for surface treatments with 1) as-glazed (AG); 2) finished and polished (FP); 3) finished, polished, and overglazed (FPOG); and 4) finished, polished, and heat-treated (FPHT) technique (n=15/group). Fracture toughness (KIC) was determined with indentation fracture toughness method at load 1 kg for AG, FPOG and 10 kg for FP, FPHT with 15 sec dwelling time. Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristic toughness (K0). Microstructures were examined with SEM and XRD. ANOVA and multiple comparisons were determined for significant differences (α=0.05). ResultsThe mean±sd value of KIC (MPa.m1/2), m, and K0 were 1.60±0.19, 7.27, 1.71 for CzAG; 9.57±0.89, 9.97, 10.96 for CzFP; 1.61±0.15, 10.56, 1.68 for CzFPOG; 6.45±0.31, 20.31, 6.60 for CzFPHT; 1.45±0.13, 10.91, 1.51 for HzAG; 6.58±0.24, 27.00, 6.70 for HzFP; 1.24±0.05, 23.90, 1.27 for HzFPOG; and 5.07±0.16, 30.51, 5.15 for HzFPHT. The KIC was significantly affected by the post-sintering process, type of zirconia (p<0.05). The Cz indicated a significantly higher KIC than Hz. The FP significantly enhanced KIC, while OG was unable to raise KIC. HT reduced KIC due to reverse phase transformation. ConclusionsPost-sintering processes caused alteration in fracture resistance of zirconia. Fracture toughness was enhanced with FP, but not with either OG or HT process for both Cz and Hz. Surface treatment of zirconia through a finished-polished process is recommended, while glazing and heat-treated are not suggested. Key words:Fracture toughness, glazing, heat treatment, polishing, post-sintering process, zirconia.

Synthesis of super-fine L10-FePt nanoparticles with high ordering degree by two-step sintering under high magnetic field

Super-fine L10-FePt nanoparticles (NPs) with high ordering degree were successfully prepared by a modified two-step sintering method, which includes low-temperature pre-sintering, and the high magnetic field (HMF) assisted post-sintering processes. The particle size of the L10-FePt NPs was obviously refined by lowering the sintering temperature. By applying the HMF during the post-sintering process, the fine size characteristics of L10-FePt NPs were retained, and the ordering degree was significantly improved. The L10-FePt NPs with sizes of about 4.5 nm, ordering degree of 0.940, and coercivity of 22.01 kOe were obtained by this two-step sintering under a magnetic field of 12 T. The mechanism investigation of HMF enhancing the ordering degree indicates that the HMF enhances lattice distortion and magnetization energy (Zeeman energy). The enhanced lattice distortions cause high stress existing in the lattice, which can effectively promote the disordered-order transition. When the magnetic field reaches to 3 T, the Zeeman energy of the NPs is higher than the thermal disturbing energy of the NPs, and the magnetization effect is stronger. Therefore, the HMF (higher than 3 T) can obviously improve the disorder-order transition by lowering the energy barrier and accelerating the orderly diffusions of atoms. The HMF is a promising assistant to synthesize the L10-phase NPs with both of high ordering degree and super-fine size.

Novel g–C3N4–carbon dots-aggregation/ferrite hybrid heterojunction photocatalyst with excellent visible-light-driven photodegradation performance toward organic pollutants

Abstract In water pollution treatment, photocatalytic technology is attracting intensive attention and photocatalysts have extensively been focused on, but high efficiency still remains expected. Herein, a spherical uniformly-dispersed aggregation photocatalyst of carbon dots (CDs) with g-C3N4 was hydrothermally synthetized through employing glucose as carbon sources for CDs and employing cyanuric chloride and dicyandiamine for the formation of g-C3N4, and then coupling with 10 wt% of new hydrothermal ferrite photocatalyst Ni0.1Co0.9Fe2O4 to fabricate a novel g–C3N4–CDs-aggregation/ferrite hybrid heterojunction photocatalyst through post sintering process. Various techniques including SEM, HRTEM, XRD, XPS, UV–vis and EIS spectroscopy were employed to analyze the as-fabricated ternary hybrid photocatalyst. Due to the uniformly-dispersed modification of CDs to g-C3N4 and the hybrid heterojunction between g–C3N4–CDs aggregation with Ni0.1Co0.9Fe2O4, the targeted hybrid photocatalyst presented excellent visible-light-driven photocatalytic degradation efficiency towards methylene blue, with a high degradation ratio of up to 96.6% in 1 h, corresponding to a photodegradation rate constant k value of up to 0.05127 min−1. Our targeted hybrid photocatalyst shows good structural and photocatalytic stability and electronic radical (e−) is the main active species during photocatalytic process.

