Sintering Process Research Articles

Thermoelectric properties of marcasite-type compounds MSb2(M = Ta, Nb): A combined experimental and computational study.

Here, we investigate the thermoelectric properties of the marcasite-type compounds MSb2(M = Ta, Nb) in the temperature range of 310-730 K. These compounds were synthesized by a solid-state reaction followed by the spark plasma sintering process. The Rietveld refinement method confirms the monoclinic phase with space groupC2/mfor both compounds. The observed values of Seebeck coefficients exhibit non-monotonic behaviour inthe studied temperature range, with the maximum magnitude of -14.4 and -22.7 µV K-1for TaSb2and NbSb2, respectively at ∼444 K. The negative sign ofSin the full temperature window signifies the n-type behaviour of these compounds. Both electrical and thermal conductivities show decreasing trends with increasing temperature. The experimentally observed thermoelectric properties are understood through the first-principles DFT and Boltzmann transport equation. A pseudogap in the density of states around the Fermi level characterizes the semimetallic behaviour of these compounds. The multi-band electron and hole pockets were found to be mainly responsible for the temperature dependence of transport properties. The experimental power factors are found to be ∼0.09 and∼ 0.42 mW m-1K-2at 300 K for TaSb2and NbSb2, respectively. We found that there is much room for improvement of power factor by tuning carrier concentration. The DFT-based calculations predict the maximum possible power factors at fairly high doping concentrations. The present study suggests that the combined DFT and Boltzmann transport theory are found to be reasonably good at explaining the experimental transport properties, and moderate power factors are predicted.&#xD.

Preparation of copper/binder composites and fused filament fabrication process

Purpose The purpose of this study is to assess the effects of fused filament fabrication (FFF) printing parameters on the surface quality and dimensional accuracy of FFF-fabricated copper green parts using the appropriate filaments. The orthogonal experiments were implemented and the errors in length, width and height were measured and analyzed. The results of range analysis and variance analysis indicated the orders of effect factors. Dissolvent debinding combined with thermal debinding was adopted to remove the binders inside the green part by calculating debinding rate. The influence mechanism of sintering temperatures on the microstructure and shrinkage was elaborated. Design/methodology/approach The extrusion-based FFF in manufacturing copper parts can overcome shortcomings for high reflectivity and heat dissipation in laser powder bed fusion process at cost-saving and materials saving. This study makes an attempt to prepare copper/binder composite filaments through mixing, extrusion and flowability evaluation. Findings The results showed that the suitable composite filaments applied for FFF should balance rigidity and plasticity. The combination of printing speed and heating temperature impacts on the surface quality significantly, and the major factor in determining the dimensional accuracy is layer thickness. Two-stage debinding procedure was beneficial for binder removal and sintering process. The higher sintering temperature results in less voids, sizes shrinkage and densified microstructure, which is attributed to the occurrence of sintering neck among the fused copper powders. Originality/value The self-prepared copper/binder composite filaments were successfully manufactured using the FFF process. This study provides unique approach and print guidance for fabricating complex structures of pure copper components.

Sintering Behaviour, Physical Properties and Environmental Assessment of Glass Foam from Waste Glass

Abstract Glass foam, a porous material, is developed by sintering waste glass with foaming agents at high temperature, yielding chemically robust structures. However, the decomposition of foaming agents and chemical changes during sintering raises concerns about emissions during sintering and leaching from the final product. Despite various sintering methods and materials studied, their environmental impacts are not well explored. A recently introduced modified curing-sintering method was developed without the use of stabilizing chemicals, which could potentially reduce emissions and environmental impacts. However, the extent of its impact is unknown. This research studies potential emissions from materials during sintering and the heavy metal leaching from glass foams made by the newly modified sintering technique. Waste glass obtained from vehicle windshields is used as the primary raw material for glass foam preparation, supplemented by commercial fly ashes and slag as additives. Emissions from raw materials during the sintering process and the changes in chemical composition after sintering have been studied. Lastly, the heavy metals leaching possibilities from the final glass foam products have been assessed. Results reveal that the decomposition of foaming agents and organic content in raw materials leads to CO2 emission during the sintering. Due to low-temperature sintering (800℃) and no reduction agents, alkali and metallic oxide levels remain constant post-sintering. Heavy metal concentrations are extremely low, and their immobilization during the curing-sintering process ensures that leaching stays below safe limits. Therefore, this research provides insight into the potential environmental impacts of glass foam made of waste glass. Graphical Abstract

Preparation and microwave dielectric properties of temperature-stable low-dielectric (1−x)Li2MoO4−xBi0.4Ce0.6VO4 ceramics for satellite communication applications