Optimization of sintering process on Li1+xAlxTi2-x(PO4)3 solid electrolytes for all-solid-state lithium-ion batteries

In this study, a NASICON-structured Li1.3Al0.3Ti1.7(PO4)3 (LATP) powder is prepared by hydrothermal methods followed by calcination, cold pressing and post-sintering processes. The white, solid product is characterized thoroughly using powder X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDS). The conductivity of the material is measured by a impedance spectroscopy as a function of temperature. Initially, hydrothermal synthesis yields a material isostructural with the orthorhombic oxyphosphate, LiTiOPO4. EDS analysis shows that the distribution of aluminum throughout this material is uniform. A systematic study is then performed to investigate how altering the sintering parameters (such as powder pre-sintering temperature and pellet sintering temperature) affect the formation of LATP. The structure is determined by Rietveld refinement against XRD data and the effects of sintering temperature on porosity, microstructure and electrical conductivity were resolved. The experimental results show that the optimum pre-sintering and sintering temperatures of LATP powders and pellets respectively are 900 °C and 1100 °C. These conditions produce materials with the highest density (99.07% of theoretical), superior conductivity (grain-, grain boundary- and total lithium-ion conductivities of 6.57 × 10−4, 4.59 × 10−4 and 2.70 × 10−4 S cm−1, respectively) and with an activation energy for Li motion of 0.17 eV.

Hierarchically porous alumina ceramic catalyst carrier prepared by powder bed fusion

Hierarchical porous ceramic catalyst carriers, which exhibit good catalytic performance, are widely used in the petrochemical industry. However, the fabrication of ceramic carriers with hierarchically porous structures is highly challenging for conventional preparation processes. Thus, a strategy for designing and manufacturing hierarchically porous alumina ceramic catalyst carriers using aluminium trihydrate as raw material and powder bed fusion (PBF) as the forming process is proposed herein. PBF process parameters were optimised to define the processing window for creating ceramics with complex structures. Controllable pore characteristics in nano- and microscales has been achieved by combining dehydroxylation, PBF, and post-sintering processes. The effects of raw material composition and process parameters on crush strength, porosity, and specific surface area were systematically investigated. The resulting porous ceramics exhibit a crush strength of 86.03 ± 18.10 N/cm, specific surface area of 1.958 ± 0.123 m2/g, and porosity of 64.85 ± 1.15% with a multipeak distribution at 95 ± 1.23 nm and 17.76 ± 0.14 μm. The possibility of complicated monolithic catalyst carrier structures with bionic leaf vein characters has been validated for potential industrial applications.

Biomass derived carbon aerogel as an ultrastable skeleton of form-stable phase change materials for efficient thermal energy storage

Direct conversion of biomass to carbon aerogel provides a promising approach to developing supporting material for phase change materials (PCMs). In present work, carrot and pumpkin derived carbon aerogels (CCA and PCA) were fabricated via a hydrothermal and post-sintering process. N2 adsorption-desorption isotherms were used to evaluate the specific surface area and pore distribution of the carbon aerogels. It showed that the carrot carbon aerogel sintered at 800 °C (CCA800) possessed a specific surface area of 33.80 m2·g−1, which is separately 168%, 165%, and 287% higher than that of carrot carbon aerogel sintered at 1000 °C (CCA1000, 12.59 m2·g−1), pumpkin carbon aerogel sintered at 800 °C (PCA800, 12.77 m2·g−1), and pumpkin carbon aerogel sintered at 1000 °C (PCA1000, 8.74 m2·g−1). Owing to its porosity, the carbon aerogels with a high loading content of palmitic acid (PA)/thiol-ene resin (TE) composite as a PCM without leakage. A thermal conductivity enhancement of 60.5% was achieved by 50PA/TE@PCA1000 compared with 50PA/TE, and DSC result showed its latent heat of 88.26 J/g. The excellent properties of PCMs composites lead to a promising application foreground.