In this study, a series of ([Formula: see text]x)Li2MoO4[Formula: see text]xBi0.4Ce0.6VO4 [x = 0.25, 0.35, 0.45, 0.55, ([Formula: see text]x)LM–xBCV] microwave dielectric ceramics, capable of being sintered at low temperatures, were synthesized using the solid-phase method. The temperature coefficient of resonance frequency in LM microwave dielectric ceramics was effectively modulated through the incorporation of BCV with tetragonal zirconia phases, resulting in the formation of composite ceramics. This approach led to the development of a low-permittivity ([Formula: see text]r ∼ 12.6) microwave dielectric ceramic material exhibiting a near-zero temperature coefficient (TCF ∼ +0.5 ppm/∘C). The composite, specifically 0.55LM–0.45BCV, achieved ultra-low temperature sintering below [Formula: see text]C and demonstrated excellent performance as low-temperature co-fired ceramic materials, with good co-firing compatibility with metallic silver. Furthermore, the volatilization of lithium and bismuth elements was effectively mitigated through the burying sintering process. Which resulted in a substantial enhancement of the [Formula: see text] (Q and f denote the quality factor and the resonant frequency, respectively) value for the 0.55LM–0.45BCV ceramics, achieving an increase of nearly threefold (Q × f [Formula: see text] [Formula: see text]GHz). To investigate the application potential of 0.55LM–0.45BCV ceramic, particularly in the context of low-orbit communication satellites, a circularly polarized patch antenna was designed utilizing 0.55LM–0.45BCV ceramic as the dielectric substrate material. The antenna demonstrated a high simulated radiation efficiency of 93.8% and a gain of 4.0[Formula: see text]dBi at a center frequency of 1.559[Formula: see text]GHz, indicating its promising applicability in the domain of orbital satellite communication.

Cost–effective additive manufacturing of metal parts using pneumatic extrusion: investigation of the sintering process

Purpose The purpose of this study is to develop a low-cost and efficient method for 3D printing CuSn15 bronze alloy parts using a pneumatic extrusion system. By avoiding complex processes such as filament preparation and solvent/catalytic debinding, the study aims to streamline the low-cost production process of metallic components while maintaining high mechanical performance. The research also seeks to evaluate the effects of different sintering temperatures and times on the mechanical properties of the printed parts. Design/methodology/approach A simple and cost-effective pneumatic extrusion system was designed to 3D print a metal paste containing CuSn15 alloy powders. The metal paste was prepared by manually mixing of CuSn15 powders, carboxymethyl cellulose and distilled water. The printed parts were subsequently dried and sintered at various temperatures and times to study the effects of these parameters on the material properties. Tensile test and scanning electron microscope analysis were conducted to assess the structural integrity and mechanical performance of the samples. Findings The study found that the pneumatic extrusion system enabled the successful 3D printing of CuSn15 bronze alloy parts without the need for complex processes. Increasing sintering temperature led to improved mechanical properties and decreased porosity. Increasing the sintering time at 820 °C led to a reduction in mechanical performance. The study demonstrated that the sintering parameters significantly influence the porosity and mechanical properties of the printed parts. Originality/value This study introduces a novel approach to 3D printing CuSn15 bronze alloy using a pneumatic extrusion system, eliminating the need for traditional filament preparation and solvent/catalytic debinding processes. The research provides new insights into the effect of sintering parameters on the mechanical properties of additively manufactured metal parts. By simplifying the production process, this study offers a low-cost, efficient method for producing complex-shaped metallic components, potentially expanding the applicability of 3D printing in industries such as electronics, marine and mechanical engineering.

316L stainless milling behaving mechanism in enamel coatings: A strategy for mechanical and corrosion improvement

AbstractTo achieve corrosion resistance and mechanical robustness properties simultaneously, 316L stainless steel powder was employed as mill additives in SiO2–B2O3–Na2O–SrO slurry system enamel coating. The sintering process, gases consuming, microstructure, interface adhesion, and corrosion mechanism of the prepared enamel coatings were investigated. The results indicated that during sintering, 316L powder reduced coatings porosity by forming internal carbides through the Cr‐poor reaction of carbon‐containing gases adsorption in the pores due to its low‐carbon activity. Additionally, the powder partially dissolved into the enamel coating matrix, contributing to a significant enhancement in the coating's mechanical properties through its own ductility and toughness. Moreover, the peeling of the gel layer from the enamel coating surface was slowed in acidic environments, thereby enhancing the enamel coatings' long‐term resistance to acid corrosion.