Comparative clinical study of the marginal discrepancy of fixed dental prosthesis fabricated by the milling-sintering method using a presintered alloy.

PURPOSEThe present study was designed to examine the clinical fit of fixed dental prosthesis fabricated by the milling-sintering method using a presintered cobalt-chromium alloy.MATERIALS AND METHODSTwo single metal-ceramic crowns were fabricated via milling-sintering method and casting method in each of the twelve consecutive patients who required an implant-supported fixed prosthesis. In the milling-sintering method, the prosthetic coping was designed in computer software, and the design was converted to a non-precious alloy coping using milling and post-sintering process. In the casting method, the conventional manual fabrication process was applied. The absolute marginal discrepancy of the prostheses was evaluated intraorally using the triple-scan technique. Statistical analysis was conducted using Mann-Whitney U test (α=.05).RESULTSEight patients (66.7%) showed a lower marginal discrepancy of the prostheses made using the milling-sintering method than that of the prosthesis made by the casting method. Statistically, the misfit of the prosthesis fabricated using the milling-sintering method was not significantly different from that fabricated using the casting method (P=.782). There was no tendency between the amount of marginal discrepancy and the measurement point.CONCLUSIONThe overall marginal fit of prosthesis fabricated by milling-sintering using a presintered alloy was comparable to that of the prosthesis fabricated by the conventional casting method in clinical use.

Facile and Green Synthesis of Graphene-Based Conductive Adhesives via Liquid Exfoliation Process.

In this study, we report a facile and green process to synthesize high-quality and few-layer graphene (FLG) derived from graphite via a liquid exfoliation process. The corresponding characterizations of FLG, such as scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM) and Raman spectroscopy, were carried out. The results of SEM show that the lateral size of as-synthesized FLG is 1–5 μm. The results of TEM and AFM indicate more than 80% of graphene layers is <10 layers. The most surprising thing is that D/G ratio of graphite and FLG are 0.15 and 0.19, respectively. The result of the similar D/G ratio demonstrates that little structural defects were created via the liquid exfoliation process. Electronic conductivity tests and resistance of composite film, in terms of different contents of graphite/polyvinylidene difluoride (PVDF) and FLG/PVDF, were carried out. Dramatically, the FLG/PVDF composite demonstrates superior performance compared to the graphite/PVDF composite at the same ratio. In addition, the post-sintering process plays an important role in improving electronic conductivity by 85%. The composition-optimized FLG/PVDF thin film exhibits 81.9 S·cm−1. These results indicate that the developed FLG/PVDF composite adhesives could be a potential candidate for conductive adhesive applications.

LiI-Doped Sulfide Solid Electrolyte: Enabling a High-Capacity Slurry-Cast Electrode by Low-Temperature Post-Sintering for Practical All-Solid-State Lithium Batteries.

All-solid-state lithium batteries (ASSLBs) based on sulfide solid electrolytes (SEs) have received great attention because of the high ionic conductivity of the SEs, intrinsic thermal safety, and higher energy density achievable with a Li metal anode. However, studies on practical slurry-cast composite electrodes show an extremely limited battery performance than the binder-free pelletized electrodes because of the poor interfacial robustness between the active materials and SEs by the presence of a polymeric binder. Here, we employ a low-temperature post-sintering process for the slurry-cast composite electrodes in order to overcome the binder-induced detrimental effects on the electrochemical performance. The LiI-doped Li3PS4 SEs are chosen because the addition of iodine not only improves the Li-ion conductivity and Li metal compatibility but also lowers the glass-transition and crystallization temperatures. Low-temperature post-sintering of composite cathodes consisting of a LiNi0.6Co0.2Mn0.2O2-active material, LiI-doped Li3PS4 SE, polymeric binder, and conducting agent shows a significantly improved electrochemical performance as compared to a conventional slurry-cast electrode containing pre-annealed SEs. Detailed analyses by electrochemical impedance spectroscopy and galvanostatic intermittent titration technique confirm that post-sintering effectively reduces the interfacial resistance and enhances the chemomechanical robustness at solid-solid interfaces, which enables the development of practical slurry-cast ASSLBs with sulfide SEs.

Post-activation of in situ B[sbnd]F codoped g-C3N4 for enhanced photocatalytic H2 evolution

Porous graphitic carbon nitride polymer (p-CN-BF) with enhanced photoproduction of H2 from water was prepared by a two-step treatment process including in-situ Boron and fluorine codoping using [Emim]BF4 as dopants followed by post-calcination in air. Several techniques were employed to characterize the modified structure and elucidate the doping state of B and F. It was shown that in-situ doping method is necessary for efficient doping of heteroatoms into the molecular composition of CN. The difference of doping state of B and F was that B doping primary existing in the inside skeleton of CN, but F doping merely presents in the surface layer. The inside doped B made for the enhanced visible light absorption and the production of uniform porous structure during post-sintering process. By the synergistic effect of BF codoping and post-activation, p-CN-BF showed much enhanced photoelectron generation, transmission and separation, therefore, it performs high photocatalytic activity for H2 evolution (351 μmol h−1), which was 13 and 5 times higher than samples only modified by BF codoping (CN-BF) or post-annealing (P-CN).

One-Step Sub-micrometer-Scale Electrohydrodynamic Inkjet Three-Dimensional Printing Technique with Spontaneous Nanoscale Joule Heating.

A one-step sub-micrometer-scale electrohydrodynamic (EHD) inkjet three-dimensional (3D)-printing technique that is based on the drop-on-demand (DOD) operation for which an additional postsintering process is not required is proposed. Both the numerical simulation and the experimental observations proved that nanoscale Joule heating occurs at the interface between the charged silver nanoparticles (Ag-NPs) because of the high electrical contact resistance during the printing process; this is the reason why an additional postsintering process is not required. Sub-micrometer-scale 3D structures were printed with an above-35 aspect ratio via the use of the proposed printing technique; furthermore, it is evident that the designed 3D structures such as a bridge-like shape can be printed with the use of the proposed printing technique, allowing for the cost-effective fabrication of a 3D touch sensor and an ultrasensitive air flow-rate sensor. It is believed that the proposed one-step printing technique may replace the conventional 3D conductive-structure printing techniques for which a postsintering process is used because of its economic efficiency.

Assessment of particulate emissions from a sinter plant in steelmaking works in China.

In this paper, five particulate emission points from a sinter plant in China, including anthracite crusher, raw material blender, sinter strand, screener, and circular cooler, were selected for particle sampling. The particle size distribution, the toxic element content (As, Cd, Co, Cr, Cu, Ni, Pb, Ti, and Zn), and the morphology of the samples were determined by the gravimetric method, the ICP-OES, and the SEM-EDS, respectively. In addition, the gray relational analysis method was used to evaluate the rank of the particulate emission points in the sinter plant. The results show that the emission factor of PMTSP, PM10, and PM2.5 of the whole sintering process is 0.121, 0.075, and 0.039kg/t-sinter, respectively. Furthermore, the total toxic element emission factor is 5282.49mg/t-sinter. The sinter strand is the most important emitter and contributes 43.8% of PMTSP, 53.3% of PM10, 56.4% of PM2.5, and 81.1% of total toxic element in the sinter plant. Nevertheless, particles emitted from the post-sintering process are non-negligible and contribute 48.8% of PMTSP, 41.3% of PM10, 38.5% of PM2.5, and 15.5% of total toxic element in the sinter plant.