Enhanced properties of fine‐grain titanium diboride with high dislocation density fabricated by high‐pressure sintering

AbstractFor the purpose of the densification of ceramics with high melting points, the traditional preparation method requires long‐term heating above 2000°C, which inevitably leads to severe grain growth and high energy consumption. In this study, TiB2 ceramics with a high density (98.9%) and a fine grain size (2.15 µm) were prepared under the pressure of 200 MPa at the low temperature of 1650°C in a carbon fiber reinforced sintering mold with reliable strength. The high‐pressure sintered sample possessed a high hardness of 30.1 GPa and a high dislocation density of 3.64 × 1014 m−2. The mechanical properties of TiB2 ceramics could be significantly improved by high‐pressure induced unique microstructures. This sintering process provides insights into subsequent sintering of other ceramics with high melting points.

Optimizing the mechanical performance of nacre‐like hydroxyapatite/polymethylmethacrylate–polyacrylic acid composites with apatite‐wollastonite

AbstractBiomimetic materials inspired by the hierarchical structure of nacre offer promising opportunities to enhance the mechanical strength and toughness of load‐bearing bone implants. This study investigates the incorporation of apatite‐wollastonite (AW) into nacre‐like hydroxyapatite (HA)/polymethylmethacrylate–polyacrylic acid (PMMA–PAA) composites to improve their mechanical properties. The composite mimics the natural nacre structure, featuring a brick‐and‐mortar architecture where ceramic components form the “bricks,” and the polymer phase acts as the “mortar.” The results showed that adding AW significantly increased the density of the ceramic scaffolds and improved the sinterability of HA. However, at higher AW concentrations (e.g., 20 wt%), excessive grain growth was observed, which could negatively affect the composite's mechanical properties. The best mechanical performance was achieved at 15 wt% AW, which enhanced the sintering process and reinforced the HA through the formation of a stronger wollastonite phase, as revealed by x‐ray diffraction analysis. Mechanical testing showed that the composite with 15 wt% AW exhibited superior properties, with flexural strength increasing from 158.2 ± 7.1 MPa (for HA/PMMA–PAA) to 188.7 ± 6.2 MPa (for AW–HA/PMMA–PAA). Fracture toughness also improved significantly, from 5.2 to 10.2 MPa m1/2. In addition to improved flexural strength and fracture toughness, the composite's Young's modulus of 28.5 ± 1.6 GPa closely matched that of cortical bone, reducing the risk of stress shielding, a common issue with commercial implants. Acellular bioactivity tests demonstrated the formation of a biologically relevant apatite layer on the composite surface, indicating its potential to promote osseointegration. Cytocompatibility assays confirmed favorable cell proliferation and viability, supporting its suitability for clinical applications. In summary, the addition of AW enhanced sinterability and introduced a stronger wollastonite phase within the HA ceramic layer, leading to improved strength and toughness of the nacre‐like HA/PMMA–PAA composites. However, there was an optimal AW concentration that balanced superior mechanical properties with controlled grain growth. The bioactive and cytocompatible composites showed great promise as candidates for next‐generation load‐bearing bone implants.

Biomass-Derived Hard Carbon Materials for High-Performance Sodium-Ion Battery

Using biomass-derived hard carbon materials as anode materials for sodium-ion batteries has facilitated resource recycling and brought significant economic benefits. However, the main obstacles to the large-scale application of these materials are the low Coulombic efficiency and high irreversible capacity of hard carbon materials. This study used waste moso bamboo as a carbon source to prepare and pre-oxidize hard carbon through a stepped temperature sintering process. The introduction of oxygen atoms into the carbon layers has been shown to increase the spacing between the carbon layers, which facilitates the insertion of sodium-ions into them. Moreover, the presence of oxygen-containing groups increases the number of edge and vacancy defects in the carbon skeleton, thereby enhancing the actual capacity of the material. Studies have indicated that different pre-oxidation times have varying impacts on the electrochemical properties of hard carbon materials. This study used discarded moso bamboo as the raw material, and the optimal pre-oxidation duration of bamboo-based hard carbon was determined to be 4.5 h through a series of comparative experiments. A high-performance biomass-derived hard carbon material was prepared via a stepwise sintering process. It exhibited a specific capacity of 301.4 mAh·g−1 at 0.1 C and a first-cycle Coulombic efficiency of 87%.

Microwave Synthesis of Luminescent Recycled Glass Containing Dy2O3 and Sm2O3

This research studied the recycling of borosilicate glass wastes from damaged laboratory glassware. The luminescent glasses were prepared by doping glass waste powder with rare earth ions, namely, dysprosium ions (Dy3+) and samarium ions (Sm3+), as well as co-doping with Dy3+ and Sm3+ at a concentration of 2% by weight. The sintering process was conducted in a microwave oven for a duration of 15 min. The photoluminescence spectra of the doped glasses were obtained under excitation at 401 nm and 388 nm. The results showed that the emission characteristics depended on the doping concentrations of Dy3+ and Sm3+ and the excitation wavelengths. Upon excitation at 401 nm, the co-doped glasses exhibited the maximum emission peak of Sm3+ at 601 nm (yellowish and orange region in the CIE chromaticity diagram) due to the energy transition from 4G5/2 to 6H7/2. When excited at 388 nm, however, the emission spectra of the co-doped glasses were similar to the characteristic emission peaks of Dy3+ (white region in the CIE chromaticity diagram), but the peak position exhibits a red shift. This could be attributed to an increase in the amount of non-bridging oxygens (NBOs) by co-doping.

Soil remediation by co-disposal in sintered brick kilns: Migration characteristics of heavy metals in bricks and the kiln.

Rapid industrialization has led to the widespread accumulation of heavy metal-contaminated soils, posing significant environmental and health risks. Utilizing remediated soil for the production of sintered bricks offers a sustainable and effective solution. However, the migration and immobilization mechanisms of heavy metals during the sintering process, both within the tunnel kiln and the brick matrix, require detailed investigation. This study examined the distribution of heavy metals in the tunnel kiln and analyzed the differences in heavy metal content and leaching behavior between the inner and outer layers of the bricks. Bricks containing 15% remediated soil were prepared, and it was observed that the majority of heavy metals were effectively immobilized, with retention rates ranging from 90.6% to 99.9%. Selenium (Se), however, exhibited significant volatility, with a retention rate of only 64.3%. The outer layer of the brick body contained higher concentrations of As and Pb compared to the inner layer. Conversely, leaching tests showed lower leaching rates of Mn, Ni, Cu, and Zn in the inner layers, while As and Pb exhibited higher leaching rates in the inner layers. These findings underscore the varying migration and transformation behaviors of different heavy metals during sintering, both within the kiln and the brick layers. The study highlights the potential of doped sintered bricks as sustainable building materials, ensuring effective heavy metal stabilization with minimal environmental risk, and providing a promising pathway for the safe reuse of contaminated soils.

Study on electromagnetic characteristics and microwave sintering process of iron oxides

Study on electromagnetic characteristics and microwave sintering process of iron oxides

Modeling the magnetocaloric effect and critical behavior near the ferromagnetic–paramagnetic transition temperature in Zn0.5-xNixMg0.5Fe2O4 (x = 0, 0.125 and 0.250) spinel ferrites

ABSTRACT The Landau model allows to estimate the Landau coefficients A(T), B(T) and C(T), which can be determined by fitting the Arrott plots in Zn0.5-xNixMg0.5Fe2O4 (x = 0, 0.125 and 0.250) ferrites. These coefficients are derived to determine − Δ S M ( T ) curves. A good correlation between − Δ S M ( T ) curves determined using Landau theory and the experimental curves estimated using the Maxwell relation was found. Then, the second-order magnetic phase transition in Zn0.5-xNixMg0.5Fe2O4 compounds was investigated. The critical properties of ferrites prepared by the double ceramic sintering process were investigated. Critical behavior near the FM–PM phase transition was studied from the magnetic data, through various techniques such as the modified Arrott plots (MAP), the Kouvel–Fisher method (KF) and critical isotherm (CI) analysis. The determined critical parameters were found to be close to the value of the mean field theory. On the other hand, the validity of the critical parameters was confirmed by the Widom scaling relation.

On-Demand Sintering of Gold Nanoparticles via Controlled Removal of o-Nitrobenzyl Thiol Ligands Under Record-Low Power for Conductive Patterns.

Metal nanoparticles-based nanoinks have shown potential for fabricating metallic components essential to the realization of innovative 3D-printed electronic devices. However, fabricating metallic patterns on flexible, heat-sensitive substrates remains challenging due to high temperature and high energy sources, such as intense pulsed light (IPL), involved in the sintering process. Here an efficient sintering method is presented using ultralow power UV by leveraging the photocleavable ligand, o-nitrobenzyl thiol (NT), - functionalized gold nanoparticles (AuNPs). The controlled removal of NT ligands upon UV irradiation enhances light absorption by reducing the filling factor of voids in the printed layer, increasing the layer temperature, and facilitating further ligand desorption. This positive feedback mechanism accelerates nanoparticle sintering at several orders of magnitude lower energy than IPL, achieving an electrical conductivity of 7.0×106Sm-1. This nanoink promises the parallel printing of multimaterial components through ultralow power photonic sintering for fabricating multifunctional 3D-printed electronic devices.

Tensile loading response of strut-based mechanical metamaterials fabricated using selective laser sintering process

Tensile loading response of strut-based mechanical metamaterials fabricated using selective laser sintering process

Suppressing Cation Interdiffusion at CeO2/ZrO2 Heterointerfaces via Dopant Segregation.

Cation interdiffusion as a result of a chemical-potential gradient occurring at heterointerfaces is often regarded as an unfavorable side reaction and is typically suppressed through the use of a diffusion barrier layer. In this study, we propose a straightforward method for suppressing interdiffusion that involves the creation of nanometer-thick diffusion barrier layers by means of dopant segregation. Using the CeO2/ZrO2 heterointerface in this study, we demonstrate that a Sc acceptor dopant tends to accumulate at the heterointerface during the sintering process, especially at the edge of the CeO2 grain boundary, thereby effectively suppressing Ce-Zr interdiffusion. Defect formation energy calculations through density functional theory indicate that the presence of the Sc layer acts to impede the formation of vacancies in the neighboring Ce layer, thereby reducing the VCe⁗ concentration, which is the source of interdiffusion. Furthermore, the implementation of the Sc segregation layer confers advantageous outcomes with respect to the full-cell operation, including lower levels of ohmic and polarization resistance, as well as enhanced long-term durability. The present study highlights the crucial role of selecting the proper dopant so as to impede interdiffusion and thereby achieve superior fuel cell performance in composite oxides.

Study of sintering process of SP40KhSMF powder steel containing iron stearate lubricantplasticizer in the initial batch

Study of sintering process of SP40KhSMF powder steel containing iron stearate lubricantplasticizer in the initial batch

Multilayer Composite Electrodes for Simultaneously Improved Mechanical and Electrochemical Performance.

Structural batteries offer a transformative approach to integrate energy storage directly into the frameworks of electric vehicles and aircrafts, enabling multifunctional construction. This study presents a nacre-inspired multilayer composite electrode fabricated via the cold sintering process (CSP), achieving a balance of enhanced electrochemical performance and mechanical robustness. The composite electrode combines active electrode materials with a ductile conducting polymer-carbon-mixture phase in a layered architecture. The resulting electrodes exhibit a material toughness of 0.635 MJ m-3, approximately 9 times greater than conventional single-layer electrodes, alongside maintained ultimate strength. Full-field strain mapping using digital image correlation (DIC) reveals the underlying strengthening mechanisms. The influence of soft-layer thickness variations on both mechanical and electrochemical properties was also systematically analyzed to achieve optimal performance. Notably, the multilayer composite electrode delivered a reversible specific capacity of 177 mAh g-1 and an areal capacity of 22 mAh cm-2 at a high mass loading of 136 mg cm-2, significantly outperforming commercial cathodes (e.g., 3 to 4.5 mAh/cm2).

The Influence of the Binder Phase on the Properties of High-Pressure Sintered Diamond Polycrystals or Composites for Cutting Tool Applications

A review of binder phases used for sintering diamond powders under high pressure and high temperature conditions along with an outline of the properties of polycrystalline diamonds or composite materials intended for cutting tools, wire drawing dies, and drilling rocks are presented. The interaction of diamond with metals from group VIII of the periodic table, carbon-forming metals, carbides, MAX phases and with silicides, borides, and alkali carbonates is presented. The interaction of the bonding phases with diamond was determined. The influences of sintering process parameters, amounts, and methods of introducing of these phases on the basic mechanical properties and thermal resistance of diamond materials are analyzed. The investigated material properties are compared with the properties of commercial PCD with a cobalt and the SiC binder phase.

In Situ Synthesis of MoSi2-SiC Composites by Two-Step Spark Plasma Sintering

The effect of different SiC doping content on the properties of MoSi2-based composites was analyzed in this study. The MoSi2-SiC composites were fabricated in situ by the SPS technique, utilizing self-synthesized carbon-containing Mo powder and Si powder as raw materials. A two-step sintering process was employed to ensure the formation of a uniform and dense composite structure. The microstructures and mechanical properties of these composites with various compositions were characterized. The results show that the composites were primarily composed of MoSi2, SiC, and a minor proportion of MoSiC phase. The introduction of SiC as a second phase was found to considerably enhance the mechanical properties of the MoSi2 matrix material. In particular, the MoSi2-26mol.%SiC sample exhibited Vickers hardness, fracture toughness, and flexural strength values of 16.1 GPa, 6.7 MPa·m1/2, and 496 MPa, respectively, corresponding to increases of 33%, 24%, and 28% compared to the pure MoSi2 material.